Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.
From the authors of a new paper just-published in the journal Nature Geoscience comes this surprising finding:
Tropical forests are less likely to lose biomass – plants and plant material – in response to greenhouse gas emissions over the twenty-first century than may previously have been thought.
A rare “not as bad as we thought” admission about the impacts of manmade global warming!
Not only that, but based on recent findings that the true climate sensitivity is much lower than climate models emulate—findings not incorporated in new study—the results are probably still even more “not as bad as they thought” than they thought!
Chris Huntingford from the U.K’s Centre for Ecology & Hydrology and colleagues coupled climate model projections to a land surface/vegetation model to see how the tropical forests in the Americas, Africa, and Asia respond to changes in atmospheric conditions. Their vegetation model includes interactions between terrestrial plants and influences such as temperature, precipitation, and the carbon dioxide concentration of the atmosphere (a plant fertilizer).
Unlike other studies which used a very limited selection of climate models and less sophisticated vegetation models, the Huntingford team found that in virtually all future simulations that the biomass of tropical forests increases over the course of the 21st century. This is a significantly different result than many previous which suggested that anthropogenic climate change would lead to, as Huntingford et al. put it, “catastrophic losses of forest cover and biomass.”
Perhaps most interestingly, the major driver for the biomass increase is the projected growth in atmospheric carbon dioxide concentration (thanks to our use of fossil fuels). The model projected changes in precipitation had little impact on the biomass predictions and the projected increase in temperature acted to decrease the biomass (although not as much as additional carbon dioxide acted to increase it).
Which is why the results probably get even better if there is less warming associated with carbon dioxide emissions than current generation climate models predict (new research suggest that climate models together produce about 50% more warming than they should).
The authors are quick to mention that uncertainty abounds, as our level of understanding of forest response to changing environmental conditions is not all that high. But even given these uncertainties, the authors are confident that their results of increasing biomass are robust. Here is how Huntingford described the situation in a press release:
The big surprise in our analysis is that uncertainties in ecological models of the rainforest are significantly larger than uncertainties from differences in climate projections. Despite this we conclude that based on current knowledge of expected climate change and ecological response, there is evidence of forest resilience for the Americas (Amazonia and Central America), Africa and Asia.
Resilience. A refreshingly honest assessment of an ecosystem response to climate change. And one that is probably a much more apt descriptor of natural systems than “delicate,” “sensitive,” or “fragile.”
Now if only the folks in charge of assembling national and international climate impact assessments would realize (or probably more accurately, admit to) this.
We are hard at work trying to focus their attention as we are vigorously reviewing the latest draft “National Assessment” of climate change. We will leak out particularly juicy snippets in these pages when the time seems right.
Huntingford, C. et al., 2013. Simulated resilience of tropical rainforests to CO2-induced climate change, Nature Geoscience, 10.1038/NGEO1741.