Summary of Climate Model Projections

Temperature

Both the Hadley and Canadian climate models predict a warmer Louisiana in the future, differing only in how much warmer. The Hadley model projects an overall temperature rise of 5 degrees F with a July heat index increasing 8 to 15 degrees F. The Canadian model's forecast is more extreme, predicting a 10 degrees F temperature rise and a sweltering July heat index more than 20 degrees warmer by the end of the century.

Sea-level Rise

The Canadian climate model projects a sea-level rise of 15.6 to 19.2 inches by the turn of the century. The Hadley model is more conservative, predicting a rise of only 8.4 inches. While this would be unsettling for residents of almost any coastline, it is particularly bad news for Louisiana. The state will not only endure a sea-level rise but will suffer subsidence rates (natural compaction of coastal soil) ranging from 8 to 31 inches if past history is an accurate predictor. When the projected rise in sea level is added to this natural subsidence, the predictions for relative sea-level rise become alarming:

• Canadian model — 23.6 to 50.2 inches
• Hadley model — 16.4 to 39.4 inches
• Average of the two models — 20 to 44.8 inches

Temperature	Relative Sea-Level Rise
5 degrees F 10 degrees F Hadley Canadian	16.4 – 39.4 Inches 23.6 – 50.2 Inches Hadley Canadian

Precipitation

It is extremely difficult to project future precipitation patterns for the southeastern U.S. because of the unpredictable influences of the mid-atmospheric jet stream and high-pressure weather systems originating over Bermuda. Not surprisingly then, the two climate models present opposite scenarios for precipitation. The Canadian model suggests that Louisiana rainfall will decrease by 20 percent; the Hadley model predicts that rainfall will increase by 20 percent. While the predicted change in rainfall for the upper Mississippi drainage basin is not so extreme, only a 5 percent increase or decrease, any changes there will dramatically affect the Mississippi's water levels in Louisiana.

Weather Patterns

The frequency and intensity of future storms and hurricanes is difficult for the models to project. However, both the Hadley and Canadian models indicate that perhaps storms may be more intense, with longer dry periods in-between.

The Hadley and Canadian model projections for the southeast United States are remarkably similar. Both models predict significantly warmer temperatures, higher sea levels and the possibility of more intense storm systems. The primary difference between the two models is in the amount of rainfall predicted, the Hadley model pointing to a drier climate and the Canadian model indicating a wetter climate.

Precipitation	Weather Patterns
+20% -20%   Hadley Canadian	Storms Will Intensify Storms Will Intensify Hadley Canadian