Precipitation changes and increased forest fires are still a threat... photo: Ygor Olivera via flickr.
Another piece of the 2007 IPCC report is coming under scrutiny. In question is a passage saying that 40% of the Amazon rainforest could be wiped out by climate change. The claim was cited to the WWF report "A Global Review of Forest Fires" which talked about how changes in precipitation increase forest fires. But is the claim actually wrong?Here's the passage in question:
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 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.
Grey Literature Again Called Into Question
The UK's Times Online goes on offensive, saying that the IPCC has been "shamed by bogus rainforest claim" in its headline.
And then goes into a review of how another non-peer reviewed report got cited by the IPCC.
The fact that the practice, right or wrong, was part of the process--so-called 'grey literature' was deemed permissible if the science seemed sound--has never been a secret. Even if it was not a widely publicized procedure until the past few weeks.
Times Online Selectively Quotes Scientist...
The Times quotes Dr Simon Lewis of Leeds University, who specializes in tropical forest ecology, as saying that the WWF report is "a mess" and that it "should not have been cited; it contains no primary research data."
Which makes it seem like a well-respected researcher thinks the conclusion of the IPCC report is wrong. Except that the BBC also quotes Lewis about the WWF report and its inclusion in the 4th Assessment.
...Who Says IPCC Statement is Basically Correct
It seems that this time, unlike with reports of Himalayan glaciers' imminent death being slightly exaggerated, that the science was right, but the attribution wasn't good. Dr Lewis:
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 meters 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.
Dr Lewis went on to say that in the most extreme die-back scenarios massive tree mortality could occur, with remaining forest changing from absorbing some two billion tonnes of CO2 annually, to emitting over three billion tonnes.
Original Science, Not NGO Reports Should Be Cited
Lewis went on to say that the IPCC should have cited original scientific research and not NGO reports. Even though these are generally accurate summaries of the science, they are written from a particular point of view.
So, in summary (and with my own particular point of view) while perhaps the IPCC should have sourced its claims differently in this case, the underlying science is broadly correct. Considering the new scrutiny that grey literature is receiving--and should receive reports like those from the IPCC should cite the original science--undoubtedly these will be corrected in the next assessment report. Moving on, nothing scandalous to see here...
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