New Research

[knocker]

2012 Great Plains drought not caused by climate change

 

From May to July 2012, the Great Plains region of the western United States faced a powerful and unpredicted drought. Following 7 months of normal rainfall, the drought was one of the largest deviations from seasonal precipitation rates seen in the region since observations began in 1895. When such extreme events take place today against the backdrop of ongoing global climate change, they raise questions about the relationship between climate change and natural disasters.

 

In a new modeling study, Kumar et al. use an ensemble of runs from an operational climate model, initialized with the observed conditions leading up to the 2012 Great Plains drought, to simulate the range of conditions that could have played out during the subsequent months. They find that the drought fell within the bounds of natural atmospheric variability. The strength of the drought, they suggest, was a consequence of the multiple complex nonlinear systems that make up the climate system and did not critically depend on the existence of a strong external forcing.

 

The authors note that their findings do not detract from the idea that climate change could enhance some extreme events. Rather, their research says that climate change was not a first-order forcing of the drought. They say that climate change and other pressures could still serve as “proximate causes,†setting the stage for or enhancing, but not necessarily causing, extreme events. That the drought was driven by natural variability not requiring a steady background forcing, they say, will limit the predictability of similar future extreme events.

Source:

Geophysical Research Letters, doi: 10.1002/grl.50657, 2013

Edited August 13, 2013 by knocker

[Polar Maritime]

Marine Ecosystems heading pole-wards. 

 

Throughout the oceans, plankton and the animals that feed off them are seeking cooler waters as the world warms. As this ecological transformation happens before our eyes over the coming decades everything we thought we knew about the distribution of life in the oceans is going to change beyond recognition. On a more practical level, fisheries will shift from one country's territorial waters into another, exacerbating existing conflicts over this resource that billions rely on as their main source of protein. 

 

A review paper published last week by scientists from 17 institutions in 8 countries summarised decades worth (in some cases up to three centuries) of global data contained in over 1,700 peer reviewed studies covering 857 species, in order to examine the shift in the lifestyles of marine organisms during this period. It was published in Nature Climate Change, and was the first ever study undertaken on a global scale, in preparation for the next IPCC report due out next year. 

Most previous studies were local and focussed on one or a few species over a limited time period. Their database will also serve as a baseline from which to assess future changes as the transformation of the oceans continues. They studied the distribution, movements, demography and life cycle of marine ecosystems and their changes through time. 

 

I leave you with their final conclusion: ' recent climate studies show that patterns of warming of the upper layers of the world’s oceans are significantly related to greenhouse gas forcing. Global responses of marine species revealed here demonstrate a strong fingerprint of this anthropogenic climate change on marine life. Differences in rates of change with climate change amongst species and populations suggest species’ interactions and marine ecosystem functions may be substantially reorganized at the regional scale, potentially triggering a range of cascading effects'.

 

http://www.imedea.uib.es/noticias.php?nid=MTI2Ng%3D%3D

http://www.natureworldnews.com/articles/3353/20130806/oceans-warm-marine-life-moves-poleward-changes-breeding-patterns.htm
http://climatetimes.com/article/marine-species-head-cooler-waters-planet-warms
http://www.futurity.org/earth-environment/sea-creatures-race-toward-cooler-waters/
http://blogs.smithsonianmag.com/smartnews/2013/08/climate-change-is-sending-marine-life-to-the-poles-in-search-of-colder-waters/
Original article, paywall access: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1958.html

Edited August 14, 2013 by Polar Maritime

[knocker]

Extreme weather events fuel climate change

Extreme meteorological events and global warming: a vicious cycle?

 

August 14, 2013

 

When the carbon dioxide content of the atmosphere rises, the Earth not only heats up, but extreme weather events, such as lengthy droughts, heat waves, heavy rain and violent storms, may  become more frequent. Whether these extreme climate events result in the release of more CO₂ from terrestrial ecosystems and thus reinforce climate change has been one of the major unanswered questions in climate research. It has now been addressed by an international team of researchers working with Markus Reichstein, Director at the Max Planck Institute for Biogeochemistry in Jena. They have discovered that terrestrial ecosystems absorb approximately 11 billion tons less carbon dioxide every year as the result of the extreme climate events than they could if the events did not occur. That is equivalent to approximately a third of global CO₂ emissions per year.

