New Research

[knocker]

Yale study: Forest emissions, wildfires explain why ancient Earth was so hot

 

The release of volatile organic compounds from Earth’s forests and smoke from wildfires 3 million years ago had a far greater impact on global warming than ancient atmospheric levels of carbon dioxide, a new Yale study finds.

 

The research provides evidence that dynamic atmospheric chemistry played an important role in past warm climates, underscoring the complexity of climate change and the relevance of natural components, according to the authors. They do not address or dispute the significant role in climate change of human-generated CO2 emissions.

 

http://news.yale.edu/2014/02/04/yale-study-forest-emissions-wildfires-explain-why-ancient-earth-was-so-hot

[knocker]

Little net clear-sky radiative forcing from recent regional redistribution of aerosols

 

Aerosols both scatter and absorb incoming solar radiation, with consequences for the energy balance of the atmosphere. Unlike greenhouse gases, atmospheric aerosols are distributed non-uniformly around the Earth. Therefore, regional shifts in aerosol abundance could alter radiative forcing of the climate. Here, I use multi-angle imaging spectroradiometer (MISR) satellite data and the Atmospheric and Environmental Research radiative transfer model¹ to assess the radiative effect of the spatial redistribution of aerosols over the past decade. Unexpectedly, the radiative transfer model shows that the movement of aerosols from high latitudes towards the Equator, as might happen if pollution shifts from Europe to southeast Asia, has little effect on clear-sky radiative forcing. Shorter slant paths and smaller upscatter fractions near the Equator compensate for more total sunlight there. Overall, there has been an almost exact cancellation in the clear-sky radiative forcing from aerosol increases and decreases in different parts of the world, whereas MISR should have been able to easily detect a change of 0.1 W m^−2 per decade due to changing patterns. Long-term changes in global mean aerosol optical depth or indirect aerosol forcing of clouds are difficult to measure from satellites. However, the satellite data show that the regional redistribution of aerosols had little direct net effect on global average clear-sky radiative forcing from 2000 to 2012.

 

http://www.nature.com/ngeo/journal/v6/n4/full/ngeo1740.html

[BornFromTheVoid]

I realise this has been mentioned by knocker and Gray-Wolf in the manmade thread, but incase anybody missed it.

 

Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus

 

An unprecedented strengthening of the trade winds is causing more upwelling of cool water in the central and western tropical Pacific, while driving warm water into the deep ocean and eastern tropical Pacific. The researchers believe that this can explain the warming "hiatus" in its entirety.

 

A review of the article

 

---------------------------------------------------------------------------------------------------------------------------

Pacific trade winds stall global surface warming—for now

 

Heat stored in the western Pacific Ocean caused by an unprecedented strengthening of the equatorial trade winds appears to be largely responsible for the hiatus in surface warming observed over the past 13 years.

New research published today in the journal Nature Climate Change indicates that the dramatic acceleration in winds has invigorated the circulation of the Pacific Ocean, causing more heat to be taken out of the atmosphere and transferred into the subsurface ocean, while bringing cooler waters to the surface.

"Scientists have long suspected that extra ocean heat uptake has slowed the rise of global average temperatures, but the mechanism behind the hiatus remained unclear" said Professor Matthew England, lead author of the study and a Chief Investigator at the ARC Centre of Excellence for Climate System Science.

"But the heat uptake is by no means permanent: when the trade wind strength returns to normal - as it inevitably will - our research suggests heat will quickly accumulate in the atmosphere. So global temperatures look set to rise rapidly out of the hiatus, returning to the levels projected within as little as a decade."

The strengthening of the Pacific trade winds began during the 1990s and continues today. Previously, no climate models have incorporated a trade wind strengthening of the magnitude observed, and these models failed to capture the hiatus in warming. Once the trade winds were added by the researchers, the global average temperatures very closely resembled the observations during the hiatus.

"The winds lead to extra ocean heat uptake, which stalled warming of the atmosphere. Accounting for this wind intensification in model projections produces a hiatus in global warming that is in striking agreement with observations," Prof England said.

"Unfortunately, however, when the hiatus ends, global warming looks set to be rapid."

The impact of the trade winds on global average temperatures is caused by the winds forcing heat to accumulate below surface of the Western Pacific Ocean.

