The Aspen Global Change Institute (AGI) has had excellent meetings in past. In the venue that they used when I attended, a rich diversity of viewpoints on climate science were presented, and subsequently summarized in reports. In this weblog, I want to communicate the main points of a summary of the presentation by Karen L. O’Brien who attended a 1997 meeting on “Elements of Change 1997: Scaling from Site-Specific Observations to Global Model Grids“.
The report on her work entitled “Scales of Change: The Climatic Impacts of Tropical Deforestation in Chiapas, Mexico” is relevant to all areas of the humid tropics. The report concludes that
“General circulation models coupled with atmosphere-biosphere models provide increasing evidence that deforestation can significantly influence the climate at a number of scales.”
Here are several of the bullet summaries based on her research, as extracted from the AGI Report:
1. “In scaling up to higher levels of analysis, emergent properties may appear as a result of synergistic interactions taking place at higher levels of system integration, such as the regional or global scale.”
2. “Tropical deforestation usually results in a mosaic pattern of land cover, and there is evidence that the atmospheric response to a heterogeneous land surface is nonlinear.”
3. “There is a growing recognition that the simulated impacts of deforestation on the climate are regionally specific, in large part due to the different scales of the deforested areas.”
4. “O’Brien’s local scale analysis shows a strong tendency for maximum daily temperatures to decrease at climate stations exhibiting high deforestation, particularly to the northeast of the station.”
5. “There is no clear-cut distinction between “forested” and “deforested” stations. Instead, deforestation appears as a continuum among stations.”
6. “There is a tendency for minimum temperatures to increase at some of the stations, but the majority of stations show no change.”
7. “Annual precipitation totals are highly variable with no clear trends, contrary to a widespread perception that rainfall has decreased in the Selva Lacandona.”
8. “The amount of deforestation in the full circle surrounding the climate stations seems to be less important than the location of the clearings. ”
9. “These results do not contradict conclusions based on global modeling studies, but they do indicate that the issue of local-scale changes is more complex than the models suggest.”
10. “Environmental change research demands an integrated approach that recognizes the complexity of scale, as well as the importance of analyzing data at a number of scales.”
I also recommend her excellent book,
“Sacrificing the Forest : Environmental & Social Struggle in Chiapas”,
which clearly exemplifies why the vulnerability paradigm is such a powerful assessment tool for policymakers.
Climate Science: Roger Pielke Sr. 