Hot

It's official: According to the National Oceanic and Atmospheric Administration, January to June 2012 was the warmest first half of any year on record for the contiguous United States. The average temperature during that period was at 52.9 degrees F, which is 4.5 degrees above the typical average.

The high-temperatures may be a warning for future warming trends, Jake Crouch, a scientist at the National Climatic Data Center, told Reuters. Whether or not pollution from carbon dioxide emissions is the main cause, the higher temperatures are becoming the "new normal." 

"It's hard to pinpoint climate change as the driving factor, but it appears that it is playing a role," he said. "What's going on for 2012 is exactly what we would expect from climate change."

The higher temperatures were aided by the recent heat wave that caused at least 65 deaths. While temperatures have cooled down, the temperature has broken more than 2,100 records since July 1. 

Every state across the contiguous U.S. had warmer than average temperatures, except Washington.  Twenty-eight states east of the Rockys had record warm temperatures, with an additional 15 states in the top 10 for warm temperatures. 

The first six months were also drier than average, producing 1.62 inches below nationally-averaged precipitation. Fourteen states had precipitation totals among their ten driest for the time period. However, wetter-than-average conditions were observed in the Northwest and upper Midwest. Minnesota, Oregon, and Washington had six-month precipitation totals among their ten wettest.

According to the U.S. National Academy of Sciences (2010):

There is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities. While much remains to be learned, the core phenomenon­, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanation­s…

From a philosophical perspective, science never proves anything… because science is fundamentally based on observations. Any scientific theory is thus, in principle, subject to being refined or overturned by new observations.

In practical terms, however, scientific uncertainties are not all the same. Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities.