Droughts and Antarctica

After yesterdays post on the gibberish proof of global warming due to increased Antarctic Circulation, Andrew drew attention to Jones, J. M. and M. Widmann, 2004, Early peak in Antarctic oscillation index claiming that the Antarctic Oscillation has changed in the last thirty to forty years, but is only where it was in the late fifties to early sixties.

Tas Van Ommen claims to have found that snowfall has increased in East Antarctica. Looking into his previous publications, one of the first I pulled up was Insignificant Change in Antarctic Snowfall Since the International Geophysical Year Abstract:

There has been no statistically significant change in snowfall since the 1950s, indicating that Antarctic precipitation is not mitigating global sea level rise as expected, despite recent winter warming of the overlying atmosphere.

OK, so if snowfall increases it is proof of global warming, but if snowfall decreases it is not mitigating global sea level rise.

Researching the links between drought in WA and increased snowfall in East Antarctica via a change in the Antarctic Circulation seems worthwhile. But the effects of snow accumulation on sea level would be relatively trivial.

This sort of discourse, and “proof of global warming” talk, sounds fabricated to embiggen the research.

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0 thoughts on “Droughts and Antarctica

  1. David,Glad you see that this research seems worthwhile. I do – because I reckon hard data and rigorous interpretation are the best thing we have in understanding the climate system. If you read the scientific papers, or even the public material on our website (http://www.aad.gov.au/default.asp?casid=37495), you will see that we do not claim “proof” of anything. Just evidence, albeit strong evidence, and more of it, that things are changing in ways that point to unusual climate impacts that are likely results from greenhouse gas and ozone changes.I harbour no wish to see AGW, but I see no physical or scientific basis for concluding otherwise.As for the papers, if you dig into them, you will find that the “insignificant change in snowfall” paper was for overall Antarctica, and actually showed that there were large regional and decadal scale changes, but that overall, no significant net effect from 1957 to around 2000.Yesterday's paper looks at one site, Law Dome, which evidence (in the other paper) indicates is representative of much of coastal East Antarctica. At this site, snowfall increase in recent decades is considerable, as discussed.Oh – and the sea-level impacts from snow accumulation are potentially very significant. Each year the amount of water that cycles in/out of Antarctica (snowfall/in – icebergs and melt/out) is equivalent to 6-7 mm of global sea-level. You can see that a sustained imbalance in either snowfall, or losses of ice can quickly matter.Best regards,Tas

  2. David,

    Glad you see that this research seems worthwhile. I do – because I reckon hard data and rigorous interpretation are the best thing we have in understanding the climate system.

    If you read the scientific papers, or even the public material on our website (http://www.aad.gov.au/default.asp?casid=37495), you will see that we do not claim “proof” of anything. Just evidence, albeit strong evidence, and more of it, that things are changing in ways that point to unusual climate impacts that are likely results from greenhouse gas and ozone changes.

    I harbour no wish to see AGW, but I see no physical or scientific basis for concluding otherwise.

    As for the papers, if you dig into them, you will find that the “insignificant change in snowfall” paper was for overall Antarctica, and actually showed that there were large regional and decadal scale changes, but that overall, no significant net effect from 1957 to around 2000.

    Yesterday’s paper looks at one site, Law Dome, which evidence (in the other paper) indicates is representative of much of coastal East Antarctica. At this site, snowfall increase in recent decades is considerable, as discussed.

    Oh – and the sea-level impacts from snow accumulation are potentially very significant. Each year the amount of water that cycles in/out of Antarctica (snowfall/in – icebergs and melt/out) is equivalent to 6-7 mm of global sea-level. You can see that a sustained imbalance in either snowfall, or losses of ice can quickly matter.
    Best regards,

    Tas

    • Tas, I appreciate you commenting as I have no interest to preaching to the choir, and a one-sided blog. It seems we are agreed that the reporting was, and still is, overblown. I think there is a need to speak out about this as it is damaging the reputation of science.

      The substantive issue on the significant change in circulation is something I have looked into with the Walker Circulation (http://landshape.org/enm/no-weakening-of-the-walker/). As I am sure you know, Power and Smith and Vecchi reported a weakening of the WC as evidence of AGW. However, since a run of strong El Ninos has eased the data indicate a return of the indices to normal and no longer support their claim to any degree, suggesting, what?

