[Vision2020] Sea Level Rise: Published Online Oct. 4, 2010: National Academy of Sciences: "Satellite-based global-ocean mass balance estimates..."

[Ted Moffett]

This new article from the National Academy of Sciences offers compelling
evidence of climate change that can remake the Earth's coastlines.  The
evidence that human activity, primarily radiative forcing from CO2
emissions, is mainly causing this trend in the hydrological cycle, is backed
by extensively researched and peer reviewed science, to a high enough degree
of probability that to insist we hesitate to act to substantially reduce
human impacts on climate, due to uncertainties in the science, is tantamount
to playing Russian Roulette with the future of Earth, and
its human inhabitants.
Article in full can be read at website below  Commentary on this science is
pasted in lower down, from the Los Angeles Times :

http://www.pnas.org/content/early/2010/09/28/1003292107.full.pdf+html

Satellite-based global-ocean mass balance estimates of interannual
variability and emerging trends in continental freshwater discharge

Tajdarul H. Syeda,b, James S. Famigliettia,c,1, Don P. Chambersd, Josh K.
Willise, and Kyle Hilburnf

Edited* by Anny Cazenave, Centre National d’Etudes Spatiales (CNES),
Toulouse Cedex 9, France, and approved August 27, 2010 (received for review
March

14, 2010)

Freshwater discharge from the continents is a key component of Earth’s water
cycle that sustains human life and ecosystem health.

Surprisingly, owing to a number of socioeconomic and political obstacles, a
comprehensive global river discharge observing system

does not yet exist. Here we use 13 years (1994–2006) of satellite
precipitation, evaporation, and sea level data in an ocean mass

balance to estimate freshwater discharge into the global ocean.  Results
indicate that global freshwater discharge averaged

36*,*055 km3∕y for the study period while exhibiting significant interannual
variability driven primarily by El Niño Southern Oscillation

cycles. The method described here can ultimately be used to estimate
long-term global discharge trends as the records of

sea level rise and ocean temperature lengthen. For the relatively short
13-year period studied here, global discharge increased by

540 km3∕y2, which was largely attributed to an increase of globalocean
evaporation (768 km3∕y2). Sustained growth of these flux

rates into long-term trends would provide evidence for increasing intensity
of the hydrologic cycle.

climate ∣ global water cycle ∣ hydrology ∣ remote sensing ∣ observations
--------------------------------------

http://latimesblogs.latimes.com/greenspace/2010/10/global-warming-river-flows-oceans-climate-disruption.html
 Global warming: a rise in river flows raises
alarm<http://latimesblogs.latimes.com/greenspace/2010/10/global-warming-river-flows-oceans-climate-disruption.html>
October 5, 2010
The volume of fresh water pouring from the world’s rivers has risen rapidly
since 1994, in what  researchers say is further evidence of global
warming.<http://www.climate.gov/>The study, led
by a team at UC
Irvine<http://www.pnas.org/content/early/2010/09/28/1003292107.full.pdf+html>,
is the first to estimate global fresh-water flow into the world’s oceans
using observations from new satellite technology rather than through
computer or hydrological models.

Published this week in the Proceedings of the National Academy of Sciences,
the study found that annual fresh-water flow increased 18% from 1994 to
2006, suggesting an acceleration in the global water cycle of evaporation
and rainfall, which influences the intensity of storms, floods and droughts.

UC Irvine Earth System Science professor Jay Famiglietti, the principal
investigator, said that the data have major implications for California,
where warmer temperatures <http://www.climatechange.ca.gov/> are already
triggering earlier snow melt. Rising sea
levels<http://www.latimes.com/news/local/la-me-global-warming-searise12-2009mar12%2C0%2C2741152.story>are
expected to significantly alter the state’s long coastline.

“Until now, we have had no continuous record of global-scale river
discharge,” said Famiglietti. He noted that the time period of the study was
short, but added, "If these trends persist, they will be a smoking gun that
the water cycle intensification, predicted by climate scientists, is already
upon us."

Globally, river flows are often a politically-fraught subject. Countries
measure the quantity of water locally, and inconsistently, with mechanical
or electronic guages, but they often refuse to share the data, according to
hydrologist Peter Gleick, editor of the biannual "World's Water" survey and
director of the Oakland-based Pacific Institute think tank. Pakistan and
India are in conflict over flows from the Indus. Israelis, Palestinians and
Lebanese all depend on the Jordan River. Ten countries are sharing water
along the Nile. *[Corrected at 9:31 p.m.: *An earlier version of this post
implied Palestine is a country. It is not.*]*

The UC Irvine study “is additional clear evidence that the hydrological
cycle is accelerating,” Gleick said. "This is exactly what climate modelers
have said would happen from climate change, and now we see it happening. How
much more evidence do we need before we take action against climate change?”

In the hydrological cycle, as grade-schoolers learn, fresh water evaporates
from the oceans, rains onto the land and flows into rivers which then empty
into the oceans. The increase in fresh-water flow, documented in the paper,
was the missing element that complemented existing evaporation, rainfall and
sea level rise data, proving that the cycle is speeding up, Famiglietti
said.

"If the water cycle intensifies, then we will see more frequent, more
intense floods, and more persistent drought," he said. He noted that because
of atmospheric circulation patterns, the impact will be uneven, with
stronger rainfall and more severe storms in the tropics and the Arctic, and
more drought in temperate regions such as California.

UC Irvine last year opened the UC Center for Hydrologic Modeling, directed
by Famiglietti, which will do more specific climate-related studies on
California, such as the implications of groundwater depletion in the Central
Valley.

The study found that the 13-year increase in fresh-water discharge of 540
cubic kilometers was mostly due to rapid evaporation from the oceans, which
led to more rainfall on land. Only 10% of the increase in discharge could be
attributed to melting ice sheets in Greenland and the Antarctic, although
those sources are expected to be a growing proportion as earth's
temperatures rise, Famiglietti said.

Other causes for the rise in river flows include melting glaciers and
permafrost on land, and practices such as groundwater pumping for
irrigation.

"Given the importance of water and the impact of climate change, we need a
comprehensive global monitoring network that can measure water stocks and
fluxes," Famiglietti said. "We need ground-based measurements of snow, ice,
permafrost, lake levels, river flows, soil moisture and groundwater levels.
We need dedicated satellite missions. The technology is all there. We just
need to make the investment in the ground, and in remote observations, and
in the predictive models to synthesize them."

The lead author on the paper, which was funded by NASA, is Tajdarul Syed of
the Indian School of Mines, who did most of the research as a graduate
student and postdoctoral associate under Famiglietti. Other authors are Don
Chambers of the University of South Florida, Joshua Willis of the Jet
Propulsion Laboratory in Pasadena, and Kyle Hilburn of Remote Sensing
Systems in Santa Rosa, CA.

-- Margot Roosevelt

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Vision2020 Post: Ted Moffett
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