The Intergovernmental Panel on Climate Change (IPCC) has stated that: Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations, mainly carbon dioxide. This conclusion is based on output from global climate computer models known as General Circulation Models (GCM).
David Douglass and John Christy, in a paper recently accepted for publication and already available on the internet, have come to a different conclusion. By considering observed, as opposed to modelled, temperature changes and at different latitude bands they conclude that:
1. El Nino and La Nina effects in the tropics have a more significant affect on global temperature anomalies than carbon dioxide, in particular it was an El Nino event that drove the 1998 global temperature maximum.
2. Variations in global temperatures since 1978 have mostly been due to climate effects in the northern hemisphere (northern extratropics) and these effects cannot be attributed to carbon dioxide.
3. Carbon dioxide has contributed a small amount to an increase in global temperatures but without what is commonly referred to as feed-back.
David Douglas and John Christy are practicing climate scientists from the Department of Physics and Astronomy, University of Rochester, and Department of Atmospheric Science and Earth System Science Center, University of Alabama, respectively. Their paper entitled ‘Limits on CO2 Climate Forcing from Recent Temperature Data of Earth’, was recently accepted for publication in Energy and Environment.
A regular at this blog, Cohenite, comments on the Douglass-Christy paper in a fairly technical note already posted at the community webpage of this blog, and entitled ‘Temperature Trends and Carbon Dioxide’, suggests that there is no evidence for a contribution from carbon dioxide to global temperatures and that the role of the sun has been underestimated.
To help beginners get this propaganda into perspective, it is desirable to look at the data. One independent statistician (at Cardiff University) recently decided to do just that, with data from the past 30 years or so around the world. He used technical forecasting expertise to project it five years to produce forecasts. He has not found ANY EVIDENCE OF WARMING. I sorry to shout that last bit. Beginners should also note, that although CO2 emissions are based on very rough guesswork, and we could no doubt do with some quality assurance checks on CO2 measurements, it is generally accepted that atmospheric CO2 levels have been increasing during this 30 year spell. The IPCC (pxss be on it) models projected very substantial temperature rises in this circumstance. Now, beginners, where should we go from here? Massive distortion of our economy? Massive injection of resentment across the world against industrialised whitey? Big conference in Copenhagen?
Here is the report from that statistician, not infected with Climate Munnchausen Syndrome: http://www.cf.ac.uk/maths/subsites/zhigljavskyaa/climatechange/time-series.html
[...] Jennifer Marohasy [...]
I'm still hoping for some clues about how to access Craig's primary data. I have seen some articles to blogs by him, but of course no contact details there. Must be patient, I suppose.
Meanwhile I'm still enjoying Jeff's amazing work, and hope to read even more eventually.
Cheers, Robin