Cloud changes could slow global warming - research
Research released by The University of Auckland on changes in cloud height in the decade to 2010 offers the first hint of a cooling mechanism that could be in play in the Earth’s climate.
Published in the journal Geophysical Research Letters, the analysis of the first 10 years of data from the NASA Terra satellite revealed an overall trend of decreasing cloud height. Global average cloud height declined by around 1 per cent over the decade, or around 30 to 40 metres. Most of the reduction was due to fewer clouds occurring at very high altitudes.
“This is the first time we have been able to accurately measure changes in global cloud height and, while the record is too short to be definitive, it provides just a hint that something quite important might be going on,” lead researcher Professor Roger Davies said.
Longer-term monitoring will be required to determine the significance of the observation for global temperatures, the researchers suggest.
However, a consistent reduction in cloud height would allow the Earth to cool to space more efficiently, reducing the surface temperature of the planet and potentially slowing the effects of global warming. This may represent a ‘negative feedback’ mechanism – a change caused by global warming that works to counteract it.
“Clouds are one of the biggest uncertainties in our ability to predict future climate,” Professor Davies said. “Cloud height is extremely difficult to model and therefore hasn’t been considered in models of future climate. For the first time we have been able to accurately measure the height of clouds on a global basis, and the challenge now will be to incorporate that information into climate models. It will provide a check on how well the models are doing, and may ultimately lead to better ones.”
The Terra satellite is scheduled to continue gathering data through the remainder of this decade. “If cloud heights come back up in the next ten years we would conclude that they are not slowing climate change,” says Professor Davies. “But if they keep coming down it will be very significant. We look forward to the extension of this climate record with great interest.”
Comments on this article
You said it
Bernard,
Real climate scientists recognise that the feedback from clouds (the largest greenhouse gas) is HIGHLY UNCERTAIN ! but you would have us believe that the science is settled !
@Timothy Northcott: "Starting
@Timothy Northcott: "Starting to discover"?
You've got to be kidding me. Scientists have known about the negative feedback from clouds for decades. Some prominent sceptics have staked their reputation on the negative feedback from clouds completely counteracting the warming influence of greenhouse gases.
Real climate scientists also recognise that clouds have *positive* feedback aspects as well, and that the *nett* feedback of clouds is highly uncertain, but probably slightly positive.
And we can discount positive feedback loops as well?
While this research might have highlighted a negative feedback, let's not forget there are positive feedback cycles as well. And how long can a negative feedbacks like airline contrails and 'cloudification' hold back the rising tide of CO2? As a dam engineer said during the recent Qld floods: there are two types of levees, those which have flooded and those which haven't flooded yet.
Cloud uncertainty
"Clouds are one of the biggest uncertainties in our ability to predict future climate,” but now that science is starting to discover that they exert a negative feedback within the climate system then the fears of tipping points and runaway warming that keeps the likes of Lord Stern awake at night can be put to bed.