Climate Conversation Group

Scientists have long debated the impact on global climate of water evaporated from vegetation. New research from Carnegie’s Global Ecology department concludes that evaporated water helps cool the earth as a whole, not just the local area of evaporation, demonstrating that evaporation of water from trees and lakes could have a cooling effect on the entire atmosphere. These findings, published on 14 September in Environmental Research Letters, have major implications for land-use decision making.

The researchers even thought it was possible that evaporation could have a warming effect on global climate, because water vapour acts as a greenhouse gas in the atmosphere.

Using a climate model, they found that increased evaporation actually had an overall cooling effect on the global climate. Read more… »

Atmospheric water vapour.

Water vapour more significant than CO2?

A study released last year reveals water vapour has an important role in global warming and more research is needed. When water vapour declines it seems to lead to global cooling, preventing overheating.

The story was covered in The Guardian on 29 January, 2010:

Water vapour caused one-third of global warming in 1990s, study reveals

Experts say their research does not undermine the scientific consensus on man-made climate change, but call for ‘closer examination’ of the way computer models consider water vapour.

Scientists have underestimated the role that water vapour plays in determining global temperature changes, according to a new study that could fuel further attacks on the science of climate change.

The research, led by one of the world’s top climate scientists, suggests that almost one-third of the global warming recorded during the 1990s was due to an increase in water vapour in the high atmosphere, not human emissions of greenhouse gases. A subsequent decline in water vapour after 2000 could explain a recent slowdown in global temperature rise, the scientists add. Read more… »

Spencer claims that climate sensitivity has been “grossly overestimated” because of confusion over cause and effect between cloud cover and temperature. All the computer models now wrongly treat cloud cover as a positive feedback, amplifying warming. But some clouds directly cause warming (a forcing) and are not the result of warming (a feedback). He gives details and says they’re having to fight to get it published. more…

New paper rips the global warming thread

    • by Richard Treadgold — based on an article published in Tool Magazine, March 2009.

The voices urging us to “change the climate” are shrieking louder than ever. Perhaps they see themselves losing ground against the global cooling of the last seven years. Those sceptical of urgency are insulted more hatefully, science and reason are abandoned and society trembles at the talk of catastrophe.

It’s the biggest alarm of all: the planet is threatened with destruction because of man-made warming. It couldn’t get any worse than that, could it? The whole planet? Wow!   Read more… »