|Description:||Sceptics are taken to task for criticising evidence that supports global warming and embracing arguments that deny it.|
|Why is Antarctic sea ice growing? - Thu, 12 Dec 2013 01:21:42 EST|
This is are-post of an article at The Conversationby Guy Williams from the University of Tasmania
Recently NASAreportedthat this year’s maximum wintertime extent of Antarctic sea ice was the largest on record, even greater than the previous year’s record.
This is understandably at odds with the public’s perception of how polar ice should respond to a warming climate, given the dramatic headlines of severe decline in Arctic summertime extent. But the“paradox of Antarctic sea ice” has been on climate scientists' minds for some time.
Continental v. sea ice
First off, sea ice is different to the“continental ice” associated with polar ice caps, glaciers, ice shelves and icebergs. Continental ice is formed by the gradual deposition, build up and compaction of snow, resulting in ice that is hundreds to thousands of metres thick, storing and releasing freshwater that influences global sea-level over thousands of years.
Sea ice, though equally important to the climate system, is completely different. It is the thin layer (typically 1-2m) of ice that forms on the surface of the ocean when the latter is sufficiently cooled enough by the atmosphere.
From there sea ice can move with the winds and currents, continuing to grow both by freezing and through collisions (between the floes that make up the ice cover). When the atmosphere, and/or ocean is suitably warm again, such as in spring or if the sea ice has moved sufficiently towards the equator, then the sea ice melts again.
Antarctic v. Arctic
Secondly, we need to understand that the Arctic and Antarctic climate systems are very different, particularly in sea ice.
In the Arctic, sea ice forms in an ocean roughly centred on the North Pole that is surrounded by continents. A relatively large (though diminishing) proportion of the ice persists over multiple years before ultimately departing for warmer latitudes through exit points such as Fram Strait between Greenland and Svalbard.
In the south, on the other hand, sea ice forms outwards from the continental Antarctic Ice Sheet, where it is exposed to and strongly influenced by the winds and waters of the Southern Ocean. Here, there is a much stronger seasonal ebb and flow to sea ice coverage as over 80% of the sea ice area grows each autumn-winter and decays each spring-summer. This annual expansion-contraction from about 4 to 19 million square kms is one of the greatest seasonal changes on the Earth’s surface.
Area v. volume
Finally we need to remember that“extent” or“areal coverage” is only one way with which we monitor and study sea ice.
Sea ice turns out to be a very complex and variable medium that is very difficult to observe over large-scales. It is also constantly moving and restructuring. Until we achieve the“holy grail” of monitoring total sea ice volume from space and how it changes over time (and there are great steps towards this with European Space Agency’s environmental research satellite CryoSat-II), we are limited to interpreting its global behaviour through area.
What happened this winter?
This winter, the maximum total Antarctic sea ice extent was reported to be 19.47 million square kilometres, which is 3.6% above the winter average calculated from 1981 to 2010. This continues a trend that is weakly positive and remains in stark contrast to the decline in Arctic summer sea ice extent (2013 was 18% below the mean from 1981-2010).
To further complicate this picture, we find this net increase actually masks strong declines in particular regions around Antarctica, such as in the Bellingshausen Sea, which are on par or greater than those in the Arctic.
So while there is much greater attention given to the Arctic decline and the prediction of“ice-free summers” at the North Pole this century, Antarctic climate scientists still have their work cut out to understand the regional declines amidst the mild“net” expansion occurring in the southern hemisphere.
Here are some of the leading hypotheses currently being explored through a combination of satellite remote sensing, fieldwork in Antarctica and numerical model simulations– to help explain the increasing trend in overall Antarctic sea ice coverage:
The take home messages is that while the increase in total Antarctic sea ice area is relatively minor compared to the Arctic, it masks the fact that some regions are in strong decline. Given the complex interactions of winds and currents driving patterns of sea ice variability and change in the Southern Ocean climate system, this is not unexpected.
But it is still fascinating to study.
|Global warming is unpaused and stuck on fast forward, new research shows - Tue, 10 Dec 2013 01:04:45 EST|
New researchby Kevin Trenberth and John Fasullo of the National Center for Atmospheric Research investigates how the warming of the Earth's climate has behaved over the past 15 years compared with the previous few decades. They conclude that while the rate of increase of average global surface temperatures has slowed since 1998, melting of Arctic ice, rising sea levels, and warmingoceanshave continued apace.
The widespreadmainstream media focus on the slowed global surface warminghas led some climate scientists like Trenberth and Fasullo to investigate its causes and how much various factors have contributed to the so-called 'pause' or 'hiatus.' However, the authors note that while the increase in global temperatures has slowed, the oceans have taken up heat at a faster rate since the turn of the century. Over 90 percent of the overall extra heat goes into the oceans, with only about 2 percent heating the Earth's atmosphere. The myth of the 'pause' is based on ignoring 98 percent of global warming and focusing exclusively on the one bit that's slowed.
