When two federal scientific behemoths disagree, what's a mere citizen to conclude? Or does it even matter?

Yesterday, both NASA and the National Oceanic and Atmospheric Administration released their data on global average temperatures for 2007. The bottom line? It was very warm, one of the warmest years on record, and continued a trend that has persisted since the beginning of the last century.

But how exactly did 2007 rank? Well, there the two agencies part company.

Climatologists at NASA's Goddard Institute for Space Studies, in New York, concluded that 2007 tied with 1998 as the planet's "second-warmest year in a century." The record-holder remains 2005. What's more, they said, "Barring a large volcanic eruption, a record global temperature clearly exceeding that of 2005 can be expected within the next few years, at the time of the next El Nino, because of the background warming trend attributable to continuing increases of greenhouse gases."

In other words, unless a volcanic blast shades the planet in dust, the warming trend will continue, and will likely peak when the periodic warming of the Pacific, known as El Nino, shifts weather patterns in ways that tend to make things warmer all over.

The map shows where 2007 average temperatures were the warmest relative to the 1951-1980 mean. Cooler colors show where they were cooler than the long-term mean.

NASA GISS also noted that the eight warmest years of the last century have all occurred since 1998, and the 14 warmest have all occurred since 1990. They also note that this especially hot year globally came during a time of low solar irradiance and of La Nina cooling in the Pacific. The steepest warming curve was in the Arctic, which observed record-low sea ice during the summer.

Okay. So what about NOAA?

NOAA's release yesterday reported that global land and ocean surface temperatures in 2007 ranked as the fifth-warmest on record. Taken separately, the average global land surface temperature was  actually the warmest on record, while global ocean tempertaure was the 9th warmest since records began in 1880.

The agency said seven of the eight warmest years on record have occurred since 2001, while the rate of warming in the last 30 years has been three times the rate during the last century.

Obviously, we are comparing different data sets here, or measuring the 2007 data against different spans of historic records. NASA seems to be using 1900 as a starting point, while NOAA goes back to 1880.

But I'm not sure it really matters. They may see the details differently, but the big picture seems clear. Things have been warming up since at least 1900, and that's not slowing down.

BTW, for the lower 48 states, NOAA found 2007 was the tenth warmest on record, averaging 1.4 degrees above the 20th Century mean of 52.8 degrees F.