 

http://www.mpg.de/7501454/weather-extreme_carbon-cycle_cimate-change

Edited August 14, 2013 by knocker

[knocker]

Historic and future increase in the global land area affected by monthly heat extremes

Climatic warming of about 0.5 ° C in the global mean since the 1970s has strongly increased the occurrence-probability of heat extremes on monthly to seasonal time scales. For the 21st century, climate models predict more substantial warming. Here we show that the multi-model mean of the CMIP5 (Coupled Model Intercomparison Project) climate models accurately reproduces the evolution over time and spatial patterns of the historically observed increase in monthly heat extremes. For the near-term (i.e., by 2040), the models predict a robust, several-fold increase in the frequency of such heat extremes, irrespective of the emission scenario. However, mitigation can strongly reduce the number of heat extremes by the second half of the 21st century. Unmitigated climate change causes most (>50%) continental regions to move to a new climatic regime with the coldest summer months by the end of the century substantially hotter than the hottest experienced today. We show that the land fraction experiencing extreme heat as a function of global mean temperature follows a simple cumulative distribution function, which depends only on natural variability and the level of spatial heterogeneity in the warming.

http://m.iopscience.iop.org/1748-9326/8/3/034018/pdf/1748-9326_8_3_034018.pdf

[knocker]

Antarctic ice core sheds new light on how the last ice age ended

 

Changes in Earth's orbit appear to be key to Antarctic warming

 

 

August 15, 2013

Analysis of an ice core taken by the National Science Foundation- (NSF) funded West Antarctic Ice Sheet (WAIS) Divide drilling project reveals that warming in Antarctica began about 22,000 years ago, a few thousand years earlier than suggested by previous records.

 

This timing shows that West Antarctica did not "wait for a cue" from the Northern Hemisphere to start warming, as scientists had previously supposed.

For more than a century scientists have known that Earth's ice ages are caused by the wobbling of the planet's orbit, which changes its orientation to the sun and affects the amount of sunlight reaching higher latitudes.

 

The Northern Hemisphere's last ice age ended about 20,000 years ago, and most evidence had indicated that the ice age in the Southern Hemisphere ended about 2,000 years later, suggesting that the South was responding to warming in the North.

 

But research published online Aug. 14 in the journal Nature shows that Antarctic warming began at least two, and perhaps four, millennia earlier than previously thought.

 

http://nsf.gov/news/news_summ.jsp?cntn_id=128808&org=NSF&from=news

[knocker]

Revisiting the evidence linking Arctic Amplification 1 to extreme weather in midlatitudes^†

Abstract

[1] Previous studies have suggested that Arctic Amplification has caused planetary-scale waves to elongate meridionally and slow-down, resulting in more frequent blocking patterns and extreme weather. Here, trends in the meridional extent of atmospheric waves over North America and the North Atlantic are investigated in three reanalyses, and it is demonstrated that previously reported positive trends are an artifact of the methodology. No significant decrease in planetary-scale wave phase speeds are found except in OND, but this trend is sensitive to the analysis parameters. Moreover, the frequency of blocking occurrence exhibits no significant increase in any season in any of the three reanalyses, further supporting the lack of trends in wave speed and meridional extent. This work highlights that observed trends in midlatitude weather patterns are complex and likely not simply understood in terms of Arctic Amplification alone.

 

 

http://onlinelibrary.wiley.com/doi/10.1002/grl.50880/abstract

Edited August 19, 2013 by knocker

[loafer]

Translation:

The previous paper where they told you they knew how it works was wrong. We don't have a Scooby*

*Scooby-doo / clue

[Coast]

I hope this in the right area of the sub-forum:

 

[UV-RAY]

I hope this in the right area of the sub-forum:

Lol, talk about flogging a dead horse. It's just as well there is a pause in our apocalyptic warming or else the attention grabbing headlines would be terrifying. :-) Edited August 20, 2013 by Sceptical Inquirer

[crikey]

I noticed the met office has added ice and snow storms  to the AGW severe weather events forecast

In fact all weather is caused by AGW..