      We have seen before where these sorts of claims are reversed by subsequent data (eg http://landshape.org/enm/wp-content/uploads/2009/06/ee-20-4_7-stockwell2.pdf).

      I wonder if this case might be similar? I would be prepared to look into it . Would you post the data for your graph showing the inverse link between rainfall in south-west Western Australia and snowfall in Antarctica (http://www.aad.gov.au/MediaLibrary/asset/MediaItems/ml_402173825925926_03_RainSnowComparisonGraph.pdf) so we can check the statistics of the relationship?

      I admit I haven’t read your paper as I didn’t see a reference to it anywhere, but if you have a reference and a link I would appreciate it.

      • Hi David,
        The paper is at Nature Geoscience (Advance Online), and I’d encourage you to take a look (and at the online supplementary information). Contact me by email if you have trouble getting the paper.

        The data are available online at the Australian Antarctic Data Centre (http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=AAS_757_LDAccu2005)
        and will be indexed too by the NASA Global Change Master Directory, which appears to be offline at present.

        Again contact me (email is better than on-blog) for specifics of data and paper access.

        On the fact that claims can be reversed by subsequent data, this sounds like a description of the advance of science via the normal method. All any of us can do is honestly report our findings and uncertainties, try to use our heads and add some interpretation (or else it is largely just a technological exercise) to guide followup studies. If they find new things out that make our work obsolete then so be it – we have helped push things forward.

        Cheers,
        Tas

      • Just an update. Tas has been more than helpful in supplying material for replicating his study, and I will be working on this over the next few days.

  3. Tas, I appreciate you commenting as I have no interest to preaching to the choir, and a one-sided blog. It seems we are agreed that the reporting was, and still is, overblown. I think there is a need to speak out about this as it is damaging the reputation of science.The substantive issue on the significant change in circulation is something I have looked into with the Walker Circulation (http://landshape.org/enm/no-weakening-of-the-wa…). As I am sure you know, Power and Smith and Vecchi reported a weakening of the WC as evidence of AGW. However, since a run of strong El Ninos has eased the data indicate a return of the indices to normal and no longer support their claim to any degree, suggesting, what? We have seen before where these sorts of claims are reversed by subsequent data (eg http://landshape.org/enm/wp-content/uploads/200…).I wonder if this case might be similar? I would be prepared to look into it . Would you post the data for your graph showing the inverse link between rainfall in south-west Western Australia and snowfall in Antarctica (http://www.aad.gov.au/MediaLibrary/asset/MediaI…) so we can check the statistics of the relationship? I admit I haven't read your paper as I didn't see a reference to it anywhere, but if you have a reference and a link I would appreciate it.

  4. Hi David,The paper is at Nature Geoscience (Advance Online), and I'd encourage you to take a look (and at the online supplementary information). Contact me by email if you have trouble getting the paper.The data are available online at the Australian Antarctic Data Centre (http://data.aad.gov.au/aadc/metadata/citation.c…)and will be indexed too by the NASA Global Change Master Directory, which appears to be offline at present.Again contact me (email is better than on-blog) for specifics of data and paper access.On the fact that claims can be reversed by subsequent data, this sounds like a description of the advance of science via the normal method. All any of us can do is honestly report our findings and uncertainties, try to use our heads and add some interpretation (or else it is largely just a technological exercise) to guide followup studies. If they find new things out that make our work obsolete then so be it – we have helped push things forward.Cheers,Tas

  5. Just an update. Tas has been more than helpful in supplying material for replicating his study, and I will be working on this over the next few days.

  6. Just a note to point out that just because I don't respond to something doesn't mean I agree. I just want to focus on the main thing, which is getting some data and crunching it. Eg I dont think that reversal of claims by subsequent data is normal scientific method, in the sense that as more data is accumulated, certainty, or the strength of claims should increase, not decrease. If they decrease, then inappropriate significance has been given to it, usually because the distribution was assumed to be Gaussian and it wasn't, there was autocorrelation in the data and it wasn't handled, and so on.False certainty is important. In 1997, Niederhoffer Investments lost 100 million in one day because he assumed the probability of the market falling more that 5% in one day was astronomically low. It fell 7.2% and he was wiped out. LTCM same story. The 'long tail' of probability got them. Its the same with climate. You have to be very careful arguing that something is outside the normal and therefore manmade when you have 1. limited data and 2. non-normal distributions. It's virtually impossible to estimate the true variance of climate data, and so usually very suspect to argue that something is 3-sigma, 1:1000 chance and so on, with any reliability.

