I was struck by the breadth with which Elizabeth Kolbert approached the evidence to evaluate the issue of global warming. In her book, one chapter is entitled The Butterfly and the Toad. What could butterfly’s and toads have to due with global warming. Here the story on butterflies.

People in England, and other parts of the world have been monitoring butterflies for hundreds of years. One particular butterfly of interest here is Polygonia C-Album (known as the Comma butterfly–as seen here).

In the 1970s, according to Elizabeth Kolbert, the British decided to focus its efforts on butterfly monitoring through its Lepidoptera Distribution Map Scheme. Hundreds of amateur butterfly observers were involved, and by the mid-eighties, they had developed an very large atlas that showed the distribution of every butterfly type in England.

The distribution map for Comma’s range up to 1994 is shown below. By the end of that decade the original map was out-of-date, as shown in the second map below.

Comma Distribution up to 1994

Comma Distribution 1995 – 1999

Kolbert reports that the authors of the most recent butterfly atlas call this expansion “remarkable.” They report that species of “general butterflies” all have moved northward since 1982. And other scientists looking at other butterflies, report that nearly 2/3’s of all species have moved northward in recent years.

This story shows how climate change can be seen in the behavior of wild-life. Individual species become indicators of climate change. As Holbert points out, individual changes of specific wildlife could be due to local changes; the only explanation proposed that makes sense of them all, is global warming.

Butterflies as indicators of climate change might be a great project for students. In the U.S., the project Journy North is worth investigating. Journey North engages students in a global study of wildlife migration and seasonal change. K-12 students share their own field observations with classmates across North America. They track the coming of spring through the migration patterns of monarch butterflies, bald eagles, robins, hummingbirds, whooping cranes — and other birds and mammals; the budding of plants; changing sunlight; and other natural events.