More benefits of climate change?

Not sure what to make of this:

Climate change may lead to lush growth rather than catastrophic tree loss in the Amazonian forests, researchers from the US and Brazil have found. A study, in the journal Science, found that reduced rainfall had led to greener forests, possibly because sunlight levels are higher when there are fewer rainclouds.

But scientists cautioned that while the finding raises hopes for the survival of the forests, there are still serious threats. Climate models have suggested that the forests will suffer as the region becomes drier and will release huge quantities of carbon dioxide into the atmosphere.

"researchers...found" Is that documented through data, or suggested by models?  "But scientists cautioned..."  Which scientists?  The same ones who found, or different ones who modeled?  I'm confused. 

Comments

[joshua corning]

I heard that higher concentrations of CO2 have helped spur forest growth as well.

[odograph]

Unfortunately Ocean Acidification Seen From Rising Carbon Dioxide

[John Whitehead]

Tim: you ought to read the piece in Science!

[Tim Haab]

Jerk

[Steve Keenan]

This is one of these pieces of pseudo-science that just refuses to die despite all evidence to the contrary.

The theory sounds reasonable that higher CO2 concentrations will 'fertilize' plants and usher in a lush green future. If CO2 was the only variable changed then I'd agree with this assessment. Unfortunately, increased temperatures and the changing hydrologic regime also characterized by increased CO2 concentrations (amongst other factors) leads to reduced plant growth.

The rainforests will likely be hit the hardest, as their name suggests, create much of their own rain due to the high transpiration rates through stoma on leaves. Higher atmospheric CO2 means that plant stoma are open for less time to draw CO2.

I could really get off on a rant about this but I'll end this by pointing out that there is a lot of new, and credible, research out that shows how all the factors combine.

[DCBob]

The carbon fertilization effect is real but not of as great importance in natural ecosystems as originally believed, mainly because it is limited by nitrogen availability. (See for example Sokolov et al., "Consequences of Considering Carbon/Nitrogen Interactions on the Feedbacks Between Climate and the Terrestrial Carbon Cycle" at http://web.mit.edu/globalchange/www/MITJPSPGC_Rpt151.pdf.) For agriculture, however, nitrogen limitations are less important since they can be overcome with fertilizers.

The Amazon issue is one of the serious uncertainties in climate projections. Models vary dramatically in their projections of precipitation patterns over the region and I think it's fair to say that we just don't yet know what the effects are likely to be at various levels of warming.

[joshua corning]

For agriculture, however, nitrogen limitations are less important since they can be overcome with fertilizers.

Read: Higher crop yields per acre, which leaves more land for ecosystems.

[joshua corning]

If CO2 was the only variable changed then I'd agree with this assessment. Unfortunately, increased temperatures and the changing hydrologic regime also characterized by increased CO2 concentrations (amongst other factors) leads to reduced plant growth.

That is funny becouse the study mentioned above says the exact opposite.

“If drought were to have the expected negative effect on canopy photosynthesis, it should have been especially observable during this period.

“The observations of intact forest canopy ‘greenness’ in the drought region, however, are dominated by a sgnificant increase, not a decline.”

Growth spurts would be “inconsistent with expectation”, they reported in the journal Science, and concluded the reduced rainfall was more than compensated for by extra sunlight.

“These observations suggest that intact Amazon forests may be more resilient than many ecosystem models assume, at least in response to short-term climatic anomolies,” they added.