What is the importance of North American lakes in understanding climate change?
Lakes are widely distributed across the Arctic and they contain a variety of evidence about past environmental and climate changes. What information do lake sediments preserve? For example, the primary producers in Arctic lakes are diatoms [microscopic algae], and the lake sediment preserves the remains of the diatoms that grow each year. We can relate the abundance of diatom remains to the warmth of the summer. Warmer summers are associated with longer open-water periods, which allow more diatoms to bloom. Changes in the abundance of diatoms that grew over the last 50 or 100 years and are preserved in the sediment at the lake bottom can be compared with temperatures from nearby weather stations. We can then apply this calibration down the sediment core to infer the changes in temperature that took place prior to thermometer-based records. How much time do Arctic lake sediments typically preserve? Most of the deeper lakes occupy basins scoured out during the last ice age, about 15,000
