Time running out for 2°C target
Time is running out to limit global warming to two degrees Celsius (3.6 degrees Fahrenheit), the UN's climate experts said yesterday, saying current trends in carbon emissions heralded disaster.
Crowning a landmark review, the Intergovernmental Panel on Climate Change (IPCC) said emissions of three key greenhouse gases were at their highest in more than 800,000 years.
Earth, it warned, is on a likely trajectory for at least 4 C warming by 2100 over pre-industrial times -- a recipe for worsening drought, flood, rising seas and species extinctions.
Many could face hunger, homelessness and conflict in the scramble for precious resources.
UN chief Ban Ki-moon, who in September hosted a special summit on climate change, threw his weight behind the report, completed at a key point in UN negotiations.
"Human influence on the climate system is clear, and clearly growing," Ban told a press conference. "Action on climate change can contribute to economic prosperity, better health and more liveable cities."
US Secretary of State John Kerry said the report was a fresh warning -- "another canary in the coal mine".
"Those who choose to ignore or dispute the science clearly laid out in this report do so at great risk for all of us and for our kids and grandkids," he said from Washington.
IPCC chief Rajendra Pachauri said the scientific case for prioritising action on climate change "is clearer than ever".
"We have little time before the window of opportunity to stay within 2 C of warming closes," he said.
"To keep a good chance of staying below 2 C, and at manageable costs, our emissions should drop by 40 to 70 percent globally between 2010 and 2050, falling to zero or below by 2100."
The report -- the first overview by the Nobel-winning organisation since 2007 -- comes ahead of UN talks in Lima next month to pave the way to a 2015 pact in Paris to limit warming to a safer 2 C.
But the negotiations have been hung up for years over which countries should shoulder the cost for reducing carbon emissions, derived mainly from oil, gas and coal -- the backbone of the world's energy supply today.
The report said switching to cleaner sources, reducing energy efficiency and implementing other emission-mitigating measures would be far cheaper than the cost of climate damage.
"Ambitious" carbon curbs would shave just 0.06 percentage points annually from global consumption this century, targeted to grow by 1.6-3.0 percent annually, the IPCC said.
Under the lowest of four emissions scenarios, global average temperatures over this century are likely to rise by 0.3-1.7 C (0.5-3.1 degrees Fahrenheit), leading to between 26-55 cm in sea-level rise.
Under the highest scenario, warming would be 2.6-4.8 C, causing sea-level rise of 45-82 cm.
The report warned bleakly that on current trends, "warming is more likely than not to exceed 4 C" by 2100 over pre-industrial levels.