Mass coral mortality under local amplification of 2 °C ocean warming

NASA Astrophysics Data System (ADS)

Decarlo, Thomas M.; Cohen, Anne L.; Wong, George T. F.; Davis, Kristen A.; Lohmann, Pat; Soong, Keryea

2017-03-01

A 2 °C increase in global temperature above pre-industrial levels is considered a reasonable target for avoiding the most devastating impacts of anthropogenic climate change. In June 2015, sea surface temperature (SST) of the South China Sea (SCS) increased by 2 °C in response to the developing Pacific El Niño. On its own, this moderate, short-lived warming was unlikely to cause widespread damage to coral reefs in the region, and the coral reef “Bleaching Alert” alarm was not raised. However, on Dongsha Atoll, in the northern SCS, unusually weak winds created low-flow conditions that amplified the 2 °C basin-scale anomaly. Water temperatures on the reef flat, normally indistinguishable from open-ocean SST, exceeded 6 °C above normal summertime levels. Mass coral bleaching quickly ensued, killing 40% of the resident coral community in an event unprecedented in at least the past 40 years. Our findings highlight the risks of 2 °C ocean warming to coral reef ecosystems when global and local processes align to drive intense heating, with devastating consequences.

Regional cooling caused recent New Zealand glacier advances in a period of global warming

NASA Astrophysics Data System (ADS)

Mackintosh, Andrew N.; Anderson, Brian M.; Lorrey, Andrew M.; Renwick, James A.; Frei, Prisco; Dean, Sam M.

2017-02-01

Glaciers experienced worldwide retreat during the twentieth and early twenty first centuries, and the negative trend in global glacier mass balance since the early 1990s is predominantly a response to anthropogenic climate warming. The exceptional terminus advance of some glaciers during recent global warming is thought to relate to locally specific climate conditions, such as increased precipitation. In New Zealand, at least 58 glaciers advanced between 1983 and 2008, and Franz Josef and Fox glaciers advanced nearly continuously during this time. Here we show that the glacier advance phase resulted predominantly from discrete periods of reduced air temperature, rather than increased precipitation. The lower temperatures were associated with anomalous southerly winds and low sea surface temperature in the Tasman Sea region. These conditions result from variability in the structure of the extratropical atmospheric circulation over the South Pacific. While this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans.

Regional cooling caused recent New Zealand glacier advances in a period of global warming

PubMed Central

Mackintosh, Andrew N.; Anderson, Brian M.; Lorrey, Andrew M.; Renwick, James A.; Frei, Prisco; Dean, Sam M.

2017-01-01

Glaciers experienced worldwide retreat during the twentieth and early twenty first centuries, and the negative trend in global glacier mass balance since the early 1990s is predominantly a response to anthropogenic climate warming. The exceptional terminus advance of some glaciers during recent global warming is thought to relate to locally specific climate conditions, such as increased precipitation. In New Zealand, at least 58 glaciers advanced between 1983 and 2008, and Franz Josef and Fox glaciers advanced nearly continuously during this time. Here we show that the glacier advance phase resulted predominantly from discrete periods of reduced air temperature, rather than increased precipitation. The lower temperatures were associated with anomalous southerly winds and low sea surface temperature in the Tasman Sea region. These conditions result from variability in the structure of the extratropical atmospheric circulation over the South Pacific. While this sequence of climate variability and its effect on New Zealand glaciers is unusual on a global scale, it remains consistent with a climate system that is being modified by humans. PMID:28195582

Warm tropical ocean surface and global anoxia during the mid-Cretaceous period.

PubMed

Wilson, P A; Norris, R D

2001-07-26

The middle of the Cretaceous period (about 120 to 80 Myr ago) was a time of unusually warm polar temperatures, repeated reef-drowning in the tropics and a series of oceanic anoxic events (OAEs) that promoted both the widespread deposition of organic-carbon-rich marine sediments and high biological turnover. The cause of the warm temperatures is unproven but widely attributed to high levels of atmospheric greenhouse gases such as carbon dioxide. In contrast, there is no consensus on the climatic causes and effects of the OAEs, with both high biological productivity and ocean 'stagnation' being invoked as the cause of ocean anoxia. Here we show, using stable isotope records from multiple species of well-preserved foraminifera, that the thermal structure of surface waters in the western tropical Atlantic Ocean underwent pronounced variability about 100 Myr ago, with maximum sea surface temperatures 3-5 degrees C warmer than today. This variability culminated in a collapse of upper-ocean stratification during OAE-1d (the 'Breistroffer' event), a globally significant period of organic-carbon burial that we show to have fundamental, stratigraphically valuable, geochemical similarities to the main OAEs of the Mesozoic era. Our records are consistent with greenhouse forcing being responsible for the warm temperatures, but are inconsistent both with explanations for OAEs based on ocean stagnation, and with the traditional view (reviewed in ref. 12) that past warm periods were more stable than today's climate.

Terra Data Confirm Warm, Dry U.S. Winter

NASA Technical Reports Server (NTRS)

2002-01-01

New maps of land surface temperature and snow cover produced by NASA's Terra satellite show this year's winter was warmer than last year's, and the snow line stayed farther north than normal. The observations confirm earlier National Oceanic and Atmospheric Administration reports that the United States was unusually warm and dry this past winter. (Click to read the NASA press release and to access higher-resolution images.) For the last two years, a new sensor aboard Terra has been collecting the most detailed global measurements ever made of our world's land surface temperatures and snow cover. The Moderate-resolution Imaging Spectroradiometer (MODIS) is already giving scientists new insights into our changing planet. Average temperatures during December 2001 through February 2002 for the contiguous United States appear to have been unseasonably warm from the Rockies eastward. In the top image the coldest temperatures appear black, while dark green, blue, red, yellow, and white indicate progressively warmer temperatures. MODIS observes both land surface temperature and emissivity, which indicates how efficiently a surface absorbs and emits thermal radiation. Compared to the winter of 2000-01, temperatures throughout much of the U.S. were warmer in 2001-02. The bottom image depicts the differences on a scale from dark blue (colder this year than last) to red (warmer this year than last). A large region of warm temperatures dominated the northern Great Plains, while the area around the Great Salt Lake was a cold spot. Images courtesy Robert Simmon, NASA GSFC, based upon data courtesy Zhengming Wan, MODIS Land Science Team member at the University of California, Santa Barbara's Institute for Computational Earth System Science

Frost injury to bitterbrush in eastern California

Treesearch

R. S. Smith; R. F. Scharpf; E. R. Schneegas

1965-01-01

Widespread dieback of Purshia tridentata, on the Inyo National Forest in eastern California in the spring of 1964, was caused by a severe 3-day frost with daily minimums down to 13°F. An unusually warm 9-day period-with temperatures up to 70°F., which preceded the frost by a week, had induced the bitterbrush to break dormancy and start shoot elongation when the frost...

Unusually Low Snow Cover in the U.S.

NASA Technical Reports Server (NTRS)

2002-01-01

New maps of snow cover produced by NASA's Terra satellite show that this year's snow line stayed farther north than normal. When combined with land surface temperature measurements, the observations confirm earlier National Oceanic and Atmospheric Administration reports that the United States was unusually warm and dry this past winter. The above map shows snow cover over the continental United States from February 2002 and is based on data acquired by the Moderate-Resolution Imaging Spectroradiometer (MODIS). The amount of land covered by snow during this period was much lower than usual. With the exception of the western mountain ranges and the Great Lakes region, the country was mostly snow free. The solid red line marks the average location of the monthly snow extent; white areas are snow-covered ground. Snow was mapped at approximately 5 kilometer pixel resolution on a daily basis and then combined, or composited, every eight days. If a pixel was at least 50 percent snow covered during all of the eight-day periods that month, it was mapped as snow covered for the whole month. For more information, images, and animations, read: Terra Satellite Data Confirm Unusually Warm, Dry U.S. Winter Image by Robert Simmon, based on data from the MODIS Snow/Ice Global Mapping Project

On the Influence of North Pacific Sea Surface Temperature on the Arctic Winter Climate

NASA Technical Reports Server (NTRS)

Hurwitz, Margaret M.; Newman, P. A.; Garfinkel, C. I.

2012-01-01

Differences between two ensembles of Goddard Earth Observing System Chemistry-Climate Model simulations isolate the impact of North Pacific sea surface temperatures (SSTs) on the Arctic winter climate. One ensemble of extended winter season forecasts is forced by unusually high SSTs in the North Pacific, while in the second ensemble SSTs in the North Pacific are unusually low. High Low differences are consistent with a weakened Western Pacific atmospheric teleconnection pattern, and in particular, a weakening of the Aleutian low. This relative change in tropospheric circulation inhibits planetary wave propagation into the stratosphere, in turn reducing polar stratospheric temperature in mid- and late winter. The number of winters with sudden stratospheric warmings is approximately tripled in the Low ensemble as compared with the High ensemble. Enhanced North Pacific SSTs, and thus a more stable and persistent Arctic vortex, lead to a relative decrease in lower stratospheric ozone in late winter, affecting the April clear-sky UV index at Northern Hemisphere mid-latitudes.

