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Posts Tagged: climate change

Bleak future for spring-run Chinook salmon

Spring-run Chinook salmon, photographed in Butte Creek (Allen Harthorn/Friends of Butte Creek)
Warming streams could spell the end of spring-run Chinook salmon in California by the end of the century, according to a study by scientists at UC Davis, the Stockholm Environment Institute (SEI) and the National Center for Atmospheric Research (NCAR).

There are options for managing water resources to protect the salmon runs, although they would impact hydroelectric power generation, said UC Cooperative Extension associate specialist Lisa Thompson, director of the Center for Aquatic Biology and Aquaculture at UC Davis. A paper describing the study was published online recently in the Journal of Water Resources Planning and Management.

“There are things that we can do so that we have the water we need and also have something left for the fish,” Thompson said.

Working with Marisa Escobar and David Purkey at SEI's Davis office, Thompson and colleagues at UC Davis used a model of the Butte Creek watershed, taking into account the dams and hydropower installations along the river, combined with a model of the salmon population, to test the effect of different water management strategies on the fish. They fed in scenarios for climate change out to 2099 from models developed by David Yates at NCAR in Boulder, Colo.

In almost all scenarios, the fish died out because streams became too warm for adults to survive the summer to spawn in the fall.

The only option that preserved salmon populations, at least for a few decades, was to reduce diversions for hydropower generation at the warmest time of the year.

“If we leave the water in the stream at key times of the year, the stream stays cooler and fish can make it through to the fall,” Thompson said.

Summer, of course, is also peak season for energy demand in California. But Thompson noted that it might be possible to generate more power upstream while holding water for salmon at other locations.

Hydropower is often part of renewable energy portfolios designed to reduce greenhouse gas emissions, Purkey said, but it can complicate efforts to adapt water management regimes to a warming world. Yet it need not be all-or-nothing, he said.

“The goal should be to identify regulatory regimes which meet ecosystem objectives with minimal impact on hydropower production,” he said. “The kind of work we did in Butte Creek is essential to seeking these outcomes.”

There are also other options that are yet to be fully tested, Thompson said, such as storing cold water upstream and dumping it into the river during a heat wave. That would both help fish and create a surge of hydropower.

Salmon are already under stress from multiple causes, including pollution, and introduced predators and competitors, Thompson said. Even if those problems were solved, temperature alone would finish off the salmon — but that problem can be fixed, she said.

“I swim with these fish, they're magnificent,” Thompson said. “We don't want to give up on them.”

Other co-authors of the paper are graduate student Christopher Mosser and Professor Peter Moyle, both in the Department of Wildlife, Fish and Conservation Biology at UC Davis. The study was funded by the U.S. Environmental Protection Agency.

Posted on Friday, September 16, 2011 at 11:17 AM

How does climate change impact plants?

All bets are off in terms of what will happen with plant species migration and crop production as the climate changes globally.

A common assumption has been that native plants and animals would “move,” or migrate, to higher elevations as temperatures rise, to maintain their “preferred” temperatures, but a new report by Jonathan Greenberg at UC Davis, shows that many California plant species moved downhill over the past 70 years.

According to Greenberg, “While the climate warmed significantly in this period, there was also more precipitation. These wetter conditions are allowing plants to exist in warmer locations than they were previously capable of.”

According to the news release summary:

“Many forecasts say climate change will cause a number of plants and animals to migrate to new ranges or become extinct. That research has largely been based on the assumption that temperature is the dominant driver of species distributions. However, Greenberg said the new study reveals that other factors, such as precipitation, may be more important than temperature in defining the habitable range of these species.

“The findings could have global relevance, because many locations . . . have had increased precipitation in the past century, and global climate models generally predict that trend will continue, the authors said.”

Many studies are showing that climate change is impacting plant and animal species, but because of the overlapping influence of so many factors, including temperature, precipitation, and elevation, and even factors such as increases in smog and carbon dioxide, it is too early to predict precisely how climate change will impact native species . . . and agricultural crop production.

Here are some UC Davis news summaries in just the last year on the impact of climate change on plant and animals species:

  • Plants moved downhill, not up, in warming world – news summary
  • Climate change impact on mountain plants at low elevations – news summary
  • Warmer ocean waters favor aliens over natives – news summary
  • Warming climate means harsher smog – news summary
  • Rising CO2 levels threaten crops – news summary
  • Changes in agriculture needed as world warms – news summary
  • Climate tipping points may give no warning – news summary
  • Butterflies reeling from impact of climate – news summary
Posted on Friday, January 21, 2011 at 4:51 PM

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