"This pumping of heat into the ocean is not very deep, however, and once the winds abate, heat is returned rapidly to the atmosphere" England explains.
"Climate scientists have long understood that global average temperatures don't rise in a continual upward trajectory, instead warming in a series of abrupt steps in between periods with more-or-less steady temperatures. Our work helps explain how this occurs," said Prof England.

"We should be very clear: the current hiatus offers no comfort - we are just seeing another pause in warming before the next inevitable rise in global temperatures."

http://phys.org/news/2014-02-pacific-stall-global-surface-warmingfor.html#jCp

 

---------------------------------------------------------------------------------------------------------------------------

[knocker]

Recent decades likely wettest in four millennia in Tibet

Researchers looked at 3,500-year-long tree ring records from North East Tibet to estimate annual precipitation. They found that recent decades have likely been the wettest on record in this semi-arid region.

 

Recent decades may have been the wettest in 3,500 years in North East Tibet – according to climate researchers at the University of East Anglia (UK) and the Chinese Academy of Sciences (Lanzhou, China).

 

http://www.uea.ac.uk/mac/comm/media/press/2014/February/tibet-rainfall

Edited February 11, 2014 by knocker

[knocker]

Radiative and dynamical contributions to past and future Arctic stratospheric temperature trends

 

Abstract. Arctic stratospheric ozone depletion is closely linked to the occurrence of low stratospheric temperatures. There are indications that cold winters in the Arctic stratosphere have been getting colder, raising the question if and to what extent a cooling of the Arctic stratosphere may continue into the future. We use meteorological reanalyses from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim and NASA's Modern-Era Retrospective-Analysis for Research and Applications (MERRA) for the past 32 yr together with calculations of the chemistry-climate model (CCM) ECHAM/MESSy Atmospheric Chemistry (EMAC) and models from the Chemistry-Climate Model Validation (CCMVal) project to infer radiative and dynamical contributions to long-term Arctic stratospheric temperature changes. For the past three decades the reanalyses show a warming trend in winter and cooling trend in spring and summer, which agree well with trends from the Radiosonde Innovation Composite Homogenization (RICH) adjusted radiosonde data set. Changes in winter and spring are caused by a corresponding change of planetary wave activity with increases in winter and decreases in spring. During winter the increase of planetary wave activity is counteracted by a residual radiatively induced cooling. Stratospheric radiatively induced cooling is detected throughout all seasons, being highly significant in spring and summer. This means that for a given dynamical situation, according to ERA-Interim the annual mean temperature of the Arctic lower stratosphere has been cooling by −0.41 ± 0.11 K decade^−1 at 50 hPa over the past 32 yr. Calculations with state-of-the-art models from CCMVal and the EMAC model qualitatively reproduce the radiatively induced cooling for the past decades, but underestimate the amount of radiatively induced cooling deduced from reanalyses. There are indications that this discrepancy could be partly related to a possible underestimation of past Arctic ozone trends in the models. The models project a continued cooling of the Arctic stratosphere over the coming decades (2001–2049) that is for the annual mean about 40% less than the modeled cooling for the past, due to the reduction of ozone depleting substances and the resulting ozone recovery. This projected cooling in turn could offset between 15 and 40% of the Arctic ozone recovery.

 

http://www.atmos-chem-phys.net/14/1679/2014/acp-14-1679-2014.pdf

[knocker]

Sea-ice extent and its trend provide limited metrics of model performance

 

Abstract. We examine how the evaluation of modelled sea-ice coverage against reality is affected by uncertainties in the retrieval of sea-ice coverage from satellite, by the usage of sea-ice extent to overcome these uncertainties, and by internal variability. We find that for Arctic summer sea ice, model biases in sea-ice extent can be qualitatively different from biases in sea-ice area. This is because about half of the CMIP5 models and satellite retrievals based on the Bootstrap and the ASI algorithm show a compact ice cover in summer with large areas of high-concentration sea ice, while the other half of the CMIP5 models and satellite retrievals based on the NASA Team algorithm show a loose ice cover. For the Arctic winter sea-ice cover, differences in grid geometry can cause synthetic biases in sea-ice extent that are larger than the observational uncertainty. Comparing the uncertainty arising directly from the satellite retrievals with those that arise from internal variability, we find that the latter by far dominates the uncertainty estimate for trends in sea-ice extent and area: most of the differences between modelled and observed trends can simply be explained by internal variability. For absolute sea-ice area and sea-ice extent, however, internal variability cannot explain the difference between model and observations for about half the CMIP5 models that we analyse here. All models that we examined have regional biases, as expressed by the root-mean-square error in concentration, that are larger than the differences between individual satellite algorithms.