That pretty much covers all bases....

[UV-RAY]

I noticed the met office has added ice and snow storms  to the AGW severe weather events forecast

In fact all weather is caused by AGW..

That pretty much covers all bases....

It's a win win situation really. 

[knocker]

A review of global ocean temperature observations: Implications for ocean heat content estimates and climate change^†

Abstract

[1] The evolution of ocean temperature measurement systems is presented with a focus on the development and accuracy of two critical devices in use today (expendable bathythermographs and CTDs – conductivity-temperature-depth instruments used on Argo floats). A detailed discussion of the accuracy of these devices and a projection of the future of ocean temperature measurements are provided. The accuracy of ocean temperature measurements is discussed in detail in the context of ocean heat content, Earth's energy imbalance, and thermosteric sea level rise. Up-to-date estimates are provided for these three important quantities. The total energy imbalance at the top-of-atmosphere is best assessed by taking an inventory of changes in energy storage. The main storage is in the ocean; the latest values of which are presented. Furthermore, despite differences in measurement methods and analysis techniques, multiple studies show that there has been a multi-decadal increase in the heat content of both the upper and deep ocean regions, which reflect the impact of anthropogenic warming. With respect to sea-level rise, mutually reinforcing information from tide gauges and radar altimetry show that presently, sea-level is rising at approximately 3 mm yr^-1 with contributions from both thermal expansion and mass accumulation from ice melt. The latest data for thermal expansion sea-level rise are included here and analyzed.

 

 

http://onlinelibrary.wiley.com/doi/10.1002/rog.20022/abstract

Edited August 20, 2013 by knocker

[knocker]

Contribution of relative sea-level rise to historical hurricane flooding in New York City

ABSTRACT

Flooding during hurricanes is a hazard for New York City. Flood height is determined by storm surge characteristics, timing (high or low tide) and relative sea-level (RSL) change. The contribution from these factors is estimated for seven historical hurricanes (1788–2012) that caused flooding in New York City. Measurements from The Battery tide gauge and historical accounts are supplemented with a RSL reconstruction from Barnegat Bay, New Jersey. RSL was reconstructed from foraminifera preserved in salt-marsh sediment that was dated using marker horizons of lead and copper pollution and ¹³⁷Cs activity. Between the 1788 hurricane and Hurricane Sandy in 2012, RSL rose by 56 cm, including 15 cm from glacio-isostatic adjustment. Storm surge characteristics and timing with respect to astronomical tides remain the dominant factors in determining flood height. However, RSL rise will raise the base level for flood heights in New York City and exacerbate flooding caused by future hurricanes.

 

 

http://onlinelibrary.wiley.com/doi/10.1002/jqs.2653/abstract

[knocker]

Retreat history of the East Antarctic Ice Sheet since the Last Glacial Maximum

Abstract

The East Antarctic Ice Sheet (EAIS) is the largest continental ice mass on Earth, and documenting its evolution since the Last Glacial Maximum (LGM) is important for understanding its present-day and future behaviour. As part of a community effort, we review geological evidence from East Antarctica that constrains the ice sheet history throughout this period (∼30,000 years ago to present). This includes terrestrial cosmogenic nuclide dates from previously glaciated regions, ¹⁴C chronologies from glacial and post-glacial deposits onshore and on the continental shelf, and ice sheet thickness changes inferred from ice cores and continental-scale ice sheet models. We also include new ¹⁴C dates from the George V Land â€“ Terre Adélie Coast shelf. We show that the EAIS advanced to the continental shelf margin in some parts of East Antarctica, and that the ice sheet characteristically thickened by 300–400 m near the present-day coastline at these sites. This advance was associated with the formation of low-gradient ice streams that grounded at depths of >1 km below sea level on the inner continental shelf. The Lambert/Amery system thickened by a greater amount (800 m) near its present-day grounding zone, but did not advance beyond the inner continental shelf. At other sites in coastal East Antarctica (e.g. Bunger Hills, Larsemann Hills), very little change in the ice sheet margin occurred at the LGM, perhaps because ice streams accommodated any excess ice build up, leaving adjacent, ice-free areas relatively unaffected. Evidence from nunataks indicates that the amount of ice sheet thickening diminished inland at the LGM, an observation supported by ice cores, which suggest that interior ice sheet domes were ∼100 m lower than present at this time. Ice sheet recession may have started ∼18,000 years ago in the Lambert/Amery glacial system, and by ∼14,000 years ago in Mac.Robertson Land. These early pulses of deglaciation may have been responses to abrupt sea-level rise events such as Meltwater Pulse 1a, destabilising the margins of the ice sheet. It is unlikely, however, that East Antarctica contributed more than ∼1 m of eustatic sea-level equivalent to post-glacial meltwater pulses. The majority of ice sheet recession occurred after Meltwater Pulse 1a, between ∼12,000 and ∼6000 years ago, during a period when the adjacent ocean warmed significantly. Large tracts of East Antarctica remain poorly studied, and further work is required to develop a robust understanding of the LGM ice sheet expansion, and its subsequent contraction. Further work will also allow the contribution of the EAIS to post-glacial sea-level rise, and present-day estimates of glacio-isostatic adjustment to be refined.

