Tuesday, 8 January 2008

Climate change nonsense in The NZ Herald

Bryan Leyland seems to be demonstrating a new denier tactic in this Herald article (1).

Working on the assumption that few people will read the whole article, he has crammed the opening lines with unscientific, denier tosh. The idea being, no doubt, that someone reading it will absorb the nonsense in the first few lines and wander off, convinced that there is reasonable grounds for scepticism.

The claims made in the opening paragraphs are as follows, with my comments in plain text:
  • "It [the science relating to AGW] cannot explain why, before the days of man-made CO2, the world was warmer during the Middle Ages, Roman and Minoan warm periods."
Of course it doesn't. It doesn't try to. Anthropogenic climate change was not repsonsible for the Medieval warm period, the little ice age or any other historic periods or warming or cooling. We know what caused these historical variations. The causes of current warming are not the same as the causes of previous warming. It doesn't fit. The theory underpinning AGW relates only to the special circumstances we are seeing now. Claiming that the IPCC or anyone is trying to explain previous warming through the science relating to AGW is dishonest or stupid.
  • "The surface temperature record used by the Intergovernmental Panel on Climate Change (IPCC) shows that the world has not warmed since 1998."
1998 was exceptionally war, due to various climate factors. Trying to argue anything, based on one year's temperature is like asking one person which party they'll vote for and predicting the outcome of an election on it. The five year rolling average temperature (2) clearly shows temperatures are still on the increase.
  • "The strategy ignores the increasingly strong evidence that solar emissions related to the sunspot cycle and cosmic rays have a major influence on our climate. Unlike the carbon dioxide driven hypothesis, this theory explains climate change in the past and predicts that the climate will cool until 2030."

There is no good evidence that solar activity is responsible for recent warming. This was investigated Lockwood & Frolich (3) and they found no evidence to support the contention that solar forcing was responsible for recent warming:

There are many interesting palaeoclimate studies that suggest that solar variability had an influence on pre-industrial climate. There are also some detection–attribution studies using global climate models that suggest there was detectable influence of solar variability in the first half of the twentieth century and that the solar radiative forcing variations were amplified by some mechanism that is, as yet, unknown. However, these findings are not relevant to any debates about modern climate change. Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified. (4)

Even Nir Shaviv (5) - often identified as a AGW sceptic - only attributed the warming in the first part of the 20th century to solar activity, and acknowledged that subsequent warming was a result of human activity:
... the truth is probably somewhere in between, with natural causes probably being more important over the past century, whereas anthropogenic causes will probably be more dominant over the next century. Following empirical evidence I describe below, about 2/3's (give or take a third or so) of the warming should be attributed to increased solar activity and the remaining to anthropogenic causes. (6)

Most readers will have given up by the time they've read Leyland's opening paragraphs and not bother with the remainder of the article. Their abiding memory will be the that there are still grave questions surrounding this 'global warming' business.

There are, but not the one's Leyland is asking. The real questions are 'How much?', How fast?' and 'What are we going to do about it?'

1 - 'Powering our future or wrecking the economy?,' by Brian Leyland in the NZ Herald, 7th of January, 2008. (http://www.nzherald.co.nz/section/3/story.cfm?c_id=3&objectid=10485514)
2 - 'Global Temperatures,' courtesy of Wikipedia,
http://en.wikipedia.org/wiki/Image:Instrumental_Temperature_Record.png.
3 - 'Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature,' by Mike Lockwood & Claus Frolich, published in Proceedings of the Royal society, 2007. (
http://publishing.royalsociety.org/media/proceedings_a/rspa20071880.pdf
4 - ibid.
5 - 'Carbon Dioxide or Solar Forcing?' by Nir Shaviv, published on his webiste,
http://www.sciencebits.com/CO2orSolar
6 - ibid.

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