New Research

[knocker]

GCM drought projections

 

http://www.ldeo.columbia.edu/~jsmerdon/papers/2014_clidyn_cooketal.pdf

[knocker]

Disappearing semi-permanent snow in the High Arctic and its consequences

 

Abstract:

Semi-permanent snow is part of the continuum between seasonal snow and glacier ice. Although ubiquitous in the High Arctic, most late-lying snow banks and snow beds have lost their perennial status over the past decade as the summers have become progressively warmer. The loss over the past decade is the most unprecedented since aerial photography of the Canadian Arctic islands was first undertaken over half a century ago, and it has produced observable thermal, hydrological and ecological impacts. Where the ground has become exposed beneath the perennial snow cover, seasonal ground thaw has deepened. Tundra ponds and patchy wetlands fed principally by meltwater in the summer have suffered water-level decline or desiccation. The water balance of headwater basins is also affected, losing a buffering vehicle that accumulates storage surplus from the wet cool years to support streamflow and evaporation in the dry warm years. The tundra vegetation, already sparse, undergoes changes in the long term. As an essential source of water in the polar desert environment, the widespread distribution of semi-permanent snow magnifies its Arctic-wide importance.

 

http://www.ingentaconnect.com/content/igsoc/jog/2014/00000060/00000219/art00018?utm_content=buffer10213&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Blasted paywalls!

 

High predictability of the winter Euro–Atlantic climate from cryospheric variability

 

Seasonal prediction skill for surface winter climate in the Euro–Atlantic sector has been limited so far^{1, 2, 3}. In particular, the predictability of the winter North Atlantic Oscillation, the mode that largely dominates regional atmospheric and climate variability, remains a hurdle for present dynamical prediction systems^{4, 5}. Statistical forecasts have also been largely elusive^{6, 7, 8}, but October Eurasian snow cover has been shown to be a robust source of regional predictability^{9, 10}. Here we use maximum covariance analysis to show that Arctic sea-ice variability represents another good predictor of the winter Euro–Atlantic climate at lead times of as much as three months. Cross-validated hindcasts of the winter North Atlantic Oscillation index using September sea-ice anomalies yield a correlation skill of 0.59 for the period 1979/1980–2012/2013, suggesting that 35% of its variance could be predicted three months in advance. This skill can be further enhanced, at the expense of a shorter lead time, by using October Eurasian snow cover as an additional predictor. Skilful predictions of winter European surface air temperature and precipitation are also obtained with September sea ice as the only predictor. We conclude that it is important to incorporate Arctic sea-ice variability in seasonal prediction systems.

 

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2118.html?utm_content=buffere8aa3&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

[knocker]

Effect of important air pollutants may be absent from key precipitation observations

 

Pioneering new research from the University of Exeter could have a major impact on climate and environmental science by drastically transforming the perceived reliability of key observations of precipitation, which includes rain, sleet and snow.Read more at: http://phys.org/news/2014-03-effect-important-air-pollutants-absent.html#jCp

[knocker]

Linkages Between Arctic Warming and Mid-Latitude Weather Patterns Report Available

 

The US National Academy's Board on Atmospheric Sciences and Climate and the Polar Research Board are pleased to announce the release of a new workshop summary: Linkages Between Arctic Warming and Mid-Latitude Weather Patterns. The PDF of the prepublication version of the report is available for free download from the National Academies Press here: http://dels.nas.edu/Workshop-Summary/Linkages-Between-Arctic-Warming/18727?bname=basc

[knocker]

The Atlantic Ocean dances with the Sun and volcanoes

 

Natural fluctuations in the ocean temperature in the North Atlantic have a significant impact on the climate in the northern hemisphere. These fluctuations are the result of a complex dance between the forces of nature, but researchers at Aarhus University can now show that solar activity and the impact of volcanic eruptions have led this dance during the last two centuries.

 

http://scitech.au.dk/en/roemer/mar14/atlanterhavet-danser-med-solen-og-vulkaner/

[knocker]

Natural variation: Warm North Atlantic Ocean promotes extreme winters in US and Europe

 

The extreme cold weather observed across Europe and the east coast of the US in recent winters could be partly down to natural, long-term variations in sea surface temperatures, according to a new study. Researchers have shown that a phenomenon known as the Atlantic Multidecadal Oscillation (AMO) -- a natural pattern of variation in North Atlantic sea surface temperatures that switches between a positive and negative phase every 60-70 years -- can affect an atmospheric circulation pattern, known as the North Atlantic Oscillation (NAO), that influences the temperature and precipitation over the Northern Hemisphere in winter.

