One of the possible sources of that is increased carbon dioxide.
Underground coal fires in China alone produce as much carbon dioxide annually as all the cars and light trucks in the United States. Fires in other countries, including the United States, are smaller but still add significantly to the total burden.
In simulations you often look for solutions that are not obvious. One country spends 100 billion going after terrorists. A competing country spends no more on security but spends 100 billion reducing drunk driving. Each reduces the addressed threat by 50%. The country being assaulted by terrorists may have ignored them, but comes out ahead of the other in total loss prevented -- that sort of thing.
In fact, a general rule is that in most complex situations, the immediate steps that people think of are usually the wrong ones. Something I got from a review of computer aided facilitation (a neat software package a vendor was offering) was that as one tracked the initiatives, there was not a single successful one that had a resolution that was a first round suggestion or approach.
The informal rule I gathered from going over the data was that first thoughts are always wrong.
Regardless of what history tells us is the truth on climate change, odds are that the first responses that come to mind will turn out to have been the wrong ones.
For those who have asked about my Dad, he has been doing much better recently. I know that things are unpredictable, but it is nice to see him able to walk for short distances, to be oriented and not in pain. I'm grateful for however long it lasts.