Climate Change and Biodiversity

What is the basis for predictions of extinction due to climate change?

Predictions of climate change driven extinctions are severe and range from 15-30 percent of all species on earth. (Scientists estimate that only abut 20 percent of all species on earth have been described, therefore the majority of future extinctions are likely to be species that are not yet known to science.) These predictions are derived from estimates of the relationship between known species and range size. As Mark Schwartz, professor of environmental science and policy, explains, the predictions assume to varying degrees that species distributions are constrained by climate, and that species are limited in terms of their ability to move to more favorable habitats.


How can the diversity of earth be managed to avoid the catastrophic levels of extinction that have been forecasted?

Species predicted as the most vulnerable to climate change are those with very small geographic ranges. These species, however, are also the ones where climate may play a minor role in determining range boundaries. Studies including those done by Mark Schwartz, professor of environmental science and policy, suggest that these range-limited species may be more robust to changing climate than previously thought. One management technique that could be used to help alleviate climate-driven extinction is to help plants and animals disperse into new habitats that are climatically suited — called assisted migration. Although some species can be rescued this way, previous experience suggests that some unintended negative consequences should be expected.


What do we know about climate change effects on fish habitat and species in California?

Peter Moyle, professor of wildlife, fish, and conservation biology, has developed methods to determine the health of mountain meadows by inventorying communities of plants, fish, aquatic invertebrates and amphibians. He is reviewing the status of all distinctive types of salmonid fishes in California, and he conducted long-term studies of fish in Sierra Nevada streams, Putah Creek and in Suisun Marsh. His research program involves developing strategies for floodplain fish conservation in the Central Valley.

Greg Pasternack, professor of land, air, and water resources, built a model to predict the number of days each year that the flow of a river prepares it for salmonids to spawn and support embryo incubation. Environmental managers may use this model to compare different rivers for their restoration potential as well as the impact of climate change on the native anadromous fish populations.


How will aquatic life at Lake Tahoe respond to climate change?

There has been a measured increase in the temperature of the lake over the last 40 years. Rises in lake temperature have profound impacts on the lake ecology. Research by Geoff Schladow, director of the Tahoe Environmental Research Center, and others looks at the impacts of climate change on algal species composition, invasive fish and aquatic weed populations, and the food web.

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