The Effects of Volcano-Induced Ozone Depletion on Short-lived Climate Forcing in the Arctic

NASA Astrophysics Data System (ADS)

Ward, P. L.

2012-12-01

Photodissociation of oxygen maintains the stratopause ~50°C warmer than the tropopause. Photodissociation of ozone warms the lower stratosphere, preventing most of this high-energy DNA-damaging solar radiation from reaching the troposphere. Ozone depletion allows more UV energy to reach the lower troposphere causing photodissociation of anthropogenic ozone and nitrogen dioxide. UV energy also penetrates the ocean >10 m where it is absorbed more efficiently than infrared radiation that barely penetrates the surface. Manmade chlorofluorocarbons caused ozone depletion from 1965 to 1994 with slow recovery predicted over the next 50+ years. But the lowest levels of ozone followed the eruptions of Pinatubo (1991 VEI=6), Eyjafjallajökull (2010 VEI=4), and Grímsvötn (2011 VEI=4). Each of the relatively small, basaltic eruptions in Iceland caused more ozone depletion than the long-term effects of chlorofluorocarbons, although total ozone appears to return to pre-eruption levels within a decade. Ozone depletion by 20% increases energy flux thru the lowermost troposphere by 0.7 W m-2 for overhead sun causing temperatures in the lower stratosphere to drop >2°C since 1958 in steps after the 3 largest volcanic eruptions: Agung 1963, El Chichón 1982, and Pinatubo. Temperatures at the surface increased primarily in the regions and at the times of the greatest observed ozone depletion. The greatest warming observed was along the Western Antarctic Peninsula (65.4°S) where minimum temperatures rose 6.7°C from 1951 to 2003 while maximum temperatures remained relatively constant. Minimum total column ozone in September-October was 40-56% lower than in 1972 almost every year since 1987, strongly anti-correlated with observed minimum temperatures. Sea ice decreased 10%, 7 ice shelves separated, 87% of the glaciers retreated and the Antarctic Circumpolar Current warmed. Elsewhere under the ozone hole, warming of continental Antarctica was limited by the high albedo (0.86) of Antarctic snow and decreasing solar zenith angles at higher latitudes. The second largest ozone depletion was in the Arctic at the times and places of greatest winter warming. Average ozone at four stations in Canada (43-59°N) compared to the 1961-1970 mean were 6% lower in December 2010 after the eruption of Eyjafjallajökull and 11% lower in December 2011 after the eruption of Grímsvötn. In 2012, ozone levels were still 10% lower in March and 7% lower in July. The regions and timing of this depletion are the regions and times of unusually warm temperatures and drought in North America during 2011-2012. The Dust Bowl droughts in 1934 and 1936 show a similar temporal relationship to a highly unusual sequence of five VEI=4-5 eruptions around the Pacific in 1931-1933. Major increases in global pollution were from 1950-1970 while ozone-destroying tropospheric chlorine rose from 1970 to 1994, along with ocean heat content and mean temperature. Pollution does not seem to cause an increase in warming until ozone depletion allows more UV into the lower troposphere. Pollutants decrease surface solar radiation but also reduce Arctic-snow albedo. Widespread observations imply that ozone depletion and associated photodissociation cause substantial warming. Several issues regarding the microphysics of absorption and radiation by greenhouse gases must be resolved before we can quantify their relative importance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacoby, G.C.; D`Arrigo, R.D.; Davaajamts, T.

A 450-year tree-ring width chronology of Siberian pine (Pinus sibirica Du Tour) growing at timberline (2450 meters) in the Tarvagatay Mountains in west central Mongolia shows wide annual growth rings for the recent century. Ecological site observations and comparisons with instrumental temperature records indicate that the ring widths of these trees are sensitive to annual temperature variations. Low-frequency variations in the Tarvagatay tree-ring record are similar to those in a reconstruction of Arctic annual temperatures, which is based on 20 tree-ring width series from northern North America, Scandinavia, and western Russia. The results indicate that recent warming is unusual relativemore » to temperatures of the past 450 years. 29 refs., 2 figs.« less

Europa Plumes Located near Warm Spot on Europa

NASA Image and Video Library

2017-04-13

These images of the surface of the Jovian moon Europa, taken by NASA's Galileo spacecraft, focus on a "region of interest" on the icy moon. The image at left traces the location of the erupting plumes of material, observed by NASA's Hubble Space Telescope in 2014 and again in 2016. The plumes are located inside the area surrounded by the green oval. The green oval also corresponds to a warm region on Europa's surface, as identified by the temperature map at right. The map is based on observations by the Galileo spacecraft. The warmest area is colored bright red. Researchers speculate these data offer circumstantial evidence for unusual activity that may be related to a subsurface ocean on Europa. The dark circle just below center in both images is a crater and is not thought to be related to the warm spot or the plume activity. https://photojournal.jpl.nasa.gov/catalog/PIA21444

Harmful Algal Bloom Hotspots Really Are Hot: A Case Study from Monterey Bay, California

NASA Astrophysics Data System (ADS)

Kudela, R. M.; Anderson, C.; Birch, J. M.; Bowers, H.; Caron, D. A.; Chao, Y.; Doucette, G.; Farrara, J. D.; Gellene, A. G.; Negrey, K.; Howard, M. D.; Ryan, J. P.; Scholin, C. A.; Smith, J.; Sukhatme, G.

2015-12-01

Monterey Bay, California is one of several recognized hotspots for harmful algal blooms along the US west coast, particularly for the toxigenic diatom Pseudo-nitzschia, which produces domoic acid and is responsible for Amnesic Shellfish Poisoning. Historical observations have linked bloom activity to anomalously warm conditions with weak and sporadic upwelling. In particular, blooms appear to be associated with El Niño conditions. Monterey, as with much of the US west coast, experienced unusual warm conditions in spring and summer 2014, leading to multiple ecosystem effects including massive algal blooms, concentration of apex predators nearshore, and unusually high levels of domoic acid. As the warm anomalies continued and strengthened into 2015, Monterey (and much of the west coast) has been experiencing the largest and most toxic algal bloom recorded in the last 15 years, as well as unprecedented coccolithophore blooms associated with warm, nutrient-depleted waters. With the strengthening El Niño conditions developing in summer 2015, it is possible that 2016 will result in a third consecutive year of unusually toxic algal blooms. Using a combination of historical observations, intensive field studies, and predictive models we explore the hypothesis that these warm anomalies lead to shifts in the typical upwelling-dominated food web leading to a collapse of the ecosystem towards the coast, unusual algal blooms, and enhanced trophic transfer of toxins, resulting in magnified negative impacts to wildlife and, potentially, humans.

Fall season atypically warm weather event leads to substantial CH4 loss in Arctic ecosystems?

NASA Astrophysics Data System (ADS)

Zona, Donatella; Moreaux, Virginie; Liljedahl, Anna; Losacco, Salvatore; Murphy, Patrick; Oechel, Walter

2014-05-01

In the last century (during 1875-2008) high-latitudes are warming at a rate of 1.360C century-1, almost 2 times faster than the Northern Hemisphere trend (Bekryaev et al., 2010). This warming has been more intense outside of the summer season, with anomalies of 1.09, 1.59, 1.730C in the fall, winter, and spring season respectively (Bekryaev et al., 2010). This substantial temperature anomalies have the potential to increase the emission of greenhouse gas (CO2 and CH4) fluxes from arctic tundra ecosystems. In particular, CH4 emissions, which are primarily controlled by temperature (in addition to water table), can steeply increase with warming. Despite the potential relevance of CH4 emissions, very few measurements have been performed outside of the growing season across the entire Arctic, due to logistic constrains. Importantly, no flux measurements achieved a temporal and spatial data coverage sufficient to estimate with confidence an annual CH4 emissions from tundra ecosystem in Alaska, and its sensitivity to warming. Fall 2013 was unusually warm in central and northern Alaska. Following a relatively warm summer with dramatically above-average rainfall, the October mean monthly temperatures was the 4th and top warmest in Barrow (1949-2013) and Ivotuk (1998-2013), respectively. As we just upgraded several eddy covariance towers to measure CO2 and CH4 fluxes year-round, the atypical weather conditions of fall 2013 represented a unique chance for testing the sensitivity of CH4 loss to these atypically warm temperatures. All our sites across a latitudinal gradient (from the northern site, Barrow, to the southern site, Ivotuk), presented substantial CH4 loss in the fall. Importantly, in two of these sites (Barrow, Ivotuk) where the fall weather was substantially warmer than the long term trend, fall CH4 emission represented between 44-63% of the June-November cumulative emission. Surprisingly, in the southernmost site (Ivotuk), when the temperature anomaly was the highest, cumulative fall CH4 emission outpaced even the summer emission. This shows the sensitivity of CH4 loss to abnormal conditions, and the importance of fall periods for the annual CH4 budget in these Arctic ecosystems. Bekryaev, R. V., I. V. Polyakov, and V. A. Alexeev. 2010. Role of polar amplification in long-term surface air temperature variations and modern Arctic warming. Journal of Climate 23(14):3888-3906.

