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Heat Waves, Water Supplies, and Drought Patterns

 

 

If you want a pdf file of any of these for educational or scientific

purposes, just ask.

Lance Olsen


SCIENCE www.sciencemag.org

R E P O R TS

13 AUGUST 2004 VOL 305

 

More Intense,More Frequent,and Longer Lasting Heat Waves in the 21st Century

Gerald A.Meehl and Claudia Tebaldi

 

ABSTRACT : A global coupled climate model shows that there is a

distinct geographic pattern to future changes in heat waves. Model

results for areas of Europe and North America, associated with the

severe heat waves in Chicago in 1995 and Paris in 2003, show that

future heat waves in these areas will become more intense,more

frequent, and longer lasting in the second half of the 21st century.

Observations and the model show that present-day heat waves over

Europe and North America coincide with a speci fic atmospheric

circulation pattern that is intensi oed by ongoing increases in

greenhouse gases,I ndicating that it will produce more severe heat

waves in those regions in the future.


NATURE

November 17, 2005

 

Potential impacts of a warming climate on water availability in

snow-dominated regions

T. P. Barnett , J. C. Adam & D. P. Lettenmaier

 

ABSTRACT : All currently available climate models predict a

near-surface warming trend under the influence of rising levels of

greenhouse gases in the atmosphere. In addition to the direct effects

on climate - for example, on the frequency of heatwaves - this

increase in surface temperatures has important consequences for the

hydrological cycle, particularly in regions where water supply is

currently dominated by melting snow or ice. In a warmer world, less

winter precipitation falls as snow and the melting of winter snow

occurs earlier in spring. Even without any changes in precipitation

intensity, both of these effects lead to a shift in peak river runoff

to winter and early spring, away from summer and autumn when demand

is highest. Where storage capacities are not sufficient, much of the

winter runoff will immediately be lost to the oceans. With more than

one-sixth of the Earth's population relying on glaciers and seasonal

snow packs for their water supply, the consequences of these

hydrological changes for future water availability-predicted with

high confidence and already diagnosed in some regions-are likely to

be severe.


 

Proceedings of the National Academy of Sciences

2005;102;15144-15148; originally published online Oct 10, 2005; PNAS

 

Regional vegetation die-off in response

to global-change-type drought

David D. Breshears a,b , Neil S. Cobb c , Paul M. Rich d , Kevin P.

Price e,f , Craig D. Allen g , Randy G. Balice h , William H. Romme i

,

 

Global climate change is projected to yield increases in frequency

and intensity of drought occurring under warming temperatures (1-3),

referred to here as global-change-type drought. Protracted,

subcontinental drought in the midlatitudes is a complex response

driven in part by anomalies associated with oscillations in sea

surface temperature (2-4), which can include oscillations over

periods of decades or longer, such as those associated with the

Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation

(4), and shorter periods spanning several years, such as those

associated with the El Nin—o Southern Oscillation (3). Greenhouse gas

forcings are expected to alter these oceanic effects on drought

patterns (1-3). Indeed, the most recent protracted drought in

southwestern North America, spanning the beginning of the 2000

millennium, exhibited anomalous sea surface temperature patterns

consistent with projections of global change response (3). Protracted

drought can trigger large-scale landscape changes through vegetation

mor-tality from water stress (5, 6), sometimes associated with bark

beetle infestations (5), but the potential for regional to

subcontinental scale vegetation die-off under global-change-type

drought remains a pivotal uncertainty in projections of climate

change impacts (1, 7, 8). Of particular concern is regional-scale

mortality of overstory trees, which rapidly alters ecosystem type,

associated ecosystem properties, and land surface conditions for

decades.

 

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