New Research

[knocker]

Ice melt, sea level rise and superstorms: Hansen on his magnum opus

 

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In this video Jim Hansen provides a “video abstract” of his latest — and longest — paper, Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous, published this week after a lengthy period in review. He, and his stellar list of co-authors, have also provided an “abbrievated” version of the paper, which I strongly recommend you read.

http://hot-topic.co.nz/ice-melt-sea-level-rise-and-superstorms-hansen-on-his-magnum-opus/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+co%2FRbRF+(Hot+Topic)

[knocker]

Ocean temps predict U.S. heat waves 50 days out, study finds

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BOULDER -- The formation of a distinct pattern of sea surface temperatures in the middle of the North Pacific Ocean can predict an increased chance of summertime heat waves in the eastern half of the United States up to 50 days in advance, according to a new study led by a scientist at the National Center for Atmospheric Research (NCAR). 

The pattern is a contrast of warmer-than-average water butting up against cooler-than-average seas. When it appears, the odds that extreme heat will strike during a particular week—or even on a particular day—can more than triple, depending on how well-formed the pattern is.

The research is being published in the journal Nature Geoscience.

http://www2.ucar.edu/atmosnews/news/20160/ocean-temps-predict-us-heat-waves-50-days-out-study-finds

[knocker]

Atmospheric response to the autumn sea-ice free Arctic and its detectability (open Access)

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We have used an Atmospheric General Circulation Model with a large ensemble (300) to explore the atmospheric responses during the autumn–winter (September to February) to the projected sea-ice free Arctic in autumn (September to November). The detectability of the responses against the internal variability has also been studied. Three ensemble experiments have been performed, the control (CONT) forced by the simulated present-day Arctic sea-ice concentration (SIC) and sea surface temperature (SST), the second forced by the projected autumn Arctic SIC free and present-day SSTs (SENSICE) and the third forced by the projected autumn Arctic SIC free and projected SSTs (SENS). The results show that the disappearance of autumn Arctic sea-ice can cause significant synchronous near-surface warming and increased precipitation over the regions where the sea-ice is removed. The changes in autumn surface heat flux (sensible plus latent), surface air temperature (SAT) and precipitation averaged over the sea-ice reduction region between the SENS and the CONT are about 46, 43 and 50 % more respectively than the changes between the SENSICE and the CONT, which is consistent with the prescribed boundary setting: the surface temperature warming averaged over the sea-ice reduction region in the SENS relative to the CONT is 48 % higher than that in the SENSICE relative to the CONT. The response shows a significant negative Arctic Oscillation (AO) in the troposphere during autumn and December. However, the negative AO does not persist into January–February (JF). Instead, 500 hPa geopotential height (GH) response presents a wave train like pattern in JF which is related to the downstream propagation of the planetary wave perturbations during November–December. The SAT increases over northern Eurasia in JF in accordance with the atmosphere circulation changes. The comparison of the atmosphere response with the atmosphere internal variability (AIV) shows that the responses of SAT and precipitation in the Arctic far exceed the AIV in autumn and the response of the 500 hPa GH is comparable to the AIV in autumn, but none of the responses during JF exceeds the AIV.

http://link.springer.com/article/10.1007%2Fs00382-015-2689-8

[mike Meehan]

http://www.theguardian.com/environment/2016/apr/07/clouds-climate-change-analysis-liquid-ice-global-warming?utm_source=esp&utm_medium=Email&utm_campaign=GU+Today+AUS+v1+-+AUS+morning+mail+callout&utm_term=165887&subid=14643256&CMP=ema_632

It may be worse than we think.

[knocker]

The Volcano Gambit

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Anyone reading pundits and politicians pontificating profusely about climate or environmental science will, at some point, have come across the “volcano gambit”. During the discussion they will make a claim that volcanoes (or even a single volcano) produce many times more pollutant emissions than human activities. Often the factor is extremely precise to help give an illusion of science-iness and, remarkably, almost any pollutant can be referenced. This “volcano gambit” is an infallible sign that indicates the author is clueless about climate science, but few are aware of its long and interesting history…

http://www.realclimate.org/index.php/archives/2016/04/the-volcano-gambit/

[knocker]

With ref. to Mike's post above.