Glacier foreland colonisation: distinguishing between short-term and long-term effects of climate change.

PubMed

Kaufmann, Rüdiger

2002-02-01

By comparing short-term (6 years) observations with long-term (>100 years) community changes reconstructed from the chronosequence along a glacier foreland, I show that the colonisation of recently deglaciated terrain by invertebrates may constitute a process reacting sensitively to temperature fluctuations. Early colonising stages (<30 years old) currently develop faster, and intermediate successional stages (30-50 years old) slower, than would be indicated by the long-term chronosequence pattern. These differences between the chronosequence approach and direct observation can be explained by a simple model relating the rate of community evolution to the temperature record. It would mean that an increase of 0.6°C in summer temperatures approximately doubled the speed of initial colonisation, whereas later successional stages were less sensitive to climate change. The present situation appears to result from unusually warm summers around 1950 and a warm period accelerating glacier retreat since 1980. In contrast to the long-term trend, all except the youngest communities have suffered a loss in diversity in recent years.

Sources of Uncertainty and the Interpretation of Short-Term Fluctuations

NASA Astrophysics Data System (ADS)

Lewandowsky, S.; Risbey, J.; Cowtan, K.; Rahmstorf, S.

2016-12-01

The alleged significant slowdown in global warming during the first decade of the 21st century, and the appearance of a discrepancy between models and observations, has attracted considerable research attention. We trace the history of this research and show how its conclusions were shaped by several sources of uncertainty and ambiguity about models and observations. We show that as those sources of uncertainty were gradually eliminated by further research, insufficient evidence remained to infer any discrepancy between models and observations or a significant slowing of warming. Specifically, we show that early research had to contend with uncertainties about coverage biases in the global temperature record and biases in the sea surface temperature observations which turned out to have exaggerated the extent of slowing. In addition, uncertainties in the observed forcings were found to have exaggerated the mismatch between models and observations. Further sources of uncertainty that were ultimately eliminated involved the use of incommensurate sea surface temperature data between models and observations and a tacit interpretation of model projections as predictions or forecasts. After all those sources of uncertainty were eliminated, the most recent research finds little evidence for an unusual slowdown or a discrepancy between models and observations. We discuss whether these different kinds of uncertainty could have been anticipated or managed differently, and how one can apply those lessons to future short-term fluctuations in warming.

The Other Side of the Vortex

NASA Image and Video Library

2018-03-19

When the polar vortex dips south it often makes headlines. Frigid air, usually confined to the arctic, spills into lower parts of the continent making it a chilly challenge for people going about their day. But there's a warm part to the story as well. While the eastern and southern United States were shivering in January the arctic was experiencing above average temperatures. In maps created with data by the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite, warmer-than-normal temperatures are colored in red and below average temperatures are colored in blue. Provided in geographic and polar projections, the maps show regions of unusually cold air hovering over the eastern and southern U.S., eastern Canada and Greenland in January. February shows colder-than-normal air blanketing the northwest U.S., Canada, Western Europe, northwest Africa and East Asia. In both cases, the arctic remains exceptionally warm. During most winters the polar vortex is like a giant counterclockwise whirlpool spinning around the north pole with cold air at its center. Occasionally the vortex splits and its parts move south, usually over the continents. At the same time, warm air from the south moves in to fill the gap, and that northward movement usually occurs over the oceans. The cold air movement gets the most attention because it typically affects many millions of people. However, that cooling is very often accompanied by warming somewhere over the Arctic -- an equally important part of the polar vortex story that usually goes unnoticed but is very apparent in the images shown here. More images are available at https://photojournal.jpl.nasa.gov/catalog/PIA22344

Ochre star mortality during the 2014 wasting disease epizootic: role of population size structure and temperature.

PubMed

Eisenlord, Morgan E; Groner, Maya L; Yoshioka, Reyn M; Elliott, Joel; Maynard, Jeffrey; Fradkin, Steven; Turner, Margaret; Pyne, Katie; Rivlin, Natalie; van Hooidonk, Ruben; Harvell, C Drew

2016-03-05

Over 20 species of asteroids were devastated by a sea star wasting disease (SSWD) epizootic, linked to a densovirus, from Mexico to Alaska in 2013 and 2014. For Pisaster ochraceus from the San Juan Islands, South Puget Sound and Washington outer coast, time-series monitoring showed rapid disease spread, high mortality rates in 2014, and continuing levels of wasting in the survivors in 2015. Peak prevalence of disease at 16 sites ranged to 100%, with an overall mean of 61%. Analysis of longitudinal data showed disease risk was correlated with both size and temperature and resulted in shifts in population size structure; adult populations fell to one quarter of pre-outbreak abundances. In laboratory experiments, time between development of disease signs and death was influenced by temperature in adults but not juveniles and adult mortality was 18% higher in the 19 °C treatment compared to the lower temperature treatments. While larger ochre stars developed disease signs sooner than juveniles, diseased juveniles died more quickly than diseased adults. Unusual 2-3 °C warm temperature anomalies were coincident with the summer 2014 mortalities. We suggest these warm waters could have increased the disease progression and mortality rates of SSWD in Washington State. © 2016 The Authors.

Ochre star mortality during the 2014 wasting disease epizootic: role of population size structure and temperature

PubMed Central

Eisenlord, Morgan E.; Yoshioka, Reyn M.; Elliott, Joel; Maynard, Jeffrey; Fradkin, Steven; Turner, Margaret; Pyne, Katie; Rivlin, Natalie; van Hooidonk, Ruben; Harvell, C. Drew

2016-01-01

Over 20 species of asteroids were devastated by a sea star wasting disease (SSWD) epizootic, linked to a densovirus, from Mexico to Alaska in 2013 and 2014. For Pisaster ochraceus from the San Juan Islands, South Puget Sound and Washington outer coast, time-series monitoring showed rapid disease spread, high mortality rates in 2014, and continuing levels of wasting in the survivors in 2015. Peak prevalence of disease at 16 sites ranged to 100%, with an overall mean of 61%. Analysis of longitudinal data showed disease risk was correlated with both size and temperature and resulted in shifts in population size structure; adult populations fell to one quarter of pre-outbreak abundances. In laboratory experiments, time between development of disease signs and death was influenced by temperature in adults but not juveniles and adult mortality was 18% higher in the 19°C treatment compared to the lower temperature treatments. While larger ochre stars developed disease signs sooner than juveniles, diseased juveniles died more quickly than diseased adults. Unusual 2–3°C warm temperature anomalies were coincident with the summer 2014 mortalities. We suggest these warm waters could have increased the disease progression and mortality rates of SSWD in Washington State. PMID:26880844

Arctic ozone depletion in 2002-2003 measured by ASUR and comparison with POAM observations

NASA Astrophysics Data System (ADS)

Kuttippurath, Jayanarayanan; KleinböHl, Armin; Sinnhuber, Miriam; Bremer, Holger; Küllmann, Harry; Notholt, Justus; Godin-Beekmann, Sophie; Tripathi, Omprakash; Nikulin, Grigory

2011-11-01

We present ozone loss estimated from airborne measurements taken during January-February and March in the Arctic winter 2002/2003. The first half of the winter was characterized by unusually cold temperatures and the second half by a major stratospheric sudden warming around 15-18 January 2003. The potential vorticity maps show a vortex split in the lower stratosphere during the major warming (MW) in late January and during the minor warming in mid-February due to wave 1 amplification. However, the warming can be termed as a vortex displacement event as there was no vortex split during the MW period at 10 hPa. Very low temperatures, large areas of polar stratospheric clouds (PSCs), and high chlorine activation triggered significant ozone loss in the early winter, as the vortex moved to the midlatitude regions. The ozone depletion derived from the ASUR measurements sampled inside the vortex, in conjunction with the Mimosa-Chim model tracer, shows a maximum of 1.3 ± 0.2 ppmv at 450-500 K by late March. The partial column loss derived from the ASUR ozone profiles reaches up to 61 ± 4 DU in 400-550 K in the same period. The evolution of ozone and ozone loss assessed from the ASUR measurements is in very good agreement with POAM observations. The reduction in ozone estimated from the POAM measurements shows a similar maximum of 1.3 ± 0.2 ppmv at 400-500 K or 63 ± 4 DU in 400-550 K in late March. Our study reveals that the Arctic winter 2002/2003 was unique as it had three minor warmings and a MW, yet showed large loss in ozone. No such feature was observed in any other Arctic winter in the 1989-2010 period. In addition, an unusually large ozone loss in December, around 0.5 ± 0.2 ppmv at 450-500 K or 12 ± 1 DU in 400-550 K, was estimated for the first time in the Arctic. A careful and detailed diagnosis with all available published results for this winter exhibits an average ozone loss of 1.5 ± 0.3 ppmv at 450-500 K or 65 ± 5 DU in 400-550 K by the end of March, which exactly matches the ozone depletion derived from the ASUR, POAM and model data. The early ozone loss together with considerable loss afterwards put the warm Arctic winter 2002/2003 amongst the moderately cold winters in terms of the significance of the ozone loss.

