The world’s states should commit to a legally binding emissions cut of 60% by 2050, with five-yearly reviews, in a Paris Protocol to replace the moribund Kyoto agreement at a climate summit later this year, according to a leaked EU document.

But environmentalists have questioned the integrity of the headline 60% figure, and a strategy which is seen as overly-tilted towards the US.

“Major economies, in particular the EU, China and the US, should show political leadership by joining the Protocol as early as possible,” says the EU’s ‘Road to Paris 2015’ communication, which the Guardian has seen. “It should enter into force as soon as countries with a share of 80% of current global emissions have ratified it.

The EU accounts for nine percent of global emissions, compared to China’s 24%, and the 12% emitted by the US, according to the document. “Combined, these targets would cover around half of global emissions,” it says.

As soon as that number reached 80% - or 40 Gigatones of CO2 equivalent pollution - the new Paris Protocol would kick in.

Environmentalists welcomed the EU’s attempt to keep emissions cuts within the rubric of a legally binding deal, rather than seeing it relegated to a protocol annex.

But many noted that the 60% CO2 cut would be measured against 2010 levels, and was thus the same as the bloc’s previous aspiration of a 50% cut measured against 1990 levels - itself a genuflection to a 2007 IPCC report seen as outdated.

“The communication is absolutely not in line with the two degrees target and is a missed opportunity after the latest IPCC report clearly stated that there is a cumulative carbon budget,” the Green MEP Bas Eickhout told the Guardian.

“It’s frustrating to see the European Commission insist on the need to keep global temperature increases below two degrees celsius, but gloss over the inadequacy of its own action on climate change,” added Brook Riley, a spokesman for Friends of the Earth Europe.

The five-yearly review suggestion is viewed by green NGOs as a concession to advance the EU’s ten-year emission-cutting model onto other countries. The previous Kyoto agreement had begun with a five-year commitment period, which President Obama implicitly acknowledged in his offer of CO2 reductions by 2025 earlier this year.

The EU’s gambit may receive a cool reception in Washington, where the Obama administration fears a Senate block on any legal agreement that gives the UN arbiter powers. But according to Eickhout, a focus on Obama’s difficulties could cement a perception in the developing world that the EU was acting as the gatekeeper for a rich world club.

“I find it worrying that the EU is still so trans-Atlantically obsessed when there is much more movement in China and among other developing countries which want a deal,” he said. “If we are able to build an alliance for a final deal with the African Union, progressive Latin Americans, Least Developed Countries and the low-lying islands - who are most affected by climate change – I don’t think the US will really block it.”

The EU’s communication does exempt the poorest countries from presenting their proposed emissions cuts in the first quarter of 2015 - unlike G20 nations – and stresses that public sector climate finance should “continue to play an important role after 2020.”

But only $10bn of a proposed $100bn a year climate aid fund by 2020 has so far been provided, raising fears that the global foundations of any deal could be eroded before negotiators have even arrived in Paris.

“The EU can do these communications but the big debate in Paris will be on finance where developing countries will ask for more,” Eickhout said. “We should send the finance ministers to Paris, not the environment ones. The EU is trying to downplay the issue but it wont be downplayed by our partners around the world.”