Beijing announced its first ever absolute climate targets at a UN summit Wednesday, pledging to reduce economy-wide emissions by 7-10 percent by 2035 relative to the year of the country's peak emissions, believed to be 2025.

"This level of ambition is clearly disappointing and given China's immense footprint, it makes reaching the world's climate goals significantly more challenging," EU climate commissioner Wopke Hoekstra said Thursday.

China is the world's second-biggest economy and the largest polluter. It accounts for nearly 30 percent of global emissions.

Observers almost universally said the targets it put forward are too modest -- but that Beijing has a record of under-promising while over-delivering, driven by its green technology boom.

The stated trajectory, similar to the path followed by the United States and EU in the decade after their peak emissions, would fall well short of what is needed to limit warming to 1.5C above pre-industrial levels -- the target set by the 2015 Paris Agreement to avoid the worst climate catastrophes.

The EU, which is also among the world's major polluters, has been by far the most committed to tackling climate change, which is intensifying disasters worldwide from floods in Pakistan to raging wildfires in Spain.

But its leadership is being sorely tested by internal divisions over the level of ambition as the bloc shifts focus to boosting defence and industry in response to the war in Ukraine and global trade tension.

Brussels has committed to cutting emissions by 55 percent by 2030 compared with 1990 levels -- and it is already at nearly 40 percent, according to the European Commission.

But it has so far failed to come up with a hard target for 2035 as required under the Paris Agreement.

Commission Chief Ursula von der Leyen on Wednesday told the UN summit the EU's member states have agreed that "would range" between 66.25 percent and 72.5 percent -- but a formal pledge will come later.

China had previously pledged to peak its carbon output before 2030 and achieve carbon neutrality by 2060, without ever previously setting near-term numeric targets for total emissions reductions.

Its pledge Wednesday came as the United States boosts fossil fuels both at home and abroad under the leadership of President Donald Trump, who calls climate change a "con job".