"The recent moves by the US to connect the climate issue with trade measures, industrial competition, and national security is something I'm sure the Chinese will raise because they have a lot of concerns on this policy direction," Li Shuo, the director of China Climate Hub at the Asia Society Policy Institute, told Business Insider.

Li said China's view was that the US prioritized economic competition at the expense of mitigating the climate emergency. The world needs affordable green technology for the energy transition, and China's record levels of investment have driven down the costs, he added.

A recent example is the remarkable rise of BYD, a Chinese automaker that briefly eclipsed Tesla this year as the world's largest seller of EVs.

However, the US views China as a threat to both national security and the climate. The country's boom in green-tech manufacturing was largely powered by dirty energy, with coal still accounting for about 60% of China's electricity, an S&P Global analysis found. And even though China is adding renewable energy to its grid faster than any other country, it's also building new coal-fired power plants at a rapid clip.

Coal is a major source of tension between the US and China, Li said. China has no policy to signal a coal slowdown, undermining its climate promises.

The issue could be inflamed following a deal this week among seven of the world's wealthiest countries to stop burning coal for power by 2035. During a G7 meeting in Italy, Japan, another major coal user, endorsed the timeline for the first time and was joined by the US, Canada, and several European nations.

For its part, the US in late April finalized stricter emissions limits on power plants, which are expected to speed up the shift away from coal. About 16% of US electricity comes from coal, a steep drop over the past decade largely due to the fracking boom that made gas a cheaper source of power.

But neither the US nor China is in a position to compromise, Li said.

China defends its coal expansion as a matter of energy security. Last year, sky-high temperatures and drought in regions reliant on hydropower forced rolling blackouts and factory closures.

Biden-administration officials, including the climate envoy John Podesta and Treasury Secretary Janet Yellen, in recent months have said the US is evaluating new strategies to counter China's dominance over green technology. Former President Donald Trump said he would impose tariffs of more than 60% on China if he won the election in November.

Given the tension, there likely won't be any major breakthroughs during this month's talks, Li said. But the fact that the world's two largest polluters are meeting in person shows that the climate still carries special weight. Few Chinese senior officials travel to the US.