The Greater Yellowstone Ecosystem has warmed considerably since 1948, but it still offers the variety of habitat and temperatures many species need to survive, according to a new paper in the journal PLOS One.
Scientists looked at data from 50 weather stations and sites across the ecosystem, said Adam Sepulveda, an author of the paper and a research zoologist with the U.S. Geological Survey. The study analyzed observational and modeling data from 1948 to 2012 from Bozeman, Mont., to south of Jackson.
The researchers already knew temperatures were warming, but they wanted to learn whether there is temperature variance within the ecosystem.
“What we know from ecology is if things look the same in a lot of different places, it means bad things for organisms,” Sepulveda said. “Organisms need variation on the landscape.”
To survive, animals need to be able to move between cooler and warmer habitats. Researchers found that every place in the ecosystem warmed, but there were still variations of temperature across the landscape.
If you think of temperature data as a bell curve, the curve didn’t change shape, it just slid across the x-axis. Sepulveda expected the curve shapes might change, getting taller, or the tails longer, showing more extremes in weather, or places never cooling. Instead, the variations in temperatures across the ecosystem remained the same. Things are getting warmer, but not everything is ending up the same temperature, he said.
“The saving grace is that, luckily, this area is so unique,” Sepulveda said.
The Greater Yellowstone’s topography covers a variety of elevations and offers a climate transition zone. Different parts of the ecosystem respond differently to precipitation. Some parts react according to the ‘southwest precipitation response’ others according to the ‘northwest precipitation response’. If there is an extreme weather event in one part of the ecosystem — like an intense heat wave or cold snap — it doesn’t necessarily impact the entire area.
That’s good news for wildlife that can move, like elk and Yellowstone cutthroat trout.
“As long as you can move, you can take advantage of that variation,” Sepulveda said.
Immobile organisms, such as plants or species trapped by habitat fragmentation, might not fare as well. The next step is to look at how species do or don’t take advantage of that variation.
The finding is a reminder for land managers to think about climate adaptation, identifying and protecting cold air and cold water refugia, and also to manage for variations across the landscape, Sepulveda said.
He anticipates the temperature bell curves will continue to slide forward, the warm temperatures getting hotter and the cold areas getting warmer. Scientists don’t yet know where most species’ thresholds lie, when even the cold areas will be too warm for survival. Some species will adapt and pass on genetics to better survive in warmer climates, Sepulveda said. How many and which ones are still unknown.
As overall temperatures warm so do the extremes, and sometimes all it takes is a short-lived extreme weather event to kill a species, like when warming water temperatures killed thousands of sockeye salmon in the Columbia River.
“That was one really, really bad day for hundreds and hundreds of fish,” Sepulveda said. “If you get too far to those extremes it could have huge consequences. But if you are looking at conservation at the landscape level … our data says there is potential you are going to get those extreme events, but those temps that are extreme are going to only affect a handful of all the sites out there.”
The Greater Yellowstone has a potential resiliency when facing climate change because there is still so much spatial variation, Sepulveda said. Temperature is just one piece of the climate portfolio impacting organisms. The study is the foundation for more research. Sepulveda said research will continue to look at amphibians, wetlands, river flows and fish.
The fact that the bell curve didn’t change shape speaks volumes. Kudos to Ms.Dayton for asking the good question.
Paul Cook