BETWEEN TWO AND THREE DEGREES OF WARMING Up to this point, assuming that governments have planned carefully and farmers have converted to more appropriate crops, not too many people outside subtropical Africa need have starved. Beyond two degrees, however, preventing mass starvation will be as easy as halting the cycles of the moon. First millions, then billions, of people will face an increasingly tough battle to survive. To find anything comparable we have to go back to the Pliocene – last epoch of the Tertiary period, 3m years ago. There were no continental glaciers in the northern hemisphere (trees grew in the Arctic), and sea levels were 25 metres higher than today’s. In this kind of heat, the death of the Amazon is as inevitable as the melting of Greenland. The paper spelling it out is the very one whose apocalyptic message so shocked in 2000. Scientists at the Hadley centre feared that earlier climate models, which showed global warming as a straightforward linear progression, were too simplistic in their assumption that land and the oceans would remain inert as their temperatures rose. Correctly as it would turn out, they predicted positive feedback. Warmer seas absorb less carbon dioxide, leaving more to accumulate in the atmosphere and intensify global warming. On land, matters would be even worse. Huge amounts of carbon are stored in the soil, the half-rotted remains of dead vegetation. The generally accepted estimate is that the soil carbon reservoir contains some 1600 gigatonnes, more than double the entire carbon content of the atmosphere. As soil warms, bacteria accelerate the breakdown of this stored carbon, releasing it into the atmosphere. The end of the world is nigh. A three-degree increase in global temperature – possible as early as 2050 – would throw the carbon cycle into reverse. Instead of absorbing carbon dioxide, vegetation and soils start to release it. So much carbon pours into the atmosphere that it pumps up atmospheric concentrations by 250 parts per million by 2100, boosting global warming by another 1.5C. In other words, the Hadley team had discovered that carbon-cycle feedbacks could tip the planet into runaway global warming by the middle of this century – much earlier than anyone had expected. https://youtube/watch?v=-ilg75uJZZU Time to wake up. or shall we sleep just a little longer... i think its about time to wake up though.. for the good of all life ?
Posted on: Sat, 17 Jan 2015 12:23:15 +0000