Our Changing Extremes
Since 1916, the amount of rain that falls during the annual largest storm in Minnesota has increased by more than an inch.
Not only has the yearly maximum rain event become more extreme, but some extreme events have become more common. A catastrophic "mega-rain event'' occurs when at least six inches of rain fall over an area of at least 1,000 square miles. Between 1973 and 2020, there were 17 mega-rain events in Minnesota, with almost two times as many happening in the 21 years between 2000 and 2020 as happened in the 27 years between 1973 and 1999.
A heatwave can be defined as a series of at least 4 days with air temperatures that would normally only occur about once every 10 years. So far there is no evidence of increasing very hot days in Minnesota, but these days are projected to become more frequent under different climate change scenarios. Climate change might make heat waves stronger and longer. As the average temperature goes up, the same relative increase in temperature during a heat wave would result in a hotter absolute temperature. For example, if a region's average temperature in July is 75 degrees Fahrenheit and a typical heatwave is when the temperature is 15 degrees Fahrenheit above normal, then the heatwave temperature is about 90 degrees Fahrenheit. But if the region's average July temperature increases to 80 degrees Fahrenheit, then a similar increase of 15 degrees Fahrenheit would result in a heatwave of 95 degrees Fahrenheit. This also doesn't account for a possible "tipping point", where moving into a new temperature range can result in a much larger change in heat waves. As the climate warms, heat waves will get excessively hotter.
References & Suggested Reading
Ebi KL, Balbus J, Kinney PL, Lipp E, Mills D, O’Neill MS, and Wilson M. 2008. Effects of global change on human health. In: Analyses of the Effects of Global Change on Human Health and Welfare and Human Systems [Gamble JL (editor), Ebi KL, Sussman FG, and Wilbanks TJ (authors)]. Synthesis and Assessment Product 4.6. U.S. Environmental Protection Agency, Washington, DC, pp. 39-87.
Federal Emergency Management Agency (FEMA). 2021. "Ready: Floods". url: http://www.ready.gov/floods. Accessed Aug 18, 2021
Great Lakes Integrated Sciences and Assessments. url:glisa.umich.edu. Accessed July 16, 2021.
Harding, K. J., and P. K. Snyder (2014), Examining future changes in the character of Central U.S. warm-season precipitation using dynamical downscaling, J. Geophys. Res. Atmos., 119, doi:10.1002/2014JD022575.
Harding, K. J., and P. K. Snyder (2015), Using dynamical downscaling to examine mechanisms contributing to the intensification of Central U.S. heavy rainfall events, J. Geophys. Res. Atmos., 120, doi:10.1002/2014JD022819.
Melillo J., Richmond, T., and Yohe, G., 2014. An assessment from the U.S. Global Change Research Program to inform the public with scientific information and methods regarding climate change.
USGCRP, 2018: Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, 1515 pp. doi: 10.7930/NCA4.2018.