Global warming is responsible for the tree-trunk obesity epidemic:

Parker’s data, which showed the trunks gradually fattening over time, indicated that many of the trees were growing two to four times faster than expected. That raised questions about climate change’s impact on the age-old rhythms of U.S. forests.

It’s also behind the tree-trunk emaciation dilemma:

In the tropics, however, some studies have seemed to show trees growing more slowly: It might now be too hot for some trees there.

All in the same article!