Nevertheless, the causes of the slowed global surface temperature increase present an interesting scientific question. In examining changes in the activity of the sun and volcanoes, Trenberth and Fasullo estimated that they can account for no more than a 20 percent reduction in the Earth's energy imbalance, which is what causes global warming. Thus the cause of the slowed surface warming must primarily lie elsewhere, and ocean cycles are the most likely culprit.
Trenberth and Fasullo found that after the massive El Niño event in 1998, the Pacific Ocean appears to have shifted into a new mode of operation. Since that time,Trenberth's research has shownthat the deep oceans have absorbed more heat than at any other time in the past 50 years.
Asa recent paper published in the journal Natureshowed, the Pacific Ocean in particular appears to be the key component of the climate's natural internal variability, and the main culprit behind the slowed global surface warming over the past 15 years. However, another important recent paper by Kevin Cowtan and Robert Way showed that the global surface temperature rise has not slowed as much as some previously thought; in fact, thesurface warming since 1997 happened more than twice as fastas previous estimates.
Trenberth and Fasullo's new paper also casts doubt on the conclusions a few recent studies that estimated the Earth's climate is less sensitive to the increased greenhouse effect than previously thought. These studies have been based on measurements of recentclimate change, including the warming of the oceans.Climate contrarians like Matt Ridleyhave of course emphasized their results, because these few papers seem to suggest the climate won't warm quite as much over the next century as climate scientists previously thought.
However, the type of approach taken by these studies suffers from some significant drawbacks. Mainly the size of the cooling effect due to human aerosol pollution remains highly uncertain, and while the oceans have been warming rapidly, just how rapidly is another unsettled question.
Previous estimates put the amount of heat accumulated by the world's oceans over the past decade equivalent to about4 Hiroshima atomic bomb detonations per second, on average, but Trenberth's research puts the estimate equivalent to more than 6 detonations per second. Trenberth and Fasullo note that using their ocean heating estimate by itself would increase theequilibrium climate sensitivityestimate in the paper referenced by Ridley from 2°C to 2.5°C average global surface warming in response to a doubling of atmospheric carbon dioxide, and using other more widespread accepted values would bring the estimate in line with the standard value of 3°C. They thus note,
|2013 SkS Weekly News Roundup #50A - Mon, 9 Dec 2013 22:14:51 EST|
Arctic thaw tied to European, US heatwaves and downpours
A thaw of Arctic ice and snow is linked to worsening summer heatwaves and downpours thousands of miles south in Europe, the United States and other areas, underlying the scale of the threat posed by global warming, scientists said on Sunday.
Their report, which was dismissed as inconclusive by some other experts, warned of increasingly extreme weather across "much of North America and Eurasia where billions of people will be affected".
The study is part of a drive to work out how climate change affects the frequency of extreme weather, from droughts to floods. Governments want to know the trends to plan everything from water supplies to what crops to plant.
But the science of a warming Arctic is far from settled.
Arctic thaw tied to European, US heatwaves and downpours: studyby Alister Doyle, Reuters, Dec 8, 2013
Canada short on time for climate plan
Canada is running out of time to offer U.S. PresidentBarack Obamaa climate change concession that might clinch the controversial Keystone XL oil pipeline, as the country's energy industry continues to resist costly curbs on greenhouse gas emissions.
Two years of negotiations between the Canadian government and the energy sector to curtail carbon pollution have not produced an agreement. Oil producers have balked at anything more than the 10-cents-a-barrel carbon tax imposed by the province of Alberta.
Late last month, Environment Minister Leona Aglukkaq pointed to "good progress" in the talks but was unable to say when a resolution might come.
Concessions from Canada would make the pipeline more palatable in Washington, experts say, since Obama has made fighting climate change a second-term priority and has said that Canada could do more to reduce carbon emissions.
As Keystone ruling nears, Canada short on time for climate planby Patrick Rucker& Nia Williams, Reuters, Dec 7, 2013
Is Bjorn Lomborg right to say fossil fuels are what poor countries need?
What do the poorest people on the planet - those likely to be the hardest hit by human-causedclimate change- need right now?
According to Bjørn Lomborg, the economist and self-titled skeptical environmentalist, what they need are cheapfossil fuels.
It's one of the those arguments that seems so counter-intuitive - so crazy-balls nuts - that it might make some stop and think that it could just be true. But not for long.
Is Bjorn Lomborg right to say fossil fuels are what poor countries need?by Graham Readfern, Planet OZ, The Guardian, Dec 6, 2013
Large Companies Prepared to Pay Price on Carbon
More than two dozen of the nation’s biggest corporations, including the five majoroilcompanies, are planning their future growth on the expectation that the government will force them to pay a price for carbon pollution as a way to control global warming.
The development is a striking departure from conservative orthodoxy and a reflection of growing divisions between the Republican Party and its business supporters.
