Smol said the change in diatoms indicates a rapid period of warming that coincides with widespread burning of coal and the beginning of the Industrial Revolution. Smol is now working with Bruce Finney, a paleoceanographer at the University of Alaska's Institute of Marine Science. Finney uses the nitrogen left behind from salmon carcasses to track hundreds of years of salmon runs in Alaska and the Pacific Northwest. When Smol and Finney compare diatoms with nitrogen levels, they find a correlation between years of high salmon runs and the abundance of diatoms that love nutrient-rich water. Smol's colleagues at Queen's University also have used diatoms to check the former salinity of water bodies in the Great Plains.
Salinity is an indicator of massive droughts in the past.
Some researchers have used salt-water diatoms found in freshwater lakes to determine the dates of past tsunamis that have crashed inland. Smol said diatoms can even be used to help date ancient bits of pottery, and to find the water sources with which the pots were made. Not too bad for creatures so small that hundreds of them could sit on the head of a pin without bumping elbows.