Resources for a sustainable future

31/1/2010 BBC In his regular column, BBC environment analyst Roger Harrabin considers whether another mistake by the Intergovernmental Panel on Climate Change has come to
light.After the Intergovernmental Panel on Climate Change (IPCC) admitted it had made
a mistake in its Himalaya glacier forecast in its Fourth Assessment Report,
climate “sceptics” are busy searching the rest of the panel’s report for more
mistakes.
It appears that this week, they have found one. In parts of the blogosphere it
has been dubbed “Amazongate”.
There was a dire warning in chapter 13 of the report of IPCC Working Group II:
“Up to 40% of Amazonian forests could react drastically to even a slight
reduction in precipitation; this means that the tropical vegetation, hydrology
and climate system in South America could change very rapidly to another steady
state, not necessarily producing gradual changes between the current and the
future situation,” it observed.
“It is more probable that forests will be replaced by ecosystems that have more
resistance to multiple stresses caused by temperature increase, droughts and
fires, such as tropical savannas.”
Closer inspection reveals that the authors referenced for this work are, in
fact, an expert linked to environmental group WWF and a green journalist.
Euro-sceptic blogger Richard North said: “The IPCC also made false predictions
on the Amazon rainforests, referenced to a non-peer reviewed paper produced by
an advocacy group working with the WWF.
“This time though, the claim made is not even supported by the report and seems
to be a complete fabrication,” he observed.
“ The IPCC statement is basically correct but poorly written, and bizarrely
referenced ”
Dr Simon Lewis Leeds University
A blunder perhaps, but maybe of a different kind, because there is indeed plenty
of published science warning about drought in the Amazon.
Authors of some of that research are not happy that the IPCC chose to reference
WWF rather than the basic science itself.
Dr Simon Lewis from Leeds University, who co-authored a paper on the Amazon in
the journal Science, says the forest is surprisingly sensitive to drought.
He told me: “The IPCC statement is basically correct but poorly written, and
bizarrely referenced.
“It is very well known that in Amazonia, tropical forests exist when there is
more than about 1.5 metres of rain a year, below that the system tends to ‘flip’
to savannah.
“Indeed, some leading models of future climate change impacts show a die-off of
more than 40% Amazon forests, due to projected decreases in rainfall.
“The most extreme die-back model predicted that a new type of drought should
begin to impact Amazonia, and in 2005 it happened for the first time: a drought
associated with Atlantic, not Pacific sea surface temperatures.
“The effect on the forest was massive tree mortality, and the remaining Amazon
forests changed from absorbing nearly two billion tonnes of CO2 from the
atmosphere a year, to being a massive source of over three billion tonnes.”
So, it appears that, unlike in the case of “Glaciergate”, the IPCC’s science may
be right but its referencing wrong.
Dr Lewis’s Science paper came too late for the Fourth Assessment Report’s
deadline.
But, he said: “They should have cited the papers by Peter Cox and colleagues on
the modelling side, and a paper by Dan Nepstad on a massive drought exclusion
experiment.”
I have tried to contact the lead author of Working Group II to ask why his team
cited WWF not the journals – but without success so far.
My guess is that NGO reports often offer an easy synthesis of already-published
evidence.
In my experience, NGO papers are often both accessible and accurate – though
clearly written from a point of view.
But it is obvious that the next IPCC report will have to be much more meticulous
about flagging up the provenance of its sources.
There will need to be more clarification of what is known as “grey” literature
(not peer-reviewed) and IPCC panel participation.
It all points to the need for much greater transparency, though that will throw
up issues of its own for a body striving to offer a coherent view to
policymakers of an issue dominated by risk, uncertainty and values, rather that
unambiguous science.
Just this week, for instance, there were two pieces of published research in
Science and Nature suggesting that the very worse effects of climate change may
have been overestimated.
The researchers of both papers say they are still concerned about man-made
climate change, though.
The unfinished science of climate change goes on.

Go to: http://news.bbc.co.uk/go/pr/fr/-/1/hi/sci/tech/8488395.stm