water vapour
illconsidered | February 25, 2009Contrary to the popular talking point, climate models do take into account H2O as a greenhouse gas. In fact, it is the largest single feedback factor in the climate system. And also contrary to another popular talking point, models are being validated in many ways.
Go have a read at Gristmill for a post by Andrew Dessler on a recent paper he co-authored[PDF] that seeks to assess the state of current climate science literature on the topic of water vapor feedback in models and the climate system. He describes papers raw material as a "mountain of evidence" supporting a strongly positive…
illconsidered | April 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Clouds are a very large negative feedback that will stop any drastic warming. The climate models don't even take cloud effects into account.
Answer:
All of the Atmospheric Global Climate Models used for the kind of climate projections reported on by the IPCC take the effects of clouds into account. You can read a discussion about cloud processes and feedbacks in the IPCC TAR.
It is true however that clouds are one of the largest sources…
illconsidered | February 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Climate scientists never talk about water vapor, which is the strongest greenhouse gas, because it undermines their CO2 theory.
Answer:
There is no climate model or climate textbook that does not discuss the role water vapor plays in the Greenhouse Effect. It is the strongest Greenhouse gas, contributing 36% - 66% to the overall effect for vapor alone, 66% to 85% when you include clouds. It is however, not considered as a climate "forcing…
illconsidered | January 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
H2O is 95% of the Greenhouse effect, CO2 is insignificant.
Answer:
According to all of the scientific literature and climate experts I am aware of regarding this question, CO2 contributes anywhere from 9 to 30% towards the overall greenhouse effect. Depending on the method you use to determine these percentages they may even add up to more then 100% due to overlap and saturation of the particular frequencies of infra-red radiation each…