http://www.the-cryosphere.net/8/229/2014/tc-8-229-2014.pdf

[knocker]

Increase in Arctic Cyclones is Linked to Climate Change, New Study Shows

 

Winter in the Arctic is not only cold and dark, it is also storm season when hurricane-like cyclones traverse the northern waters from Iceland to Alaska. These cyclones are characterized by strong localized drops in sea level pressure, and as Arctic-wide decreases in sea level pressure are one of the expected results of climate change, this could increase extreme Arctic cyclone activity, including powerful storms in the spring and fall.

 

A new study in Geophysical Research Letters uses historical climate model simulations to demonstrate that there has been an Arctic-wide decrease in sea level pressure since the 1800's.

 

“This research shows that the Arctic appears to be expressing symptoms expected from ongoing climate change,†said Dr. Stephen Vavrus from the University of Wisconsin-Madison. “The long-term decline in atmospheric pressure over most of the Arctic is consistent with the response typically simulated by climate models to greenhouse warming, and this study finds a general corresponding increase in the frequency of extreme Arctic cyclones since the middle 19th century.â€

 

Tracking changes in Arctic cyclone activity through time, Vavrus calculated a statistically significant, though minor, increase in extreme Arctic cyclone frequency over the study period, with increases strongest near the Aleutian Islands and Iceland. Dr. Vavrus suggests that, as of yet, the effect of climate change on Arctic cyclone activity has been minimal, but that future changes in polar climate will drive stronger shifts.

 

“One societally relevant implication is that more storminess probably means more erosion of Arctic coastlines, especially in tandem with declines in buffering sea ice cover and increases in thawing coastal permafrost,†concluded Dr. Varnus. “Erosion of Arctic coastlines has already been growing more severe during recent decades, and this study points to a contributing factor that will likely become an even more recognizable culprit in the future.â€

 

http://eu.wiley.com/WileyCDA/PressRelease/pressReleaseId-110301.html

Edited February 18, 2014 by knocker

[knocker]

Small Volcanic Eruptions Add to Larger Impact on Climate

 

The recent slow down in global warming has been attributed to a number of factors, including excess heat being stored in the deep ocean and reductions of certain greenhouse gases. Now add volcanic eruptions to the mix of contributing factors.

 

A new analysis published in Nature Geosciences on Sunday shows that a series of relatively small eruptions since 2000 have likely helped dampened the rise in temperatures.

 

 

http://www.climatecentral.org/news/small-volcanic-eruptions-add-to-larger-impact-on-climate-17112

Edited February 24, 2014 by knocker

[knocker]

Understanding and attributing the Euro-Russian summer blocking signatures

 

 

Abstract

In this work, we focus on summer blocking events over the Euro-Russian region related with heat waves. An analysis of the main characteristics of summer Euro-Russian blocking events in global Reanalysis as well as in the 20th century CLIVAR atmospheric simulations is carried out to assess whether anthropogenic forcing might have affected the blocking events occurrence and the associated heat waves strength in recent decades. Over the Euro-Russian region, blocking episodes, associated to warm events over Northern and Central Europe, become significantly longer in the second half of the century when the anthropogenic forcing is included in the simulations.

 

http://onlinelibrary.wiley.com/doi/10.1002/asl2.490/abstract

[knocker]

Funny that this should turn up now.

 

Dartmouth-led research shows temperature, not snowfall, driving tropical glacier size

 

Temperature, not snowfall, has been driving the fluctuating size of Peru's Quelccaya Ice Cap, whose dramatic shrinkage in recent decades has made it a symbol for global climate change, a Dartmouth-led study shows.

 

The findings support many scientists' suspicions that tropical glaciers are rapidly shrinking because of a warming climate, and will help scientists to better understand the natural variability of past and modern climate and to refine models that predict tropical glaciers' response to future climate change.

 

http://www.sciencecodex.com/dartmouthled_research_shows_temperature_not_snowfall_driving_tropical_glacier_size-128600

[The PIT]

Mmmm interesting http://www.theregister.co.uk/2014/02/27/natural_pine_aerosols_could_prevent_climate_change_really_being_a_problem/

[johnholmes]

Mmmm interesting http://www.theregister.co.uk/2014/02/27/natural_pine_aerosols_could_prevent_climate_change_really_being_a_problem/

 

ys that was on the BBC News web site, not sure if it is still there?

