The Global Warming Policy Foundation doesn’t understand second derivatives!

I noticed the following tweet from the Global Warming Policy Foundation

The link goes to a press release also stating that the Polar Ice Melt May be a Natural Event.

The press release itself seems to simply copy what was probably released by some university press office, but the title and tweet are clearly intended to imply that the melting observed in the polar regions is natural and not a consequence of anthropogenic global warming (AGW).

This press release appears to be referring to a recent Nature Geoscience paper called Limits in detecting acceleration of ice sheet mass loss due to climate variability. Below I include the abstract of the paper

The Greenland and Antarctic ice sheets have been reported to be losing mass at accelerating rates1, 2. If sustained, this accelerating mass loss will result in a global mean sea-level rise by the year 2100 that is approximately 43 cm greater than if a linear trend is assumed2. However, at present there is no scientific consensus on whether these reported accelerations result from variability inherent to the ice-sheet–climate system, or reflect long-term changes and thus permit extrapolation to the future3. Here we compare mass loss trends and accelerations in satellite data collected between January 2003 and September 2012 from the Gravity Recovery and Climate Experiment to long-term mass balance time series from a regional surface mass balance model forced by re-analysis data. We find that the record length of spaceborne gravity observations is too short at present to meaningfully separate long-term accelerations from short-term ice sheet variability. We also find that the detection threshold of mass loss acceleration depends on record length: to detect an acceleration at an accuracy within ±10 Gt yr−2, a period of 10 years or more of observations is required for Antarctica and about 20 years for Greenland. Therefore, climate variability adds uncertainty to extrapolations of future mass loss and sea-level rise, underscoring the need for continuous long-term satellite monitoring.

So, this is not about ice loss as such, it is about whether or not it is accelerating. The claim in the paper is that to determine if the acceleration is a long-term trend, 10 years or more is needed for Antarctica while 20 years or more is needed for Greenland. There’s no real disagreement about whether the ice mass loss in the polar regions is being driven by AGW (it is) there is simply some debate about whether or not the recent acceleration is a natural fluctuation or an indication of a human-induced acceleration. The basic point being that if we want to determine the long-term trends for Antarctic and Greenland ice-mass-loss we need to know if this acceleration is just a short-term variation or not. If not, the resulting sea-level rise by 2100 will be smaller than if it is a long-term acceleration of the ice-mass-loss.

Watts Up With That (WUWT) seems to be making a similar mistake by claiming Dueling press releases on ice melt – one says ‘uncertainty is large’ the other quantifies a number. This post compares two press releases about two different papers, one of which is the one I discuss above. This WUWT post certainly makes a big deal out of the suggestion in the above paper that the “uncertainty is large”. Sure, but there’s not much uncertainty about whether or not melting is taking place in Antarctica and Greenland. There’s just uncertainty about whether or not it is accelerating and hence there is uncertainty about the associated sea-level rise in 2100.

The other study quoted in the WUWT post seems to be a study that combines the Earth’s climate history with computer models to predict what sea-level rises we should expect for certain increases in surface temperature. The study I discuss above was, on the other hand, using satellite observations of the polar ice to determine the rate of change and possible acceleration. They’re essentially different types of studies. One was trying to establish if we could make a prediction about sea-level rises at a given point in time in the future (based on current loss rates and accelerations) the other was trying to determine the total sea-level rise after a given change in surface temperature using past climate history and computer models.

If Anthony had given this some thought he should have realised that these two studies are probably entirely consistent with each other. I will be generous and accept that the GWPF and WUWT may simply have misunderstood these studies rather than them intentionally mis-representing what these studies were suggesting. Others may, of course, disagree with this assessment.

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12 Responses to The Global Warming Policy Foundation doesn’t understand second derivatives!

  1. You are far too diplomatic to be writing for the internet 😀

  2. Thanks, I think. Trying to stick to my subtitle – for the moment at least 🙂

  3. Well diplomatic? A guy that does not see the difference between a study on the relation between sea level rise and temperature and a study on whether melting is accelerating can not be very science literate or prudent. Which is not exactly a compliment about someone who daily claims to understand the climate better than almost all climatologists combined.

    That would be forgiveable if it happened once by a modest person, but not if it happens daily by …. Let’s try to keep the discussion civil.

  4. Maybe you could clarify because I’m slightly confused by your comment – although I’ve had a long day and am rather tired, so it may just be me.

  5. Rachel says:

    As someone who is not a scientist but who has read a few scientific papers, I am not surprised that people misinterpret them. The language is often inaccessible to the layperson. But the right thing to do here would be for them to acknowledge that they got it wrong and then fix the mistake.

  6. Let’s try again.

    To me it is pretty obvious that the two articles are dealing with fully different questions. Yes, they both have as topics ice and climate, but the questions are completely different.

    That may be a professional bias and I understand that scientific papers can be hard to understand.

    However, if Anthony Watts has problems seeing that these two questions are different, if reading a scientific paper does not come naturally to him, if he is lacking the same talent and experience, you have to ask why he is blogging about climatology of all topics and especially why he is fiercely attacking people who do have these skills day in, day out.

    It is okay for Watts to have trouble with understanding science. Personally I am not very knowledgeable about soccer. However, for me the consequence is not to blog about soccer and especially not to criticise the opinion of people who do know about soccer post after post.

    I wish that Watts would make a fair judgement of his strengths and weaknesses and would do something he is good at and make this world a better place that way.

    The way I see the current situation is that his denial spin is almost dead anyway. Blogs like WUWT have convinced the people that climate “sceptics” have no solid arguments and need to disinform to pretend to have arguments. It is time for Watts to look for a new job.

  7. BBD says:

    Yes, doubtless all an unfortunate misunderstanding with apologies and correction to follow.

    It would be the civil thing to do.

  8. Thanks, yes I agree. For a while I thought you were being critical about me trying to keep the discussion civil 🙂 Indeed, he clearly does not understand the science and uses his lack of understanding to cherry pick what he presents and to present it in such a way as to suit his bias.

    I have a feeling that you’re right about his blog and others like it. The rhetoric seems to be getting more extreme which could be an indication that they’re starting to realise (consciously or unconciously) that the evidence for AGW (and climate change) is becoming stronger and so their ability to fight it by highlighting actual uncertainties is getting more and more difficult.

  9. To be honest, I would say that the evidence for AGW was already pretty solid in the beginning of the 1990ies. We understand the subcompartments of the climate system better, we understand our tools better and consequently we are less afraid of unknown unknowns. But for the main questions, the ones the “sceptics” think are wrong, not that much has happened.

    Humanity has wasted at least 2 decades and the later we take action, the faster everything will have to be implemented and the more expensive reducing AGW becomes. Fortunately we only wasted it partially as many smart people have pressed ahead, many companies saw profitable future markets and did not wait for the rest.

    What has changed is the public debate. When I was young you would only get on a soap box, I you knew what you were saying. That is no longer the case, people are no longer ashamed of sprouting nonsense. I guess now the public begins to notice that and to realise that you should not believe all the “facts” of random people on soap boxes. The public seems to have learned that you have to be more selective about your information sources nowadays.

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