California's economy ranks among the top seven countries in the world, and it is the most populated (estimated at 35 million people in 2002) and fastest growing state in the United States. California supplies one-half of all the agricultural products consumed in the United States each year and its natural ecosystems face serious threats from human activities and development.
According to Conservation International, human population pressures have rendered California one of the four most ecologically degraded states in the country, with all or part of the nation's most threatened ecosystems represented: beach and coastal strand, southern coastal sage scrub, large rivers and streams, riparian forests and wetlands, native grasslands, old-growth ponderosa pine forests, cave and karst systems, and the ancient forests of the Pacific Northwest.
Direct pressures on ecosystems include urbanization, pollution, and habitat encroachment; expansion of large-scale agriculture; strip mining and oil extraction; invasive alien species; road construction; livestock grazing; logging; increasing use of off-road vehicles; and suppression of natural fires.
According to the World Wildlife Organization, the American pika may be one of the first North American mammals to fall victim to global warming.
Research by USGS ecologist Dr. Erik Beever, indicates that global warming may have contributed to local extinctions of pika populations in the Great Basin area east of the Sierra Nevada . During the last part of the 20th century, American pikas disappeared from seven of twenty-five study areas.
Research suggests that as temperatures rise, many alpine animals will seek higher elevations or migrate northward to find suitable habitat. Pikas may be especially vunerable to global warming because:
- They cannot easily migrate since their habitat is restricted to small, disconnected habitat "islands" in mountain ranges.
- Pikas do not appear to move large distances, and individuals may spend their entire lifespan within a half-mile radius
- They do not live in burrows, which could mitigate extreme summer temperatures
- Pikas are densely furred and cannot easily dissipate heat. Hotter temperatures during high activity periods may cause thermal stress.
- They are active year-round and cure summer vegetation for their winter survival. Changes in vegetation or earlier maturation of plants due to global warming may have negative effects.
- Studies suggest that climate change combined with other factors like shrinking habitat and proximity to roads may increase risk of extinction.
The burning of fossil fuels —coal, oil and gas —releases carbon dioxide (CO 2) into the atmosphere where it traps heat and contributes to global warming. Reducing emissions is the first step in stopping global warming.
What You Can Do
Make smart energy choices.
- Photovoltaic arrays and windmills help gather energy without heat-trapping emissions.
- Hybrid Cars
The pika is a small, thick furred, tailless mammal found at high elevations in the Cascades and the Sierra Nevada. They forage during the day and retire to grass-lined nests, hidden in rock crevices, just after sunset. They are active throughout the winter under the snow and subsist on stacks of cured grasses and sedges that were stockpiled during the summer. Their most dangerous predator is the ermine, which can follow them into the rocky tunnels. Other predators include eagles, hawks, bears, and foxes.
The North American pika, Ochotona princeps, may be the first contemporary example of global warming contributing to local extinctions. Pikas live at high altitudes in rocky areas and are unable to survive in warm temperatures - less than 6 hours in 77 degrees F. As temperatures rise due to increasing levels of greenhouse gases, many montane animals are expected to migrate northward or seek higher elevations in an attempt to find suitable habitat. The pika appears unable to handle this environmental shift.