Resolution 7478 hazard mitigation

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2024 Hennepin County All -Jurisdiction Hazard Mitigation Plan Volume 2 — Hazard Inventory d�Hazard Assessment: CLIMATE CHANGE 4.3.1.1. Definition Climate change is a significant and ongoing change in the long-term statistical and/or spatial behavior of weather patterns and variables, as global temperatures rise in response to the intensified combustion of fossil fuels and deforestation, both of which increase concentrations of atmospheric carbon dioxide and other greenhouse gases. The increasing global temperatures have, in turn, added additional moisture to the air through higher evaporations rates, and modified patterns of global atmospheric circulation. Climatic Background Hennepin County has a highly variable, continental -type climate with seasonal extremes and a wide range of weather hazards. Its position near the center of the continent, and halfway between the Equator and North Pole, subjects it to a wide variety of air mass types throughout the year. During a single year, Hennepin County will experience heavy snow, frigid wind chills, howling winds, intense thunderstorms, torrential rains, and heat waves, as well as dozens of bright and sunny days. In addition to extreme variations between our seasons, Hennepin County's climate also can include large variations from one year to the next, or even at decadal and multi-decadal scales. The extremely dry years of 1910, 1936, 1976, and 1988 each were followed within 1-3 years by extremely wet ones. In a six -year span of the 2010s, Hennepin County experienced its warmest November through March on record in 2011-12, its 51h coldest on record in 2013-14, and its 4th warmest on record in 2015-16. Climate Change in Hennepin County In Hennepin County, climate change has meant distinct, measurable trends towards warmer, wetter, and more humid conditions on average, even as occasional swings towards dry or cold conditions continue to be part of the climate. As shown in TABLE 4.3.1A, county -averaged temperature and precipitation have increased by 3.1° F and 3.0 inches, respectively since 1895. The warmest year, winter, and spring, and the wettest summer and winter, have all occurred since the year 2000. Additionally, nine of the county's 10 warmest years and seven of the 10 wettest years from 1895 through 2023 occurred after 1970, with the vast majority occurring after 1990. The county's most extreme precipitation events also occurred during this period, with major flash -flooding in 1977, 1987, 1997, 2014, and 2016. Record -level humidity extremes occurred more frequently from 2000 through 2023 than at any other time in 121 years of record. 45