Reference
Ihm, B.-S., Lee, J.-S., Kim, J.-W. and Kim, J.-H. 2007. Relationship between global warming and species richness of vascular plants. Journal of Plant Biology 50: 321-324.
What was done
"Based on data from the 1997 IUCN Red List of Threatened Plants (Walter and Gillett, 1998)," the authors calculated the number or richness of vascular plant species per unit area of land for 79 nations of the Northern Hemisphere with the goal of determining the effect of global-scale environmental change on the degree of variability in national plant species richness, particularly within the context of 20th-century global warming.
What was learned
For the 79 countries included in their analysis, Ihm et al. report that "vascular plant species richness showed large variability, ranging from 377 to 51,220 species per country, or 0.0003 to 0.2896 species per km2." In addition, they found that "variability declined while richness gradually increased as one moved from Arctic to Equator regions." Based on this relationship, and noting that "over the past 100 years, the global average temperature has increased by approximately 0.5°C," their derived relationship indicated that this 100-year elevation in air temperature was associated with a species richness increase of 0.8%. And when they "estimated the effect of higher temperatures," such as those predicted for the future, they found that "a 1 or 2°C rise in global warming produced an increase in species richness of 1.6 or 3.2%."
What it means
The real-world data employed in this study would tend to suggest that global warming leads to an increase in local species richness almost everywhere on earth, which is also the finding of our major report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere? Truly, the economy of nature is such that the biological wealth of nations will only increase in response to global warming, as we also know to be true from the real-world experiences of the Dark Ages Cold Period-to-Medieval Warm Period transition and the Little Ice Age-to-Current Warm Period transition.
Reference
Walter, K.S. and Gillett, J.H. 1998. 1997 IUCN Red List of Threatened Plants. The World Conservation Monitoring Centre. IUCN - The World Conservation Union, Gland, Switzerland and Cambridge.