Time is running out to avert "a climate catastrophe,” UN chief Ban Ki-moon warned Monday as ministers opened a frenetic week of talks in Paris to forge a 195-nation accord to brake global warming.
Scientists predict Earth will become increasingly hostile for mankind as it warms, with disastrous storms, floods and droughts, and rising sea levels that will consume islands and eat away at populated coasts.
Four laborious years in the making, the envisaged accord to come out of the Paris talks would take effect in 2020 and would revolutionize the world's energy industry — replacing coal, oil and gas with cleaner sources that do not emit heat-trapping greenhouse gases.
"The clock is ticking towards a climate catastrophe," the UN secretary general told policymakers gathered in Paris.
"The world is expecting more from you than half-measures and incremental approaches. It is calling for a transformative agreement. Paris must put the world on track for long-term peace, stability and prosperity. The decisions you make here will reverberate down the ages."
The talks opened Nov. 30 with a record-breaking gathering of 150 world leaders who issued a chorus of warnings about mankind's fate if planet warming went unchecked.
"The future is one that we have the power to change right here, right now, but only if we rise to this moment," U.S. President Barack Obama told the summit.
Negotiators spent the rest of that week trying to address the many deep and complex divisions among countries with competing national interests — rows that have condemned previous U.N. efforts to failure.
While none of the major arguments was resolved, negotiators did meet a Saturday deadline to produce a draft 48-page blueprint that agrees on the need for urgent action but is littered with problems.
Environment and foreign ministers must now take the tough decisions to eliminate hundreds of bracketed words or sentences that denote disagreement.
Ban urged policymakers to be ambitious, pressing them to agree to five-year reviews of the deal, starting even before it comes into effect in 2020.
The goal would be to strengthen greenhouse gas-cutting commitments to ensure humanity is on track to limit warming of the planet to less than 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-Industrial Revolution levels.
"Current ambition must be the floor, not the ceiling for our common efforts," Ban said
The head of the U.N.'s panel of climate experts rammed home the message of urgency.
"The climate is already changing,, and we know it is due to human activity," said Hoesung Lee, newly-appointed chairman of the Intergovernmental Panel on Climate Change.
"By the end of this year we may already have reached the temperature increase of 1 degree Celsius. Whatever text you agree [to] here in Paris, please be ambitious and start real action immediately."
One of the big disputes this week in Paris is over a demand by many poor and vulnerable nations to enshrine the target of limiting global warming to 1.5 C or less, which until now has been an alternative and tougher goal.
"Any further temperature increase beyond 1.5 degrees Celsius will spell the total demise of Tuvalu and other low-lying island nations," Tuvalu Prime Minister Enele Sosene Sopoaga told the conference on Monday.
Key big polluters, such as the United States and China, are content with aiming for limiting warming to 2 degrees Celsius.
Another potential deal-blocker centers on demands by developing nations for hundreds of billions of dollars to pay for shifting to renewable energy and coping with the impacts of climate change.
Rich nations committed six years ago to muster $100 billion a year annually for developing nations by 2020, when the Paris agreement would take effect.
But the United States and other wealthy countries have yet to show how this would happen. Developing countries also insist the Paris agreement must spell out how aid would ramp up beyond 2020.
"Climate funding is the glue that will make the Paris agreement stick," said Oxfam's head of advocacy and campaigns, Celine Charveriat.
"It will be the difference between a minimalist agreement and one that starts to deliver for the world's poorest people."
France has set a Dec. 11 deadline for wrapping up the talks, setting a seemingly impossible short period of time to settle enduring rows that primarily pit rich nations against developing ones.
Despite some progress last week, all those directly involved, as well as environmental groups who follow the negotiations closely, emphasized that success was not even close yet to being assured.
"Let's be frank: all the difficult political issues remain unresolved," European Climate and Energy Commissioner Miguel Arias Canete said at the weekend.