 

http://www.sciencedaily.com/releases/2014/04/140401210414.htm

Edited April 2, 2014 by knocker

[knocker]

 

A current paper in Nature from a long list of authors, including Neukom, Gergis and Karoly, on Southern Hemisphere proxies, is attracting attention. It's emphasis is on inter-hemispheric comparisons. The paper is here, the extensive SI here, and the data here. A press release is here.There are critical posts at WUWT (here and here) and at Climate Audit.So far I don't have an opinion on the study itself. But as with previous studies by Marcott et al and Pages2K, I have posted an active viewer, which gives easy access to plots and metadata. It's below the jump.

 

http://moyhu.blogspot.co.uk/2014/04/active-viewer-for-neukom-et-al-proxies.html

[knocker]

Less winter cloud aids summer 2013 Arctic sea ice return from 2012 minimum

 

n September 2012, Arctic sea ice cover reached a record minimum for the satellite era. The following winter the sea ice quickly returned, carrying through to the summer when ice extent was 48% greater than the same time in 2012. Most of this rebound in the ice cover was in the Chukchi and Beaufort Seas, areas experiencing the greatest decline in sea ice over the last three decades. A variety of factors, including ice dynamics, oceanic and atmospheric heat transport, wind, and solar insolation anomalies, may have contributed to the rebound. Here we show that another factor, below-average Arctic cloud cover in January–February 2013, resulted in a more strongly negative surface radiation budget, cooling the surface and allowing for greater ice growth. More thick ice was observed in March 2013 relative to March 2012 in the western Arctic Ocean, and the areas of ice growth estimated from the negative cloud cover anomaly and advected from winter to summer with ice drift data, correspond well with the September ice concentration anomaly pattern. Therefore, decreased wintertime cloud cover appears to have played an important role in the return of the sea ice cover the following summer, providing a partial explanation for large year-to-year variations in an otherwise decreasing Arctic sea ice cover.

 

http://iopscience.iop.org/1748-9326/9/4/044002/pdf/1748-9326_9_4_044002.pdf

[knocker]

Evidence of increasing drought severity caused by temperature rise in southern Europe

 

We use high quality climate data from ground meteorological stations in the Iberian Peninsula (IP) and robust drought indices to confirm that drought severity has increased in the past five decades, as a consequence of greater atmospheric evaporative demand resulting from temperature rise. Increased drought severity is independent of the model used to quantify the reference evapotranspiration. We have also focused on drought impacts to drought-sensitive systems, such as river discharge, by analyzing streamflow data for 287 rivers in the IP, and found that hydrological drought frequency and severity have also increased in the past five decades in natural, regulated and highly regulated basins. Recent positive trend in the atmospheric water demand has had a direct influence on the temporal evolution of streamflows, clearly identified during the warm season, in which higher evapotranspiration rates are recorded. This pattern of increase in evaporative demand and greater drought severity is probably applicable to other semiarid regions of the world, including other Mediterranean areas, the Sahel, southern Australia and South Africa, and can be expected to increasingly co

 

http://iopscience.iop.org/1748-9326/9/4/044001/pdf/1748-9326_9_4_044001.pdf

[Gray-Wolf]

http://www.reportingclimatescience.com/news-stories/article/researchers-find-new-phenomenon-in-atmosphere.html

 

This is interesting.

[knocker]

Researchers find arid areas absorb unexpected amounts of atmospheric carbon

http://www.sciencecodex.com/researchers_find_arid_areas_absorb_unexpected_amounts_of_atmospheric_carbon-131217

[knocker]

DECADAL CLIMATE PREDICTION

 

An Update from the Trenches

 

http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-12-00241.1

[knocker]

No 'permanent El Nino,' scientists say—and the tropics may get even hotter

 

New research by Yale University scientists challenges a long-standing paradigm for temperature variability in the Pacific Ocean, casting doubt on the existence of a past period of "permanent" El Niño-like conditions and suggesting that the tropics could grow markedly hotter.Read more at: http://phys.org/news/2014-04-permanent-el-nino-scientists-sayand.html#jCp

[BornFromTheVoid]

Statistical analysis rules out natural-warming hypothesis with more than 99% certainty

An analysis of temperature data since 1500 all but rules out the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate, according to a new study by McGill University physics professor Shaun Lovejoy.

The study, published online April 6 in the journal Climate Dynamics, represents a new approach to the question of whether global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels. Rather than using complex computer models to estimate the effects of greenhouse-gas emissions, Lovejoy examines historical data to assess the competing hypothesis: that warming over the past century is due to natural long-term variations in temperature.