Michael E. Mann and Trude Storelvmo on new, higher estimates of climate sensitivity.

 

[Polar Maritime]

Earth Is Tipping Because of Climate Change

The north pole is on the run. Although it can drift as much as 10 meters across a century, sometimes returning to near its origin, it has recently taken a sharp turn to the east. Climate change is the likely culprit, yet scientists are debating how much melting ice or changing rain patterns affect the pole’s wanderlust.

http://www.scientificamerican.com/article/earth-is-tipping-because-of-climate-change1/

[knocker]

Significant implications of permafrost thawing for climate change control (Open Access)

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Large amounts of carbon are stored as permafrost within the Arctic and sub-Arctic regions. As permafrost thaws due to climate warming, carbon dioxide and methane are released. Recent studies indicate that the pool of carbon susceptible to future thaw is higher than was previously thought and that more carbon could be released by 2100, even under low emission pathways. We use an integrated model of the climate and the economy to study how including these new estimates influence the control of climate change to levels that will likely keep the temperature increase below 2 °C (radiative forcing of 2.6 Wm−2). According to our simulations, the fossil fuel and industrial CO2 emissions need to peak 5–10 years earlier and the carbon budget needs to be reduced by 6–17 % to offset this additional source of warming. The required increase in carbon price implies a 6–21 % higher mitigation cost to society compared to a situation where emissions from permafrost are not considered. Including other positive climate feedbacks, currently not accounted for in integrated assessment models, could further increase these numbers.

http://rd.springer.com/article/10.1007%2Fs10584-016-1666-5

[knocker]

 

[BornFromTheVoid]

Over on /r/science on reddit, we're currently hosting an AMA (Q&A) with the authors of the recent paper of climate change consensus. Here's the link https://www.reddit.com/r/science/comments/4f6f6g/science_ama_series_we_just_published_a_study/

Science AMA Series: We just published a study showing that ~97% of climate experts really do agree humans causing global warming. Ask Us Anything!

Hello there, /r/Science!
We* are a group of researchers who just published a meta-analysis of expert agreement on humans causing global warming.
The lead author John Cook has a video backgrounder on the paper here, and articles in The Conversation and Bulletin of the Atomic Scientists](http://thebulletin.org/yes-there-really-scientific-consensus-climate-change9332). Coauthor Dana Nuccitelli also did a background post on his blog at the Guardian here.
You may have heard the statistic “97% of climate experts agree that humans are causing global warming.” You may also have wondered where that number comes from, or even have heard that it was “debunked”. This metanalysis looks at a wealth of surveys (of scientists as well as the scientific literature) about scientific agreement on human-caused global warming, and finds that among climate experts, the ~97% level among climate experts is pretty robust .
The upshot of our paper is that the level of agreement with the consensus view increases with expertise .
When people claim the number is lower, they usually do so by cherry-picking the responses of groups of non-experts, such as petroleum geologists or weathercasters.
Why does any of this matter? Well, there is a growing body of scientific literature that shows the public’s perception of scientific agreement is a “gateway belief” for their attitudes on environmental questions (e.g. Ding et al., 2011, van der Linden et al., 2015, and more). In other words, if the public thinks scientists are divided on an issue, that causes the public to be less likely to agree that a problem exists and makes them less willing to do anything about it. Making sure the public understands the high level of expert agreement on this topic allows the public dialog to advance to more interesting and pressing questions, like what as a society we decided to do about the issue.
We're here to answer your questions about this paper and more general, related topics. We ill be back later to answer your questions, Ask us anything!
*Joining you today will be:
John Cook aka /u/SkepticScience
Stuart Carlton
Sarah Green
Peter Jacobs aka /u/past_is_future
Stephan Lewandowsky aka /u/StephanLewandowsky
Dana Nuccitelli aka @dana1981
Andy Skuce aka /u/AndySkuce
Bart Verheggen aka @BVerheggen
and perhaps some others if they have time
Mod Note: Due to the geographical spread of our guests there will be a lag in some answers, please be patient!

