The Weekend Wonk: What This Week’s Antarctic Study Means

April 2, 2016

Is it possible that the most recent study of ice instability in Antarctica is cracking the unstable cliff face of climate denial? (how’s that for a tortured metaphor?)
Not enough information.

Above, National Snow and Ice Data Center lead scientist Ted Scambos sketches out the details. Below, I’ve posted Jason Box’s description of how many of the same processes anticipated for Antarctica are already  at work in Greenland.

Media Matters:

A new climate change study “jolts sea-rise predictions,” according to The Washington Post, with sea levels projected to increase so much that The New York Times says they would “likely provoke a profound crisis within the lifetimes of children being born today.” This disturbing news made the top-foldfront pages of the Post and the Times, but it was completely ignored by the broadcast television networks’ nightly news programs.


The nightly newscasts’ failure to cover this study follows a paltry year of climate change coverage on the broadcast networks in 2015. A Media Matters study found that ABC, CBS, and NBC collectively devoted less time to covering climate change during their nightly news and Sunday show broadcasts than they did in the previous year, even though 2015 was a landmark year for climate-related news that included the EPA finalizing the Clean Power Plan, Pope Francis issuing a climate change encyclical, President Obama rejecting the Keystone XL pipeline, and 195 countries around the world reaching a historic climate agreement in Paris.

Note: CBS mentions the study on a web page, but not, so far as I know, on the air where it might make a difference. Who makes these decisions?

Slate:

The latest information comes via a breakthrough in simulating the behavior of Antarctica’s vast and complex network of glaciers and ice shelves. That’s brought a more complete understanding of how warmer air temperatures—projected to surpass those regularly experienced on Earth at any point during at least the last few million years—are affecting the sea level. At the same time, the study provides new certainty that—should the world act immediately to curb carbon emissions at a scale far beyond current efforts—virtually all Antarctic ice melt could be avoided.

We should take this result very seriously. The new study prompted a lapse into Ciceronian prose from the New York Times and an instant revision to sea level rise projection maps for coastal cities worldwide, with many observers noting that, at current effort levels, humanity is veering dangerously close to the worst-case scenario.

“Under the high emissions scenario, the 22nd century would be the century of hell,” Ben Strauss, a sea level scientist at Climate Central told the Washington Post. “There would really be an unthinkable level of sea rise. It would erase many major cities and some nations from the map.”

 

But well before then, in the lifetimes of people being born today, the new study points to a potentially existential threat for cities like Miami; Guangzhou, China; Mumbai, India; New Orleans; Boston; and Alexandria, Egypt. In a scenario in which global carbon emissions remain essentially unchecked, the study argues the world’s coastal cities could see an additional two feet of sea level by 2100 above previous estimates—about five feet total.

In an interview with Slate, lead author Rob DeConto said that his results would be “really, really bad news for the business-as-usual future.”

icewashpost

iceshelf2

Nature:

“That is literally remapping how the planet looks from space,” says study co-author Rob DeConto, a geoscientist at the University of Massachusetts Amherst. The good news, he says, is that it projects little or no sea-level rise from Antarctic melt if greenhouse-gas emissions are reduced quickly enough to limit the average global temperature rise to about 2 °C.

The findings add to a growing body of research that suggests that Antarctic ice is less stable than once thought. In its 2013 report2, the Intergovernmental Panel on Climate Change estimated that Antarctic melting would contribute just a few centimetres to sea-level rise by 2100. But as scientists develop a better understanding of how the ocean and atmosphere affect the ice sheet, their projections of the continent’s future are growing more dire.

DeConto and co-author David Pollard, a palaeoclimatologist at Pennsylvania State University in University Park, developed a climate model that accounts for ice loss caused by warming ocean currents — which can eat at the underside of the ice sheet — and for rising atmospheric temperatures that melt it from above. Ponds of meltwater that form on the ice surface often drain through cracks; this can set off a chain reaction that breaks up ice shelves and causes newly exposed ice cliffs to collapse under their own weight.