 

yes it is, link below

http://www.bbc.co.uk/news/science-environment-26340038

Edited February 27, 2014 by johnholmes

[knocker]

A slight problem with that John and also the rapid warming prior to the turn of the century to quote Scott A Mandia, Co-founder Climate Science Rapid Response Team (http://climaterapidresponse.org ) & Climate Science Legal Defense Fund (http://climatesciencedefensefund.org )

 

"Never ceases to amaze me how "no warming" can melt ice, heat oceans, break record temps, raise sea levels, etc"

Edited February 27, 2014 by knocker

[knocker]

How Ancient Greek Plays Allow us to Reconstruct Europe’s Climate

 

The open air plays of the ancient Greeks may offer us a valuable insight into the Mediterranean climate of the time, reports new research in Weather. Using historical observations from artwork and plays, scientists identified ‘halcyon days’, of theatre friendly weather in mid-winter.

 

“We explored the weather conditions which enabled the Athenians of the classical era to watch theatre performances in open theatres during the midwinter weather conditions,†said Christina Chronopoulou, from the National and Kapodestrian University of Athens. “We aimed  to do so by gathering and interpreting information from the classical plays of Greek drama from 5^th and 4^th centuries B.C.â€

 

Ancient Athenians would enjoy the open theatre of Dionysus in the southern foothills of the Acropolis and when possible  they would have watched drama in the middle of winter between 15 January and 15 February.

 

From Second World War bombing raids, to medieval Arabic writings  historians and climatologists continue to turn to surprising sources to help piece together the climate of our ancestors. In this case the team turned to the writings of 43 plays by Aeschylus, Sophocles, Euripides and Aristophanes and several were found to contain references about the weather. Greece enjoys long, hot, dry summers, yet in contrast the rare theatre friendly ‘halcyon days’ of clear, sunny weather during winter appeared to be especially noteworthy.

 

“The comedies of Aristophanes, often invoke the presence of the halcyon days,†concluded said Dr. Chronopoulou. “Combining the fact that dramatic contests were held in mid-winter without any indication of postponement, and references from the dramas about the clear weather and mild winters, we can assume that those particular days of almost every January were summery in the fifth and maybe in the fourth centuries BC.â€

 

http://eu.wiley.com/WileyCDA/PressRelease/pressReleaseId-110387.html

[knocker]

The European climate under a 2 C global warming

 

 

Paper

A global warming of 2 °C relative to pre-industrial climate has been considered as a threshold which society should endeavor to remain below, in order to limit the dangerous effects of anthropogenic climate change. The possible changes in regional climate under this target level of global warming have so far not been investigated in detail. Using an ensemble of 15 regional climate simulations downscaling six transient global climate simulations, we identify the respective time periods corresponding to 2 °C global warming, describe the range of projected changes for the European climate for this level of global warming, and investigate the uncertainty across the multi-model ensemble. Robust changes in mean and extreme temperature, precipitation, winds and surface energy budgets are found based on the ensemble of simulations. The results indicate that most of Europe will experience higher warming than the global average. They also reveal strong distributional patterns across Europe, which will be important in subsequent impact assessments and adaptation responses in different countries and regions. For instance, a North–South (West–East) warming gradient is found for summer (winter) along with a general increase in heavy precipitation and summer extreme temperatures. Tying the ensemble analysis to time periods with a prescribed global temperature change rather than fixed time periods allows for the identification of more robust regional patterns of temperature changes due to removal of some of the uncertainty related to the global models' climate sensitivity.

 

http://iopscience.iop.org/1748-9326/9/3/034006/pdf/1748-9326_9_3_034006.pdf

[knocker]

Analyses of trends in air temperature in the United Kingdom using gridded data series from 1910 to 2011

 

Abstract

Gridded temperature datasets covering the UK at 5 km × 5 km resolution have been analysed for temporal and spatial patterns of change and variability. Decadal-scale variability is visualized by smoothing the data series using a kernel smoother. Trends have been analysed by comparing averages for a baseline period with averages for a recent period, as well as using linear regression. Spatial patterns of change have been mapped by calculating trends for each grid point.

