2017-05-23_GENERAL DOCUMENTS - M1977472

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dust control measures); • Minimize surface disturbing activities during windy events and/or for long periods when steady winds are forecasted that would transport dust in the direction of human populated areas (residences, places of business or similar) or to parks, wildernesses or other similar areas (minimizes PM emissions transported to human occupied locations and visibility impacts to parks/wildernesses; also could minimize potential ozone formation in the ozone NAA). Projected Climate Impacts The future climate equilibrium is dependent upon warming caused by past anthropogenic emissions, future anthropogenic emissions, and natural variability. Global mean surface temperature change for the period 2016-2035 relative to 1986-2005 is similar for the four RCPs and will likely be in the range 0.3°C to 0.7°C (medium confidence). The projection assumes no major volcanic eruptions, changes in natural emissions sources (e.g., CHa and N20), or unexpected changes in total solar irradiance. By 2050, the magnitude of the projected climate change is significantly affected by the overall emissions path the world is tracking along. The projected increase of global mean surface temperature by the end of the 21 st century (2081- 2100) relative to 1986-2005 is likely to be 0.3°C to 1.7°C under RCP2.6, 1.VC to 2.6°C under RCP4.5, 1.4°C to 3.1°C under RCP6.0 and 2.6°C to 4.8°C under RCP8.5. It is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales, as global mean surface temperature increases. It is also very likely that heat waves will occur with a higher frequency and longer duration. Occasional cold winter extremes will continue to occur, due to the inherent variability within the climate system. Changes in precipitation patterns will not be uniform, but in general and regions are expected to become dryer while wetter areas can expect more frequent exceptional precipitation events. Oceans will continue to warm, with the greatest impacts occurring at the surface of tropical and northern hemisphere subtropical regions. Models also predict ocean acidification will increase for all RCP scenarios, where surface pH can be expected to decrease by 0.06 to 0.07 (15 to 17%) for RCP2.6 and 0.14 to 0.15 (38 to 41%) for RCP4.5. Year-round reductions in Arctic sea ice are projected for all RCP scenarios and it is virtually certain that near-surface (upper 3.5 m) permafrost extent at high northern latitudes will be reduced (37% - RCP2.6 to 81% - RCP8.5) as global mean surface temperature increases. Global mean sea level rise will very likely continue at a faster rate than observed from 1971 to 2010. For the period 2081-2100 relative to 1986- 2005, the rise will likely be in the ranges of 0.26 to 0.55 in for RCP2.6, and of 0.45 to 0.82 in for RCP8.5. It is very likely that the sea level will rise in more than about 95% of the ocean area, where about 70% of coastlines worldwide would experience a sea level change within±20% of the global mean. All climate model projections indicate future warming in Colorado. Statewide average annual temperatures are projected to warm by+2.5°F to +5°F by 2050 relative to a 1971-2000 baseline under RCP4.5. Under the high emissions scenario (RCP8.5), the projected warming is +3.5°F to +6.5°F and would occur later in the century as the two referenced scenarios diverge. Summer temperatures are projected to warm slightly more than winter temperatures, where the DOI-BLM-CO-N020-2017-0003 22