Global Climate Change endorsements = 705
Global Climate Change rejections = 5
Global Climate Change consensus = 99.3%
Global Warming endorsements = 3300
Global Warming rejections = 74
Global Warming consensus = 97.8%
Title: Managing the nations water in a changing climate
Authors: Lins, HF; Stakhiv, EZ
Self-Endorsement Level: 5.0000
Among the many concerns associated with global climate change,
the potential effects on water resources are frequently cited as the
most worrisome. In contrast, those who manage water resources do not
rate climatic change among their top planning and operational concerns.
The difference in these views can be associated with how water managers
operate their systems and the types of stresses, and the operative time
horizons, that affect the Nation's water resources infrastructure.
Climate, or more precisely weather, is an important variable in the
management of water resources at daily to monthly time scabs because
water resources systems generally are operated on a daily basis. At
decadal to centennial time scales, though, climate is much less
important because (1) forecasts, particularly of regional precipitation,
are extremely uncertain over such time periods, and (2) the magnitude
of effects due to changes in climate on water resources is small
relative to changes in other variables such as population, technology,
economics, and environmental regulation. Thus, water management agencies
find it difficult to justify changing design features or operating
rules on the basis of simulated climatic change at the present time,
especially given that reservoir-design criteria incorporate considerable
buffering capacity for extreme meteorological and hydrological events.
Title:
Water and carbon cycles in the Mississippi River basin: Potential
implications for the Northern Hemisphere residual terrestrial sink
Authors: Lee, DH; Veizer, J
Self-Endorsement Level: 7.0000
The hydrologic cycle plays an important role in carbon cycling,
due to the coupling of vapor release and CO2 uptake during
photosynthesis. This coupling, expressed as Water Use Efficiency (WUE)
or Transpiration Ratio, can provide an inexpensive alternative for
estimating the Net Primary Productivity (NPP) of terrestrial ecosystems.
The D/H and O-18/O-16 trends of river water in the Mississippi basin
are mostly indistinguishable from those of precipitation. This, combined
with isotopic mass balance relationships, suggests that direct
evaporation of surface water is small and evapotranspiration (ET) flux
from the basin therefore consists mostly of interception and
transpiration, with interception approximated from field studies. The
calculated water flux associated with transpiration is 1500.8 km(3)
(77.3% of the evapotranspiration flux). Utilizing the average WUE of 864
mol H2O for each mole of CO2, the NPP of the Mississippi River basin
amounts to 1.16 Pg C/yr, similar to the model estimates of the
heterotrophic soil respiration flux of 1.12 Pg C/yr. This does not favor
the postulated existence of a major sink for atmospheric CO2 in the
temperate Northern Hemispheric ecosystems of the conterminous United
States, but due to uncertainties in the input parameters we cannot
discount the possibility that these ecosystems act as a modest sink.