New climate record shows pace of today's warming

摘要

It's all about speed - and quicker isn't better. One of the most extensive analyses yet of past temperatures shows that the world is warming faster than at any time in the last 11,300 years. The study has produced the first detailed extension of the famous - and sometimes contentious - "hockey stick" temperature graph right back to the end of the last ice age. It suggests that Earth is not quite out of its natural range of temperature variation yet, but will be by the end of the century. The finding comes as atmospheric carbon dioxide levels made their second-biggest leap on record. Monitoring stations in Hawaii recorded them rising by 2.67 parts per million between January and December 2012. The biggest jump was in 1998, when they rose by 2.93 ppm. Last year they averaged 393.81 ppm, up from 315.97 ppm in 1959 when records began. Climatologists estimate that CO_2 needs to plateau at 450 ppm for a 50 per cent chance of avoiding dangerous warming of 2 ℃ or more.