With less ice, summer stream levels will drop. Scientists say that glaciers historically provided NCNP streams with about half of their late-summer flow. In the Thunder Creek drainage, levels have dropped 31 percent, threatening salmon spawning. Thunder is also a major tributary of the Skagit River Watershed, the only one in the nation that contains all Pacific salmon species. So the threat to biodiversity extends to the entire Puget Sound ecosystem. Scientists have identified 1,600 plant species and 3,000 fungi in eight distinct zones here–more than any other national park. In a warmer climate, temperate evergreen forests would slowly spread into subalpine zones, altering the habitat for that flora.
These changes will create real safety issues for explorers, like outdated park topos and sketchier alpine routes. Years ago, the famous Ptarmigan Traverse–a route from Cascade Pass to Dome Peak–involved more glacier travel and less technical scrambling. “The mountaineering could get more difficult,” Josberger says, “with fewer chances to bail.”
In five years, this Arizona park’s iconic cacti will face a huge new fire threat.
“What we have here is the first unhinging of a major American ecosystem,” says Julio Betancourt, a paleoecologist with the University of Arizona’s Desert Laboratory. He means the climate-related expansion of an insatiable neotropical plant called buffel grass, introduced in south Texas in the 1940s and now taking over Southwest parks like Saguaro.
What’s so bad about buffel grass? It usurps the space, nutrients, and water that saguaro cacti, nicknamed “desert monarchs,” need to survive, and it will eventually turn the cactus forest along the Hugh Norris Trail and other routes into endless prairie. Though it’s been around for decades, this 4-foot-tall grass only started spreading quickly in the mid-1980s, when winter and spring temps in the Sonoran Desert started rising. According to a recent Intergovernmental Panel on Climate Change (IPCC) report, future rain patterns might shift in the Southwest, creating even more advantageous conditions for the invasive plant.
Buffel grass is highly flammable, and thrives in post-fire conditions. “These deserts haven’t been flammable in 10,000 years,” says Betancourt. There used to be plenty of space between cacti and scrub vegetation, making it hard for flames to spread. Now, the grass fills those spaces. If the saguaros burn, they may never come back. “In as little as five years, southern Arizona will be converted to a fire-prone grassland,” Betancourt says.
This all comes at a time when the desert can ill afford to lose water. Richard Seager, a scientist at Columbia University’s Lamont-Doherty Earth Observatory, recently published a study in Science analyzing 19 computer models that all forecast a permanent drought by 2050, and a 15 percent drop in surface moisture. Similar conditions, he says, led to the Dust Bowl. “It might not necessarily be warmer,” says Betancourt, “but it will be much more dry.” That’s more bad news for the saguaro, which need summer monsoons to germinate. Add in the area’s building boom–”Saguaro was founded as a wilderness park, and now it’s a suburban park,” says Luther Propst, executive director of the Sonoran Institute–and the cacti have nowhere to migrate from their present sky-island habitat. “If we don’t get control of this fast,” Betancourt warns, “the parks in southern Arizona are dead meat.”