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U d L R L u F d 0 D U.S. Temperature increase per Centrry Atlantic Ocean Surface 50-Year Average Temperature Range in Sargasso Sea During Past 3,®00 Years Oregon Dsy-Night and Seasonal Temperatare Range Earth Day-Night & Seasonal 20 40 60 FO lae 120 140 Temperature Range'C Figure 4: Annual mean surface temperatures in the contiguous United States between 1880 and 2006 (10). The slope of the least-squares trend line for this 127-year record is 0.5 °C per century. have little effect, as shown in Figures 2 and 3. The 6-fold increase in hydrocarbon use since 1940 has had no noticeable effect on atmo- spheric temperature or on the trend in glacier length. While Figure 1 is illustrative of most geographical locations, there is great variability of temperature records with location and regional climate. Comprehensive surveys of published temperature records confirm the principal features of Figure 1, including the fact that the current Earth temperature is approximately 1 °C lower than that dur- ing the Medieval Climate Optimum 1,000 years ago (11,12). Surface temperatures in the United States during the past century reflect this natural warming trend and its correlation with solar activ- ity, asshown in Figures 4 and 5. Compiled U.S. surface temperatures have increased about 0.5 °C per century, which is consistent with other historical values of 0.4 to 0.5 °C per century during the recov- ery from the Little Ice Age (13-17). This temperature change is slight as compared with other natural variations, as shown in Figure 6. Three intermediate trends are evident, including the decreasing trend used to justify fears of "global cooling" in the 1970s. Between 1900 and 2000, on absolute scales of solar irradiance and degrees Kelvin, solar activity increased 0.19%, while a 0.5 °C temperature change is 0.21 %. This is in good agreement with esti- mates that Earth's temperature would be reduced by 0.6 °C through particulate blocking of the sun by 0.2% (18). Solar activity and U.S. surface temperature are closely correlated, as shown in Figure 5, but U.S. surface temperature and world hydro- carbon use are not correlated, as shown in Figure 13. The U.S. temperature trend is so slight that, were the temperature U d -. F v Figure 5: U.S. surface temperature from Figure 4 as compared with total so- laz imadiance (19) from Figure 3. 1374 e 372 G Y u 370 -. 3fi Figure 6: Comparison between the current U.S. temperature change per cen- tury, the 3,000-year temperature range in Figure 1, seasonal and diurnal range in Oregon, and seasonal and diurnal range throughout the Earth. change which has t<~tken place during the 20th and 21st centuries to occur in an ordinary room, most of the people in the room would be unaware of it. During the current period of recovery from the Little Ice Age, the U.S. climate has improved somewhat, with more rainfall, fewer tor- nados, and no increase in hurricane activity, as illustrated in Figures 7 to 10. Sea level has trended upward for the past 150 years at a rate of 7 inches per century, with 3 intermediate uptrends and 2 periods of no increase as shown in Figure 11. These features are confirmed by the glacier record as shown in Figure 12. If this trend continues as ffi a 0 ~.: as .y a a a e C d rte. U.S. RaMfaH to Increasing at 1.8 Inehes per Century 19110 1920 1940 1960 1980 2000 Year Figure 7: Annual precipitation in the contiguous 48 United States between 1895 and 2006. U.S. National Climatic Data Center, U.S. Department of Commerce 2006 Climate Review (20). The trend shows an increase in rain- fall of 1.8 inches per century -approximately 6% per century. F L d 0 d a 8 0 z ~w Number of Severe Tornados ls• M U.S. Is DecreasMg 100 • ~ ~• • ~ ~ M ~ • ~ ~ ~ ~ ~ ~ • 1930 1960 197A 1980 1990 2000 Year Figure 8: Annual number of strong-to-violent category F3 to FS tornados during the March-to-August tornado season in the U.S. between 1950 and 2006. U.S. National Climatic Data Center, U.S. Department of Commerce 2006 Climate Review (20). During this period, world hydrocarbon use in- creased 6-fold, while violent tornado frequency decreased by 43%. -2- raau r9w 192 1940 1910 1900 2000 Year IOaO 1900 1920 1940 1960 19M 2000 Year