According to NASA, 2007 was tied with 1998 as the second-warmest year in a century.

According to the NASA Goddard Institute for Space Studies (GISS), the eight warmest years in the GISS record have all occurred since 1998, and the 14 warmest years in the record have all occurred since 1990.

The article goes on to say:

The greatest warming in 2007 occurred in the Arctic, and neighboring high latitude regions. Global warming has a larger affect in polar areas, as the loss of snow and ice leads to more open water, which absorbs more sunlight and warmth. Snow and ice reflect sunlight; when they disappear, so too does their ability to deflect warming rays. The large Arctic warm anomaly of 2007 is consistent with observations of record low geographic extent of Arctic sea ice in September 2007.

“As we predicted last year, 2007 was warmer than 2006, continuing the strong warming trend of the past 30 years that has been confidently attributed to the effect of increasing human-made greenhouse gases,” said James Hansen, director of NASA GIS

The data in the graph above are pretty conclusive. The planet’s climate is changing. Now what are we going to do about it?