[knocker]

Strongly increasing heat extremes in the Middle East and North Africa (MENA) in the 21st century

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The ensemble results of CMIP5 climate models that applied the RCP4.5 and RCP8.5 scenarios have been used to investigate climate change and temperature extremes in the Middle East and North Africa (MENA). Uncertainty evaluation of climate projections indicates good model agreement for temperature but much less for precipitation. Results imply that climate warming in the MENA is strongest in summer while elsewhere it is typically stronger in winter. The summertime warming extends the thermal low at the surface from South Asia across the Middle East over North Africa, as the hot desert climate intensifies and becomes more extreme. Observations and model calculations of the recent past consistently show increasing heat extremes, which are projected to accelerate in future. The number of warm days and nights may increase sharply. On average in the MENA, the maximum temperature during the hottest days in the recent past was about 43 °C, which could increase to about 46 °C by the middle of the century and reach almost 50 °C by the end of the century, the latter according to the RCP8.5 (business-as-usual) scenario. This will have important consequences for human health and society.

http://rd.springer.com/article/10.1007%2Fs10584-016-1665-6

[mikeworst]

A polite question please. Would it be possible to present alternative research/opinions on this forum in accordance with accepted scientific criteria or are we as sceptical scientists excluded because of our perception of the issue? I am not talking of belief here because belief belongs in the realm of religion or political manipulation. Please let me know so that I can contribute.

[Paul]

Mike, as I think I've explained to you personally before, and as has been posted numerous times in here. It's not about the view, it's about the way it's presented. So if you can post your views, with reasoned, science based evidence to back them up without personal attacks then all fine, if not then...

[knocker]

Researchers discover fate of melting glacial ice in Greenland

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Athens, Ga. - Over the past several decades, scientists have observed a significant increase in the melting of glacial land ice on the island of Greenland, spurring concerns about global sea level rise and the long-term effects of atmospheric warming. What has been less clear, however, is what happens to this meltwater once it enters the ocean.

Now, a team of researchers led by faculty at the University of Georgia has discovered the fate of much of the freshwater that pours into the surrounding oceans as the Greenland ice sheet melts every summer. They published their findings today in the journal Nature Geoscience.

http://www.eurekalert.org/pub_releases/2016-04/uog-rdf042516.php

[knocker]

Greenland Blocking Index 1851–2015: a regional climate change signal (Open Access)

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We present an extended monthly and seasonal Greenland Blocking Index (GBI) from January 1851 to December 2015, which more than doubles the length of the existing published GBI series. We achieve this by homogenizing the Twentieth Century Reanalysis version 2c-based GBI and splicing it with the NCEP/NCAR Reanalysis-based GBI. For the whole time period, there are significant decreases in GBI in autumn, October and November, and no significant monthly, seasonal or annual increases. More recently, since 1981 there are significant GBI increases in all seasons and annually, with the strongest monthly increases in July and August. A recent clustering of high GBI values is evident in summer, when 7 of the top 11 values in the last 165 years – including the two latest years 2014 and 2015 – occurred since 2007. Also, 2010 is the highest GBI year in the annual, spring, winter and December series but 2011 is the record low GBI value in the spring and April series. Moreover, since 1851 there have been significant increases in GBI variability in May and especially December. December has also shown a significant clustering of extreme high and low GBI values since 2001, mirroring a similar, recently identified phenomenon in the December North Atlantic Oscillation index, suggesting a related driving mechanism. We discuss changes in hemispheric circulation that are associated with high compared with low GBI conditions. Our GBI time series should be useful for climatologists and other scientists interested in aspects and impacts of Arctic variability and change.

http://onlinelibrary.wiley.com/doi/10.1002/joc.4673/full

[Nouska]

 

2 hours ago, knocker said:

A recent clustering of high GBI values is evident in summer, when 7 of the top 11 values in the last 165 years – including the two latest years 2014 and 2015 – occurred since 2007

That's an interesting one....

Doesn't bode well for our summers if it is a response to Arctic ice melt as it will be a reinforcing signal from here on in.

