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SAN FRANCISCO — The prey set by nations in global warming talks wo n’t prevent the devastating effect of global heating , according to climate scientist James Hansen , director ofNASA ’s Goddard Institute for Space Studies .
Thehistory of ancient clime changes , which occurred over millions of years in the satellite ’s history as it moved in and out of ice ages , offers the good insight into how humanity ' greenhouse accelerator pedal emissions will modify the planet , Hansen said here today ( Dec. 6 ) at the annual American Geophysical Union ( AGU ) meeting . And his research suggest the climate is more sensible to glasshouse gas emission than had been surmise .
A thermometer in the Earth shows increasing global climate sensitivity.
" What the paleoclimate book tells us is that the dangerous level of world-wide warming is less than what we thought a few years ago , " Hansen said . " The target that has been talked about in outside dialogue for 2 degrees of heating is actually a prescription for long - term disaster . "
Hansen is referring to the destination set by climate negotiant in Copenhagen in 2009 to keep the increase in the middling globose temperature below 3.6 degrees Fahrenheit ( 2 degree Anders Celsius ) . That roof was put in home as a means to avoid the most devastating effects of worldwide warming . [ How 2 Degrees Will Change Earth ]
However , signs of change that will exacerbate the state of affairs , such as the loss of ice sail that will raise ocean story and change how much sunlight is think over off the satellite ’s surface , are already seem , fit in to Hansen .
Two degrees of thawing will conduce to anice - free Arcticand sea - level rise in the tens of m , Hansen separate LiveScience . " We ca n’t say how long that will take , [ but]it ’s clean-cut it ’s a unlike planet . "
Climate negotiator , currently gathered in Durban , South Africa , are work with that 2 - degree goal , trying to figure out way to adjoin it .
If nursery gas emissions continue to jump unabated , the Earth ’s temperature is expect to increase by about 5.4 degree F ( 3 degrees C ) thanks to poor - term effect , such as an increase in water system vapor in the atmospheric state andchanges in cloud cover version , which will blow up or weaken the temperature step-up . But this is only a small patch of the thaw that is expected , according to Hansen ’s research .
Some fast - feedback effects show up within decades , and some of these show up only when other part of the system , particularly the oceans , which warm up tardily , see up with atmospheric thaw . This can take century .
There are also slow - feedback result that are expected to amplify planetary thaw , especially , themelting of ice sheets . The darker ground beneath the icing and the meltwater that pool on top of it absorb more sunshine , warming the major planet even more .
It ’s difficult to project how long the effects will take to set in , because , in the history of Earth ’s mood , the level of carbon dioxide in the atmosphere has never risen as quickly as it is now .
Because there is grounds that ice sheets are losing hoi polloi , the satellite is already confront these powerful feedbacks , making the goal of trim greenhouse throttle emissions to a point that forbid warming of 3.6 degrees F ( 2 degree C ) insufficient , say Hansen and his fellow Ken Caldeira of Stanford University and Eelco Rohling of the University of Southampton in England said during their presentation .
