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Posted by wmmbb in CLIMATE CHANGE.

According to sceintists at UNSW the global temperatures are set to rise faster than expected.

 Global temperatures may double by mid Century. Increased cloud coverage, incorporated in the assumptions of some climate models, is not likely to provide the moderating influence it was though likely to do. Just how this research demonstrates the findings is not made clear.

Peter Hannam reports greater detail  in The Sydney Morning Herald:

Temperatures are on course to rise at least 4 degrees by the end of the century, according to research that finds earlier climate models projecting smaller increases are likely to be wrong. The research, by a team led by the University of NSW, says a 4-degree rise in temperature would be potentially catastrophic for agriculture in warm regions of the world, including Australia. It cracks open one of the biggest problems in climate science

Forecasts in many climate models for lower temperature rises were based on assumptions that clouds might help limit temperature increases. New research suggests temperatures will rise between 3-5 degrees for a doubling of C02. But the team claims to have found the key to predicting cloud behaviour, and forecasts that clouds will not be nearly as helpful as thought in many models.

Current models estimate a doubling of carbon dioxide in the atmosphere – a level that may be reached by mid-century – will result in temperature rises of between 1.5 degrees and 5 degrees. Instead, the likely range will be 3-5 degrees for twice the amount of C02, the study found.

. . . Steven Sherwood, lead author of the report and a professor at UNSW’s climate change research centre, said the biggest uncertainty in modelling climate change in the past 25 years had been the changes in clouds. ”[This research] cracks open one of the biggest problems in climate science,” he said. The key to the climate’s responsiveness to rising carbon dioxide levels is the behaviour of clouds and whether they help to limit increases by cooling the surface as well as reflecting sunlight back to space. Sometimes the air rises only a few kilometres to a boundary layer before descending back to Earth. At other times it may climb as high as 10-15 kilometres.

The more optimistic of the 43 models the researchers examined predict air mostly reaches the higher level, forming clouds which have a cooling effect. ”These models have been predicting a lower climate sensitivity but we believe they’re incorrect,” Professor Sherwood said. Shallower circulations, instead, tend to pull water vapour away from the level at which clouds form, causing them to dissipate. ”Such mixing dehydrates the low-cloud layer at a rate that increases as climate warms”, the report found. ”The net effect of [climate change] is you have less cloud cover,” Professor Sherwood said.

The CO2 level of the atmosphere in 2012 was 393 parts per million, or 41 per cent higher than in pre-industrial times, the World Meteorological Organisation said. The level is rising at an accelerating rate – more than two parts per million a year – as humans burn more fossil fuels and cut down forests. Global temperatures have risen about 0.8 degrees since about 1880, with system lags and air pollution reflecting sunlight partly explaining why the rise has not been higher. ”We’ve been hoping for the best and not planning for the worst,” Professor Sherwood said. ”And now it’s looking like the best is not very likely.”

The article notes these research findings are made been published as Maurice Newman pontificates that global warming is a “delusion” and asserts climate change policy has destroyed Australia’s manufacturing sector and competitiveness. The latter assertion is not supported by economists. “Climate change madness” is likely to be doing too little. A four year old today, will be just forty at the middle of the century.

This video provides some visual information:


Tim Radford from Climate News Network (via Truthdig) reports noting agreement of French and Australian scientists.

What Sherwood and his colleagues from Pierre and Marie Curie University in Paris did was to start with some real-world observations of what happens when water vapour gets into the atmosphere.

They report in Nature that updraughts of water vapour can rise 15 kms to form high clouds that produce heavy rains, or the vapour can rise just a few kilometers before coming back to the surface without forming rain clouds.

When this happens the process actually reduces the overall cloud cover because it dessicates the clouds above: it draws away water vapour from the higher regions in a process called convective mixing.



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