A National Climatic Data Center weather analysis released last week found that 2012 was the hottest year ever recorded in the United States since records began being kept in the lower 48 states in 1895. The average temperature rose to 55.3 degrees Fahrenheit, a full 1 degree higher than in the previous highest year. Skeptics of global warming may not recognize it, but the new record should spur action toward a tax on carbon emissions.
Last year's record-breaking heat and severe drought are stunning in their own right. They're even more remarkable when viewed in context with the rising heat trends and extreme weather events of recent decades. Differences in annual average temperatures are typically measured in fractions of a degree: a full 1 degree increase over the previous high, in 1998, is exceedingly rare. The 2012 high temperature averages across the country that helped squash the national 1998 record are equally dramatic examples of an alarming trend of ever hotter weather.
A weather station log kept by Weather Channel meteorologist Guy Walton, The New York Times reported, showed that 34,008 daily high temperature records were recorded across the country, while just 6,664 record lows were set in 2012. That differential reflects significant weather pattern changes. The ratio between average high temperature records and average low temperature records was fairly even until the 1970s. Since then, the margin has been shifting significantly toward many more high temperature records around the country, and far fewer low temperature records. Yet the imbalance between the two had never been as dramatic as it was last year.
"The heat was remarkable," the National Climatic Data Center's Jack Crouch told The Times. "It was prolonged. That we beat the record by one degree is quite a big deal."
Crouch further noted the significance of the temperature margin between the coldest year on record in the lower 48 states, in 1917, versus the previous hottest year, in 1998. The differential between the two records was just 4.2 degrees Fahrenheit. The 2012 record, increasing that margin by a full 1 degree, marks an usually higher percentage shift.
It comes as well as part of a larger backdrop of increasingly warmer average temperatures. The 10 warmest years on record in the United States all came within the past 15 years. The last year in which the average global temperature dropped below the 20th century average temperature was 1985.
Perhaps more reflective of the heat waves of 2012 is the number of extreme weather events that occurred in the United States, and the severe drought that plagued more than 60 percent of the country -- killing crops and trees at a record pace. Eleven major weather disasters exceeded the $1 billion mark in damage. These included severe tornado outbreaks, major hurricanes like Isaac and Sandy -- the latter has already been given a $60 billion price tag -- and the "derecho," the broad line of severe, rapidly moving thunderstorms that pummeled central and eastern states in late June.
As the climate continues to warm because of increasing levels of greenhouse gas emissions -- chiefly the carbon released in the burning of fossil fuels -- the number of extreme weather events continues to rise apace around the globe. For instance, Australia, now in summer, is already experiencing more record heat waves and ferocious wildfires in all its parched states. What rain it gets also continues to come in deluges, reflecting the extremes of drought and floods.
Climate science confirms this dynamic has been worsening around the world for years. As the warming atmosphere triggers ice and tundra melt, it warms oceans and fans volatile weather patterns. Hotter temperatures spur drought and dry soil, and are followed by greater moisture uptake from warmer oceans and subsequent deluges and floods.
Scientists reasonably predict that as the Earth's natural carbon sinks are destroyed -- as forests are clearcut and polar ice and permafrost melt and oceans warm, the carbon sequestered in these sinks over eons is released -- the rate of global warming will increase exponentially. Which means the tipping point for more rapid global warming is already near, and probably beyond the carbon-restraints that would return us to the normal weather we used to enjoy.
At this point, the best we can hope is that political leaders will impose carbon-tax policies to finance the things that nations must do to cope with worsening climate change. Yet in Washington, such political will isn't yet on the horizon.