Historical Ecology & Climate Change
Historical ecology uses historical data such as photographs, oral histories and amateur and scientific natural history observations to ask scientific questions. I have been interested in the use of historical ecology in studying the effects of climate change on natural systems.
One example is resurveys conducted by myself, Sarah Gilman, Jim Barry, and Chuck Baxter of the ecological transect first surveyed by W.G. Hewatt at Hopkins Marine Station in 1930. Hewatt was a graduate student at Hopkins, and as part of his thesis he counted and recorded the abundance of every invertebrate he could see in each square yard of his 105 yard-long transect. In 1993 we relocated brass bolts that marked the transect and resurveyed invertebrate populations in the exact locations where Hewatt counted. The graph below shows that compared to the same places in 1930, we have greater populations of southern species today and lower numbers of northern species.

These changes occurred while ocean temperatures at Hopkins rose significantly by nearly 1 degree C.

But data and numbers don't tell the whole story. You can also see dramatic changes in comparative photos of intertidal landscapes, or even individual rocks. Although the granite rocks are extremely resistant to erosion and have stayed very similar, the things growing on the rocks, especially the algae, have changed dramatically. Put your cursor on any photo on this page to see before (c. 1930) and after (c. 1995) photos.

Above is Hopkins Marine Station in 1930 and (when you put your cursor on the photo) in 1995. The main difference is that the dark algal band that used to be a rich layer of the rock weed Silvetia compressa is now mostly algal turf like Endocladia muricata with almost no rockweed. This change can also be seen in the close-up of the same intertidal rock (right).

Other examples of historical ecology in studying climate change appear in the field of phenology, which looks at long-term trends in the timing of natural events such as migrations, mating and ice melting. For more reading check out some of my publications.
Rafe Sagarin