Four European research groups involved in a joint assessment said on Wednesday that emission cuts currently promised by nations for Paris were insufficient, and would still result in average warming of around 3 degrees Celsius by 2100, compared to pre-industrial levels. The UN's stated target is to limit warming to 2 degrees Celsius.
To uphold that, overall emissions must be rapidly and jointly slashed, they insisted.
So far, 56 governments have made pledges, known as Intended National Determined Contributions or INDCs. They are the focus of preparatory UN talks this week in Bonn to hone an 83-page text for the world body's Paris summit in December.
Those 56 nations account for about 70 percent of the world's current emissions.
The research groups looked at strategies outlined by 15 major countries for the period beyond 2020, using an assessment tool called the Climate Action Tracker (CAT).
Black marks for seven countries
It lists seven nations as "inadequate" contributors in the attempt to limit warming: Australia, Canada, Japan, New Zealand, Singapore, South Korea and Russia.
Six were rated for "medium" efforts, including top emitters, China, the European Union bloc, and the the United States whose president, Barack Obama, is in Alaska this week highlighting glacier shrinkage.
Only Ethiopia and Morocco were rated via the tracker method as making "sufficient" pledges to help restrain warming to 2 degrees.
To stay under the 2-degree threshold scientists reckon that world's emissions of so-called greenhouse gases, for example, carbon dioxide from burning fossil fuels, need to drop from the current level of 50 billion tons per year -- measured in carbon dioxide equivalents.
By 2025, those emissions would need to fall to 39-43 billion tons, and by 2030 to 36-45 billion tons, according to the CAT data.
'Almost impossible' target of 2 degrees C
Targets currently stated by individual nations for 2030 made the 2-degree goal "almost impossible," they said.
The average temperature rise - in relation to pre-industrial times - would be closer to 2.9 or 3.1 degrees, said Bill Hare of Climate Analytics, a CAT contributor.
"It is clear that if the Paris meeting locks in present climate commitments for 2030, holding warming below 2 C could essentially become infeasible, and 1.5 C beyond reach," Hare said.
Another CAT contributor, Niklas Hoehne of the NewClimate Institute said "most governments" that had already submitted an INDC needed to "strengthen them."
Other countries still preparing their targets needed to "aim as high as possible," he added.
The ten highest emitters whose INDC targets are still awaited by UN climate officials are India, Brazil, Iran, Indonesia, Saudi Arabia, South Africa, Thailand, Turkey, Ukraine and Pakistan.
Chances for Paris, 'much better'
Former UN climate chief Yvo de Boer, referring to a chaotic Copenhagen climate summit in 2009, said the chances for Paris were "much better."
The United States and China were more engaged this time, he said.
In Bonn, France's climate ambassador Laurence Tubiana said: "Paris is not the end of the process; it is the start of the process."
Emerging nations represented in Bonn, where the UN's climate agency is based, have called for greater compensation for losses caused by rising sea levels.
David Waskow of the World Resources Institute, a Washington-based think-tank, said the Paris summit should adopt a mechanism to oblige nations to review their pledges at regular intervals, with a view to strengthening them.
Alarming forest losses continue
New satellite data presented by the institute on Wednesday revealed a rapid loss of tropical rain forests in Cambodia, parts of West Africa and Madagascar, and in the Grand Chaco region of South America.
While Brazil and, to a lesser extent, Indonesia, had slowed deforestation, tree loss had accelerated at a "truly alarming" pace in the other equatorial regions, said Nigel Sizer, who directs the institute's forest studies.
The analysis uses data from the Landsat satellite system, providing coverage every eight days.
"We now have an unprecedented ability to monitor global forest change," said Matt Hansen, a geography professor at the University of Maryland.
On Tuesday, the University of South California warned that one of the key oceanic micro-organisms that returns nitrogen to the food chain, Trichodesmium, could be "irreversibly" upset by climate change.
ipj/msh (AFP, Reuters, AP)