 

 

http://www.sciencedirect.com/science/article/pii/S0277379113002898

[knocker]

Wasn't sure where to put this but some thoughts by Steve Easterbrook, Professor of Computer Science at U Toronto. Student of climatology.

 

Why Systems Thinking?

 

http://www.easterbrook.ca/steve/2013/08/why-systems-thinking/

[Coast]

[knocker]

In the constant search to improve my image.

 

The potential for successful climate predictions! Hindcast experiments capture long-term climate fluctuations

Will there be rather warm or cold winters in Germany in the coming years? We may have a long way to go before reliable forecasts of this kind can be achieved. However, marine scientists, under the auspices of the GEOMAR Helmholtz Centre for Ocean Research Kiel, recently managed to successfully hindcast climate shifts in the Pacific. These shifts also have a profound effect on the average global surface air temperature of the Earth. The most recent shift in the 1990s is one of the reasons that the Earth's temperature has not risen further since 1998. The study, published in the online edition of Journal of Climate, shows the potential for long-term climate predictions.

 

 

http://www.eurekalert.org/pub_releases/2013-08/hcfo-tpf082213.php

[knocker]

Sea ice decline spurs the greening of the Arctic

Sea ice decline and warming trends are changing the vegetation in nearby arctic coastal areas, according to two University of Alaska Fairbanks scientists.

 

 

http://www.gi.alaska.edu/node/1667

[knocker]

More from Steve Easterbrook

 

The Climate as a System, part 1: the central equilibrium loop

 

The Climate as a System, part 1: the central equilibrium loop

I wrote earlier this week that we should incorporate more of the key ideas from systems thinking into discussions about climate change and sustainability. Here’s an example: I think it’s very helpful to think about the climate as a set of interacting feedback loops. If you understand how those feedback loops work, you’ve captured the main reasons why climate change is such a massive challenge for humanity. So, this is the first in a series of posts where I attempt to substantiate my argument. I’ll describe the global climate in terms of a set of balancing and reinforcing feedback loops. (Note: This is a very elementary introduction. If you prefer a detailed mathematical treatment of feedbacks in the climate system, try this paper by Gerard Roe)

 

 

http://www.easterbrook.ca/steve/2013/08/the-climate-as-a-system-part-1-the-central-equilibrium-loop/

Edited August 23, 2013 by knocker

[knocker]

Tropical cyclone wind speed constraints from resultant storm surge deposition: A 2500 year reconstruction of hurricane activity from St. Marks, FL

[1] Recent work suggests that the patterns of intense (≥category 3 on the Saffir-Simpson scale) hurricane strikes over the last few millennia might differ from that of overall hurricane activity during this period. Prior studies typically rely on assigning a threshold storm intensity required to produce a sedimentological overwash signal at a particular coastal site based on historical analogs. Here, we improve on this approach by presenting a new inverse-model technique that constrains the most likely wind speeds required to transport the maximum grain size within resultant storm deposits. As a case study, the technique is applied to event layers observed in sediments collected from a coastal sinkhole in northwestern Florida. We find that (1) simulated wind speeds for modern deposits are consistent with the intensities for historical hurricanes affecting the site, (2) all deposits throughout the ∼2500 year record are capable of being produced by hurricanes, and (3) a period of increased intense hurricane frequency is observed between ∼1700 and ∼600 years B.P. and decreased intense storm frequency is observed from ∼2500 to ∼1700 and ∼600 years B.P. to the present. This is consistent with prior reconstructions from nearby sites. Changes in the frequency of intense hurricane strikes may be related to the degree of penetration of the Loop Current in the Gulf of Mexico.