A new report by the environmental data company CDP has found that at least 29 companies, some with close ties to Republicans, includingExxonMobil, Walmart and American Electric Power, are incorporating a price on carbon into their long-term financial plans.
Both supporters and opponents of action to fight global warming say the development is significant because businesses that chart a financial course to make money in a carbon-constrained future could be more inclined to support policies that address climate change.
Large Companies Prepared to Pay Price on Carbonby Coral Davenport, New York Tiems, Dec 5, 2013
Local climate predictions stay uncertain
Uncertainty will continue to mark attempts to predict detailed, local climates, scientists say, though they are confident that widespread and significant changes are coming.
Local climate predictions stay uncertainby Tim Radford, Climate News Netwok, Dec 6, 2013
Short-cut to produce hydrogen seen as step to cleaner fuel
Scientists have produced hydrogen by accelerating a natural process found in rocks deep below the Earth's surface, a short-cut that may herald the wider use of what is a clean fuel, a study showed on Sunday.
Short-cut to produce hydrogen seen as step to cleaner fuelby Alister Doyle, Reuters, Dec 8, 2013
Some good news (and plenty of bad) in NRC abrupt climate change report
Abrupt climate change— and also associated abrupt ecological and economic impacts sometimes triggered by more gradual climate change— gets a renewed look from a National Research Council science panel, which recommends development of an‘early warning system.’
Some Good News (and Plenty of Bad) in NRC Abrupt Climate Change Reportby Bud Ward, The Yale Forum on Climate Change& The Media, Dec 5,
Thanks for killing the planet, boomers!
Unfortunately, the world as we know it is ending, and no one can reasonably hope to avoid the constellation of catastrophic, ecological and social disasters that are all but certain to manifest, exacerbating one another’s horrific, deadly consequences. And yet our politicians can’t be bothered to care, a substantial portion of Americans aren’t convinced that it’s even happening (despite overwhelming, unimpeachable evidence to the contrary), and the enormity of the issue is downplayed basically everywhere outside the bounds of the largely-ghettoized“environmental/green reporting,” uniformly marginalized and dismissed by the mainstream press.
Thanks for killing the planet, boomers!by Tim Donovan, Dec 2, 2013
The apocalypse is coming— and technology can’t save us
Last week, Salon ran an article,“Thanks for killing the planet, boomers!,” where I argued that it’s wholly unrealistic to assume humanity will undertake the massive, world-changing, economy-disrupting policy solutions needed for us to even stand a chance of long-term survival. Given that our local political and economic systems are as fragile, stalled and polarized as they’ve been in most of American history, these predictions only seem more dire, and the problem only more intractable.
Which is why I’m constantly amazed by the notion that our technology will somehow save us, what I’ve come to consider the deus ex machina defense.
We are deluding ourselves: The apocalypse is coming— and technology can’t save usby Tim Donovan, Dec 9, 2013
The (in)sanity of climate change
Last year a friend of mine and her husband set out with their three children on a trek from Missouri to the boreal forests of central Canada to raise awareness about climate change. She read Bill McKibben's article "Global Warming's Terrifying New Math" and, just like that, dropped everything to walk a thousand miles with her family accompanied only by their home-built "Conestoga" wagon.
Here's the thing: My friend is NOT insane. She digested McKibben's measured words, backed by the painstaking research of highly trained scientists, and came to this conclusion: "This is indeed terrifying and as a human who cares about myself, as a mother who cares about my children and, as a planetary being that cares about my fellow life beings, I have to do something, I can't just sit on my ass watching from the sidelines."
Here's another other thing: If you have taken the time to learn about climate change and feel afraid, angry or sad, if you feel an urge to take action, then you are not insane either. It is really that simple. If a human being with intact faculties learns of a preventable situation that is causing suffering and wants to do something about it, this is a deeply sane response.
The (IN)Sanity of Climate Changeby David Goldstein, The Blog/The Huffington Post, Dec 6, 2013
The Montreal Protocol, a little treaty that could
Here is a remarkable fact aboutglobal warming: It might be twice as bad right now were it not for a treaty negotiated by a conservative American president, for an entirely different purpose, based on motives no one has ever quite understood.
That treaty is known, in shorthand, as the Montreal Protocol. Its formal purpose is to save the ozone layer in the upper atmosphere, which protects the planet and its people from debilitating levels ofcancer-causing ultraviolet radiation.
The negotiations on behalf of the United States, in the 1980s, were carried out by the Reagan administration. And the treaty is turning out to beone of the more momentous stepsRonald Reagantook as president.
The Montreal Protocol, a Little Treaty That Couldby Justin Gillis, New York
The other climate problem: CO2 threatens marine life
The IPSO report draws an unsettling comparison between conditions today and climate change events in the past that have resulted in mass extinctions: "On a lot of these major extinction events we see the fingerprints of high temperatures and acidification, similar effects to the ones that we are experiencing today."
The other climate problem: CO2 threatens marine lifeby Irene Quaile, Deutsche Welle (DW), Dec 4, 2013