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50 Articles

New Aerosol Study Implies Lower Climate Sensitivity

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High estimates of climate sensitivity to double CO2 determined from climate models rely on "highly negative aerosol forcing" to offset high CO2 forcing estimates so the forecasts approximately match the 20th century warming. A new study by Bjorn Stevens shows the aerosol forcing is much less negative than previously estimated. Climate scientist Nicholas Lewis has calculated new lower climate sensitivity estimates utilizing the new aerosol estimates. His best estimate equilibrium climate sensitivity is only 1.45 C with a likely range of 1.2 to 1.8 C, which is much less that the AR5 range estimate of 1.5 to 4.5 C.



McKitrick on Climate Change

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Dr. Ross McKitrick, University of Guelph, explains that the "pause" in global warming reveals that there are flaws in the climate models. The models say there should be an increase but there is no increase in global temperature. “Social costs of carbon” are based on faulty climate models, not reality.



AR5 Attribution Studies

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Dr. Clive Best reviews the IPCC fifth assessment report (AR5) attribution statement, which is based on comparing climate models to the global temperature record before this century. The statement "depends critically on them [models] being able to simulate both anthropogenic forcing and natural variability. Chapter 9 of the IPCC report shows that models are tuned so as to describe past observations. The model control runs exhibit long-term drifts. Any ‘natural’ trends generated by models in the temperature data are assumed to be an artifact and simply removed. The procedure assumes there in no natural climate change despite the recovery from the little ice age. However, the Atlantic Multidecadel Oscillation alone added 0.2 C warming to the 1950 - 2010 trend. The result is that the AR5 attribution statement is useless.



Dr. Judith Curry US Senate Testimony on Climate Change

Climatologist Dr. Judith Curry presented this testimony to the US Senate Committee on Environment and Public Works. She says "Multiple lines of evidence presented in the recent IPCC 5th assessment report suggest that the case for anthropogenic warming is now weaker than in 2007. For the past 16 years, there has been no significant increase in surface temperature. There is a growing discrepancy between observations and climate model projections. Observations since 2011 have fallen below the 90% envelope of climate model projections. The IPCC does not have a convincing or confident explanation for this hiatus in warming. CO2 is not a control knob that can fine tune climate."



A Climate Essay from Dr. Bill Gray

Essay by Dr. William Gray, climate scientist at Colorado State University. He writes, "there is considerable evidence that the global warming we have experienced over the last 30 years and over the last 100 years is largely natural." He says that many thousands of scientists do not accept the human-induced global warming hypothesis as presented by the IPCC reports. Climate models "have basic flaws". It is very difficult to obtain government grants to study natural climate change. "The normal scientific process of objectively studying both sides of a question has not yet occurred.".




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