Scientists to 'fast-track' evidence linking global warming to wild
weather
Aim is to thwart sceptics from dismissing extreme event as 'natural
weather variation'
 Scientists are to challenge the climate-change sceptics by vastly
improving the speed with which they can prove links between a heatwave
or other extreme weather event and man-made changes to the atmosphere.
It typically takes about a year to determine whether human-induced
global warming played a role in a drought, storm, torrential downpour or
heatwave - and how big a role it played.
This allows climate sceptics to dismiss any given extreme event as
part of the "natural weather variation" in the immediate aftermath,
while campaigners automatically blame it on global warming. By the time
the truth comes out most people have lost interest in theevent, the
Oxford University scientists involved in the project say.
They are developing a new scientific model that will shrink to as
little as three days the time it takes to establish or rule out a link
to climate change, in large part by using highly accurate estimates of
sea surface temperatures rather than waiting for the actual readings to
be published - a process that can often take months.
"We want to clear up the huge amounts of confusion around how climate
change is influencing the weather, in both directions. For example, the
typhoon in the Philippines that dominated the UN climate change talks in
Warsaw last November and that many people put down to climate change -
it turned out it had no detectable evidence. And the same goes for
Hurricane Sandy," Dr Friederike Otto, of Oxford University's
Environmental Change Institute, said.
But there are plenty of other cases where climate change is likely to
have been involved, she said. Examples include last year's record
heatwave in Australia - the severity of which an eminent scientist
concluded this week "was virtually impossible without climate change" -
and the flooding in the UK at the start of the year, which Dr Otto's
department has just established was made 25 per cent more likely by
global warming.
"It's very much like the kinds of risks we see in the health sector,
with different levels of confidence in the role played by climate change
depending on the situation.
"It's like a weather autopsy. We know from rigorous scientific
testing that smoking increases the likelihood of cancer and work out the
conditional probability accordingly," said Dr Heidi Cullen, chief
scientist with Climate Central, an organisation in Princeton, New
Jersey, that is also working on the project.
The group aims to have the new model up and running by the end of
next year. In some weather events it may establish that there is no
link, in others the connection may be weak or uncertain and in others it
could be very strong, or almost definite, the group says.
"We hope to inject truth into the link between extreme weather and
climate change at the point when it is top-of-mind, using a transparent
and peer-reviewed methodology," said Dr Cullen.
So far, scientists have found it easier to establish climate change
links with natural hazards directly driven by temperature and rising
seas, such as heatwaves or storm surges.But with floods and droughts,
which are driven by rainfall, it is more difficult to establish a link,
Dr Cullen said.
Research published, for example, could not come to a unanimous
decision on whether the drought afflicting California had been
exacerbated by human activity.
However, it did conclude that regardless of the causes, the effects
of the drought had been worsened by global warming. This is because
whatever rain does fall in California tends to evaporate faster in the
hotter climate, leading to drier conditions.
- The Independent
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