Statistics and No AGW Statistical Significance

[nautonnier]

An interesting paper for those of a statistical bent is flagged up in WUWT today.

"From the journal Earth System Dynamics billed as “An Interactive Open Access Journal of the European Geosciences Union” comes this paper which suggests that the posited AGW forcing effects simply isn’t statistically significant in the observations, but other natural forcings are."

wattsupwiththat.com/2013/01/03/agw-bombshell-a-new-paper-shows-statistical-tests-for-global-warming-fails-to-find-statistically-significantly-anthropogenic-forcing/

and the actual paper:

Polynomial cointegration tests of anthropogenic impact on global warming

M. Beenstock1, Y. Reingewertz1, and N. Paldor2
1Department of Economics, the Hebrew University of Jerusalem, Mount Scopus Campus, Jerusalem, Israel
2Fredy and Nadine Institute of Earth Sciences, the Hebrew University of Jerusalem, Edmond J. Safra campus, Givat Ram, Jerusalem, Israel

Abstract. We use statistical methods for nonstationary time series to test the anthropogenic interpretation of global warming (AGW), according to which an increase in atmospheric greenhouse gas concentrations raised global temperature in the 20th century. Specifically, the methodology of polynomial cointegration is used to test AGW since during the observation period (1880–2007) global temperature and solar irradiance are stationary in 1st differences whereas greenhouse gases and aerosol forcings are stationary in 2nd differences. We show that although these anthropogenic forcings share a common stochastic trend, this trend is empirically independent of the stochastic trend in temperature and solar irradiance. Therefore, greenhouse gas forcing, aerosols, solar irradiance and global temperature are not polynomially cointegrated. This implies that recent global warming is not statistically significantly related to anthropogenic forcing. On the other hand, we find that greenhouse gas forcing might have had a temporary effect on global temperature.


www.earth-syst-dynam.net/3/173/2012/esd-3-173-2012.pdf

And its NOT behind a paywall So you've no excuse get reading However those of a non-statistics bent may find things a little heavy going. I would think that McIntyre and McKitrick will be going through this in detail. As from its title this could be seen as a huge threat to the CAGW industry.

[nautonnier]

From the paper referenced above:

"However, the fact that they do not share the same order of integration over this period means that scientists who make strong interpretations about the anthropogenic causes of recent global warming should be cautious. Our polynomial cointegration tests challenge their interpretation of the data."

This may well become a famous paper.

[magellan]

I posted a link to that last month, but only the title, thinking people would know to click on the hyperlink.

solarcycle24com.proboards.com/index.cgi?action=gotopost&board=globalwarming&thread=2014&post=85423

[nautonnier]

Jan 3, 2013 18:16:17 GMT magellan said:

I posted a link to that last month, but only the title, thinking people would know to click on the hyperlink.

solarcycle24com.proboards.com/index.cgi?action=gotopost&board=globalwarming&thread=2014&post=85423

I apologize - I must've missed that in my travels. There are comments on WUWT that it has been around in earlier versions for sometime.

landshape.org/enm/agw-doesnt-cointegrate-beenstocks-challenging-analysis-published/

In any case a new thread on AGW stats seemed apposite

[throttleup]

Other quotes from the paper magellan and nautonnier have referenced:

“…We show that although these anthropogenic forcings share a common stochastic trend, this trend is empirically independent of the stochastic trend in temperature and solar irradiance. Therefore, greenhouse gas forcing, aerosols, solar irradiance and global temperature are not polynomially cointegrated. This implies that recent global warming is not statistically significantly related to anthropogenic forcing.

“…our rejection of AGW is not absolute; it might be a false positive, and we cannot rule out the possibility that recent global warming has an anthropogenic footprint. However, this possibility is very small, and is not statistically significant at conventional levels.”

“We have shown that anthropogenic forcings do not polynomially cointegrate with global temperature and solar irradiance. Therefore, data for 1880–2007 do not support the anthropogenic interpretation of global warming during this period.”

“The fact that since the mid 19th century Earth’s temperature is unrelated to anthropogenic forcings does not contravene the laws of thermodynamics, greenhouse theory, or any other physical theory. Given the complexity of Earth’s climate, and our incomplete understanding of it, it is difficult to attribute to carbon emissions and other anthropogenic phenomena the main cause for global warming in the 20th century.”

“…our results challenge the data interpretation that since 1880 global warming was caused by anthropogenic phenomena.”

As icefisher wisely stated, demand data for what you DO believe in.

Unless, of course, your religious beliefs prevent you.

[zaphod]

Thankyou, I pretty much understand the thrust of the paper although I had to look several things up. I wonder what prominence this report will achieve in the press? I shall look out for it.

[sigurdur]

Thanks nautonnier.

[socold]

I would put this down to a fervent climate skeptic* of a non-climate field (economics) trying to push through a dud argument in a paper that will just be ignored by climatologists and forgotten by everyone else in 6 months time (make that 1 month). The only glimmer of light it will have is the Monthly Bombshell on WUWT. No-one remembers these "bombshells" ever again. AGW has to be the most bombshelled theory that yet still survives.

