http://www.wikio.co.uk Sodium Haze: Extreme weather – due to climate change?

Sunday, 3 July 2011

Extreme weather – due to climate change?

This report in The Independent says that a group of scientists are now getting together to research whether extreme weather events in recent years are attributable to man-made climate change.
Peter Stott, a climate scientist with the Met Office Hadley Centre in Exeter said:

“We’ve certainly moved beyond the point of saying that we can’t say anything about attributing extreme weather events to climate change,”

“It’s very clear we’re in a changed climate now which means there’s more moisture in the atmosphere and the potential for stronger storms and heavier rainfall is clearly there.”
This was echoed by Kevin Trenberth from the US National Centre for Atmospheric Research (NCAR) in Boulder, Colorado:


“The environment in which all storms form has changed owing to human activities, in particular it is warmer and more moist than it was 30 or 40 years ago,” Dr Trenberth said.

“We have this extra water vapour lurking around waiting for storms to develop and then there is more moisture as well as heat that is available for these storms [to form]. The models suggest it is going to get drier in the subtropics, wetter in the monsoon trough and wetter at higher latitudes. This is the pattern we're already seeing.”.

The Met Office and NCAR and the US National Oceanic and Atmospheric Organisation are to carry out detailed investigations of extreme weather events.
Dr Stott said:

“There is strong evidence if you look across the world that we are seeing an increase in heatwaves and floods and droughts and extreme rainfall and extreme temperatures,”

“The evidence is clear from looking at the observational records globally that extreme temperatures and extreme rainfall are changing. But you can’t jump from that and say that a specific event is straightforwardly attributable because we know that natural variability could have played a part.

“We’ve been developing the science to be increasingly more quantitative about the links and make more definitive statements about how the risk has changed. You look sensibly about these things by talking about changing risk, or changing probability of these events.”

Dr Stott had his colleagues have already carried out studies of the 2003 heatwave in Europe and the UK floods in 2000.

In both cases, the scientists found that the contribution of man-made greenhouse gases to global warming substantially increased the risk of such extreme events occurring.

The group is also investigating the exceptional warm April in Britain this year, which was the warmest since central England records were kept in 1659 and 0.5C warmer on average than the previous warmest April.

The tornadoes across the southeastern US and the flooding of major rivers such as the Mississippi and Missouri led many people to question whether they were exacerbated by global warming. In the past scientists have been reluctant to link single weather events such as these with climate change, but Dr Trenberth believes this is wrong.
 
“I will not say that you cannot link one event to these things. I will say instead that the environment in which all of these storms are developing has changed,”

“It’s not so much the instantaneous result of the greenhouse effect, it’s the memory of the system and the main memory is in the oceans and the oceans have warmed up substantially, at depth, and we can measure that.


I will assert that every event has been changed by climate change and the main time we perceive it is when we find ourselves outside the realms of the previous natural variability, and because natural variability is so large this is why we don't notice it most of the time.

“When we have things that occur usually 4 per cent of the time start to occur 10 per cent of the time, that’s when we begin to notice. The main way we perceive climate change is in changes in the extremes? this is when we break records.”

The Haze thinks this is bound to cause controversy as the science involved in making these claims is young and still under development. However - we broadly welcome this development and anything that erodes the sway of climate change denial.
 
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