Quote

James Hansen of NASA GISS analyzed the data and said that the 2004 average temperature at Earth’s surface around the world was 0.48 degrees Celsius or 0.86 Fahrenheit above the average temperature from1951 to 1980.

Globally, 1998 has proven to be the warmest year on record, with 2002 and 2003 coming in second and third, respectively. “There has been a strong warming trend over the past 30 years, a trend that has been shown to be due primarily to increasing greenhouse gases in the atmosphere,” Hansen said.

Global temperatures vary from year to year and place to place, but weather stations and satellite data provide accurate records. By recording them over time, scientists develop a record of the climate, and have been able to see how it’s been changing...

Even though big climate events like El Niño affect global temperatures, the increasing role of human-made pollutants plays a big part. Scientists, like Hansen, have been working to try and predict how human impacts on our climate will affect the annual world temperature trends in the future.