I'll translate because it's interesting and was not immediately obvious (to me)
The south had ticks before (global warming), yet no (few?) Borrelia bacteria.
Therefore there is no indication other than a timely coincidence that global warming is responsible for Borrelia bacteria appearing more frequently in the south.
There were articles last year that did not reference coincidence, but expanded range of the carriers for the bacteria. The first story is interesting because there's a bit about the scientists who are trying to disrupt the lifecycle of the bacteria on a small scale to find a solution.
I don't see it any different than malaria, caused by plasmodium and also a serious health problem in some parts of the world ( https://en.wikipedia.org/wiki/Malaria ): not all mosquitoes carry malaria, but the only way to eradicate malaria in some area is to manage to not have mosquitoes there, it's known since approximately the end of the 19th century, and still true. And the spreading of malaria has also different dynamics from the spreading of all of mosquitoes. So yes, the changes in environment that make for the insects to easy to spread in the areas where they couldn't before is something that should concern the humans, especially if there is a proof that humans helped the spread.
The south had ticks before (global warming), yet no (few?) Borrelia bacteria.
Therefore there is no indication other than a timely coincidence that global warming is responsible for Borrelia bacteria appearing more frequently in the south.