he Environmental Protection Agency tracks the number of Lyme cases, along with heat-related deaths and severe weather events, as an indicator of global warming. That’s because researchers think climate change is another major driver of the trend — and they expect the situation to get much worse during the 21st century.
One of the most important determinants of where ticks can live is temperature, because they can’t survive in very cold climates. Now that we are experiencing warmer winters, ticks are able to live further and further north. “Tick survival depends on the local climate, and the distribution or geographic range of where ticks occur is increasing — and this is driven in part by climate change” and, in particular, higher winter temperatures, Walter explained. Warmer temperatures can also increase the developmental rate of ticks — the time it takes for an immature tick to fully develop. In one study, researchers estimated global warming increased tick reproduction by up to two times in the US, and up to five times in Canada.
So climate change is aiding the disease two-fold: helping ticks reproduce, and helping them live in more parts of the US.