“This study will be a blow to any remaining climate-change deniers,†Lovejoy says. “Their two most convincing arguments – that the warming is natural in origin, and that the computer models are wrong – are either directly contradicted by this analysis, or simply do not apply to it.â€

 

More here http://www.mcgill.ca/research/channels/news/global-warming-just-giant-natural-fluctuation-235236

The study itself Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming

[VillagePlank]

Statistical analysis rules out natural-warming hypothesis with more than 99% certainty

An analysis of temperature data since 1500 all but rules out the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate, according to a new study by McGill University physics professor Shaun Lovejoy.

The study, published online April 6 in the journal Climate Dynamics, represents a new approach to the question of whether global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels. Rather than using complex computer models to estimate the effects of greenhouse-gas emissions, Lovejoy examines historical data to assess the competing hypothesis: that warming over the past century is due to natural long-term variations in temperature.

“This study will be a blow to any remaining climate-change deniers,†Lovejoy says. “Their two most convincing arguments – that the warming is natural in origin, and that the computer models are wrong – are either directly contradicted by this analysis, or simply do not apply to it.â€

 

More here http://www.mcgill.ca/research/channels/news/global-warming-just-giant-natural-fluctuation-235236

The study itself Scaling fluctuation analysis and statistical hypothesis testing of anthropogenic warming

 

Their conclusions fail on a Type II error basis. Very last paragraph of the pre-published piece (so it could be the case that peer-review has got them to edit out that part of their conclusions) They assumed that CO₂ could be used as a proxy for all non-natural climate phenomena and subsequently use a linear model which we know to be incorrect.

Edited April 12, 2014 by Sparkicle

[knocker]

Interesting

 

Climate paradox deciphered from the Miocene era

 

A supposed climate paradox from the Miocene era has been deciphered by means of complex model simulations. When the Antarctic ice sheet grew to its present-day size around 14 million years ago, it did not get colder everywhere on the Earth, but there were regions that became warmer. This appears to be a physical contradiction, and this research aims to address that.

 

http://www.sciencedaily.com/releases/2014/04/140411103128.htm?utm_source=twitterfeed&utm_medium=twitter&utm_campaign=Feed%3A+Cryonews+%28CryoNews%29

Edited April 13, 2014 by knocker

[knocker]

El Niño modulations over the past seven centuries

 

Predicting how the El Niño/Southern Oscillation (ENSO) will change with global warming is of enormous importance to society^{1, 2, 3, 4}. ENSO exhibits considerable natural variability at interdecadal–centennial timescales⁵. Instrumental records are too short to determine whether ENSO has changed⁶ and existing reconstructions are often developed without adequate tropical records. Here we present a seven-century-long ENSO reconstruction based on 2,222 tree-ring chronologies from both the tropics and mid-latitudes in both hemispheres. The inclusion of tropical records enables us to achieve unprecedented accuracy, as attested by high correlations with equatorial Pacific corals^{7, 8} and coherent modulation of global teleconnections that are consistent with an independent Northern Hemisphere temperature reconstruction⁹. Our data indicate that ENSO activity in the late twentieth century was anomalously high over the past seven centuries, suggestive of a response to continuing global warming. Climate models disagree on the ENSO response to global warming^{3, 4}, suggesting that many models underestimate the sensitivity to radiative perturbations. Illustrating the radiative effect, our reconstruction reveals a robust ENSO response to large tropical eruptions, with anomalous cooling in the east-central tropical Pacific in the year of eruption, followed by anomalous warming one year after. Our observations provide crucial constraints for improving climate models and their future projections.

 

http://www.nature.com/nclimate/journal/v3/n9/full/nclimate1936.html

[knocker]

Twice Is Nice! Double counting evidence in climate model confirmation

 

 

Charlotte Werndl (LSE) is speaking at Western University on Monday (the talk will be live-streamed) on evidence and climate change modeling. Having recently read her paper (with co-author Katie Steele) entitled “Climate Models, Calibration, and Confirmation†(CMCC) I thought I would post about it. The paper focuses on the use of evidence in confirming climate models with particular attention paid to double counting, which in this context means using the same evidence for two purposes (more on this use of the term later). I believe the paper is an important one, as it nicely separates concerns about double counting from other, related, confirmatory issues, and I think successfully shows where a form of double counting is legitimate. Still, despite being a casual fan of Bayesianism, I wonder if it gives us what we want in this particular circumstance. I can’t cover all the threads of argument made in the paper, so here I’ll simply discuss what double counting is, why we should worry about it, and how Steele and Werndl (S+W) argue that it could be legitimate in some circumstances.

