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Climate Change Assessment for Water Resources Region 03 0 lip �a S 0 M 0 E XX rt U x'. r: .. x x a°:- e� c.� tin ra ca ra ers r�r �v ;°w ? r� ez n rr cx r rt°s rw r rw r_'w 15, (d) ep: n s ua 0 ;. South Atlantic -Gulf Figure 3.18. Projected change in streamflow, southeast USA (Georgia and Florida): 2061 — 2080 vs. 1960 — 1990. (Bastola, 2013). Lastly, the third NCA (Carter et al., 2014) presents projections of a mild decrease in water availability for the southeast region of the country through the next century in agreement with only some of the study results presented above. Key point: No clear consensus was found in projected str eal'ttflow changes in the South Adantzc- df Region. Swolne studies point toward nazld increases inflow, others point toward nazld dccr eases inflow. 3.4. Summary of Future Climate Projection Findings There is strong consensus in the literature that air temperatures will increase in the study area, and throughout the country, over the next century. The studies reviewed here generally agree on an increase in mean annual air temperature of approximately 2 to 4 °C by the latter half of the 21" century for the South Atlantic -Gulf Region. The largest increases are projected for the summer months. Reasonable consensus is also seen in the literature with respect to projected increases in extreme temperature events, including more frequent, longer, and more intense summer heat waves in the long term future compared to the recent past. Projections of precipitation in the study area are less certain than those associated with air temperature. Results of the studies reviewed here are roughly evenly split with respect to projected increases vs. decreases in future annual precipitation. This is not unexpected as, according to the recently released NCA (Carter et al., 2014); the southeast region of the country (inclusive of the South Atlantic -Gulf Region) appears to be located in a "transition zone" between the projected wetter conditions to the north and dryer conditions to the west. There is, however, moderate consensus among the reviewed studies that future storm events in the region will be more intense and more frequent compared to the recent past. Similarly, clear consensus is lacking in the hydrologic projection literature. Projections generated by coupling GCMs with macro -scale hydrologic models in some cases indicate a reduction in future streamflows but in other cases indicate a potential increase in streamflows in the study region. Of the limited number of studies reviewed here, results are approximately evenly split between the two. A number of studies reviewed here employed probabilistic modeling methods to capture and quantify some of this projection uncertainty, resulting from both climate and runoff modeling USACE Institute for Water Resources 35 January 9, 2015