Unusual aerobic performance at high temperatures in juvenile Chinook salmon, Oncorhynchus tshawytscha

PubMed Central

Poletto, Jamilynn B.; Cocherell, Dennis E.; Baird, Sarah E.; Nguyen, Trinh X.; Cabrera-Stagno, Valentina; Farrell, Anthony P.; Fangue, Nann A.

2017-01-01

Understanding how the current warming trends affect fish populations is crucial for effective conservation and management. To help define suitable thermal habitat for juvenile Chinook salmon, the thermal performance of juvenile Chinook salmon acclimated to either 15 or 19°C was tested across a range of environmentally relevant acute temperature changes (from 12 to 26°C). Swim tunnel respirometers were used to measure routine oxygen uptake as a measure of routine metabolic rate (RMR) and oxygen uptake when swimming maximally as a measure of maximal metabolic rate (MMR) at each test temperature. We estimated absolute aerobic scope (AAS = MMR − RMR), the capacity to supply oxygen beyond routine needs, as well as factorial aerobic scope (FAS = MMR/RMR). All fish swam at a test temperature of 23°C regardless of acclimation temperature, but some mortality occurred at 25°C during MMR measurements. Overall, RMR and MMR increased with acute warming, but aerobic capacity was unaffected by test temperatures up to 23°C in both acclimation groups. The mean AAS for fish acclimated and tested at 15°C (7.06 ± 1.76 mg O2 kg−1 h−1) was similar to that measured for fish acclimated and tested at 19°C (8.80 ± 1.42 mg O2 kg−1 h−1). Over the entire acute test temperature range, while MMR and AAS were similar for the two acclimation groups, RMR was significantly lower and FAS consequently higher at the lower test temperatures for the fish acclimated at 19°C. Thus, this stock of juvenile Chinook salmon shows an impressive aerobic capacity when acutely warmed to temperatures close to their upper thermal tolerance limit, regardless of the acclimation temperature. These results are compared with those for other salmonids, and the implications of our findings for informing management actions are discussed. PMID:28078086

Global warming: it's not only size that matters

NASA Astrophysics Data System (ADS)

Hegerl, Gabriele C.

2011-09-01

Observed and model simulated warming is particularly large in high latitudes, and hence the Arctic is often seen as the posterchild of vulnerability to global warming. However, Mahlstein et al (2011) point out that the signal of climate change is emerging locally from that of climate variability earliest in regions of low climate variability, based on climate model data, and in agreement with observations. This is because high latitude regions are not only regions of strong feedbacks that enhance the global warming signal, but also regions of substantial climate variability, driven by strong dynamics and enhanced by feedbacks (Hall 2004). Hence the spatial pattern of both observed warming and simulated warming for the 20th century shows strong warming in high latitudes, but this warming occurs against a backdrop of strong variability. Thus, the ratio of the warming to internal variability is not necessarily highest in the regions that warm fastest—and Mahlstein et al illustrate that it is actually the low-variability regions where the signal of local warming emerges first from that of climate variability. Thus, regions with strongest warming are neither the most important to diagnose that forcing changes climate, nor are they the regions which will necessarily experience the strongest impact. The importance of the signal-to-noise ratio has been known to the detection and attribution community, but has been buried in technical 'optimal fingerprinting' literature (e.g., Hasselmann 1979, Allen and Tett 1999), where it was used for an earlier detection of climate change by emphasizing aspects of the fingerprint of global warming associated with low variability in estimates of the observed warming. What, however, was not discussed was that the local signal-to-noise ratio is of interest also for local climate change: where temperatures emerge from the range visited by internal climate variability, it is reasonable to assume that changes in climate will also cause more impacts than temperatures that have occurred frequently due to internal climate variability. Determining when exactly temperatures enter unusual ranges may be done in many different ways (and the paper shows several, and more could be imagined), but the main result of first local emergence in low latitudes remains robust. A worrying factor is that the regions where the signal is expected to emerge first, or is already emerging are largely regions in Africa, parts of South and Central America, and the Maritime Continent; regions that are vulnerable to climate change for a variety of regions (see IPCC 2007), and regions which contribute generally little to global greenhouse gas emissions. In contrast, strong emissions of greenhouse gases occur in regions of low warming-to-variability ratio. To get even closer to the relevance of this finding for impacts, it would be interesting to place the emergence of highly unusual summer temperatures in the context not of internal variability, but in the context of variability experienced by the climate system prior to the 20th century, as, e.g. documented in palaeoclimatic reconstructions and simulated in simulations of the last millennium (see Jansen et al 2007). External forcing has moved the temperature range around more strongly for some regions and in some seasons than others. For example, while reconstructions of summer temperatures in Europe appear to show small long-term variations, winter shows deep drops in temperature in the little Ice Age and a long-term increase since then (Luterbacher et al 2004), which was at least partly caused by external forcing (Hegerl et al 2011a) and therefore 'natural variability' may be different from internal variability. A further interesting question in attempts to provide a climate-based proxy for impacts of climate change is: to what extent does the rapidity of change matter, and how does it compare to trends due to natural variability? It is reasonable to assume that fast changes impact ecosystems and society more than slow, gradual ones. Also, is it really the mean seasonal temperature that counts, or should the focus change to extremes (see Hegerl et al 2011b)? Is seasonal mean exceedance of the prior temperature envelope a good and robust measure that also reflects these other, more complex diagnostics? Lots of food for thought and research! References Allen M R and Tett S F B 1999 Checking for model consistency in optimal finger printing Clim. Dyn. 15 419-34 Hall A 2004 The role of surface albedo feedback in climate J. Clim. 17 1550-68 Hasselmann K 1979 On the signal-to-noise problem in atmospheric response studies Meteorology of Tropical Oceans ed D B Shaw (Bracknell: Royal Meteorological Society) pp 251-9 Hegerl G C, Luterbacher J, Gonzalez-Ruoco F, Tett S F B and Xoplaki E 2011a Influence of human and natural forcing on European seasonal temperatures Nature Geoscience 4 99-103 Hegerl G, Hanlon H and Beierkuhnlein C 2011b Climate science: elusive extremes Nature Geoscience 4 142-3 IPCC 2007 Climate Change 2007: Impacts, Adaption and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change ed M L Parry, O F Canziani, J P Palutikof, P J van der Linden and C E Hanson (Cambridge: Cambridge University Press) Jansen E et al 2007 Palaeoclimate Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change ed S Solomon et al (Cambridge: Cambridge University Press) Luterbacher J et al 2004 European seasonal and annual temperature variability, trends, and extremes since 1500 Science 303 1499-503 Mahlstein I, Knutti R, Solomon S and Portmann R W 2011 Early onset of significant local warming in low latitude countries Environ. Res. Lett. 6 034009

Snow drought in western U.S. mountains: proximate causes, regional differences, and implications for streamflow and forests

NASA Astrophysics Data System (ADS)

Harpold, A. A.; Dettinger, M. D.; Rajagopal, S.

