Whether it’s saguaros, quaking aspens, tundra forests or coral reefs, the Southwest and the country are seeing climate change impacts on a range of species and landscapes, says an Arizona State University scientist.
But ecological impacts aren’t limited to birds and bunnies, says Nancy Grimm, an ASU live sciences professor and a lead author of a chapter on that subject for the new National Climate Assessment.
People will feel them, too: increased flooding due to disappearance of coastal marshes, Colorado River stream-flow reductions and pollution of Eastern rivers, says Grimm.
Grimm speaks tonight at the University of Arizona in a panel discussion on the climate assessment.
Here’s a Q&A with Grimm:
Q. The report says “many iconic species” may disappear from regions where they have been prevalent or go extinct due to climate change. Can you cite examples besides the polar bear?
A. The saguaro is an iconic species. If you think of the Sonoran Desert, that’s what you think of. Fire is much more frequent in the desert now, due to climate change, compounded by invasions of introduced species such as buffelgrass and foxtail. If fire frequency continues to increase, we may see a transformation in the landscape.
Q. Have fires impacted saguaro populations?
A. I can point to several areas I know personally where there have been large fires in the past 30 years and they still have no regrown saguaros. There are some patches along routes to my field research sites northeast of Phoenix where wildfire has burned, but it is clear to me as I pass by that certain large areas have regrown vegetation but few to no saguaros.
A. Western forests are more susceptible to drought and wildfire, and the quaking aspen is a forest type that people travel to see. Coral reefs — due to a compounded effect of climate change and acidification (from higher CO2 emissions) — many are being lost and this is certainly an iconic seascape.
In Alaska, mountain ecotones, forests, are moving up in areas that have been tundra ... what people might experience as an open, treeless landscape will become one with a forest. These shifts happen slowly, but many have been documented.
I’d say trout are iconic. Think of the great fishing rivers of the West. Trout are intolerant of warm water, and (projections are) that nearly half of the current trout habitat in the continental U.S. will be unsuitable for them by midcentury. Also, the replacement of conifer forests in Yellowstone by grassland and woodland is projected due to more frequent fire.
Q. How can landscape changes affect us?
A. The most clear example in the news is Hurricane Sandy. There’s a tendency when we develop coastlines to remove all the ecosystem areas, natural areas, like marshes along coastal areas and mangroves in the South. They tend to buffer storm surges. When those are gone, you have a coastline directly exposed to storms.
Q. What about the dangers to ecosystems and people here from our drought and stream-flow reductions in the Colorado River?
A. It’s a pretty big deal for urban ecosystems and agricultural ecosystems in the Southwest that are dependent on it for a water supply. But a lot of what we wrote about is that in many areas, we expect to see increases in precipitation, storms and flooding, that will impact water quality.
Here, if you have less water in the system, you have higher concentrations of dissolved materials in the water.
In the East, where the forecasts are for more precipitation and bigger storms, it will enable more material to be transported off land into rivers and coastal areas. That will involve things like nitrogen and phosphorus running off from agricultural land, which is already known to cause ... the death and decompositions of algal blooms, producing dead zones. The reductions in oxygen from that result in fish kills.
Q. The report talks adaptation strategies: manipulating habitats, trying to conserve populations of species with more genetic diversity, and replanting species that are better suited for future climates. It mentions moving species and populations to new areas expected to become more suitable in the future. What’s the outlook for these tools?
A. I don’t think we’re very far off from it. This sort of stuff is already happening in some places. There is a great debate in the conservation biology world, over preservation versus active management. One thing we have to realize as humans is that we have an influence on the vast majority of terrestrial and oceanic surface of the Earth. That management is something we are doing even if we say we are not.