Revisiting the climate evidence

Julia Gillard’s determination as Prime Minister to revisit the debate about an Australian response to the potential dangers of climate change calls for a review of the evidence to ensure that any response is proportionate and effective. In my view, the relevant data show less and less reason to attribute recent warming to human activities (‘anthropogenic warming’).

Although empiricism probably underdetermines the truth about climate—and as we know from Ross Garnaut’s report, underdetermines climate policy—it is worth laying out the reasons seriously to doubt the ‘man-made climate‘ claims once more because Gillard says she is seeking a national consensus. I think we should take no steps other than to seek a better understanding of climate; but I fear that a Labor party that is fond of condemning ‘denialism’ won’t include such contrary views in the ‘consensus’ discovery processes.

Argument

The imposition of a tax (or administered price) on an element that is not only essential to current production but the very stuff of a big proportion of Australia’s national product is an extraordinary measure requiring extraordinary reasons. But those reasons are not evident in the data; on the contrary:

  1. Official and ‘peer-reviewed’ data on historical climate—let alone on current trends—strongly shows there is nothing unusual about 20th century climate variations and no reasonable prospect of a climate emergency;
  2. The continuing disconnect between observed atmospheric carbon dioxide (and methane) concentrations and estimates of global tropospheric temperatures gives little reason to believe that climate trends would be affected by cutting the emission of carbon gasses.

In the past year the demand for cooperative action by Australia to cut emissions has disappeared. The UN Climate Convention’s Copenhagen conference demonstrated that any measures we take will be echoed by, at most, a minority of other economies. There is little doubt that they will be futile in achieving even their primary goal (a reduction in atmospheric CO2) let alone their strategic goal.

We could perhaps justify their dire impact on our national welfare by reference to a national psychology (if such a thing exists) or a collective dread; but this would be only to say the measures could not be justified by reference to any objective basis for public policy.

Evidence

To show there are insufficient grounds for ‘extraordinary’ Australian emissions controls, I have to show only good reasons to doubt the ‘man-made climate‘ case; I don’t need a conclusive demonstration of the contrary case (if it exists). So I’ll rely on just four pictures to support my two arguments.

First: that official and ‘peer-reviewed’ data on historical climate—let alone on current trends—strongly shows there is nothing remarkable about 20th century climate variations.

DomeIceCoreTempsData_tmb.png This graphic showing new, high-resolution, estimates of temperatures (using deuterium proxies that are not controversial) at two East Antarctic sites over 140 thousand years until the present has been copied from a recently published, ‘peer-reviewed’ journal article (B. Stenni et al. / Quaternary Science Reviews 29 (2010) 146–159).

The ice-core data makes it clear that temperatures in Antarctia have varied a great deal in geologically ‘recent’ history; that temperatures in the distant past (120 thousand years ago) were much higher than those of the present century and were higher even in historical times (1,000 years ago in the ‘Mediaeval Warm Period’ and in Roman times 2,000 years ago). All of this must be attributed to ‘natural causes’; there is no reason to seek a man-made explanation for variable temperature trends.

ClimateEpisodeVariationsChart_tmb.png

This variability of surface temperatures and their independence of human influence is not, of course, a secret hidden in Antarctic ice: it has always been there. Many proxy series for historical temperatures tell a similar, closely correlated, story.The chart at left (remote link) represents the amplitude of known episodes of climatic variation over the past seven thousand years—roughly, since the dawn of agriculture—taken from official (NOAA) data. The 0.7°C increase in estimated global temperature since 1880 is the smallest of the historical warming episodes over all that time.

Second: that the continuing disconnect between observed atmospheric carbon dioxide (and methane) concentrations and estimates of global tropospheric temperatures gives little reason to believe that climate trends would be affected by cutting the emission of carbon gasses.

GlobalLandOceanTempsAndCO2_tmb.png The chart at left (remote link), drawn from oficial data series (including GISS temperatures, the Antarctic ‘Law Dome’ ice-core and the NOAA Mauna Loa atmospheric CO2 series) shows the actual levels and trend increases for atmospheric CO2 and global temperature estimates over the period since 1880. Not only are the trends very different but the variations show no evidence of a relationship. The chart also shows the temperature projections of the MIT atmospheric model which are out of touch with any physical reality.

MaunaLoaVsHadCrut_tmb.jpg

A second chart based on the UK’s HadCRUT temperature series and the Mauna Loa CO2 series shows the period since 1960 in greater detail. Once again, the only remarkable fact is that the trends in the data are entirely unrelated, contradicting the IPCC’s ‘certainty’ that one explains the other. Over the period since 1960 the trends have been negatively correlated up to about 1977, then positively correlated up to about 2002, then negatively correlated again.

Conclusion

Since shortly after the IPCC began to build its eventually-hyperbolic case for concern about climate change in the mid-1990s, temperature trends have flattened and—depending on the period you select—have even shown a decline.

However embarrassing, a reversal of the trend, on its own, doesn’t point to a fault in their science. The fault would be to resist revision of their theory—and especially of their ‘certainty’—in the fact of an accumulation of contrary facts. What I’ve tried to show here is that the contradictions are mounting. The contrary facts draw attention to the lacunae (clouds, aerosols, indirect solar influcences) and crude construction (100-150km grids) in the IPCC climate models and the increasingly doubtful status of their predictions.

There are signs that, in response to the new data, the IPCC will adjust but not abandon their underlying claim that man makes climate change. Above all they will cling to their assertions of ‘certainty’ in order to retain their political ascendency. That’s not unusual in public science either (see the Tomkow link in my second para.).

But in doing so, the IPCC risks allowing their theory to become myth. We must decide not to jeopardise our national welfare in support of a mere faith.

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