Global Warming and Butterfly Species Richness in Canada

By | July 25, 2007


One of the especially nasty predictions of climate alarmists is that global warming will lead to the extinctions of hordes of species of plants and animals, among which is the ubiquitous butterfly. For an in-depth discussion of this subject, see our major report The Specter of Species Extinction: Will Global Warming Decimate Earth's Biosphere. For a synopsis of one of the newer studies in the field, read on.

What was done

The authors, in their words, "report butterfly species' range shifts across Canada between 1900 and 1990 and develop spatially explicit tests of the degree to which observed shifts result from climate or human population density," the latter of which factors they describe as "a reasonable proxy for land use change," within which broad category they include such things as "habitat loss, pesticide use, and habitat fragmentation," all of which anthropogenic-driven factors have been tied to declines of various butterfly species. In addition, they say that to their knowledge, "this is the broadest scale, longest term dataset yet assembled to quantify global change impacts on patterns of species richness."

What was learned

White and Kerr found that butterfly species richness "generally increased over the study period, a result of range expansion among the study species," and they further found that this increase "from the early to late part of the 20th century was positively correlated with temperature change," which had to have been the cause of the change, for they also found that species richness was "negatively correlated with human population density change."

What it means

Contrary to the doom-and-gloom prognostications of the world's climate alarmists, the supposedly unprecedented (and dreaded) global warming of the 20th century has been nothing but beneficial for the butterfly species that inhabit Canada, as their ranges have expanded and greater numbers of species are now being encountered in most areas of the country.


White, P. and Kerr, J.T. 2006. Contrasting spatial and temporal global change impacts on butterfly species richness during the 20th century. Ecography 29: 908-918.