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Earth is Becoming a Greener Greenhouse The Temperature Connection: Ground-based meteorological measures of temperature indicate that global surface temperature in 1998 is the warmest in the instrumental record. The rate of temperature change was higher in the past 25 years than during any previous period. The northern latitudes (23.6N-90N) have warmed by about 0.8C since the early 1970s, but not all areas have warmed uniformly. The warming rate in the United States is smaller than in most of the world, and there is a slight cooling trend in the eastern United States over the past 50 years. The time series for NDVI and land temperature anomaly between 40N-70N were generated by spatially averaging over all vegetated pixels with composite NDVI values greater than 0.1. On both continents, NDVI is positively correlated with the temperature anomaly during the growing season at the 1% significance level (see the figure below). These results suggest that warmer temperatures may have promoted plant growth in the north during the 1980s and 1990s.
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Sep-04-2001 |
