In February 2005, Dr. James Hansen, head of the NASA Goddard Institute for Space Studies (GISS), analyzed the temperature data compiled for 2004 and determined that the Earth's surface temperature worldwide was 0.86°F (0.48°C) above the average temperature for the time period from 1951 to 1980.
Dr. Hansen noted that, "There has been a strong warming trend over the past 30 years, a trend that has shown to be due primarily to increasing greenhouse gases in the atmosphere." Even though natural climate change does have a noticeable effect on the climate—such as El Niño and volcanic eruptions—scientists believe anthropogenic pollution plays a much more significant role in warming.
Present evidence makes scientists like Hansen interested in predicting future trends of climate warming. Hansen and his researchers have been able to figure out that the Earth's surface absorbs more of the Sun's energy than what gets reflected back to space. Hansen and his team have also determined that global warming has reached a serious enough level that it has started to affect the seasons, making them warmer than they traditionally have been.
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