Projections of Future Climate from the GCMs

Peter J. SousounisGeography Department

Michigan State University, East Lansing, MI

Climate Scenarios - Temperature Changes

NW SW/California Great Plains/Rockies Heartland/Great Lakes SE NE USBoth of the GCMs used for the Great Lakes Regional Assessment indicate a warmer future climate by the end of this century. The Canadian Model becomes considerably warmer than the Hadley Model in many US regions.

CANADIAN HADLEY

Monthly Thickness - Future Conditions

Thickness of the lower half of the atmosphere reflects surface temperature in a large scale way. The Canadian Model shows significant increases in thickness throughout the year by the end of this century. The Hadley Model shows overall smaller changes than the Canadian Model and greater increases in fall and winter than in spring and summer.

CANADIAN HADLEY

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Interannual Variability in Hot Days for SW Michigan

The number of extremely hot (90+ F) days will likely increase considerably by the end of this century.

Changes in the Growing Season…The growing season will likely increase by 30 to 50 days but interannual variability may still constrain safe planting and harvest dates.

NW SW/California Great Plains/Rockies Heartland/Great Lakes SE NE US

Both of the GCMs indicate more precipitation in the future. The Canadian Model is drier than the Hadley Model in eastern US regions and wetter in the southwestern and mountain regions.

Climate Scenarios - Precipitation Changes

CANADIAN HADLEY

Monthly Precipitation - Future Conditions

The Canadian Model shows an increase of ~8% in annual precipitation by the end of this century. Most of the increase occurs during Jan-Jun. The Hadley Model shows an increase of 12%. Most of the increase occurs during Jul-Dec.

CANADIAN HADLEY

More frequent storms Slower storms Stronger storms Moister storms More efficient storms

Why Should Precipitation Increase…?

Annual Precip Category Changes for Detroit, MICAT (mm) DAYSPCN (MM) DAYSPCN (MM) DAYS PCN

0.25-1.25 88 58.08 84 56.771.26-6.35 101 303.97 98 299.616.36-12.7 31 269.35 30 257.92 -7 -1712.8-25.4 18 326.14 20 345.89

> 25.4 8 337.07 11 471.97 5 155

CAN 1900 CAN 2000

CAT (mm) DAYSPCN (MM) DAYSPCN (MM) DAYS PCN

0.25-1.25 67 45.18 62 40.641.26-6.35 90 270.91 81 246.576.36-12.7 31 276.86 30 264.85 -15 -4112.8-25.4 19 314.12 23 401.92

> 25.4 2 59.79 6 178.28 8 206

HAD 1900 HAD 2000

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Interannual Variability in Hvy Precip for Detroit, MI

Both models suggest an increase in interannual variability - CAN increases from 6 to 8 days and HAD increases from 3 to 6 days.

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HVY PCN (MM)

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Interannual Variability in Hvy Precip for Detroit, MI

Both models suggest an increase in interannual variability - CAN increases from 160 to 240 mm and HAD increases from 68 to 133 mm.

Precipitation - Canadian Extreme PCN Pattern

CURRENT FUTURE

Both models show similar patterns for the current and future climate scenarios but with lows farther to the southwest. The Canadian Model shows increases from 40 to 47 mm…

The current observed pattern for extreme precipitation shows a precip max of 22 mm with a 1006 hPa low centered 200 km to the west, suggesting these events are warm frontal.

CURRENT FUTURE

Precipitation - Hadley Extreme PCN Pattern

The Hadley Model shows a precipitation increase from 23 to 29 mm. The heavier precipitation will likely result from slightly more intense lows and sharper warm fronts.

Both models show a decrease in cyclones and a reduction in associated windspeed. The Canadian Model shows a big decrease in cyclones from late spring/ mid summer and from late fall/ mid winter. The Hadley Model shows a big decrease in cyclones in winter and a bigger decrease in spring.

CANADIAN HADLEY

Monthly Cyclones - Future Climate

Monthly Winds - Future Conditions

Windspeeds in general will likely decrease. The reason for this is that melting polar ice will result in greater warming at high latitudes, a reduced pole-to-equator temperature gradient, and weaker jet streams.

CANADIAN HADLEY

Future Winter Flow Patterns…

Both models suggest more frequent and intense El Ninos - especially the Hadley Model…

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CURRENT FUTURE

Climate change in the Great Lakes region will be manifested by changes in winds and storm tracks as well as by changes in temperature and precipitation.

Extreme hot days will occur at least twice as frequently, extreme precipitation events will increase in frequency and intensity. The number of cyclones will decrease by ~15% and windspeeds will decrease by 10%.

Interannual variability will also likely increase.

The magnitudes of the climate changes will have significant impacts on agricultural yields and practices.

Summary