Hansen’s “Evidence” Of AGW

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According to John Christy’s graphic (linked below) the only point of contact between Hansen’s three scenarios (A, B, C) and the observed temperature trend is the unusually strong El Niño warming in 1998. This means that real life observations are not in accordance with Hansen’s hypothesis. Since at least 2001, temperatures have not increased, despite increasing levels of carbon dioxide in the atmosphere. Steve McIntyre’s interpretation of how Hansen’s projections compare to recent temperature histories differs in that it shows a correlation with Hansen’s “Scenario C,” which is an irrelevant scenario as it assumes massive cuts in emissions beginning in 1988. In addition, it has been noted that there are THREE different scenarios projected here by Hansen, which are all across the board with GHGs and temperatures, so of course reality is going to fall SOMEWHERE within that range! Moreover, how is a computer scenario a “piece of evidence”?

“Had Hansen used a climate model with a climate sensitivity of approximate 3.4°C for 2xCO2 (at least in the short-term, it’s likely larger in the long-term due to slow-acting feedbacks), he would have projected the ensuing rate of global surface temperature change accurately. Not only that, but he projected the spatial distribution of the warming with a high level of accuracy. The take-home message should not be “Hansen was wrong therefore climate models and the anthropogenic global warming theory are wrong;” the correct conclusion is that Hansen’s study is another piece of evidence that climate sensitivity is in the IPCC stated range of 2-4.5°C for 2xCO2.”

‘Hansen’s 1988 prediction was wrong’

‘John Christy – Red, orange and yellow prediction scenarios from Hansen’s 1988 testimony’

‘Global Climate Changes as Forecast by Goddard Institute for Space Studies Three-Dimensional Model’

‘Is Jim Hansen’s Global Temperature Skillful?’

‘Steve McIntyre – Thoughts on Hansen et al 1988’

‘Steve McIntyre – Hansen et al 1988 Projections (2008)’

6 October, 2010



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