President Xi Jingping's schedule is tightly controlled, his statements meticulously scripted, and his public appearances neatly choreographed.

So his high-profile meeting Tuesday with California Gov. Jerry Brown, which was splashed across state-run newspapers the next morning, was significant for several reasons -- not the least of which was its timing.

The Democratic governor's six-day trip to China focused on combating climate change. After stops in Jiangsu and Sichuan provinces, it culminated in Beijing for an appearance at the Clean Energy Ministerial Conference, which unites public and private delegations to focus on developing cleaner energy

The meeting took on a different tone this year, coming just days after US President Donald Trump announced his intention to withdraw from the landmark 2015 climate accord signed in Paris.

Xi and Brown met just as the Beijing conference was kicking off. They discussed the fight against climate change and how China and California could work together to wage it.

"It's highly significant that the governor of California can meet with the President of China and talk about the foremost issue of our time," Brown told CNN.

Though Brown and Xi didn't directly discuss the Paris accord, Brown told an audience at a forum in Beijing that climate change could be more dangerous than the threat of fascism during World War II. He has called Trump's decision to drop the Paris accord "crazy."

A thinly veiled message?

Xi and his government were not unaware of the governor's views or his intense rhetoric. And yet, they went ahead with a one-on-one meeting, making sure it got positive reviews in state-controlled media.

China has not explicitly criticized the US decision to leave the agreement. But Xi's meeting with Brown could easily be interpreted as a thinly veiled message to the Trump administration: China believes climate change is a problem and doesn't think the US is doing enough to solve it.

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On its face, it might not seem odd that Xi would meet with Brown. California is, on its own, the sixth-largest economy in the world. Xi's father also knew the governor.

But the fact remains that China's president rarely meets with officials below the top cabinet level.

It can be seen as beneath the president to take meetings with lower-level officials. China's government is also wary of meetings with representatives of non-nation states, given its sensitivities over sovereignty issues in places like Tibet and Taiwan.

Xi's decision to meet with Brown in spite of all that, and in such a public way, could signal how serious China is about fighting climate change.

Curbing coal use

China already spends more than any other country in the world on renewable energy projects -- more than $200 billion in 2015 and 2016. It announced plans for another $360 billion in investment by 2020.

China has curbed its coal use three years running, and although it has committed to peak its carbon emissions by 2030, experts say it likely will meet that goal ahead of schedule.

As the largest remaining economy left in the Paris agreement and the biggest emitter of greenhouse gases, China seems poised to take the global lead on the issue.

Taking a meeting with one of the biggest proponents of fighting climate change in the US -- and one of Trump's biggest critics -- would appear to be just the latest indication of how much importance China places on the issue -- even more so, given what could be at stake.

The Trump administration has worked hard to curry favor with China , seeking further cooperation on issues like North Korea.

How the Trump administration will respond to a perceived slight, if at all, remains to be seen. But it could call into question how effective both sides will be in working together on issues outside of climate change, like trade and national security.