![]() In the snow belts of the Great Lakes, average lake-effect snowfall activity has increased since the early twentieth century for Lakes Superior, Michigan-Huron, and Erie. It picks up moisture from Lakes Nipigon, Superior, and Michigan and deposits it as snow further downwind. In this image, the wind is moving from the northwest to the southeast. ![]() Clouds build overhead and eventually develop into snow showers as they move downwind. Lake-effect snow occurs when cold dry air passes over a large, warm lake and picks up moisture and heat. Satellite image of lake-effect snow occurring over the Great Lakes region. Increases in the frequency and intensity of extreme precipitation are projected across the Great Lakes region. Some regional climate model projections using the same emissions scenarios also project increased spring precipitation and decreased summer precipitation, though these expected patterns are not as significantly altered as they are to the south of the Great Lakes. By late this century, under a higher emissions scenario, models project average winter and spring precipitation to increase 10 to 20 percent, relative to 1970–2000 under the same conditions, changes in summer and fall precipitation are not projected to be larger than natural variations. Model projections for future precipitation are less certain than those for temperatures. Observations have not documented any change in drought duration in the region (or the larger Midwest region) over the past century. Some of this increase is attributable to increases in the intensity and duration of the heaviest rainfalls-a trend that is projected to continue into the future. The number in each black circle is the percent change over the entire period (1958–2016).Īnnual precipitation in the Great Lakes region has generally increased over the past several decades. The map shows percent increases in the amount of precipitation falling in daily events that exceed the 99th percentile of all non-zero precipitation days (top 1 percent of all daily precipitation events) from 1958 to 2016 for each region of the United States. Temperatures in the winter and at night are warming faster than in other seasons or in the daytime. The average temperature in northern portions of the region has increased by more than 1.5☏ compared to the 1901–1960 average, and the rate of warming has increased in the last decade. Temperatures in the Great Lakes region have been rising over the past several decades. These impacts are particularly concerning to the region because a major component of the regional economy relies on the fisheries, recreation, tourism, and commerce generated by the Great Lakes and the northern forests. The effects of increased heat stress, flooding, drought, and late spring freezes may be magnified by other changes, such as a change in the prevalence of diseases and pests, increased competition from invasive species, land use change, an increase in air pollution, and economic shocks from extreme weather events. Note on regional modeling uncertaintiesĬlimate change will tend to amplify existing risks that impact people, ecosystems, and infrastructure. ![]() Oscaleta, middle in size, tends to mix next, and Waccabuc is the slowest to turnover in both spring and fall. That means in the fall, water temperatures in Rippowam are lower than the other lakes, and in spring, the water warms more quickly. Rippowam, the smallest and shallowest of our three lakes, mixes first because the small volume of water changes temperature most rapidly. This mixing turns the lake water murky, and algae can take advantage of all the nutrients that are carried up into the light. Waters carrying oxygen, nutrients, and sediment mingle. At some point in the spring and fall, the temperature will be the same throughout the lake from top to bottom, which allows the lake water to mix, called turnover. The lack of oxygen in the deep water allows nutrients and other compounds to dissolve in that water. In the summer, the warm, oxygenated water floats on top of cold, dense, and anoxic water. Differences in the temperature of lake water keep the water column from mixing for most of the year. You might know about lake turnover – but just in case, here’s a quick review.
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