2017-12-01

Although drought is a recurring problem, recent extreme snow droughts have refocused attention on the interaction of meteorological extremes and snow accumulation in mountains. Only recently have two distinct types of snow drought been defined that help to differentiate a variety of water management implications. Dry snow drought is caused by deficits of winter precipitation and resulting low snow accumulation. Warm snow drought is characterized by temperature extremes causing faster and earlier snowmelt and/or shifts from snow to rain. Here we use 462 Snow Telemetry (SNOTEL) sites in the western U.S. to quantify snow drought as 75% of the long-term average snow water equivalent (SWE). We further subdivide dry snow droughts using SWE to winter precipitation (SWE/P) ratios that were near normal from warm snow droughts where SWE/P ratios were below normal and experienced SWE losses (warm-melt) or received unusual amounts of winter rain (warm-rain snow drought). Using this method we show clear regional patterns in the type and frequency of snow drought. Warm snow droughts on April 1st were most common in all but the highest elevations of the Rocky Mountains. The middle Rocky Mountains sites also experienced less frequent snow drought than the maritime and southern mountains. Warm-melt snow droughts were the primary cause in the Cascade Mountains and the southwestern sites, with only the Sierra Nevada and Wasatch mountains showing consistent warm-rain snow drought. These regional differences limited the predictability of snow drought with simple models of temperature and precipitation. We will discuss the effects of snow drought type and magnitude on streamflow forecasting skill using empirical relationships developed by water management agencies. We expect these types of snow drought to differentially affect streamflow regime and its predictability, as well as forest growth and mortality during and following drought.

Aerial Observations of Symmetric Instability at the North Wall of the Gulf Stream

NASA Astrophysics Data System (ADS)

Savelyev, I.; Thomas, L. N.; Smith, G. B.; Wang, Q.; Shearman, R. K.; Haack, T.; Christman, A. J.; Blomquist, B.; Sletten, M.; Miller, W. D.; Fernando, H. J. S.

2018-01-01

An unusual spatial pattern on the ocean surface was captured by thermal airborne swaths taken across a strong sea surface temperature front at the North Wall of the Gulf Stream. The thermal pattern on the cold side of the front resembles a staircase consisting of tens of steps, each up to ˜200 m wide and up to ˜0.3°C warm. The steps are well organized, clearly separated by sharp temperature gradients, mostly parallel and aligned with the primary front. The interpretation of the airborne imagery is aided by oceanographic measurements from two research vessels. Analysis of the in situ observations indicates that the front was unstable to symmetric instability, a type of overturning instability that can generate coherent structures with similar dimensions to the temperature steps seen in the airborne imagery. It is concluded that the images capture, for the first time, the surface temperature field of symmetric instability turbulence.

The 2014-2015 Warming Anomaly in the Southern California Current System: Glider Observations

NASA Astrophysics Data System (ADS)

Zaba, K. D.; Rudnick, D. L.

2016-02-01

During 2014-2015, basin-wide patterns of oceanic and atmospheric anomalies affected surface waters throughout the North Pacific Ocean. We present regional physical and biological effects of the warming, as observed by our autonomous underwater gliders in the southern California Current System (SCCS). Established in 2006, the California Glider Network provides sustained subsurface observations for monitoring the coastal effects of large-scale climate variability. Along repeat sections that extend to 350-500 km in offshore distance and 500 m in depth, Spray gliders have continuously occupied CalCOFI lines 66.7, 80, and 90 for nearly nine years. Following a sawtooth trajectory, the gliders complete each dive in approximately 3 hours and over 3 km. Measured variables include pressure, temperature, salinity, chlorophyll fluorescence, and velocity. For each of the three lines, a comprehensive climatology has been constructed from the multiyear timeseries. The ongoing surface-intensified warming anomaly, which began locally in early 2014 and persists through present, is unprecedented in the glider climatology. Reaching up to 5°C, positive temperature anomalies have been generally confined to the upper 50 m and persistent for over 20 months. The timing of the warming was in phase along each glider line but out of phase with equatorial SST anomalies, suggesting a decoupling of tropical and mid-latitude dynamics. Concurrent physical oceanographic anomalies included a depressed thermocline and high stratification. An induced biological response was apparent in the deepening of the subsurface chlorophyll fluorescence maximum. Ancillary atmospheric data from the NCEP North American Mesoscale (NAM) model indicate that a combination of surface forcing anomalies, namely high downward heat flux and weak wind stress magnitude, caused the unusual warm, downwelling conditions. With a strong El Niño event in the forecast for winter 2015-2016, our sustained glider network will continue to measure the evolution of the shallow warm pool in the SCCS and its potential interaction with ENSO-related anomalies.

The Detection of Change in the Arctic Using Satellite and Buoy Data

NASA Technical Reports Server (NTRS)

Comiso, Josefino C.; Yang, J.; Honjo, S.; Krishfield, R.; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

The decade of the 1990s is the warmest decade of the last century while the year 1998 is the warmest year ever observed by modern techniques with 9 out of 12 months of the year being the warmest month. Since the Arctic is expected to provide early signals of a possible warming scenario, detailed examination of changes in the Arctic environment is important. In this study, we examined available satellite ice cover and surface temperature data, wind and pressure data, and ocean hydrographic data to gain insights into the warming phenomenon. The areas of open water in both western and eastern regions of the Arctic were found to follow a cyclical pattern with approximately decadal period but with a lag of about three years between the two regions. The pattern was interrupted by unusually large anomalies in open water area in the western region in 1993 and 1998 and in the eastern region in 1995. The big 1998 open water anomaly occurred at the same time when a large surface temperature anomaly was also occurring in the area and adjacent regions. The infrared temperature data show for the first time the complete spatial scope of the warming anomalies and it is apparent that despite the magnitude of the 1998 anomaly, it is basically confined to North America and the Western Arctic. The large increases in open water areas in the Western Sector form 1996 to 1998 were observed to be coherent with changing wind directions which was predominantly cyclonic in 1996 and anti-cyclonic in 1997 and 1998. Detailed hydrography measurements up to 500 m depth over the same general area in April 1996 and April 1997 also indicate significant freshening and warming in the upper part of the mixed layer suggesting increases in ice melt. Continuous ocean temperature and salinity data from ocean buoys confirm this result and show significant seasonal changes from 1996 to 1998, at depths of 8 m, 45 m, and 75 m. Long data records of temperature and hydrography were also examined and the potential impact of a warming, freshening, and the presence of abnormally large open areas on the state of the Arctic climate system are discussed.

The World's Largest Experiment Manipulating Solar Energy Input To Earth Resumed In 2003

NASA Astrophysics Data System (ADS)

Ward, P. L.

2010-12-01

Small amounts of solar-ultraviolet-energy absorbing gases such as ozone, SO2, and NO2 play an unusually large role warming the atmosphere. A mere 3 to 8 ppmv ozone at elevations of 15 to 50 km and associated exothermic chemical reactions warm the atmosphere >50oC, forming the stratosphere. All three molecules have an asymmetric top shape that, unlike linear molecules of CO2, forms a permanent electromagnetic dipole enhancing interaction with electromagnetic radiation. Planck’s postulate (Energy = a constant times frequency) implies that solar ultraviolet energy strongly absorbed by SO2 is 43 times greater than infrared energy radiated by earth and strongly absorbed by CO2. Solar energy in the blue visible spectrum and ultraviolet causes electronic transitions and an absorption spectrum that is a continuum, absorbing far more energy per unit gas than spectral line absorption of infrared energy caused by rotational and vibrational transitions. Absorption of electromagnetic energy by atmospheric gases increases rapidly with increasing frequency, an observation not accounted for by the use of specific heat in atmospheric models to link energy flux with temperature. While SO2 in the stratosphere is oxidized to a sulfuric acid aerosol that reflects sunlight, cooling the earth, SO2 in the troposphere is oxidized much more slowly than commonly assumed. Well-documented concentrations of tens of ppbv SO2 emitted by humans burning fossil fuels, especially coal, in northern mid-latitudes are contemporaneous, with suitable time delays for warming the ocean, with increased global warming during the 20th century, greatest by nearly a factor of two in the northern hemisphere. A decrease by 18% of anthropogenic SO2 emissions between 1979 and 2000 aimed at reducing acid rain had the unintended effect of reducing the global mean rate of temperature increase to zero by 1998. By 2003, global SO2 emissions began to rise sharply due to the rapid increase in number of new coal-burning power plants in Asia. The 20th century rate of increase in tropospheric methane also approached zero by 1998 but began to increase in 2007 as explained by SO2 reducing the oxidizing capacity and thus the troposphere’s ability to remove methane. SO2 does not last long in the atmosphere, but a continual and increasing flux causes increased concentrations. SO2 from China is traceable across the Pacific Ocean even to eastern America, perhaps playing a major role in the unusually high air temperatures in 2010. Atmospheric circulation in the northern hemisphere moves SO2 towards the pole where it is the primary cause of Arctic Haze. In polar regions, solar radiation travels longer path lengths through the atmosphere during longer summer days than in equatorial regions, contributing to the well-documented excessive global warming in the Arctic. The resumed increase in SO2 emissions since 2003 provides the world’s largest geoengineering experiment and an excellent chance to measure, especially in China and India, the effects of SO2 and NO2 on global warming. Technology exists to reduce SO2 emissions economically. The time has come to control this large geoengineering experiment in the hopes that we can minimize continued global warming.