They found that by including all of these processes, they could better simulate key geological periods that have long puzzled scientists. Before the last ice age began 130,000–115,000 years ago, for instance, sea levels were 6–9 metres higher than today — yet atmospheric carbon-dioxide levels were about 30% lower. And 3 million years ago, when CO2 levels roughly equalled today’s, the oceans may have been 10–30 metres higher.

 

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12 Responses to “The Weekend Wonk: What This Week’s Antarctic Study Means”

  1. dumboldguy Says:

    We are never going to address CAGW adequately until the scientists stop injecting little bits of wishful thinking and bright-sidedness into their otherwise hinest (but gloomy) analyses. To wit, from the post (emphasis added)

    “At the same time, the study provides new CERTAINTY that—SHOULD the world act IMMEDIATELY to curb carbon emissions at AT A SCALE FAR BEYOND current efforts—virtually all Antarctic ice melt COULD be avoided”.

    “The good news, he says, is that it projects little or no sea-level rise from Antarctic melt IF greenhouse-gas emissions are REDUCED QUICKLY ENOUGH to limit the average global temperature rise to about 2 °C”.

    A more realistic view—-much more CERTAINTY here.
    http://climatenewsnetwork.net/renewable-energy-demands-undoable/?

    “…Not enough”

    “….renewable energy sources deliver just 10.3% of global electrical power. Neither the report’s authors nor anyone else thinks that is enough to slow climate change driven by rising global temperatures as a consequence of greenhouse gas emissions from fossil fuels.

    “In the last century, this has already climbed by 1°C. In Paris in December 2015, 195 nations agreed on a global plan to limit global warming to a figure no more than 2°C above the long-term average for most of human history.

    “This will be difficult, according to Glenn Jones, professor of marine sciences at Texas A&M University in the US.

    “It would require rates of change in our energy infrastructure and energy mix that have never happened in world history and that are extremely unlikely to be achieved,” he says.

    “In 2015, the world installed the equivalent of 13,000 five-megawatt wind turbines. But to contain global warming to a figure less than 2°C nations would have to ramp up renewable investment by 2028 to the annual equivalent of 485,000 such wind turbines.

    “That’s a 37-fold increase in the annual installation rate in only 13 years just to achieve the wind power goal,” Professor Jones said.

    “Fifty per cent of our energy will need to come from renewable sources by 2028, and today it is only 9% . . . For a world that wants to fight climate change, the numbers just don’t add up to do it”

    Is anyone as shocked as I am by the “13,000 vs 485,000” and “37-fold increase in the annual installation rate in 13 years” figures?


  2. where to start? so many questions need answering before we can take this breathless report anywhere near as seriously as it’s being presented. So much so it makes the presentation of it seem to come from parties who are not up to speed with how these studies are meant to be assembled etc. For now it’s just another eye-roll…

    • greenman3610 Says:

      by all means, start anywhere. I’ll wait.

      • dumboldguy Says:

        Yes DUBL-D, why don’t you make us a movie about AGW? It would be a far more serious venture than some you’ve made.

        That’s if you can tear yourself away from all the inane tweeting you do with the likes of Patrick Moore, Judith Curry, Steve Goddard, Steve Milloy, Matt Ridley, Bjorn Lomborg, and the infamous Scottish Sceptic.

        The only questions that need answering for me are:

        1) Can you give us any evidence that YOU yourself are “up to speed on how these studies are MEANT be assembled”? (or even understand any of the science that IS “being seriously presented” in them?)
        2) Why do you bother to come to Crock and spout such BS?

        I will remain “breathless” and try to refrain from eye-rolling as I await your response.

    • Gingerbaker Says:

      John – you are a filmmaker who values the environmental positions of Bjorn Lomberg and Judith Curry. You believe a sea level “analysis” published in Forbes by a philosopher who writes for the moral case for fossil fuels is trenchant.

      And we are supposed to think that your incredulity to the veracity of these scientists and their study – published in Nature, for heaven’s sake – has any credibility? That YOU of all people have a clue about what it takes to be “up to speed with how these studies are meant to be assembled etc.”.

      What have you been smoking??!?

