Tick Migration and Climate Change in North America

As temperatures continue to increase globally, the ecosystem will ultimately adapt to this change. More specifically, deer ticks are adapting to increases in temperature. This may spread Lyme disease and increase the risk for humans if ticks start to inhabit more area than ever before.

According to Climate Central,  a recent study concluded that deer ticks live longer in higher relative humidities. Relative humidities between 85-95% are favorable for deer ticks. With rising temperatures and increased humidity across western North America, reaching this favorable environment for deer ticks is likely.

 In Canada, these favorable conditions are increasing as well. Canada’s National Observer claims that in the past, ticks have been carried over by birds into Canada for years. "Only in the last 10 to 15 years, amid a changing climate and the creation of new habitats in the north, that populations of deer ticks have been able to establish a permanent beachhead in Canada.” as stated in the National Observer. There has already been an increase in the number of reported Lyme cases according to Canada’s Lyme surveillance efforts. The Lyme surveillance has a list of Lyme disease cases reported between 2009 and 2017. In 2009 there were 144 reported cases and in 2017 there were 2,025 reported cases. In 2016, over 88% of these cases were reported in Ontario, Quebec, and Nova Scotia. This shows that just like the United States, there is a trend of deer tick population increase in the east, rather than the west.

Why are deer tick populations increasing in eastern North America and not western North America? The simple answer is climate differences between the regions. Climate Central explains that in the east, it tends to be more humid. In the west, there is usually less humidity creating a dry and hot environment which is not favorable for deer tick. This is however, favorable for another species of ticks called lone star ticks. These ticks do not carry Lyme's disease but, they do carry ehrlichiosis. This disease causes fatigue and aches.

Overall, there is a trend of increasing tick populations in North America due to increasing temperatures, whether it increases relative humidity or not. This has resulted in a higher likelihood of getting a tick-borne disease.

(Credit: Climate Central, Canada’s National Observer, Canada’s Surveillance of Lyme's disease)

©2019 Weather Forecaster Brittany Connelly