A large proportion of America's national parks are already experiencing what researchers describe as catastrophic consequences. The Grand Canyon, Yosemite and many others are at risk, and will become increasingly dry and hot.
America's national parks are not doing well. In fact, they are the areas of the United States most severely affected by climate change. Temperatures here have risen at twice the rate of the rest of the US over the period from 1895 to 2010. Within the timeframe considered, nine of the ten parks with the highest temperatures are located in Alaska; Denali National Park and Preserve, for example, recorded an increase of 4.3°C. By contrast, precipitation has fallen by 12 per cent, compared to the national average of 3 per cent.
These are some of the most striking findings that catch the eye when leafing through the pages of "Disproportionate magnitude of climate change in United States national parks", a substantial study carried out by researchers at the University of Berkeley and the University of Wisconsin. The research examined data collected from all 417 American national parks to measure, for the first time, the degree to which protected areas are exposed to climate change.
"This disproportionate rise in temperature occurs because much of the surface area of the national parks lies in the Arctic or at high altitudes," the document reads. Here the atmosphere is thinner and warming accelerates the melting of snow cover while simultaneously reducing the reflective surface. This translates into a feedback mechanism that only serves to amplify the effects of rising temperatures.
"Two centuries of fossil fuels have produced twice as much carbon as forests and oceans could absorb, and the excess carbon in the atmosphere has reflected sunlight back onto the Earth," Patrick Gonzalez, who led the research, told the Washington Post. "It is a natural process, but human activity has contributed to adding carbon dioxide to the atmosphere at levels not seen for 800,000 years." These are certainly not new figures, but they evidently continue to fail to attract the attention they deserve from certain quarters of the political world.
The situation is serious: in a maximum-emissions scenario, between now and 2100 temperatures could rise by between 3°C and 9°C, with effects on flora and fauna that are difficult to quantify. Even in an emissions-reduction scenario, the temperature rise would exceed 2°C in 58 per cent of national parks. This would mean that Glacier National Park in Montana might have to change its name, due to the disappearance of its glaciers. Or that the world's oldest national park, Yellowstone, would have to contend with increasingly frequent and devastating wildfires, or that the Grand Canyon could become inhospitable due to excessively high temperatures.
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Our own national parks are also experiencing a similar fate. Beyond the retreat of glaciers, Italy's freshwater reservoirs, the alpine environment has already seen a shift of 0.5–4 metres per decade in plant species towards higher altitudes. According to a document from the Ministry of the Environment dating from 2013, by 2080 the treeline in alpine areas is expected to advance by hundreds of metres, with a consequent loss of 62 per cent of mountain plant species, compounded by the foreseeable extinction of animal species of great symbolic importance, such as the wolf, the bear and the chamois. But the country's national parks, woodlands and wetlands are also fundamental sites for CO2 storage: some 460 million tonnes of carbon, a natural capital valued at 1 billion 200 million a year. A form of natural income that has too often been taken for granted.