What was done
The authors searched the ISI Web of Science bibliographic database over the period 1945 to October 2004 to see what research has been published about peripheral populations, focusing on rear-edge populations that reside at the current low-latitude and -altitude margins of their ranges.

What was learned
The literature search yielded a total of 382 studies dealing with range margins, the vast majority of which were conducted in either Europe or North America and dealt with front-edge populations that reside at the current high-latitude and -altitude margins of their ranges.  Only 63 studies dealt with some aspect of rear-edge populations.  The authors characterized this fact as unfortunate, because the rear edge, in their words, is often "disproportionately important for the survival and evolution of biota."  As a result, they call for a renewed focus of interdisciplinary research with long-term experimental studies capable of distinguishing climate effects from other factors, such as habitat fragmentation, genetic load in small populations or biotic interactions.

A second important conclusion of Hampe and Petit relates to model studies of species responses to climate change, which often predict complete disappearance of populations at the rear edges of their ranges.  Such predictions, they assert, are "hazardous," because they make "a number of unrealistic assumptions" and leave "little long-term prospects for rear edge populations, despite observations of the importance and historical continuity of many rear edge populations."

What it means
It is clear from Hampe and Petit's review that the climate-alarmist vision of vast and manifold species extinctions as a result of CO2-induced global warming is unsupported by the existing scientific literature and unlikely to ever occur, especially when one considers the rear edge of their ranges, which is where species would be most negatively affected in a warming world.  In our own review of the subject posted two years ago on our website - The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere? - we came to the same conclusion, based on the fact that under CO2-enriched conditions, plants generally prefer warmer temperatures.