 

Monthly gridded datasets of daily maximum, minimum and mean air temperatures are available from 1910 to date. These show statistically significant increases for all parts of the UK, with the rate of change increasing from the north and west to the south and east. Seasonally, the least significant changes have occurred in the winter, with significant increases for most districts for all of the other seasons.

 

Derived indices based on daily temperature are available from 1961 onwards. There have been significant decreases in heating degree days and increases in growing degree days for all districts, while changes in cooling degree days are less significant as the values are low and inter-annual variability dominates. There have been significant decreases in frost days, especially in spring and autumn, and this is linked to significant increases in growing season length, especially for Scotland.

 

http://onlinelibrary.wiley.com/doi/10.1002/joc.3944/abstract;jsessionid=BF9BAAF7D1FA450E452FB70B5E34E58D.f03t04

Edited March 8, 2014 by knocker

[knocker]

Poleward ocean heat transports, sea ice processes and Arctic sea ice variability in NorESM1-M simulations

 

Abstract

Results from the NorESM1-M coupled climate model were used to examine relationships between Arctic sea ice area and ocean heat transports through the primary Arctic gateways. Comparisons were made with two other models (CNRM-CM5, MRI-CGM3) that are part of the CMIP5 archive which have the required outputs for calculating ocean heat transports. Based on an evaluation, NorESM1-M was found to be best suited to study the effects of heat transports on sea ice area, and conclusions are based on results from this model. The Artic Ocean was divided into two regions, the Barents Sea and the Central Arctic Ocean. The sea ice area variability was further analyzed in terms of frazil and congelation growth, top and bottom melting, and heat transports in the Barents Sea Opening (BSO) and the Fram Strait (FS). In the Barents Sea, increased heat transport in the BSO has a strong influence on sea ice area in terms of reduced congelation growth, while bottom melting is important for the variability in the Central Arctic Ocean. The negative trend in sea ice area is considerably greater in the Barents Sea than in the Central Arctic Ocean, despite the Central Arctic Ocean area being much larger, and reflects the major trend in the BSO heat transport. The model results in this study suggest that the ocean has stronger direct impact on changes in sea ice mass in terms of freezing and melting than the atmosphere, both in the mean and with respect to variability.

 

http://onlinelibrary.wiley.com/doi/10.1002/2013JC009435/abstract?utm_content=buffercf345&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[skadi]

Contact: Heath Jeffries
jeffrieshv1@cardiff.ac.uk
44-790-882-4029
 Sun's energy influences 1,000 years of natural climate variability in North Atlantic  

 IMAGE: This is a composite created from three images received from MODIS instruments carried on NASA's Terra and Aqua polar orbiting satellites. The images were received at the Dundee Satellite Receiving...

Click here for more information.

 

Changes in the sun's energy output may have led to marked natural climate change in Europe over the last 1000 years, according to researchers at Cardiff University.

Scientists studied seafloor sediments to determine how the temperature of the North Atlantic and its localised atmospheric circulation had altered. Warm surface waters flowing across the North Atlantic, an extension of the Gulf Stream, and warm westerly winds are responsible for the relatively mild climate of Europe, especially in winter. Slight changes in the transport of heat associated with these systems can led to regional climate variability, and the study findings matched historic accounts of climate change, including the notoriously severe winters of the 16th and 18th centuries which pre-date global industrialisation.

The study found that changes in the Sun's activity can have a considerable impact on the ocean-atmospheric dynamics in the North Atlantic, with potential effects on regional climate.

Predictions suggest a prolonged period of low sun activity over the next few decades, but any associated natural temperature changes will be much smaller than those created by human carbon dioxide emissions, say researchers.

The study, led by Cardiff University scientists, in collaboration with colleagues at the University of Bern, is published today in the journal Nature Geoscience.

Dr Paola Moffa-Sanchez, lead author from Cardiff University School of Earth and Ocean Sciences, explained: "We used seafloor sediments taken from south of Iceland to study changes in the warm surface ocean current. This was done by analysing the chemical composition of fossilised microorganisms that had once lived in the surface of the ocean. These measurements were then used to reconstruct the seawater temperature and the salinity of this key ocean current over the past 1000 years."

The results of these analyses revealed large and abrupt temperature and salinity changes in the north-flowing warm current on time-scales of several decades to centuries. Cold ocean conditions were found to match periods of low solar energy output, corresponding to intervals of low sunspot activity observed on the surface of the sun. Using a physics-based climate model, the authors were able to test the response of the ocean to changes in the solar output and found similar results to the data.