  7. Tas, I appreciate you commenting as I have no interest to preaching to the choir, and a one-sided blog. It seems we are agreed that the reporting was, and still is, overblown. I think there is a need to speak out about this as it is damaging the reputation of science.The substantive issue on the significant change in circulation is something I have looked into with the Walker Circulation (http://landshape.org/enm/no-weakening-of-the-wa…). As I am sure you know, Power and Smith and Vecchi reported a weakening of the WC as evidence of AGW. However, since a run of strong El Ninos has eased the data indicate a return of the indices to normal and no longer support their claim to any degree, suggesting, what? We have seen before where these sorts of claims are reversed by subsequent data (eg http://landshape.org/enm/wp-content/uploads/200…).I wonder if this case might be similar? I would be prepared to look into it . Would you post the data for your graph showing the inverse link between rainfall in south-west Western Australia and snowfall in Antarctica (http://www.aad.gov.au/MediaLibrary/asset/MediaI…) so we can check the statistics of the relationship? I admit I haven't read your paper as I didn't see a reference to it anywhere, but if you have a reference and a link I would appreciate it.

  8. Hi David,The paper is at Nature Geoscience (Advance Online), and I'd encourage you to take a look (and at the online supplementary information). Contact me by email if you have trouble getting the paper.The data are available online at the Australian Antarctic Data Centre (http://data.aad.gov.au/aadc/metadata/citation.c…)and will be indexed too by the NASA Global Change Master Directory, which appears to be offline at present.Again contact me (email is better than on-blog) for specifics of data and paper access.On the fact that claims can be reversed by subsequent data, this sounds like a description of the advance of science via the normal method. All any of us can do is honestly report our findings and uncertainties, try to use our heads and add some interpretation (or else it is largely just a technological exercise) to guide followup studies. If they find new things out that make our work obsolete then so be it – we have helped push things forward.Cheers,Tas

  9. Just a note to point out that just because I don’t respond to something doesn’t mean I agree. I just want to focus on the main thing, which is getting some data and crunching it.

    Eg I dont think that reversal of claims by subsequent data is normal scientific method, in the sense that as more data is accumulated, certainty, or the strength of claims should increase, not decrease. If they decrease, then inappropriate significance has been given to it, usually because the distribution was assumed to be Gaussian and it wasn’t, there was autocorrelation in the data and it wasn’t handled, and so on.

    False certainty is important. In 1997, Niederhoffer Investments lost 100 million in one day because he assumed the probability of the market falling more that 5% in one day was astronomically low. It fell 7.2% and he was wiped out. LTCM same story. The ‘long tail’ of probability got them.

    Its the same with climate. You have to be very careful arguing that something is outside the normal and therefore manmade when you have 1. limited data and 2. non-normal distributions. It’s virtually impossible to estimate the true variance of climate data, and so usually very suspect to argue that something is 3-sigma, 1:1000 chance and so on, with any reliability.

  10. Just an update. Tas has been more than helpful in supplying material for replicating his study, and I will be working on this over the next few days.

  11. Just a note to point out that just because I don't respond to something doesn't mean I agree. I just want to focus on the main thing, which is getting some data and crunching it. Eg I dont think that reversal of claims by subsequent data is normal scientific method, in the sense that as more data is accumulated, certainty, or the strength of claims should increase, not decrease. If they decrease, then inappropriate significance has been given to it, usually because the distribution was assumed to be Gaussian and it wasn't, there was autocorrelation in the data and it wasn't handled, and so on.False certainty is important. In 1997, Niederhoffer Investments lost 100 million in one day because he assumed the probability of the market falling more that 5% in one day was astronomically low. It fell 7.2% and he was wiped out. LTCM same story. The 'long tail' of probability got them. Its the same with climate. You have to be very careful arguing that something is outside the normal and therefore manmade when you have 1. limited data and 2. non-normal distributions. It's virtually impossible to estimate the true variance of climate data, and so usually very suspect to argue that something is 3-sigma, 1:1000 chance and so on, with any reliability.

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