Warming Arctic linked to southwest droughts
November 14th, 2009California experienced centuries-long droughts in the past 20,000 years that coincided with the thawing of ice caps in the Arctic, according to a new study published in Earth and Planetary Science Letters. The findings came from analyzing stalagmites from Moaning Cavern in the central Sierra Nevada.
Study co-author Isabel Montañez said the study found a link between a warmer Arctic and a drier California:
We can’t quantify precipitation, but we can see a relative shift from wetter to drier conditions with each episode of warming in the northern polar region,” Montañez said.
The researchers didn’t attempt to explain the connection between Arctic temperatures to precipitation over California, but pointed to climate models developed by others suggest that when Arctic sea ice disappears, the jet stream – high-altitude winds with a profound influence on climate – shifts north, moving precipitation away from California.
Arctic sea ice has declined by about 3 percent a year over the past three decades, and some forecasts predict an ice-free Arctic ocean as soon as 2020. Montañez warns a connection between Arctic sea ice and weather in the west is bad news:
If there is a connection to Arctic sea ice then there are big implications for us in California.
Recent research has found that the jet stream has been migrating northward at a minimum of 12.5 miles per decade, or 18 feet per day. As it moves north, high pressure and clear skies converge in its wake, leaving the South and Southwest hotter and drier.
Cristina Archer and Ken Caldeira of the Carnegie Institution’s Department of Global Ecology have been tracking changes in the average position and strength of jet streams. Archer says changes in the jet streams have global implications:
The jet streams are the driving factor for weather in half of the globe. So, as you can imagine, changes in the jets have the potential to affect large populations and major climate systems.
Scientists are predicting that under current trends, Colorado River reservoirs could dry up, even as the urban population that depends on those reservoirs for water and energy continues to grow.
Even conservatives, industrial interests and development boosters are waking up to the fact that the impacts of water shortages are likely to be catastrophic, around the globe.