"By using the climate model it was also possible to explore how the changes in solar output affected the surface circulation of the Atlantic Ocean," said Prof Ian Hall, a co-author of the study. "The circulation of the surface of the Atlantic Ocean is typically tightly linked to changes in the wind patterns. Analysis of the atmosphere component in the climate model revealed that during periods of solar minima there was a high-pressure system located west of the British Isles. This feature is often referred to as atmospheric blocking, and it is called this because it blocks the warm westerly winds diverting them and allowing cold Arctic air to flow south bringing harsh winters to Europe, such as those recently experienced in 2010 and 2013."

Meteorological studies have previously found similar effects of solar variability on the strength and duration of atmospheric winter blockings over the last 50 years, and although the exact nature of this relationship is not yet clear, it is thought to be due to complex processes happening in the upper layers of the atmosphere known as the stratosphere.

Dr Paola Moffa-Sanchez added: "In this study we show that this relationship is also at play on longer time-scales and the large ocean changes, recorded in the microfossils, may have helped sustain this atmospheric pattern. Indeed we propose that this combined ocean-atmospheric response to solar output minima may help explain the notoriously severe winters experienced across Europe between the 16th and 18th centuries, so vividly depicted in many paintings, including those of the famous London Frost Fairs on the River Thames, but also leading to extensive crop failures and famine as corroborated in the record of wheat prices during these periods."

The study concludes that although the temperature changes expected from future solar activity are much smaller than the warming from human carbon dioxide emissions, regional climate variability associated with the effects of solar output on the ocean and atmosphere should be taken into account when making future climate projections.

 

###

 

Notes for Editors:

Funding for this research has come from the Natural Environment Research Council, UK, the National Science Foundation, Switzerland, the European Commission and NCAR's Computational and Information Systems Laboratory (CISL). This research forms part of the Climate Change Consortium of Wales (C3W; http://c3wales.org/).

To arrange media interviews with Professor Ian Hall or Dr Paola Moffa-Sanchez, please contact Heath Jeffries, Media Manager, Cardiff University, on 07908 824029 or 02920 870917; email jeffrieshv1@cardiff.ac.uk

Cardiff University is recognised in independent government assessments as one of Britain's leading teaching and research universities and is a member of the Russell Group of the UK's most research intensive universities. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, University Chancellor Professor Sir Martin Evans. Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University's breadth of expertise encompasses: the College of Arts, Humanities and Social Sciences; the College of Biomedical and Life Sciences; and the College of Physical Sciences, along with a longstanding commitment to lifelong learning. Cardiff's four flagship Research Institutes are offering radical new approaches to cancer stem cells, catalysis, neurosciences and mental health and sustainable places.

Edited March 9, 2014 by skadi

[knocker]

Just to add the severe winters, and summers, between the 16th and 18th centuries could be said to be global.

[knocker]

UEA research reveals four new man-made gases in the atmosphere

 

Scientists at the University of East Anglia have identified four new man-made gases in the atmosphere – all of which are contributing to the destruction of the ozone layer.

New research published today in the journal Nature Geoscience reveals that more than 74,000 tonnes of three new chlorofluorocarbons (CFCs) and one new hydrochlorofluorocarbon (HCFC) have been released into the atmosphere.

 

http://www.uea.ac.uk/mac/comm/media/press/2014/March/new-CFCs

[knocker]

Impact of a 30% reduction in Atlantic meridional overturning during 2009–2010

 

 

AbstractThe Atlantic meridional overturning circulation comprises warm upper waters flowing northward, becoming colder and denser until they form deep water in the Labrador and Nordic Seas that then returns southward through the North and South Atlantic. The 5 ocean heat transport associated with this circulation is 1.3PW, accounting for 25% of the maximum combined atmosphere–ocean heat transport necessary to balance the earth’s radiation budget. We have been monitoring the circulation at 25 N since 2004. A 30% slowdown in the circulation for 15 months during 2009–2010 reduced northward ocean heat transport across 25 N by 0.4PW and resulted in colder upper 10 ocean waters north of 25 N and warmer waters south of 25 N. The spatial pattern of upper ocean temperature anomalies helped push the wintertime circulation 2010–2011 into record-low negative NAO conditions with accompanying severe winter conditions over northwestern Europe. The warmer temperatures south of 25 N contributed to the high intensity hurricane season in Summer 2010.