Negative response of photosynthesis to natural and projected high seawater temperatures estimated by pulse amplitude modulation fluorometry in a temperate coral.

PubMed

Caroselli, Erik; Falini, Giuseppe; Goffredo, Stefano; Dubinsky, Zvy; Levy, Oren

2015-01-01

Balanophyllia europaea is a shallow water solitary zooxanthellate coral, endemic to the Mediterranean Sea. Extensive field studies across a latitudinal temperature gradient highlight detrimental effects of rising temperatures on its growth, demography, and skeletal characteristics, suggesting that depression of photosynthesis at high temperatures might cause these negative effects. Here we test this hypothesis by analyzing, by means of pulse amplitude modulation fluorometry, the photosynthetic efficiency of B. europaea specimens exposed in aquaria to the annual range of temperatures experienced in the field (13, 18, and 28°C), and two extreme temperatures expected for 2100 as a consequence of global warming (29 and 32°C). The indicators of photosynthetic performance analyzed (maximum and effective quantum yield) showed that maximum efficiency was reached at 20.0-21.6°C, slightly higher than the annual mean temperature in the field (18°C). Photosynthetic efficiency decreased from 20.0 to 13°C and even more strongly from 21.6 to 32°C. An unusual form of bleaching was observed, with a maximum zooxanthellae density at 18°C that strongly decreased from 18 to 32°C. Chlorophyll a concentration per zooxanthellae cell showed an opposite trend as it was minimal at 18°C and increased from 18 to 32°C. Since the areal chlorophyll concentration is the product of the zooxanthellae density and its cellular content, these trends resulted in a homogeneous chlorophyll concentration per coral surface across temperature treatments. This confirms that B. europaea photosynthesis is progressively depressed at temperatures >21.6°C, supporting previous hypotheses raised by the studies on growth and demography of this species. This study also confirms the threats posed to this species by the ongoing seawater warming.

Improved ground-based remote-sensing systems help monitor plant response to climate and other changes

USGS Publications Warehouse

Dye, Dennis G.; Bogle, Rian

2016-05-26

Scientists at the U.S. Geological Survey are improving and developing new ground-based remote-sensing instruments and techniques to study how Earth’s vegetation responds to changing climates. Do seasonal grasslands and forests “green up” early (or late) and grow more (or less) during unusually warm years? How do changes in temperature and precipitation affect these patterns? Innovations in ground-based remote-sensing instrumentation can help us understand, assess, and mitigate the effects of climate change on vegetation and related land resources.

On the Origins of the Recent Greenland Melt in the US 2012 Heat Wave

NASA Astrophysics Data System (ADS)

Neff, W. D.; Shupe, M.; Ralph, F. M.; Compo, G.; Turner, D. D.

2012-12-01

Recent reports had the majority of the Greenland ice sheet surface melting on 8-12 July 2012 (http://www.nasa.gov/topics/earth/features/greenland-melt.html). Even at Summit Station, the temperature reached 1Co above freezing. A companion paper (Miller et al., AGU) describes the cloud and radiation properties at Summit during this episode that affected boundary layer exchange processes. Here we describe the likely synoptic processes, coupling mid-latitudes with the polar regions, at work leading to this unusual event. These include back trajectories that originated ten days earlier in the US Midwest where 8oC surface temperature anomalies were present on 1 July and then exited over the Atlantic Ocean gaining substantial moisture in the process. Over the ocean, a thin filament of moisture transport formed at the boundary of a trough of low pressure (extending from the high Arctic) with a subtropical ridge. Such filaments are often referred to as atmospheric rivers (ARs) and account for a substantial portion of the northward transport of moisture from the tropics and extratropics (Zhu and Newell 1998 Mon. Wea. Rev.). Examination of SSMIS imagery from this event shows the evolution of this AR over several days and oriented along the path of the back-trajectory from Summit Station on 11 July. In its final stage, the AR impinged and spread along the southern coast of Greenland. Moisture content in this AR was exceptionally high for this latitude, exceeding 6 cm of vertically integrated water vapor. This event was also characterized by a distortion of the polar vortex corresponding to negative 2-sigma anomaly in the Arctic Oscillation (AO). Such melting episodes are rare over Greenland with ice-core evidence suggesting a return period averaging about 150 years with the last such episode reportedly in 1889 (http://dartmouthigert.wordpress.com/2012/07/21/new-summit-melt-layer/). Using the 20th Century Reanalysis (Compo et al., 2012), we have examined synoptic patterns present in June and July 1889 during positive anomalies in surface temperatures over this two-month period. During one such event on 30 July 1889, a strong trough-ridge pattern had set up, potentially bringing warm southerly flow from the eastern US to Greenland. One of the unique features of the most recent event was prolonged drought and high temperatures over North America during the spring and summer of 2012 - an implication being that having a persistent source of unusually warm air over North America, coupled with a relatively rare, and short-lived negative anomaly in the AO created almost perfect conditions for the warming of Greenland above the freezing point. This is one example of how an extreme event that appears to be part of the general picture of a warming Arctic may in fact have its origins in the mid-latitudes.

Climatic warming in China during 1901–2015 based on an extended dataset of instrumental temperature records

DOE PAGES

Cao, Lijuan; Yan, Zhongwei; Zhao, Ping; ...

2017-05-26

Monthly mean instrumental surface air temperature (SAT) observations back to the nineteenth century in China are synthesized from different sources via specific quality-control, interpolation, and homogenization. Compared with the first homogenized long-term SAT dataset for China which contained 18 stations mainly located in the middle and eastern part of China, the present dataset includes homogenized monthly SAT series at 32 stations, with an extended coverage especially towards western China. Missing values are interpolated by using observations at nearby stations, including those from neighboring countries. Cross validation shows that the mean bias error (MBE) is generally small and falls between 0.45more » °C and –0.35 °C. Multiple homogenization methods and available metadata are applied to assess the consistency of the time series and to adjust inhomogeneity biases. The homogenized annual mean SAT series shows a range of trends between 1.1 °C and 4.0 °C/century in northeastern China, between 0.4 °C and 1.9 °C/century in southeastern China, and between 1.4 °C and 3.7 °C/century in western China to the west of 105 E (from the initial years of the stations to 2015). The unadjusted data include unusually warm records during the 1940s and hence tend to underestimate the warming trends at a number of stations. As a result, the mean SAT series for China based on the climate anomaly method shows a warming trend of 1.56 °C/century during 1901–2015, larger than those based on other currently available datasets.« less

Climatic warming in China during 1901–2015 based on an extended dataset of instrumental temperature records

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Lijuan; Yan, Zhongwei; Zhao, Ping

Monthly mean instrumental surface air temperature (SAT) observations back to the nineteenth century in China are synthesized from different sources via specific quality-control, interpolation, and homogenization. Compared with the first homogenized long-term SAT dataset for China which contained 18 stations mainly located in the middle and eastern part of China, the present dataset includes homogenized monthly SAT series at 32 stations, with an extended coverage especially towards western China. Missing values are interpolated by using observations at nearby stations, including those from neighboring countries. Cross validation shows that the mean bias error (MBE) is generally small and falls between 0.45more » °C and –0.35 °C. Multiple homogenization methods and available metadata are applied to assess the consistency of the time series and to adjust inhomogeneity biases. The homogenized annual mean SAT series shows a range of trends between 1.1 °C and 4.0 °C/century in northeastern China, between 0.4 °C and 1.9 °C/century in southeastern China, and between 1.4 °C and 3.7 °C/century in western China to the west of 105 E (from the initial years of the stations to 2015). The unadjusted data include unusually warm records during the 1940s and hence tend to underestimate the warming trends at a number of stations. As a result, the mean SAT series for China based on the climate anomaly method shows a warming trend of 1.56 °C/century during 1901–2015, larger than those based on other currently available datasets.« less

Tracing the Inter-Hemispheric Coupling During Polar Summer Periods of 2002-2010 Using TIMED/SABER Measurements

NASA Technical Reports Server (NTRS)

Goldberg, Richard; Feoflow, Artem; Pesnell, Dean; Kutepov, Alexander

2010-01-01

It has been found that for more than one polar summer season between 2002-2010, the northern polar mesospheric region near and above the mesospheric maximum was warmer than normal. The strongest warming effect of this type was observed to occur during northern summer 2002. Theoretical studies have implied that these "anomalies" were preceded by unusual dynamical processes occurring in the southern hemisphere. We have analyzed temperature distributions measured by the SABER limb scanning infrared radiometer aboard the NASA TIMED satellite between 2002-2010 at altitudes from 15 to 110 km and for latitudes between 83 deg. S to 83 deg. N. We describe the approach to trace the inter-hemispheric temperature correlatoins and to identify the global features that were unique for the "anomalous" northern polar summers.

