It’s another bad day for planet Earth. The hole in the ozone layer over the Antarctic opened early this year according to the UN’s World Meteorological Organization, although it may end up smaller than in previous years (Reuters leads on it being early, Bloomberg on it being small). This news broke as climate scientists in the United States blamed greenhouse gases for unusually high US temperatures in 2006. Previously El Nino had been suspected.

“Last year’s average temperature was the second highest since record-keeping began in 1895. The team found that it was very unlikely that the 2006 El Niño played any role …” said researchers from the National Oceanic and Atmospheric Administration (press release). Their findings are due to be published in the Geophysical Research Letters journal. Data from 10 previous El Ninos and 42 simulations from 18 climate models were scrutinised. El Nino appeared to actually cause a slight cooling across the United States. The work showed that last year’s temperatures matched the warming expected from greenhouse gases but were “completely inconsistent” with the pattern expected from El Nino, according to the press release.

Actually though, we already know greenhouse gases are the major cause of warming – the International Panel on Climate Change report from the start of this year stated the probability that “most of the warming” over the second half of the twentieth century was due to increases in greenhouse-gas emissions was higher than 90% (Nature, subscription required). What this research does is exonerate El Nino for 2006.

“What we found was a very strong footprint of the observed warming, consistent with the greenhouse gas effect,” one of the researchers told Reuters. AP quotes cartoon character Pogo: “We have met the enemy, and he is us.”

Image: NASA