 

http://thebubblechamber.org/2014/04/twice-is-nice-double-counting-evidence-in-climate-model-confirmation/

Edited April 14, 2014 by knocker

[knocker]

Probable causes of the abnormal ridge accompanying the 2013-14 California drought: ENSO precursor and anthropogenic warming footprint

 

Abstract

The 2013-14 California drought was accompanied by an anomalous high-amplitude ridge system. The anomalous ridge was investigated using reanalysis data and the Community Earth System Model (CESM). It was found that the ridge emerged from continual sources of Rossby wave energy in the western North Pacific starting in late summer, and subsequently intensified into winter. The ridge generated a surge of wave energy downwind and deepened further the trough over the northeast U.S., forming a dipole. The dipole and associated circulation pattern is not linked directly with either ENSO or Pacific Decadal Oscillation; instead it is correlated with a type of ENSO precursor. The connection between the dipole and ENSO precursor has become stronger since the 1970s, and this is attributed to increased GHG loading as simulated by the CESM. Therefore, there is a traceable anthropogenic warming footprint in the enormous intensity of the anomalous ridge during winter 2013-14, the associated drought and its intensity.

 

http://onlinelibrary.wiley.com/doi/10.1002/2014GL059748/abstract

 

News release.

 

http://news.cisc.gmu.edu/doc/CA_drought_research.pdf

[knocker]

Warm U.S. West, cold East: 4,000-year pattern; Global warming may bring more curvy jet streams during winter

 

Last winter’s curvy jet stream pattern brought mild temperatures to western North America and harsh cold to the East. A new study shows that pattern became more pronounced 4,000 years ago, and suggests it may worsen as Earth’s climate warms.

 

http://www.sciencedaily.com/releases/2014/04/140416090305.htm

[knocker]

Today's Antarctic region once as hot as California, Florida

 

Parts of ancient Antarctica were as warm as today's California coast, and polar regions of the southern Pacific Ocean registered 21st-century Florida heat, according to scientists using a new way to measure past temperatures.

 

The findings, published the week of April 21 in the Proceedings of the National Academy of Sciences, underscore the potential for increased warmth at Earth's poles and the associated risk of melting polar ice and rising sea levels, the researchers said.

 

Led by scientists at Yale, the study focused on Antarctica during the Eocene epoch, 40-50 million years ago, a period with high concentrations of atmospheric CO2 and consequently a greenhouse climate. Today, Antarctica is year-round one of the coldest places on Earth, and the continent's interior is the coldest place, with annual average land temperatures far below zero degrees Fahrenheit.

 

But it wasn't always that way, and the new measurements can help improve climate models used for predicting future climate, according to co-author Hagit Affek of Yale, associate professor of geology & geophysics.

 

"Quantifying past temperatures helps us understand the sensitivity of the climate system to greenhouse gases, and especially the amplification of global warming in polar regions," Affek said.

 

http://www.sciencecodex.com/todays_antarctic_region_once_as_hot_as_california_florida-132150

[knocker]

The upper end of climate model temperature projections is inconsistent with past warming

 

Climate models predict a large range of possible future temperatures for a particular scenario of future emissions of greenhouse gases and other anthropogenic forcings of climate. Given that further warming in coming decades could threaten increasing risks of climatic disruption, it is important to determine whether model projections are consistent with temperature changes already observed. This can be achieved by quantifying the extent to which increases in well mixed greenhouse gases and changes in other anthropogenic and natural forcings have already altered temperature patterns around the globe. Here, for the first time, we combine multiple climate models into a single synthesized estimate of future warming rates consistent with past temperature changes. We show that the observed evolution of near-surface temperatures appears to indicate lower ranges (5–95%) for warming (0.35–0.82 K and 0.45–0.93 K by the 2020s (2020–9) relative to 1986–2005 under the RCP4.5 and 8.5 scenarios respectively) than the equivalent ranges projected by the CMIP5 climate models (0.48–1.00 K and 0.51–1.16 K respectively). Our results indicate that for each RCP the upper end of the range of CMIP5 climate model projections is inconsistent with past warming.

 

http://m.iopscience.iop.org/1748-9326/8/1/014024/pdf/1748-9326_8_1_014024.pdf

[knocker]

Extremes in wet, dry spells increasing for South Asian monsoons, Stanford scholars say

 

Stanford scientists have identified significant changes in the patterns of extreme wet and dry events that are increasing the risk of drought and flood in central India, one of the most densely populated regions on Earth.

 

http://news.stanford.edu/news/2014/april/monsoon-extremes-india-042814.html

[knocker]

New study sheds light on global warming trends

 

TALLAHASSEE, Fla. — New research by a team of Florida State University scientists shows the first detailed look at global land surface warming trends over the last 100 years, illustrating precisely when and where different areas of the world started to warm up or cool down.

 

The research indicates that the world is indeed getting warmer, but historical records show that it hasn't happened everywhere at the same rate.

 

http://www.sciencecodex.com/new_study_sheds_light_on_global_warming_trends-132983