I have little doubt the paper is wrong because the method is so simplistic and yet reaches a bold conclusion. It completely ignores physics and just treats the data as a bunch of physics-less numbers. So temperature is just a number rather than a physical quantity and same with CO2 and solar irradiance. If it was possible to determine attribution by merely running a statistical test people would have done this all along. In reality it isn't.

*The main author of the paper shows his stripes here:
www.dnaindia.com/world/report_global-warming-may-become-global-cooling-this-century_1345011

[zaphod]

The Met Office may end up agreeing with the statistical analysis:

www.metoffice.gov.uk/research/climate/seasonal-to-decadal/long-range/decadal-fc

[nautonnier]

Jan 5, 2013 19:24:44 GMT socold said:

I would put this down to a fervent climate skeptic* of a non-climate field (economics) trying to push through a dud argument in a paper that will just be ignored by climatologists and forgotten by everyone else in 6 months time (make that 1 month). The only glimmer of light it will have is the Monthly Bombshell on WUWT. No-one remembers these "bombshells" ever again. AGW has to be the most bombshelled theory that yet still survives.

I have little doubt the paper is wrong because the method is so simplistic and yet reaches a bold conclusion. It completely ignores physics and just treats the data as a bunch of physics-less numbers. So temperature is just a number rather than a physical quantity and same with CO2 and solar irradiance. If it was possible to determine attribution by merely running a statistical test people would have done this all along. In reality it isn't.

*The main author of the paper shows his stripes here:
www.dnaindia.com/world/report_global-warming-may-become-global-cooling-this-century_1345011

Hey fancy seeing you here SoCold -- Happy New Income Tax !

You say 'the method is so simplistic' perhaps you could elucidate on what one method it was the paper was using that was so simplistic?

[raytomes]

Excellent. I have argued for some time that differences in CO2 and temperature should be correlated rather than the variables themselves. e.g., see cyclesresearchinstitute.wordpress.com/2011/06/23/which-causes-which-out-of-atmospheric-temperature-and-co2-content/

[sigurdur]

Jan 11, 2013 8:32:40 GMT raytomes said:

Excellent. I have argued for some time that differences in CO2 and temperature should be correlated rather than the variables themselves. e.g., see cyclesresearchinstitute.wordpress.com/2011/06/23/which-causes-which-out-of-atmospheric-temperature-and-co2-content/

Ray: Thanks.

We now know, from measurements, that CO2 is not a large climate driver.

This has actually been shown, via proxy data, for decades. At the end of each inter-glacial, CO2 continues to rise, even as the temperature drops.

I don't know of anyone who argues this obvious point, which documents how little effect CO2 actually has via climate.

[steve]

One red flag would be the paper's claim that water vapour and ocean heat content are dependent on temperature, and therefore variations in these two values can be ignored! That's a pretty strong claim to make when there is no real consensus about measurements of water vapour, and the only consensus is that data prior to the 1970s is very poor.

Even if the measurements were good, most people here admit, or insist, that ENSO or PDO can affect the evolution of temperature for years to decades. I think the only difference between mine and some of your points of view is that I don't think this is evidence that undermines my expectations about climate sensitivity.

So if you have variations of temperature of years to decades caused by ocean cycles, and your dataset is only 140 years long, then ignoring the ocean is just plain stupid.

[sigurdur]

Jan 12, 2013 9:28:43 GMT steve said:

One red flag would be the paper's claim that water vapour and ocean heat content are dependent on temperature, and therefore variations in these two values can be ignored! That's a pretty strong claim to make when there is no real consensus about measurements of water vapour, and the only consensus is that data prior to the 1970s is very poor.

Even if the measurements were good, most people here admit, or insist, that ENSO or PDO can affect the evolution of temperature for years to decades. I think the only difference between mine and some of your points of view is that I don't think this is evidence that undermines my expectations about climate sensitivity.

So if you have variations of temperature of years to decades caused by ocean cycles, and your dataset is only 140 years long, then ignoring the ocean is just plain stupid.

" That's a pretty strong claim to make when there is no real consensus about measurements of water vapour, and the only consensus is that data prior to the 1970s is very poor."

Steve: Thank you for the above quote. That is why I don't make a really big deal about H2O vapour. While it may look like the trend has a negative bias, the ability to measure it with confidence is still poor.

The claims that we are going to have downpours because of increased precipitatable water are not a valid claim.

[sigurdur]

Jan 12, 2013 9:28:43 GMT steve said:

One red flag would be the paper's claim that water vapour and ocean heat content are dependent on temperature, and therefore variations in these two values can be ignored! That's a pretty strong claim to make when there is no real consensus about measurements of water vapour, and the only consensus is that data prior to the 1970s is very poor.

Even if the measurements were good, most people here admit, or insist, that ENSO or PDO can affect the evolution of temperature for years to decades. I think the only difference between mine and some of your points of view is that I don't think this is evidence that undermines my expectations about climate sensitivity.

So if you have variations of temperature of years to decades caused by ocean cycles, and your dataset is only 140 years long, then ignoring the ocean is just plain stupid.

Also, just as you posted, our understanding of ocean currents/cycles is so poor at this time, that once again to make claims that C02 is the driving force is unbelievably naive.