China has for the first time made specific emission cut pledges, though its goal of reducing planet-warming greenhouse gases to just 7-10% by 2035 is seen as far too modest.
Its pledge offers a path towards more ambitious efforts to tackle climate change.
The pledge, delivered via video by President Xi Jinping to a UN climate summit where some 120 nations will outline plans to curb global warming, comes as disasters intensify worldwide - from catastrophic floods in Pakistan to raging wildfires in Spain.
While the headline target may seem modest, China has a record of under-promising while overdelivering, driven by its green technology boom.
The new target for 2035 is backed by commitments to expand wind and solar six times over 2020 levels, drastically expand forests, and ramp up electric cars production.
The European Union said China's targets fell "well short" of what the bloc thought was "both achievable and necessary" by the world's top polluter.
"This level of ambition is clearly disappointing, and given China's immense footprint, it makes reaching the world's climate goals significantly more challenging," Wopke Hoekstra, the European Commissioner for Climate said.
Why it matters
China is the world's second-biggest economy and the largest polluter. It accounts for nearly 30% of global emissions.
It is also a clean energy powerhouse, and sells most of the world's solar panels, batteries and electric cars.
China's trajectory determines whether the world will limit end-of-century warming to 1.5C and avoid the most catastrophic impacts of climate disruption.
Under the Paris Agreement, countries must update their "Nationally Determined Contributions" every five years.
Many are racing to do so before the COP climate summit in Brazil this November.
Beijing pledged in 2021 to peak carbon dioxide emissions before 2030 and reach carbon neutrality by 2060. But it gave no near-term numerical targets for reducing emissions.
The geopolitical context has raised the stakes: the United States has again quit the Paris accord under President Donald Trump, who dismisses climate change as a "con job," while a fractious European Union has yet to set new targets.
Under the 2015 accord - which nearly every country is part of - nations freely set their own targets but most are behind schedule, notably the European Union, where several states fear moving too fast could hurt industry.
France, for example, faces shaky finances and political turmoil, and wants more clarity on investment frameworks before committing to deeper decarbonisation.
Under the new plan, China pledges to:
- Cut economy-wide net greenhouse gas emissions by 7-10% from peak levels, while "striving to do better." Some analysts believe China's emissions have already peaked or will do so soon.
- To align with 1.5C, Beijing needs to cut emissions around 30% within a decade from 2023 levels. The United States peaked CO2 emissions in 2007 and reduced them by approximately 14.7% a decade later.
- Increase non-fossil fuels in total energy consumption to over 30% and expand wind and solar capacity to more than six times 2020 levels, reaching 3,600 gigawatts.
- Increase forest cover to over 24 billion cubic meters.
- Make electric vehicles "mainstream" in new sales.
- Expand the national carbon trading scheme to cover high-emission sectors and establish a "climate adaptive society".
What experts think
Observers almost universally say the targets are too modest - but that China is likely to surpass them thanks to its booming clean technology sector.
"China has often under-promised and over-delivered," said Andreas Sieber, associate director of policy and campaigns at advocacy group 350.org.
The new target is "underwhelming," but "it anchors the world's largest emitter on a path where clean-tech defines economic leadership," he added.
Others echoed that sentiment.
"What's hopeful is that the actual decarbonisation of China's economy is likely to exceed its target on paper," said Yao Zhe of Greenpeace East Asia.
China is installing renewable energy at a record pace that far outstrips the rest of the world, and it dominates the production chain of many clean-tech sectors.
But it has also continued to install coal capacity, and its decision to use an unspecified "peak" rather than set a baseline year for emissions cuts raised concerns.
That keeps "the door open to near-term increases in emissions," warned Lauri Myllyvirta, lead analyst at the Centre for Research on Energy and Clear Air.
The pledges serve as "a floor, not a ceiling, for China's ambition," he added.
Still, many observers believe China's economy is now committed to the energy transition and the pledges will cement that.
"The good news is that in a world increasingly driven by self-interest, China is in a stronger position than most to drive climate action forward," said Li Shuo of the Asia Society.
Paris Agreement 'has made a difference'
The UN is trying to strike a balance between warning of catastrophe and maintaining hope.
On one hand, UN Secretary-General Antonio Guterres said last week that chances of limiting warming to 1.5C are on the verge of "collapsing," a view echoed by climatologists, with current temperatures already about 1.4C above pre-industrial levels.
But yesterday, he struck a more positive note, saying the landmark Paris Agreement "has made a difference".
"In the last 10 years, projected global temperature rise has dropped from four degrees Celsius to less than three," Mr Guterres said.
Part of that progress stems from China.
A decade ago, three-quarters of its electric mix came from coal - a figure now down to half. Its booming exports of solar panels, batteries, and electric cars are cutting emissions abroad as well.
