"Ever since the 2009 climate talks in Copenhagen, world leaders have agreed on 2 degrees Celsius (3.6 degrees F) as the maximum acceptable global warming above pre-industrial levels to avert the worst impacts of climate change (today we’re at about 0.8 degrees C)," writes Tim McDonnell. "But a new study, led by climatologist James Hansen of Columbia University, argues that pollution plans aimed at that target would still result in 'disastrous consequences,' from rampant sea-level rise to widespread extinction."
The study, which was co-authored by Columbia economist Jeffrey Sachs and published in the journal PLOS ONE, concludes that "[f]ossil fuel emissions must be kept to [500 billion metric tons] and global warming held to about 1.8 degrees to avert disastrous consequences," notes Tony Barboza in the Los Angeles Times.
Barbosa also looks at a new National Research Council report that raises the spectre of sudden shifts in natural and human systems resulting from changes to the climate. To prepare for such threats, the report "[calls] for an early warning system to anticipate sudden climate shifts."
"'We watch our streets, we watch our banks ... but we do not watch our environment with the same amount of care and zeal,' said James White, a climatologist at the University of Colorado, Boulder and chairman of the committee that wrote the report."