The effects of climate change are numerous: ocean levels are rising, meteorological events are becoming stronger and increasingly unpredictable and the incidence of heat-related illness is increasing across the world. Yet experts are just beginning to understand one effect of a changing climate: the capacity for pathogens to migrate around the globe and infect populations that have previously never been in contact with these microorganisms.

Combined, these effects have the potential to cause extreme poverty. Loss of property and life resulting from rising sea levels and strong storms deprive people of both wealth and other resources.

However, the global health conundrum that is changing pathogen ranges is also a poverty issue in its own right. Poor human health places burdens on individuals and their family members that may cause them to lose employment opportunities and large sums of money. Being ill is no easy fortune, but the impoverishment that often accompanies illness can be worse yet.

As warming weather drives animals toward more hospitable environments, pathogens too are expanding their ranges and at the same time, are finding hosts they’ve never met. While it’s working out well for these pathogens, humans, other animals and plants aren’t faring too well.

A species of sea otters in the Pacific Ocean off the coast of Alaska has become ill from a virus that originated in the northern Atlantic Ocean; science writer Chris Solomon suggests that due to declining sea ice levels, “disease is finding new lanes of travel.”

It makes sense – pathogens are highly dependent on temperature for survival, and many bacteria and viruses thrive in the type of warm, wet environments that are becoming more and more prevalent as the climate changes. Not only do rising sea levels give pathogens access to a wider range of space (and accordingly, hosts) but also as animals move around seeking cooler climates, they take pathogens and parasites along with them, allowing them to infect entirely new populations.

What does this mean for humans? Well, the effects of expanding pathogen ranges are manifold. First, like Alaska’s sea otters, humans may soon fall prey to microorganisms not previously seen in their parts of the world. Prevention and treatment of illnesses caused by unfamiliar pathogens will be difficult and costly.

Inevitably, some humans – though it is impossible now to estimate just how many – will die.

Since human health is directly related to poverty outcomes, the expanding pathogen ranges means expanded poverty “ranges;” if more people fall ill due to pathogens, more people will experience poverty.

Secondly, and this is an effect that agricultural communities are already beginning to observe, new pathogens will infect crops and jeopardize the livelihood of the peoples who depend on the harvest for either food or for employment.

According to a study from the Universities of Exeter and Oxford, crop threats include pests and pathogens spreading toward the poles at a rate of 3.2 kilometers per year. A fungus that infects yeast harvests has already wreaked havoc in Brazil, threatening farmers there with impoverishment.

It’s difficult to fathom that such tiny organisms could have such large effects, but pathogens have the potential to cause a lot of harm, in terms of both illness and poverty. Despite that their migration is one of the least publicized effects of climate change; however,  it is one of which humans should be wary.

Elise L. Riley

Sources: NPR, NASA