Climate change threatens Sierra, delta, group says CLIMATE CHANGE

Cattle graze in sight of the Antioch Bridge, rear on Sherman Island that's surrounded by both the Sacramento-San Joaquin Rivers and totally protected by the Delta Levee system. Thursday June 24, 2010. Levee collapses from the Sacramento-San Joaquin Rivers are a constant threaten to towns and farms built next to the levee system, but to introduction of salt water to the system is viewed negatively by most that riley on the levees. Ran on: 06-27-2010 Cattle graze within sight of Antioch Bridge on Sherman Island, which is surrounded by the Sacramento and San Joaquin rivers and protected by delta levees. Ran on: 06-27-2010 Cattle graze within sight of Antioch Bridge on Sherman Island, which is surrounded by the Sacramento and San Joaquin rivers and protected by delta levees. less Cattle graze in sight of the Antioch Bridge, rear on Sherman Island that's surrounded by both the Sacramento-San Joaquin Rivers and totally protected by the Delta Levee system. Thursday June 24, 2010. Levee ... more Photo: Lance Iversen, The Chronicle Photo: Lance Iversen, The Chronicle Image 1 of / 3 Caption Close Climate change threatens Sierra, delta, group says 1 / 3 Back to Gallery

Two of California's most treasured natural settings are also among the most imperiled landscapes on Earth, as disruptive changes in climate patterns promise to melt glaciers, dry out rivers and set forests ablaze in coming generations, says a coalition of conservation, sporting and community groups.

Unless people significantly alter the way they manage water supplies and fuel their cars and homes, the Sierra Nevada and Sacramento-San Joaquin River Delta will become increasingly hostile to already-dwindling wildlife and fish species, the Endangered Species Coalition said in a report released Wednesday.

Likewise for the Hawaiian Islands, Southwest deserts, Arctic sea ice and shallow-water coral reefs around the globe.

"Climate change is no longer a distant threat on the horizon," said Leda Huta, executive director of the Washington group. "It has arrived and is threatening ecosystems that we all depend upon, and our endangered species are particularly vulnerable."

In the report, "It's Getting Hot Out There," the coalition ranks the top 10 "hot spots" for vulnerable species, mostly within the United States with a few beyond. No. 1 on the list: the Arctic ice sheets where polar bears, seals, walruses and sea ducks make their home. Tropical coral reefs were second. The delta is No. 5 and the Sierra Nevada No. 6 on the list.

The group's message isn't necessarily a new one. But it comes during a particularly pivotal time in California, where policymakers are at the forefront of cutting heat-trapping greenhouse gases and under pressure this year to complete a long-term plan for the delta that restores the ecosystem and ensures water supplies for cities and farms.

Water is key

In both the estuary and the mountain range, a key question centers on water. With most climate models showing rising global temperatures over the next century, scientists fear that the marshes and channels of the delta will simply grow too warm for cool-water fish such as the Pacific salmon, as well as Central Valley steelhead, green sturgeon and the now-famous delta smelt.

The report notes that 12 of the original 29 native delta species are either extinct or endangered.

"The predictions for climate change related to sea level rise and increasing temperatures - paired with more demands for water and physical pressure on the delta levees - are going to create more stressors for salmon and many other fish," said Mark Rockwell, California coordinator for the Endangered Species Coalition.

Hundreds of miles away in the alpine forests of the Sierra Nevada, drier weather and higher temperatures could radically alter various habitats. For instance, a stream-fed meadow could turn into a barren, rocky field over a long-enough time span. In turn, species that lived in the meadow would have to move farther upslope to find a suitable home.

Story of the pika

The report highlighted the American pika as a kind of canary-in-the-coal-mine species, saying the cute, plant-loving cousin of the rabbit is disappearing from boulder fields in lower elevations as it struggles to find cooler ground.

U.S. Forest Service biologist Connie Millar agrees that the Sierra Nevada might become a harsher environment for some animals that wander atop the highest peaks, such as the alpine chipmunk and yellow-bellied marmot.

But Millar's recent research suggests the pika is much hardier and inhabits a wider range than previously thought. What's more, her 2010 study found that the animal had not abandoned warmer lower-level habitats as some other scientists have contended, lending credence to the argument that certain animals may be able to adapt to gradual changes in their environments.

Pika are "one of the more adaptable alpine mammals," Millar said. "Of course, if their habitat turned to rock and they had no vegetation, it would be harder. But the heat would have to spike up quickly."