A catalogue of 136 microbial draft genomes from Red Sea metagenomes

NASA Astrophysics Data System (ADS)

Haroon, Mohamed F.; Thompson, Luke R.; Parks, Donovan H.; Hugenholtz, Philip; Stingl, Ulrich

2016-07-01

Earth is expected to continue warming and the Red Sea is a model environment for understanding the effects of global warming on ocean microbiomes due to its unusually high temperature, salinity and solar irradiance. However, most microbial diversity analyses of the Red Sea have been limited to cultured representatives and single marker gene analyses, hence neglecting the substantial uncultured majority. Here, we report 136 microbial genomes (completion minus contamination is ≥50%) assembled from 45 metagenomes from eight stations spanning the Red Sea and taken from multiple depths between 10 to 500 m. Phylogenomic analysis showed that most of the retrieved genomes belong to seven different phyla of known marine microbes, but more than half representing currently uncultured species. The open-access data presented here is the largest number of Red Sea representative microbial genomes reported in a single study and will help facilitate future studies in understanding the physiology of these microorganisms and how they have adapted to the relatively harsh conditions of the Red Sea.

A catalogue of 136 microbial draft genomes from Red Sea metagenomes.

PubMed

Haroon, Mohamed F; Thompson, Luke R; Parks, Donovan H; Hugenholtz, Philip; Stingl, Ulrich

2016-07-05

Earth is expected to continue warming and the Red Sea is a model environment for understanding the effects of global warming on ocean microbiomes due to its unusually high temperature, salinity and solar irradiance. However, most microbial diversity analyses of the Red Sea have been limited to cultured representatives and single marker gene analyses, hence neglecting the substantial uncultured majority. Here, we report 136 microbial genomes (completion minus contamination is ≥50%) assembled from 45 metagenomes from eight stations spanning the Red Sea and taken from multiple depths between 10 to 500 m. Phylogenomic analysis showed that most of the retrieved genomes belong to seven different phyla of known marine microbes, but more than half representing currently uncultured species. The open-access data presented here is the largest number of Red Sea representative microbial genomes reported in a single study and will help facilitate future studies in understanding the physiology of these microorganisms and how they have adapted to the relatively harsh conditions of the Red Sea.

Increased temperatures negatively affect Juniperus communis seeds: evidence from transplant experiments along a latitudinal gradient.

PubMed

Gruwez, R; De Frenne, P; Vander Mijnsbrugge, K; Vangansbeke, P; Verheyen, K

2016-05-01

With a distribution range that covers most of the Northern hemisphere, common juniper (Juniperus communis) has one of the largest ranges of all vascular plant species. In several regions in Europe, however, populations are decreasing in size and number due to failing recruitment. One of the main causes for this failure is low seed viability. Observational evidence suggests that this is partly induced by climate warming, but our mechanistic understanding of this effect remains incomplete. Here, we experimentally assess the influence of temperature on two key developmental phases during sexual reproduction, i.e. gametogenesis and fertilisation (seed phase two, SP2) and embryo development (seed phase three, SP3). Along a latitudinal gradient from southern France to central Sweden, we installed a transplant experiment with shrubs originating from Belgium, a region with unusually low juniper seed viability. Seeds of both seed phases were sampled during three consecutive years, and seed viability assessed. Warming temperatures negatively affected the seed viability of both SP2 and SP3 seeds along the latitudinal gradient. Interestingly, the effect on embryo development (SP3) only occurred in the third year, i.e. when the gametogenesis and fertilisation also took place in warmer conditions. We found strong indications that this negative influence mostly acts via disrupting growth of the pollen tube, the development of the female gametophyte and fertilisation (SP2). This, in turn, can lead to failing embryo development, for example, due to nutritional problems. Our results confirm that climate warming can negatively affect seed viability of juniper. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Increasing risk of Amazonian drought due to decreasing aerosol pollution.

PubMed

Cox, Peter M; Harris, Phil P; Huntingford, Chris; Betts, Richard A; Collins, Matthew; Jones, Chris D; Jupp, Tim E; Marengo, José A; Nobre, Carlos A

2008-05-08

The Amazon rainforest plays a crucial role in the climate system, helping to drive atmospheric circulations in the tropics by absorbing energy and recycling about half of the rainfall that falls on it. This region (Amazonia) is also estimated to contain about one-tenth of the total carbon stored in land ecosystems, and to account for one-tenth of global, net primary productivity. The resilience of the forest to the combined pressures of deforestation and global warming is therefore of great concern, especially as some general circulation models (GCMs) predict a severe drying of Amazonia in the twenty-first century. Here we analyse these climate projections with reference to the 2005 drought in western Amazonia, which was associated with unusually warm North Atlantic sea surface temperatures (SSTs). We show that reduction of dry-season (July-October) rainfall in western Amazonia correlates well with an index of the north-south SST gradient across the equatorial Atlantic (the 'Atlantic N-S gradient'). Our climate model is unusual among current GCMs in that it is able to reproduce this relationship and also the observed twentieth-century multidecadal variability in the Atlantic N-S gradient, provided that the effects of aerosols are included in the model. Simulations for the twenty-first century using the same model show a strong tendency for the SST conditions associated with the 2005 drought to become much more common, owing to continuing reductions in reflective aerosol pollution in the Northern Hemisphere.

Temperature Trends in the Polar Mesosphere between 2002-2007 using TIMED/SABER Data

NASA Technical Reports Server (NTRS)

Goldberg, Richard A.; Kutepov, Alexander A.; Pesnell, William Dean; Latteck, Ralph; Russell, James M.

2008-01-01

The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The TIMED/SABER instrument is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as the temperature of the region. In this study, we have concentrated on the polar mesosphere, to investigate the temperature characteristics as a function of spatial and temporal considerations. We used the recently revised SABER dataset (1.07) that contains improved temperature retrievals in the Earth polar summer regions. Weekly averages are used to make comparisons between the winter and summer, as well as to study the variability in different quadrants of each hemisphere. For each year studied, the duration of polar summer based on temperature measurements compares favorably with the PMSE (Polar Mesospheric Summer Echoes) season measured by radar at the ALOMAR Observatory in Norway (69 N). The PMSE period should also define the summer period suitable for the occurrence of polar mesospheric clouds. The unusual short and relatively warm polar summer in the northern hemisphere

TOPEX/El Nino Watch - La Nina Conditions Likely to Prevail, October 10, 1999

NASA Technical Reports Server (NTRS)

1999-01-01

A repeat of last year's mild La Nina conditions -- with a stormy winter in the Pacific Northwest and a dry winter in the southwestern United States -- will be the likely outcome of sea-surface heights observed by NASA's TOPEX/Poseidon satellite, scientists say.

TOPEX/Poseidon has detected lower than normal sea-surface heights in the eastern North Pacific and unusually high sea-surface heights in the western and mid-latitude Pacific. The height of the sea surface over a given area is an indicator of ocean temperature and other factors that influence climate.

The latest measurements, taken during a 10-day data cycle October 5-15, are available at http://www.jpl.nasa.gov/elnino . Sea-surface height is shown relative to normal (green) and reveals cooler water (blue and purple) measuring about 14 centimeters (6 inches) lower in the eastern North Pacific, from the Gulf of Alaska to central Alaska, and along the equator. The cooling trend sets the stage for another La Nina this winter.

'A mirror image of that oceanic profile prevails in the western and mid-latitude Pacific Ocean, where higher than normal sea-surface heights (red and white) are currently about 20 centimeters or 8 inches. Unusually warm temperatures (shown in red and white) have persisted and topped last year's temperatures,' said Dr. William Patzert, an oceanographer at NASA's Jet Propulsion Laboratory, Pasadena, CA.

'These unbalanced conditions will undoubtedly exert a very strong influence on climate over North America this fall and winter,' Patzert said. 'Our profile of high sea-surface heights and warm temperatures in the western Pacific Ocean contrasts with low sea-surface heights and cool conditions in the eastern and equatorial Pacific. Those conditions will have a powerful impact on the weather system delivering jet streams out of the North Pacific.'

Conditions are ripe for a stormy, wet winter in the Pacific Northwest and a dry, relatively rainless winter in Southern California and the Southwest, the data show. 'Clearly, these unusual conditions, which have persisted for 2 1/2 years, will not be returning to normal any time soon,' Patzert said. 'This climate imbalance is big and we're definitely going through a decade of wild climatic behavior. But when we look back at the climate record over the past century, we've seen behavior like this before.'

The TOPEX/Poseidon satellite's measurements have provided scientists with a detailed view of the 1997-1999 El Nino/La Nina climate pattern by measuring the changing sea-surface height with unprecedented precision.

