Although sea levels are predicted to rise 1 to 2 meters by 2100, the more immediate effects of global warming are weather extremes. The number of natural disasters since 1996 costing $1 billion or more doubled compare...Although sea levels are predicted to rise 1 to 2 meters by 2100, the more immediate effects of global warming are weather extremes. The number of natural disasters since 1996 costing $1 billion or more doubled compared with the previous 15-year period. Extreme summer heat anomalies now cover about 10% of land area, up from 0.2% in 1950-1980. The human influence on global warming is evident from climate data and physical modeling. Since the beginning of the industrial era, carbon dioxide (CO2) increases correlate with those of temperature. Carbon dating shows that the CO2 increase is from burning ancient fossil fuels. Increasing CO2 and other greenhouse gases blanket and warm the earth’s surface, allowing less heat to reach the stratosphere, which is cooling. This is consistent with satellite measurements showing that solar irradiance is not changing. The present CO2 rate increase of 2 ppm/year is 300 times higher than the rate at which the earth recovered from the ice age 18,000 years ago. Without the radiative forcing of noncondensing persistent CO2, the terrestrial greenhouse would collapse, plunging the global climate into an icebound earth state. Will new technologies lower our carbon emissions in time to prevent more weather extremes? Electric cars now get the equivalent of 100 miles per gallon. The cost of electricity from solar photovoltaic cells has reached grid parity.展开更多
文摘Although sea levels are predicted to rise 1 to 2 meters by 2100, the more immediate effects of global warming are weather extremes. The number of natural disasters since 1996 costing $1 billion or more doubled compared with the previous 15-year period. Extreme summer heat anomalies now cover about 10% of land area, up from 0.2% in 1950-1980. The human influence on global warming is evident from climate data and physical modeling. Since the beginning of the industrial era, carbon dioxide (CO2) increases correlate with those of temperature. Carbon dating shows that the CO2 increase is from burning ancient fossil fuels. Increasing CO2 and other greenhouse gases blanket and warm the earth’s surface, allowing less heat to reach the stratosphere, which is cooling. This is consistent with satellite measurements showing that solar irradiance is not changing. The present CO2 rate increase of 2 ppm/year is 300 times higher than the rate at which the earth recovered from the ice age 18,000 years ago. Without the radiative forcing of noncondensing persistent CO2, the terrestrial greenhouse would collapse, plunging the global climate into an icebound earth state. Will new technologies lower our carbon emissions in time to prevent more weather extremes? Electric cars now get the equivalent of 100 miles per gallon. The cost of electricity from solar photovoltaic cells has reached grid parity.