[knocker]

Influence of sea-ice loss on Arctic warming is shaped by temperatures in the Pacific Ocean

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The crucial role that sea-ice loss plays in rapid Arctic warming is regulated by variable climate patterns taking place in the Pacific Ocean, a pioneering new study has found.

The Arctic amplification phenomenon refers to the faster rate of warming in the Arctic compared to places farther south. Arctic amplification has been linked to a spike in the number of persistent cold spells experienced in recent years over Europe and North America.

New research led by University of Exeter expert Dr James Screen and published in leading scientific journal Nature Climate Change has shown that the influence of sea-ice loss on warming in the far north during winter is dependent on a recurring ocean temperature pattern in the North Pacific.

Read more at: http://phys.org/news/2016-05-sea-ice-loss-arctic-temperatures-pacific.html#jCp

 

[knocker]

 

[knocker]

 

[Nouska]

Power point presentation of the above paper - gives some illustrations of the model findings.

http://www.cesm.ucar.edu/events/meetings/20160208/presentations/cvcwg/lsun.pdf

Interesting diversity of opinion on this subject.

[knocker]

An interesting article

AMOC slowdown: Connecting the dots

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I want to revisit a fascinating study that recently came from (mainly) the Geophysical Fluid Dynamics Lab in Princeton. It looks at the response of the Atlantic Ocean circulation to global warming, in the highest model resolution that I have seen so far. That is in the CM2.6 coupled climate model, with 0.1° x 0.1° degrees ocean resolution, roughly 10km x 10km. Here is a really cool animation.

http://www.realclimate.org/index.php/archives/2016/05/amoc-slowdown-connecting-the-dots/

[knocker]

Earth’s climate may not warm as quickly as expected, suggest new cloud studies

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Clouds need to condense around small particles called aerosols to form, and human aerosol pollution—primarily in the form of sulfuric acid—has made for cloudier skies. That’s why scientists have generally assumed Earth’s ancient skies were much sunnier than they are now. But today, three new studies show how naturally emitted gases from trees can also form the seed particles for clouds. The results not only point to a cloudier past, but they also indicate a potentially cooler future: If Earth’s climate is less sensitive to rising carbon dioxide (CO2) levels, as the study suggests, future temperatures may not rise as quickly as predicted. 

"It's been long thought that sulfuric acid is really the key player [in cloud formation]," says atmospheric chemist Chris Cappa of the University of California, Davis, who was not involved in the research. The studies “show pretty convincingly that we don't need sulfuric acid around to allow new particles to grow.”

There are links to the three studies in the article

http://www.sciencemag.org/news/2016/05/earth-s-climate-may-not-warm-quickly-expected-suggest-new-cloud-studies

EDIT

I should add this tweet from Gareth Jones

 

Edited May 26, 2016 by knocker

[knocker]

 

[knocker]

Satellites Detect Both Steady and Accelerated Ice Loss

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A new study published in Geophysical Research Letters reports the findings of a pair of satellites that measure gravity to get a clearer picture of the continued ice mass loss in Greenland, the Gulf of Alaska, and the Canadian Arctic Archipelago. The study found accelerated ice loss in the Arctic, and steady loss in Alaska, which will have significant implications for sea level rise globally.

http://glacierhub.org/2016/05/24/satellites-detect-both-steady-and-accelerated-ice-loss/

[knocker]

Melt onset over Arctic sea ice controlled by atmospheric moisture transport

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The timing of melt onset affects the surface energy uptake throughout the melt season. Yet the processes triggering melt and causing its large interannual variability are not well understood. Here, we show that melt onset over Arctic sea ice is initiated by positive anomalies of water vapor, clouds, and air temperatures that increase the downwelling longwave radiation (LWD) to the surface. The earlier melt onset occurs, the stronger are these anomalies. Downwelling shortwave radiation (SWD) is smaller than usual at melt onset, indicating that melt is not triggered by SWD. When melt occurs early, an anomalously opaque atmosphere with positive LWD anomalies preconditions the surface for weeks preceding melt. In contrast, when melt begins late, clearer than usual conditions are evident prior to melt. Hence, atmospheric processes are imperative for melt onset. It is also found that spring LWD increased during recent decades, consistent with trends towards an earlier melt onset.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL069330/abstract