For more information, please visit the TOPEX/Poseidon project web page at http://topex-www.jpl.nasa.gov/

Late-Holocene climate and environmental change on the Antarctic Peninsula: multi-proxy palaeoclimate records from frozen moss banks

NASA Astrophysics Data System (ADS)

Roland, T.; Amesbury, M.; Royles, J.; Hodgson, D.; Convey, P.; Griffiths, H.; Charman, D.

2017-12-01

The Antarctic Peninsula (AP) has been one of the most rapidly warming regions on Earth, with air temperature increases of 3°C recorded since the mid-20th century. However, instrumental climate records are mostly limited to the late 1950s onwards and existing palaeoenvironmental data that provide a longer-term context to recent climate and biological changes are often spatially isolated and temporally fragmented. Ice-core records from the AP are not suitably located to be able to examine the spatial signature of climate changes over time. Moss banks located along the western AP are ideal archives for palaeoclimate research as they are well-preserved, have sufficiently high accumulation rates to permit decadally resolved analyses using multiple proxies over the last c. 4000 years, and are easily dated with 14C and 210Pb. Potential climate proxies (moss accumulation and growth rates, Δ13C in moss cellulose, testate amoebae concentration) are sensitive to regional temperature change, moderated by water availability and surface microclimate. Here we present multi-proxy records of biological change from these archives of late Holocene climate variability. We identified significant changepoints in six cores at three sites, across a transect spanning c. 600 km, observing that biological response to recent rapid warming on the AP is pervasive and unprecedented over the last 150 years. Longer records show that recent change is also unusual in the context of the past 4000 years and suggest that westerly wind strength linked to the Southern Annular Mode is the most likely driver of centennial-scale AP temperature variability. Widespread changes in the terrestrial biosphere of the AP in response to past temperature suggest that terrestrial ecosystems will alter rapidly under future warming scenarios, leading to major changes in the biology and landscape of this iconic region — an Antarctic greening to parallel well-established observations in the Arctic.

Studying the Inter-Hemispheric Coupling During Polar Summer Mesosphere Warming in 2002

NASA Technical Reports Server (NTRS)

Goldberg, Richard A.; Feofilov, Artem; Pesnell, William; Kutepov, Alexander A.

2010-01-01

It has been found that the northern summer polar mesopause region in 2002 was warmer than normal and of shorter duration than for other years analyzed. Theoretical studies have implied that the abnormal characteristics of this polar summer were generated by unusual dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA TIMED Satellite to study these processes for polar summer periods of 2002-2009. For background, SABER is a broadband limb scanning radiometer that measures a large number of minor atmospheric constituents as well as pressure and temperature in the 13-110 km altitude range over most of the globe.We will use SABER temperature data to illustrate the correlated heating seen between the southern and northern hemispheres during June and July 2002. We will then describe the approach to study the wave characteristics of the atmospheric temperature profiles and demonstrate the features that were unique for 2002 compared to the other years.

The Teleconnection Between Atlantic Sea Surface Temperature and Eastern Pacific Tropical Cyclones

NASA Astrophysics Data System (ADS)

Patricola, C. M.; Saravanan, R.; Chang, P.

2016-12-01

The El Niño-Southern Oscillation (ENSO) is a major source of seasonal tropical cyclone (TC) predictability, in both local and remote ocean basins. Unusually warm eastern tropical Pacific sea-surface temperature (SST) during El Niño tends not only to enhance local TC activity in the eastern North Pacific (ENP) but also to suppress Atlantic TCs via well-known teleconnections. Here, we demonstrate that Atlantic SST variability likewise exerts a significant influence on remote TC activity in the eastern Pacific basin using observations and 27 km resolution tropical channel model simulations. Observed and simulated accumulated cyclone energy in the ENP is substantially reduced during the positive phase of the Atlantic Meridional Mode (AMM), which is characterized by warm and cool SST anomalies in the northern and southern tropical Atlantic respectively, and vice versa during the cool AMM phase. We find that the observed anti-correlation in seasonal TC activity between the Atlantic and ENP basins is driven by interannual climate variability in both the tropical Pacific (ENSO) and Atlantic (AMM). The physical mechanisms that drive the teleconnection between Atlantic SST and ENP TC activity will also be presented. This work provides information that can be used to improve seasonal forecasts and future projections of ENP tropical cyclone activity.

Effects of the Blob on settlement of spotted sand bass, Paralabrax maculatofasciatus, to Mission Bay, San Diego, CA.

PubMed

Basilio, Anthony; Searcy, Steven; Thompson, Andrew R

2017-01-01

The West Coast of the United States experienced variable and sometimes highly unusual oceanographic conditions between 2012 and 2015. In particular, a warm mass of surface water known as the Pacific Warm Anomaly (popularly as "The Blob") impinged on southern California in 2014, and warm-water conditions remained during the 2015 El Niño. We examine how this oceanographic variability affected delivery and individual characteristics of larval spotted sand bass (Paralabrax maculatofasciatus) to an estuarine nursery habitat in southern California. To quantify P. maculatofasciatus settlement patterns, three larval collectors were installed near the mouth of Mission Bay, San Diego CA, and retrieved weekly from June-October of 2012-2015. During 'Blob' conditions in 2014 and 2015, lower settlement rates of spotted sand bass were associated with higher sea surface temperature and lower wind speed, chlorophyll a (chl a) and upwelling. Overall, the number of settlers per day peaked at intermediate chl a values across weeks. Individual characteristics of larvae that settled in 2014-2015 were consistent with a poor feeding environment. Although settlers were longer in length in 2014-15, fish in these years had slower larval otolith growth, a longer larval duration, and a trend towards lower condition, traits that are often associated with lower survival and recruitment. This study suggests that future settlement and recruitment of P. maculatofasciatus and other fishes with similar life histories may be adversely affected in southern California if ocean temperatures continue to rise in the face of climate change.

Effects of the Blob on settlement of spotted sand bass, Paralabrax maculatofasciatus, to Mission Bay, San Diego, CA

PubMed Central

Basilio, Anthony; Thompson, Andrew R.

2017-01-01

The West Coast of the United States experienced variable and sometimes highly unusual oceanographic conditions between 2012 and 2015. In particular, a warm mass of surface water known as the Pacific Warm Anomaly (popularly as “The Blob”) impinged on southern California in 2014, and warm-water conditions remained during the 2015 El Niño. We examine how this oceanographic variability affected delivery and individual characteristics of larval spotted sand bass (Paralabrax maculatofasciatus) to an estuarine nursery habitat in southern California. To quantify P. maculatofasciatus settlement patterns, three larval collectors were installed near the mouth of Mission Bay, San Diego CA, and retrieved weekly from June–October of 2012–2015. During ‘Blob‘ conditions in 2014 and 2015, lower settlement rates of spotted sand bass were associated with higher sea surface temperature and lower wind speed, chlorophyll a (chl a) and upwelling. Overall, the number of settlers per day peaked at intermediate chl a values across weeks. Individual characteristics of larvae that settled in 2014–2015 were consistent with a poor feeding environment. Although settlers were longer in length in 2014–15, fish in these years had slower larval otolith growth, a longer larval duration, and a trend towards lower condition, traits that are often associated with lower survival and recruitment. This study suggests that future settlement and recruitment of P. maculatofasciatus and other fishes with similar life histories may be adversely affected in southern California if ocean temperatures continue to rise in the face of climate change. PMID:29176818

Role of internal variability in recent decadal to multidecadal tropical Pacific climate changes

NASA Astrophysics Data System (ADS)

Bordbar, Mohammad Hadi; Martin, Thomas; Latif, Mojib; Park, Wonsun

2017-05-01

While the Earth's surface has considerably warmed over the past two decades, the tropical Pacific has featured a cooling of sea surface temperatures in its eastern and central parts, which went along with an unprecedented strengthening of the equatorial trade winds, the surface component of the Pacific Walker Circulation (PWC). Previous studies show that this decadal trend in the trade winds is generally beyond the range of decadal trends simulated by climate models when forced by historical radiative forcing. There is still a debate on the origin of and the potential role that internal variability may have played in the recent decadal surface wind trend. Using a number of long control (unforced) integrations of global climate models and several observational data sets, we address the question as to whether the recent decadal to multidecadal trends are robustly classified as an unusual event or the persistent response to external forcing. The observed trends in the tropical Pacific surface climate are still within the range of the long-term internal variability spanned by the models but represent an extreme realization of this variability. Thus, the recent observed decadal trends in the tropical Pacific, though highly unusual, could be of natural origin. We note that the long-term trends in the selected PWC indices exhibit a large observational uncertainty, even hindering definitive statements about the sign of the trends.