    • ubrew12 Says:

      “where to start? so many questions need answering” Yes, many questions. I notice your contribution was to add one more…

  3. Glen Koehler Says:

    1. RE “the study argues the world’s coastal cities could see an additional two feet of sea level by 2100 above previous estimates—about five feet total.”the study argues the world’s coastal cities could see an additional two feet of sea level by 2100 above previous estimates—about five feet total.

    Study midpoint estimate is 1.05 meters (= ca. 44 inches) addtional sea level rise contribution by Antarctic by 2100 with RCP8.5 high emissions scenario. IPCC 2013 estimate includes only “a few centimeters by 2100”. So the new addition to this study is over 40 inches (3.3 feet), not 2 feet as stated.

    One more foot makes a big difference.

    2. The animation of retrograde bedrock ice shelf melting is too fast to read, please slow it down or make it stoppable,

    3. Bad news – RCP8.5 high emissions scenario is actually LESS than recent trajectory, but reasonable to expect, or at least hope, us to begin reducing human emissions below assumptions in that scenario in near future. However that scenario does account for permafrost contributions that may begin increasing faster than reductions in human reductions.
    Also, the 1.05 meter addition to the IPCC estimate does not account for similar effects increasing Greenland contribution, which are also underrepresented in the IPCC estimate. Moreover, even if Hansen et al. meltwater feedback scenario is even 10% correct in terms of increasing sea level rise, that’s another boost.
    For those of us on East Coast of U.S., the gravitational effect of reducing mass of West Antarctic will result in additional gains to local sea level above global average.
    Miami was already doomed by 2100. The new study appears to bring the date earlier. The Antarctic contribution they found doesn’t start kicking in until ca. 2050. Rough guess is that in the updated scenario, global average sea level rise of 1 meter (3.3 feet) arrives roughly 2070.

    4. I expected the DeConto & Pollard study to be headline news. My very small sample suggests that major broadcast news outlets barely mentioned it. Kudos to the Washington Post, and Chris Mooney in particular for excellent climate change coverage. They deserve a Pulitzer Prize. Shame on the usually good Nat. Public Radio and PBS Newshour for missing this immensely important news.

    5. Presidential candidates should be making this centerpiece of their campaigns. Politicians who lack the integrity to face the physical facts will eventually be recognized for that lack.

    6. Easy to get depressed about all this. It IS depressing. But we’ve got to work to not let it happen, or at least reduce the damage. Join a local climate change group like Citizen’s Climate Lobby (CCL), 350.org etc., write to your political representatives. Support policies to accelerate no/low carbon energy sources. Support CCL’s carbon fee and dividend which even sane Republicans promote.

    And Peter, thanks for your great and essential work
    – Glen

    • Glen Koehler Says:

      2070 estimate just my back of the envelope quick guess of course. If you have better estimate for that or explanation for 2 ft. vs. 3 ft Antarctic contribution please do tell.

    • pendantry Says:

      2. The animation of retrograde bedrock ice shelf melting is too fast to read, please slow it down or make it stoppable

      I took the liberty of doctoring the animation, slowing the frame transitions to five seconds each. Result is here.


  4. […] while these possibilities are sobering, and recent evidence suggests things may be moving faster than anticipated, the McPherson scenario seems improbable to me. That does not at all mean everything’s okay. […]


  5. While there was no hard evidence until these works, I bet a lot of people, including myself, familiar with the maths of complex systems and differential equations suspected that non-modelled nonlinearities would drive things faster, not slower.

    There is also the March 2016 publication in Nature Geoscience by T. Storelvmo, T. Leirvik, U. Lohmann, P. C. B. Phillips and M.Wild (“Disentangling greenhouse warming and aerosol cooling to reveal Earth’s climate sensitivity”, published online: 14 MARCH 2016 | DOI: 10.1038/NGEO2670) which finds that transient climate sensitivity is 2.0K +- 0.8K.

    As far as depression goes, there is a good (and entertaining) piece on that which National Geographic put out, which I recently posted at my blog. Whether or not you buy McPherson’s viewpoint (I don’t; see why at the blog), it sets things in the right context.


  6. […] The Weekend Wonk: What This Week’s Antarctic Study Means […]


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