There are those who claim the ability of humanity to change environmental conditions on Earth is extremely limited. For example, it is common to hear people say that the idea that humans could be altering Earth’s climate is arrogant, and the Earth is far too large and complex for our puny efforts to have any noticeable effect. But there is plenty of evidence that humans can make noticeable changes to the environment, on scales that certainly encompass the entire globe.
Lake McDonald, in the western section of Glacier National Park in Montana, is the largest lake in the park. Carved by glaciers, it is 10 miles (16.1 km) long and nearly 500 feet (152.4 m) deep. And since its tributary streams are largely fed by snowmelt, the waters are crystal clear. The overall setting gives the impression of a pristine landscape, untouched by the hand of humanity.
It is, largely, but there are indications that even a place like Glacier National Park, as seemingly isolated from areas of large-scale urbanization as it is, cannot escape the human influence. In 2014, a study conducted jointly by the U.S. Geological Survey and the National Park Service, focused on mercury levels in fish in 21 national parks located in 10 Western states (see link below). While the majority of fish across the region had concentrations that were below most benchmarks associated with impaired health of fish, wildlife and humans; whitefish and bull trout in Lake McDonald had mercury concentrations that approached or exceeded the EPA criterion for protection of human health and the level at which reproductive impairment to fish-eating birds could occur.
The occurrence of such high levels of mercury in a relatively isolated location speaks to the interaction of human industrial processes with natural cycles and processes. Mercury can be injected into atmospheric circulation patterns after being vaporized in certain industrial processes. This mercury can then be distributed to almost any point on the globe. Unfortunately, mercury levels in fish in Lake McDonald in Glacier National Park is but one small example of the power of human industrial society to reshape environmental conditions on Earth.
Keep this in mind the next time you hear someone say it is silly or arrogant to think that humans can do anything that would alter the Earth’s climate. We can, and we do.