September 25, 2007

Questioning 20th Century Warmth

In 2006, an article appeared in Science magazine reconstructing the temperature of the Northern Hemisphere back to 800 AD based on 14 smoothed and normalized temperature proxies (e.g., tree ring records). Osborn and Briffa proclaimed at the time that “the 20th century is the most anomalous interval in the entire analysis period, with highly significant occurrences of positive anomalies and positive extremes in the proxy records.” Obviously, concluding that the Northern Hemisphere has entered a period of unprecedented warmth is sure to make the news, and indeed, Osborn and Briffa’s work was carried in papers throughout the world and was loudly trumpeted by the American Association for the Advancement of Science (AAAS) that publishes the journal Science.

A recent issue of Science contains an article not likely to receive any press coverage at all. Gerd Bürger of Berlin’s Institut für Meteorologie decided to revisit the work of Osborn and Briffa, and his results raise serious questions about the claim that the 20th century has been unusually warm. Bürger argues that Osborn and Briffa did not apply the appropriate statistical tests that link the proxy records to observational data, and as such, Osborn and Briffa did not properly quantify the statistical uncertainties in their analyses. Bürger repeated all analyses with the appropriate adjustments and concluded “As a result, the ‘highly significant’ occurrences of positive anomalies during the 20th century disappear.” Further, he reports that “The 95th percentile is exceeded mostly in the early 20th century, but also about the year 1000.” Needless to say, Gerd Bürger is not going to win any awards from the champions of global warming – nothing is more sacred than 20th century warming!


September 21, 2007

Climate Carpetbaggers

Filed under: Climate Politics

Coming soon to a state near you: global warming carpetbaggers who care not a whit about any discussion of global warming science.

That’s about as charitable thing as can be said about the Center for Climate Strategies (CCS), an offshoot of the radical Pennsylvania Environmental Council, a group famous for environmental scaremongering.

CCS is fanning teams of “facilitators” nationwide, presenting itself as some neutral body promoting a “consensus” on global warming policy, and specifically instructing the states that they are not to discuss global warming science when talking about climate change policy.


Soil Moisture Matters

For decades, climate scientists have run numerical experiments to predict the climate response to the buildup of greenhouse gases and the answer consistently falls on the side of warming on the global scale. The climate models have become more sophisticated by orders of magnitude over the past 40 years, and the prediction of warming given increased concentrations of greenhouse gases remains as the central pillar in the global warming issue. The fact that the Earth has warmed over the past three decades makes it very easy to claim that greenhouse gases are increasing, models predict warming, the Earth’s temperature is increasing, and therefore, the science debate on the issue is over.

We at World Climate Report have confessed repeatedly that some part of the observed warming over the past three decades is very likely related to the ongoing buildup of greenhouse gases. However, thousands (actually, millions on the internet) of presentations on global warming feature claims that climate models are predicting more floods, more droughts, more hurricanes, more glacial melting, more sea level rise, more species extinctions, more … anything you can possibly name (assuming what you name is potentially catastrophic). Our essays repeatedly show that (a) models really don’t make such predictions, (b) models are not capable of such predictions, and/or (c) there is no evidence that such predictions are supported by observational data.


September 14, 2007

Sea-Level Slowdown?

We have heard a million times that if we don’t stop emitting greenhouse gases, our inexcusable actions will result in a warmer earth, and the warming of the planet will cause icecaps and mountain glaciers to melt and sea level to rise. Island nations will be drowned, coastlines around the world will go underwater, Florida will cease to exist, and the World Trade Center Memorial could someday be a sight seen only by scuba enthusiasts. The United Nations Intergovernmental Panel on Climate Change says very clearly in the Summary for Policymakers “Global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961 to 2003. The rate was faster over 1993 to 2003: about 3.1 [2.4 to 3.8] mm per year. Whether the faster rate for 1993 to 2003 reflects decadal variability or an increase in the longer-term trend is unclear. There is high confidence that the rate of observed sea level rise increased from the 19th to the 20th century.” The IPCC crew reminds us that “Global average sea level in the last interglacial period (about 125,000 years ago) was likely 4 to 6 m higher than during the 20th century, mainly due to the retreat of polar ice.” It seems that sea levels fell and rose many times in the past and long before humans had any chance interfere with the natural order of things. There is no reason whatsoever to expect sea level to remain constant – it never has and it never will.

We have covered this sea-level rise issue many times in the past at World Climate Report and we fully agree that sea level is rising – sea level has been somewhat steadily rising for the past 10,000 years. During the last glacial advance, a large amount of fresh water was tied up in ice, and as the glaciation ended, that water returned to the oceans. Furthermore, as the earth warmed up following the last glacial advance, thermal expansion of the ocean water occurred, and sea level rose even more. There is little doubt that the sea-level rise will continue into the future, but the rate of rise is the focus of an interesting paper published recently in Global and Planetary Change by a team of scientists from France and Spain.


September 10, 2007

Increasing Variability in a Warmer World?

Filed under: Temperature History

One of the pillars of the global warming scare is that as temperatures rise, the variability of climate will increase and we will see an increase in temperature extremes. More heat waves will result, more lives will be lost, and the increase in greenhouse gases will be to blame. The concept is illustrated in the Figure 1 – should the temperature distribution simply shift up a few degrees (as seen in a), fewer low temperatures would be experienced while the incidence of high temperatures would increase. However, should the variance of the temperature distribution increase (as seen in b), then the corresponding increase in extreme high temperatures would be even greater. Even the occurrence of record-breaking low temperatures can be blamed on global warming if one accepts the hypothesis that temperature variance is related to any change in mean temperature.

Figure 1. Schematic diagram illustrating the shifts in extremes that can occur under changing mean conditions, through either a symmetrical change in the probability density function of temperature (a), or through a shift in probability density function where the variance and the kurtosis of the distribution changes (b) (from Beniston and Goyette, 2007).


September 5, 2007

Antarctica: Warming, Cooling, or Both?

Filed under: Antarctic, Polar

The ice caps are melting – right? If you visit thousands of websites on climate change, watch Gore’s film or many similar documentaries, you would be left with no doubt that the icecaps are warming and melting at an unprecedented rate. However, with respect to Antarctica, you might be surprised when you examine what the United Nations Intergovernmental Panel on Climate Change says in their 2007 Summary for Policymakers. Believe it or not, IPCC reports “Antarctic sea ice extent continues to show inter-annual variability and localized changes but no statistically significant average trends, consistent with the lack of warming reflected in atmospheric temperatures averaged across the region.” Furthermore, they note “Current global model studies project that the Antarctic ice sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall.”


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