 

 

http://www.ocean-sci-discuss.net/11/789/2014/osd-11-789-2014.pdf

[knocker]

Can't remember if this paper has been posted or not.

 

Distinctive climate signals in reanalysis of global ocean heat content

 

 

The elusive nature of the post-2004 upper ocean warming has exposed uncertainties in the ocean’s role in the Earth’s energy budget and transient climate sensitivity.Here we present the time evolution of the global ocean heat content for 1958 through 2009 from a new observation based reanalysis of the ocean. Volcanic eruptions andEl Niño events are identified as sharp cooling events punctuating a long-term ocean warming trend, while heating continues during the recent upper-ocean-warming hiatus, but the heat is absorbed in the deeper ocean. In the last decade, about 30% of the warming has occurred below 700 m, contributing significantly to an acceleration of the warming trend. The warming below 700 m remains even when the Argo observing system is withdrawn although the trends are reduced. Sensitivity experiments illustrate that surface wind variability is largely responsible for the changing ocean heat vertical distribution. Citation: Balmaseda, M. A., K. E. Trenberth, and E. Källén (2013), Distinctive climate signals in reanalysis of global ocean heat content, Geophys. Res. Lett., 40, doi:10.1002/grl.50382. 

 

http://www.cgd.ucar.edu/cas/Trenberth/website-archive/trenberth.papers-moved/Balmaseda_Trenberth_Kallen_grl_13.pdf

[knocker]

The rush to rain

 

Dust kicked up in Asia strengthens Indian monsoon within a week

 

http://www.eurekalert.org/pub_releases/2014-03/dnnl-trt031214.php

Edited March 16, 2014 by knocker

[knocker]

Climatologists offer explanation for widening of Earth's tropical belt

 

UC Riverside-led research points to the Pacific Decadal Oscillation and anthropogenic pollutants

RIVERSIDE, Calif. — Recent studies have shown that the Earth's tropical belt — demarcated, roughly, by the Tropics of Cancer and Capricorn — has progressively expanded since at least the late 1970s. Several explanations for this widening have been proposed, such as radiative forcing due to greenhouse gas increase and stratospheric ozone depletion.

 

Now, a team of climatologists, led by researchers at the University of California, Riverside, posits that the recent widening of the tropical belt is primarily caused by multi-decadal sea surface temperature variability in the Pacific Ocean. This variability includes the Pacific Decadal Oscillation (PDO), a long-lived El Niño-like pattern of Pacific climate variability that works like a switch every 30 years or so between two different circulation patterns in the North Pacific Ocean. It also includes, the researchers say, anthropogenic pollutants, which act to modify the PDO.

 

http://www.eurekalert.org/pub_releases/2014-03/uoc--coe031714.php

 

Abstract

 

 

The tropical belt has widened by several degrees latitude since 1979, as evidenced by shifts in atmospheric circulation and climate zones^{1, 2, 3, 4, 5}. Global climate models also simulate tropical belt widening, but less so than observed^{6, 7}. Reasons for this discrepancy and the mechanisms driving the expansion are uncertain. Here we analyse multidecadal variability in tropical belt width since 1950 using the Coupled Model Intercomparison Project Phase 5 climate model runs and find that simulated rates of tropical expansion over the past 30 years—particularly in the Northern Hemisphere—are in better agreement with observations than previous models. We find that models driven by observed sea surface temperatures over this interval yield the largest rate of tropical expansion. We link the tropical expansion in the Northern Hemisphere to the leading pattern of sea surface temperature variability in the North Pacific, the Pacific Decadal Oscillation. We also find, both from models and observations, that the tropical belt contracted in the Northern Hemisphere from 1950 to 1979, coincident with the reversal of the Pacific Decadal Oscillation trend. In both time periods, anthropogenic aerosols act to modify the Pacific Decadal Oscillation and therefore contribute to the width of the tropical belt. We conclude that tropical expansion and contraction are influenced by multidecadal sea surface temperature variability associated with both the Pacific Decadal Oscillation and anthropogenic aerosols.

 

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2091.html

[Gray-Wolf]

As oceans warm PDO trigger temps become muddied. How does this play into more recent observations? Should we lose Arctic sea ice could we also lose the polar Jet? how would the rapid northerly migration of the sub tropical Jet impact the belt widths?