 

 

http://onlinelibrary.wiley.com/doi/10.1002/ggge.20217/abstract

[knocker]

Global warming amplified by reduced sulphur fluxes as a result of ocean acidification

Climate change and decreasing seawater pH (ocean acidification)¹ have widely been considered as uncoupled consequences of the anthropogenic CO₂ perturbation^{2, 3}. Recently, experiments in seawater enclosures (mesocosms) showed that concentrations of dimethylsulphide (DMS), a biogenic sulphur compound, were markedly lower in a low-pH environment⁴. Marine DMS emissions are the largest natural source of atmospheric sulphur⁵ and changes in their strength have the potential to alter the Earth’s radiation budget⁶. Here we establish observational-based relationships between pH changes and DMS concentrations to estimate changes in future DMS emissions with Earth system model⁷ climate simulations. Global DMS emissions decrease by about 18(±3)% in 2100 compared with pre-industrial times as a result of the combined effects of ocean acidification and climate change. The reduced DMS emissions induce a significant additional radiative forcing, of which 83% is attributed to the impact of ocean acidification, tantamount to an equilibrium temperature response between 0.23 and 0.48 K. Our results indicate that ocean acidification has the potential to exacerbate anthropogenic warming through a mechanism that is not considered at present in projections of future climate change.

 

 

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1981.html

[knocker]

Global warming slowdown linked to cooler Pacific waters

 

Scientists say the slow down in global warming since 1998 can be explained by a natural cooling in part of the Pacific ocean.

 

Although they cover just 8% of the Earth, these colder waters counteracted some of the effect of increased carbon dioxide say the researchers.

 

But temperatures will rise again when the Pacific swings back to a warmer state, they argue.

 

The research is published in the journal Nature.

 

http://www.bbc.co.uk/news/science-environment-23854904

Edited August 29, 2013 by knocker

[jonboy]

 

Global warming slowdown linked to cooler Pacific waters

 

Scientists say the slow down in global warming since 1998 can be explained by a natural cooling in part of the Pacific ocean.

 

Although they cover just 8% of the Earth, these colder waters counteracted some of the effect of increased carbon dioxide say the researchers.

 

But temperatures will rise again when the Pacific swings back to a warmer state, they argue.

 

The research is published in the journal Nature.

 

http://www.bbc.co.uk/news/science-environment-23854904

 What I find interesting its fine to blame natural oscillations for any cool down but not the other way equally we now also have stated that due to these oscillations CO2 only works its magic on melting the Artic in summer. Equally they acknowledge that they don't understand the mechanisum but must be true because their model says so!!!

I am happy to say that by 2100 we will have a warmer world than today because solar cycles 26 and 27 will be significant cycles leading to that warming.

[knocker]

Actually I think it might but it's difficult without reading the complete paper. Odd to use the word 'blame' rather than seeking a scientific explanation.

 

Abstract

Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century^{1, 2}, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming^{3, 4, 5, 6}, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970–2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase.

 

Edited August 29, 2013 by knocker

[Methuselah]

 

 What I find interesting its fine to blame natural oscillations for any cool down but not the other way equally we now also have stated that due to these oscillations CO2 only works its magic on melting the Artic in summer. Equally they acknowledge that they don't understand the mechanisum but must be true because their model says so!!!

I am happy to say that by 2100 we will have a warmer world than today because solar cycles 26 and 27 will be significant cycles leading to that warming.

That's because increasing anthropogenic CO₂ is not an oscillation...And, as for solar cycles 26 and 27, no one knows how they will pan out.