However it is hard to evaluate who is more corrupt (in the sense of "cheating" with certificates), so at the end of the day we do not really know and have to rely on the facts.
The facts are that we have strong reasons to believe that humans are responsible for climate change in recent years and endanger several aspects of our ecosystem (there is a lot more data on that than on the analysis of the credibility of Chinese officials) and that a recently elected leader of a nation that has a big impact on world politics and economics thinks that it is a hoax by a foreign country.
There are two narratives that one could construct:
0. "Climate change influenced by the industrialization of
our society packed by big amounts of scientific data.
Elected leader is uninformed and on the wrong side of
history."
1. "Climate change is a hoax setup by a foreign country
and powers supporting it are part of a big conspiracy
thing going on that even goes miles to grant
fake-certificates to political leaders to support
the hoax."
I have seen no evidence that China invented climate change. I chalk that up to Trump's propensity for hyperbole, but who first came up with it is irrelevant to what we do about it now. Also a fake-certificate is about the easiest thing to fabricate.
Let's just disagree.