Climate

Wildfire risk in California no longer coupled to winter precipitation

Fire_SierraNationalForest_CA_USFS_1

Wet winters no longer predict possible relief from severe wildfires for California, according to a new study from an international team that includes a University of Arizona scientist.

From 1600 to 1903, the position of the North Pacific jet stream over California was linked to the amount of winter precipitation and the severity of the subsequent wildfire season, the team found. Wet winters brought by the jet stream were followed by low wildfire activity, and dry winters were generally followed by higher wildfire activity. After 1904, the connection between winter moisture brought by the jet stream from December through February and the severity of the wildfire season weakened. The weakened connection between precipitation and wildfires corresponds to the onset of a fire suppression policy on U.S. federal lands, the team reports in the March 4 issue of the Proceedings of the National Academy of Sciences.

California, Wildfire, Climate Change

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Adapt, Move or Die: How Biodiversity Reacted to Past Climate Change

American Pika; Public Domain

A new paper reviews current knowledge on climate change and biodiversity. In the past, plants and animals reacted to environmental changes by adapting, migrating or going extinct. These findings point to radical changes in biodiversity due to climate change in the future. The paper is published in the scientific journal Trends in Ecology and Evolution by an international group of scientists led by the Center for Macroecology, Evolution and Climate, University of Copenhagen.

Nature is reacting to climate change. We see altered behaviour and movement among plants and animals; flowers change flowering period and owls get darker body colour, due to warmer winters. So, how does the future for biodiversity look like? Will plants and animals be able to adjust quickly enough to survive the changing temperatures, precipitation and seasons?

Climate Change

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Prehistoric Changes in Vegetation Help Predict Future of Earth's Ecosystems

A few of jagged mountains and Big Bend National Park; Credit: NPS

As the last ice age came to an end and the planet warmed, the Earth's vegetation changed dramatically, reports a University of Arizona-led international research team.

The current warming from climate change may drive an equally dramatic change in vegetation within the next 100 to 150 years unless greenhouse-gas emissions are reduced, the team wrote.

"We found that ecosystems all over the globe experienced big changes," said Connor Nolan, a doctoral candidate in the UA Department of Geosciences. "About 70 percent of those sites experienced large changes in the species that were there and what the vegetation looked like."

Climate Change

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Linking Atmospheric Rivers to Wildfire Patterns in the Southwest

This winter, parts of drought-stricken California have been besieged by heavy flooding, mudslides, and feet of snow. The cause? A meteorological phenomenon known as an atmospheric river, which carries high concentrations of water vapor in narrow bands from the warm tropics up to western North America.
 
In the western U.S., atmospheric rivers are relatively common and are critical providers of winter rain and snow. However, they can also be a source of extreme flooding and costly damage to transportation networks, public utilities, and other infrastructure. While the economic and social impacts of strong atmospheric rivers are well understood, we know much less about how they can impact ecosystems.

Climate Change, atmospheric river

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Forest Fires in Sierra Nevada Driven by Past Land Use

Firefighter with drip torch setting a prescribed burn

Changes in human uses of the land have had a large impact on fire activity in California’s Sierra Nevada since 1600, according to new research

Forest fire activity in California's Sierra Nevada since 1600 has been influenced more by how humans used the land than by climate, according to new research led by University of Arizona and Penn State scientists.

For the years 1600 to 2015, the team found four periods, each lasting at least 55 years, where the frequency and extent of forest fires clearly differed from the time period before or after.

However, the shifts from one fire regime to another did not correspond to changes in temperature or moisture or other climate patterns until temperatures started rising in the 1980s.

Forest Service, Wildfire, Sierra Nevada

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