Great Lakes Regional Climate Change Maps

GLISA created the following maps of projected climate changes from analyses provided by the University of Wisconsin-Madison Nelson Institute Center for Climatic Research. The maps are based on an ensemble average of six Global Climate Models (GCMs) dynamically downscaled to a 25-km grid spacing according to the RCP8.5 scenario using the International Centre for Theoretical Physics (ICTP) Regional Climate Model Version 4 (RegCM4). ^{1 2} No individual model is perfect, and each model has strengths and weaknesses. We present the following maps as an overall regional consensus of the ensemble average for temperature and precipitation projections, but these individual models vary tremendously when comparing specific locations or different seasons within the region. To improve the precision and accuracy of future projections, GLISA is actively developing a Great Lakes Ensemble to identify models that best represent climate conditions in our region.

These maps may be cited in documents or presentation materials as such:

“Regional maps produced by the Great Lakes Integrated Sciences and Assessments (glisa.umich.edu) using data from the University of Wisconsin Nelson Institute Center for Climatic Research.”

Change in Average Temperature

The projected increases in annual and seasonal (below) average temperatures from 2040-2059 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. Northern parts of the region will likely see greater warming by the mid-century. Parts of Minnesota, Wisconsin, and Ontario may see the highest changes compared to the rest of the region.

Number of Days per Year Over 90°F

The projected change in the number of days over 90°F from 2040-2059 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. Southern parts of the region will experience the greatest increase in the number of days over 90°F, with parts of Illinois and Indiana experiencing the highest amounts. Nothern areas will see changes, but they will not be as drastic compared to the southern areas of the region.  

Number of Days per Year Over 100°F

The projected change in the number of days over 100°F from 2040-2059 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. Southern parts of the region will experience the greatest increase in the number of days over 100°F, with the southern parts of Illinois experiencing the highest amounts. Nothern areas will see changes, but they will not be as drastic compared to the southern areas of the region.  

Number of Days per Year Falling Below 20°F

The projected change in the number of days falling below 20°F from 2040-2059 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. The northern parts of the region may see the greatest changes in number of days below 20°F, and this trend may indicate the reduction in the number of days falling below freezing (i.e., less than 32°F).   

Change in the Frost-Free Season

The projected change in the number of days for the length of the frost-free season (i.e., growing season) from 2080-2099 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. The frost-free season is the period between the last spring freeze and the first fall freeze. As the winters shorten, the typical year at the end of the century may see 1-2 months increase in the frost-free season.   

Change in Cooling Degree Days

The projected change in the number of Cooling Degree Days (CDD) from 2080-2099 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. Cooling Degree Days are accumulated on days warmer than 65°F when cooling is required. Greater increases in CDD indicate increased usage of air conditioning and energy use associated with cooling. Southern areas of the region will see the greatest increases, but areas in the north will see noticeable increases due to less-accustomed conditions.

Change in Total Precipitation

The projected changes in annual and seasonal (below) total precipitation from 2040-2059 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. Projections of precipitation are highly variable by location, individual model, and the timeframe considered for the projections. The ensemble projection suggests more annual precipitation, but not necessarily during all seasons, such as the summer.      

Number of Days per Year Over 1″ Precipitation

The projected change in the number of days with over 1″ precipitation from 2040-2059 compared to the 1980-1999 period, assuming the high emissions scenario of RCP8.5. The projections of heavy precipitation are variable by location, individual model, and the threshold of precipitation used. Heavy precipitation events are anticipated to increase throughout the region, but some areas may see decreases by mid-century.       

References