Tag Archives: climate change

How not to discuss the Water Vapor feedback

I want to do a post soon on feedbacks, but just a quicky here

There is a lot of discussion about climate feedbacks in climate science, notably the role of water vapor. In short, the total amount of atmospheric water vapor should go up in a warmer climate under the assumption of approximately fixed relative humidity, at an increase of ~7% per degree Celsius warming, as per the Clausius-Clapeyron relationship. Water vapor is the strongest greenhouse gas, and so increases in water vapor will amplify any temperature changes from any initial forcing (e.g., CO2). However, many times the “water vapor feedback” being discussed on the internet is not the water vapor feedback at all. For example, in a recent web blog by Roger Pielke Sr., entitled Third Follow Up To Climate Metric Reality Check #3 – Evidence For A Lack Of Water Vapor Feedback On The Regional Scale or here, Dr. Pielke discusses how the WV feedback may not be showing up on the regional level and thereby questioning our understanding of how the climate reacts to temperature increase.

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The Scientific Basis for Anthropogenic Climate Change

The Scientific Basis for Anthropogenic Climate Change

Note* The graphs that appear here can be clicked for enhanced versions

Climate Science can be a bit like detective work when dealing with an issue such as global warming. First of all, we have a “detection and attribution” process where we spot a problem, and then try to find a suspect. Like they do on CSI, you find a body, and then go and find evidence to put blame on someone or something. Right now, the problem is the globe is warming, and it appears that anthropogenic CO2 plays a large part in this trend.

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