The US had its warmest year on record in 2012 as carbon levels grew and Arctic sea ice melted. Another downer: the global sea level hit an all-time high last year as well. These and other troubling environmental records were published Tuesday in the 32nd edition of the American Meteorological Society's State of the Climate report. This year, the annual AMS-written report was compiled with contributions from the National Oceanic and Atmospheric Administration (NOAA) and more than 380 scientists from 52 countries. The overall message of the 258-page document? Global warming is taking its toll and there is evidence of problematic, long-term trends all over the planet.
Last year, Earth was hot enough to break into the top 10 warmest years on record — either the eigth or ninth warmest depending on what dataset is used, the AMS report says. Meanwhile, both the US and Argentina had their warmest years on record. And the Arctic ocean also continued to warm, which caused sea ice to shrink yet again. In 2012, the Arctic warmed at a rate of about double the levels seen in lower latitudes, the report says. Arctic sea ice shrunk to a record low, at one point receding to 1.32 million square miles — 18 percent lower than the previous record low of 1.61 million square miles set back in 2007. NOAA has previously projected that the Arctic ocean could be essentially ice-free by 2050.
Temperatures, sea level, greenhouse gases — they're all up
On a worldwide scale, the sea saw record-setting temperatures last year as well. The AMS says that four independent datasets found 2012 to be among the 11 warmest years on record when it comes to average sea surface temperature. The Earth's average sea level also rose last year, after falling a bit in 2011 due to La Niña. "Global average sea level in 2012 was 1.4 inches above the 1993-2010 average," the report says. The increased sea surface temperatures and sea level go hand in hand: the warmer the water, the greater its volume.
Among the major contributing factors to our continually warming planet are, of course, greenhouse gasses. In 2012 the levels of carbon dioxide, methane, and nitrous oxide in our atmosphere each rose. The AMS says that global carbon dioxide emissions, from the burning of fuel and the production of cement, hit a record high last year — up to 2.1 parts-per-million to a global average of 396.2 parts-per-million on a worldwide average. Another record from the report: for the first time, carbon dioxide levels hit 400 parts-per-million at several Arctic observational sites — locations far from cement factories, car-filled cities, or major manufacturing plants where massive amounts of fossil fuels would be burned.