The tropics are expanding pushing the earth's jet streams and its bands of deserts further from the equator, and closer to the poles. The bands of deserts are moving North in the Northern Hemisphere and South in the Southern Hemisphere as global warming intensifies.
This shift of the Earth's deserts will drastically impact every continent (except Antarctica) and their ecosystems. The same ecosystems that hundreds of millions of people in those regions have come to depend on. That raises the specter of populations being displaced as millions flee their ancestral homelands on the edges of the encroaching deserts. Competition for resources in the midst of increasing climate in flux is likely to become much more intense, and fractious.
Jet streams moving toward the poles will produce other unpredictable changes beyond shifting the earth's desert zones.
Deserts growing, study finds Jet stream shift could mean drought-stricken areas will get even drier PDF file
By ANDREW BRIDGES / Associated Press
WASHINGTON Deserts in the American Southwest and around the globe are creeping toward heavily populated areas as the jet streams shift, researchers reported Thursday.
The result: Areas already stressed by drought might get even drier.
Satellite measurements made from 1979 to 2005 show that the atmosphere in the subtropical regions north and south of the equator is heating up. As the atmosphere warms, it bulges out at the altitudes where the northern and southern jet streams slip past like swift and massive rivers of air. That bulging has pushed both jet streams about 70 miles closer to the Earth's poles.
Because the jet streams mark the edge of the tropics, in essence framing the hot zone that hugs the equator, their outward movement has widened the tropics about 140 miles. That means the relatively drier subtropics move as well, pushing closer to places such as Salt Lake City, where Dr. Thomas Reichler, co-author of the new study, teaches meteorology.
"One of the immediate consequences one can think of is those deserts and dry areas are moving poleward," said Dr. Reichler, of the University of Utah. Details appear today in the journal Science.
The movement has allowed the subtropics to edge toward populated areas, including the American Southwest, southern Australia and the Mediterranean basin. In those places, the lack of precipitation already is a worry.
Additional creep could move Africa's Sahara Desert farther north, worsening drought conditions that are already a serious problem on that continent and bringing drier weather to the countries that ring the Mediterranean Sea.
The American Southwest will come to resemble present day northern Mexico more and more as ecological zones shift northward along with the Earth's band of deserts.
Now South Texas and South Australia both are experiencing extreme droughts. People in these areas may well be getting a glimpse of their region's warmer drier future.
Deserts Might Grow as Tropics Expand
"If they move another 2 to 3 degrees poleward in this century, very dry areas such as the Sahara desert could nudge farther towards the pole, perhaps by a few hundred miles," said study team member John Wallace from the University of Washington.
Another 2 to 3 degrees translates to 140 to 210 miles on top of the 70 miles the ecological zones have already moved poleward. In other words it's like global warming has already moved your your home 70 miles south within the earth's climate zones and may move it as much as another 140 to 210 miles southward by the end of this century.
My brother went to Antarctica as a volunteer in the Teachers in Science program. He spent an Antarctic summer (average temperature hovered around 0 F) living in a tent on the ice sheet and drilling ice cores in a number of locations reached from his base camp by snowmobile.
A previous milestone study done collaboratively by scientists from Russia France and the U.S. was able to extract an ice core that gave scientists a detailed history of the Earth's climate and atmoshpereic makeup going back 420,000 years.
USGCRP Seminar
Overview
Vostok, one of the coldest places on Earth, is a permanent Russian station in East Antarctica where annual precipitation in the form of snow represents the equivalent of 2 cm of water.
A collaborative, international research program involving Russia, the U.S. and France was deployed from 1989 to 1998, to study ice core records of climate change from deep drilling. This project achieved both a technical and scientific milestone by reaching 3623 meters below the surface, the deepest ice core ever drilled, representing the longest, continuous, annual climate record extracted from the ice, encapsulating the last 420,000 years of Earth history.
The latest Vostok records of climate change provide a unique context or backdrop for examining human-induced changes in the concentrations of important greenhouse gases such as CO2 (carbon dioxide) and CH4 (methane) over the last 200 years. Comparatively speaking, human activities have resulted in present-day concentrations of CO2 and CH4 that are unprecedented over the last 420,000 years of Earth history. By extension of this comparison, the present rate of CO2 build-up also seems to be greater than what has been observed in ice-core records of climate change spanning the last 420,000 years.
As Global Warming becomes a more serious threat with each passing month, some scientists have become frustrated with the snail's pace that this urgent problem is being addressed by governments. They have turned to the tactics of civil disobedience to draw more attention to the problem in the MSM. A couple of weeks ago NASA's former senior climate scientist James Hansen was arrested at a protest against a Mountain Top Removal Coal Mine in West Virginia.
New Yorker
Hansen is opposed to coal in general—he believes that all coal-burning power plants will have to be shut by 2030 in order to avert catastrophic climate change—and to mountaintop-removal mining in particular. The practice is, as he put it to me recently, “doubly bad”—bad for the climate and devastating for the local environment. Many critics of the practice had hoped that the Obama Administration would put an end to mountain-removal mining; however, earlier this month, the Administration announced that it had decided only to regulate the practice more tightly.
Yesterday here in Seattle we had the hottest day on record during what's shaping up to be the hottest week on record. Yes I know this is the result of weather not climate, but it made me think about what could change in our planet's near future. It has me wondeing if it was the hottest day here since the Middle Pliocene.
I think more of us need to follow James Hanson's example before most people will come to grips with the fact that their and their children's future will be determined by how well we (meaning the entire planet's population) respond to this planet wide crisis.