Potential evapotranspiration and the likelihood of future drought

Journal Article · Wed Jun 20 00:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JD095iD07p09983· OSTI ID:5398584

Rind, D; Hansen, J ^[1]; Goldberg, R; Rosenzweig, C ^[2]; Ruedy, R ^[3]

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1. Goddard Space Flight Center, New York (USA)
2. Columbia Univ., NY (USA)
3. Central Sigma Data Services Corporation, NY (USA)

The likelihood of future drought is studied on the basis of two drought indices calculated from the Goddard Institute for Space Studies general circulation model (GISS GCM) transient and doubled CO{sub 2} climate changes. The authors use the Palmer drought severity index (PDSI) and a new supply-demand index (SDDI), the latter being the difference between the precipitation and potential evapotranspiration E{sub p}, i.e., the difference between atmospheric supply of and demand for moisture. Both indices show increasing drought for the United States during the next century, with effects becoming apparent in the 1990s. If greenhouse gas emissions continue to increase rapidly, the model results suggest that severe drought (5% frequency today) will occur about 50% of the time by the 2050s. The results are driven by the large increase in E{sub p}, associated with the simulated climate warming. E{sub p} increases most where the temperature is highest, at low to mid-latitudes, while precipitation increases most where the air is coolest and easiest to saturate by the additional moisture, at higher latitudes. The authors suggest that drought intensification has been understated in most GCM simulations, including the GISS GCM, because of their lack of realistic land surface models. Paleoclimate analogues in the Mesozoic and Cenozoic are reviewed which imply that arid conditions can result from either increased temperatures or decreased precipitation, consistent with our use of the SDDI. The results depend primarily on the temperature increase, in particular the model sensitivity of 4{degree}C warming for doubled CO{sub 2}. Global precipitation cannot keep pace with increased demand over land because the land surface warms more than the ocean surface; this effect, along with greater atmospheric opacity, reduces low level gradients and evaporation from the ocean.

• OSTI ID: 5398584
• Journal Information: Journal of Geophysical Research; (United States), Vol. 95:D7; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
01 COAL, LIGNITE, AND PEAT
CARBON DIOXIDE
ENVIRONMENTAL IMPACTS
DROUGHTS
FORECASTING
AIR POLLUTION
ATMOSPHERIC CIRCULATION
ATMOSPHERIC PRECIPITATIONS
CLIMATE MODELS
CLIMATES
COMPARATIVE EVALUATIONS
CONTINENTAL CRUST
EMISSION
EVAPORATION
GREENHOUSE EFFECT
HEATING
MOISTURE
OPACITY
PALEOCLIMATOLOGY
SEAS
SOILS
TEMPERATURE DISTRIBUTION
TRANSPIRATION
VARIATIONS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
EARTH CRUST
EVALUATION
MATHEMATICAL MODELS
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PALEONTOLOGY
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
POLLUTION
SURFACE WATERS
540110*
010900 - Coal
Lignite
& Peat- Environmental Aspects