Environment watchdogs rejected Europe's 2030 greenhouse gas-curbing plan as inadequate Wednesday, but the UN's climate chief hailed it as a "positive" step towards a new, global pact against global warming.
Traditionally a pacesetter at UN climate talks, the European Union (EU) has come under mounting pressure from poorer, vulnerable countries to beef up its pledges to cut heat-trapping carbon emissions.
On Wednesday, the European Commission, the 28-nation bloc's executive, proposed a binding reduction in greenhouse gases of 40 percent by 2030 over 1990 levels.
Renewables should account for at least 27 percent of the total energy mix by 2030, it said. This overall goal would be binding on the EU but not national governments.
"(Europe's pledge) is the benchmark for other countries. It is the first party out of the gate with an offer," Jennifer Morgan, climate director at the World Resources Institute in Washington, told AFP.
"It goes in the right direction, but it is not there yet," she said. "That 40 percent is just at the bottom of what scientists are recommending."
Christiana Figueres, head of the UN Framework Convention on Climate Change (UNFCCC), welcomed the announcement as a "positive signal for meaningful 2015 agreement."
UN members have vowed to conclude a new, global climate pact in Paris in December 2015.
The deal, to take effect from 2020, will seek to limit average global warming to 3.6 degrees Fahrenheit over pre-industrial levels.
Alden Meyer of the Union of Concerned Scientists, a US-based monitor, said EU leaders "risk setting a very low bar" for other countries fleshing out their own negotiating posture.
"That in turn will lead to a post-2020 agreement in Paris next year that will be totally insufficient."
Greenpeace said the proposals were "disappointing" given that renewables had the potential to supply almost half of Europe's energy by 2030.
"The commission's plan for 2030 is a sell-out that would knock the wind out of a booming renewables industry," said Mahi Sideridou.
NGOs urged EU member states to raise the target when they meet at a summit in March.
Economist Nicholas Stern, author of a landmark 2006 report on the cost of climate change, said a 40-percent cut was the minimum.
"Billions of euros of private investment in the low-carbon transition could be unleashed if the 2030 target gives greater confidence to companies, particularly in the power sector, that the European Union is on an optimal path towards the long-term goal of reducing emissions by at least 80 percent by 2050," he said.
The BUSINESSEUROPE lobby group said the target was only realistic if a binding climate pact was concluded next year.
The Confederation of British Industry (CBI) insisted that EU member states must have flexibility to "decarbonise" in the most cost-effective way.
"It is now imperative that we get political agreement on these proposals, which will provide some much needed certainty for investors," the CBI said.
The 2030 blueprint replaces an earlier plan for a 20-percent cut in European emissions by 2020 and a 20-percent share for renewables.
By end-2012, the EU had cut emissions by 18 percent, while renewables had a share of 12.4 percent in 2010, according to the latest official figures.