There is new evidence that global warming is playing out differently between Earth’s air, water and land. A study by researchers at the Washington State University shows the world’s lakes are warming rapidly, by about 0.3OC every decade. Scientists fear that warming could have already triggered major ecological shifts, from devastating algal blooms to thinning of fish and other aquatic animal populations. The study, which tracks lake temperatures from 1985 to 2009, also found some lakes had cooled in the period—one explanation for this could be another manifestation of global warming, the rapid melting of glaciers that feed frigid water to these lakes. Space-based studies have already showed that lakes at higher altitudes are warming faster. Given lakes are widely held to be important indicators of localised effects of climate change, the new study is likely to inform greater understanding of the already-occurring effects of climate change phenomenon.
Nature reports that the most rapidly warming lakes dot the globe. Lake Baikal in Siberia, one of the oldest natural lakes on the planet, is warming so fast that it is already threatening the Baikal seal, whose pups are born on the ice covering the lake. The warming waters of Lake Erie, one of North America’s Great Lakes, saw a debilitating algal bloom this year, fed by water that ran off agricultural fields, carrying dissolved nutrients from fertilisers. Even moderate warming is playing havoc with ecology and human society. The study found that fish populations declined in Africa’s Lake Tanganyika after moderate warming caused its warmer top water to become less likely to mix with the bottom, colder layers of water. The consequent slide in algal growth has affected food stock for fish, and the decline in fish populations, in turn, is impoverising the fishing communities dependent on the lake.