March 2006 ISSUE
backgrounder
the Other Major Greenhouse Gas
Editor’s Note: The following is one in a series of environmental articles solicited by the APEGGA Environment Committee. These opinion and background pieces are designed to broaden the discussion on the environmental issues within the professions and do not necessarily represent the views of APEGGA.
BY BRUCE PEACHEY, P.ENG.
President, New Paradigm Engineering Ltd.
The Intergovernmental Panel on Climate Change believes that global warming is causing climate change. But the IPCC admits that, despite years of effort, it has no proof that the two are linked.
The greenhouse gas theory of global warming does have theoretical merit. However, the magnitude of the climate changes that global warming alone can cause are still based on models that cannot yet match atmospheric water vapour distributions, precipitation patterns or clouds. Even features as large as hurricane Katrina are too small for global models to simulate or predict.
Yet energy and water fluxes, rather than temperature, are the indicators of climate change, and drive the floods and storms responsible for growing public concern. There are other human activities, besides hydrocarbon fuel use, that are large enough to impact the regional water and energy fluxes that drive weather events and climate.
The Facts
The IPCC, in Climate Change 2001: The Scientific Basis, indicates that precipitation
on land areas in the Northern Hemisphere has increased by 10-15 per cent over
the past few decades, while overall average land precipitation has increased
by two per cent over the last century. Low altitude atmospheric water vapour
content over Northern Hemisphere land areas has increased by as much as one per
cent per year (Oltmans & Hoffman, Nature, 375, 1995).
In northern areas, water flow to the ocean appears to be increasing in many, although not all, rivers flowing to the Arctic Ocean, as a result of increased precipitation in cold regions. The origin of the extra water entering the atmosphere, to allow this increased precipitation, is still uncertain, but has generally been assumed, and empirically modeled, to be due to increased evaporation from warming oceans, due to global warming caused by increasing CO2 and methane levels.
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At the same time, the IPCC, in Climate Change 2001: Impacts, Adaptation, and Vulnerability, and other studies report river water flow to the ocean has decreased by 10 per cent, or about 4,500 cubic kilometres in areas such as the southwestern United States, China, Europe and the Indian subcontinent. These decreases are not due to global warming but to human water withdrawals, mainly for irrigation, thermal power generation and industrial cooling.
In the book, Global Warming — The Complete Briefing, by Sir John Houghton, co-chairman of the Science Assessment Working Group of the IPCC, it is reported that the 10 per cent, or four teratonnes, reduction in return flow to the ocean is based on the IPCC’s estimate of anthropogenic water withdrawals. These withdrawals are reducing ocean discharge flows in lower latitude, Northern Hemisphere rivers, such as the Nile, the Colorado, the Yellow, the Rio Grande and others, which are all heavily used for irrigation.
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Water demand on river systems as a percentage of potential supply can be very large. Houghton reports that in the United States, for the Missouri river basin it is 30 per cent, for the Rio Grande 64 per cent and for the lower Colorado 96 per cent. “Almost none of the water in the Colorado River reaches the sea,” he writes.
What isn’t covered in the book was an explanation of where the water goes, once it is withdrawn, to close the mass balance.
The Global Water
and Energy Balances
The IPCC scientific basis report never refers to human enhanced water evaporation
anywhere in its 800-plus pages. The 1,000-plus-page impacts report never speculates
where the evaporated water goes to, or what impact it might have on climate or
precipitation.
Yet these must be addressed in a global water balance. Putting the data in the two reports into a global water balance gives the results in Figures 1 and 2. This analysis appears to indicate that most of the increased precipitation observed could be due to human enhanced water evaporation rather than greenhouse gas global warming, yet this is never addressed in the IPCC reports and these emissions are not input to global climate models.
Water is one of the most powerful greenhouse gases and most of the IPCC predicted warming is due to the impact of the assumed water “feedback loop.” That means human enhanced water evaporation could also make a major change in surface temperatures in regions downwind of large water emission sources, which would average out into general global warming.
Regional Impacts
Unlike other greenhouse gases, water is not evenly distributed in the atmosphere.
This is a major problem for climate models.
On average a water molecule will spend about 10 days in the atmosphere and could travel a few hundred or thousands of kilometres before it comes out as precipitation. Changes in atmospheric water distribution could produce large regional changes in climate activity, and such changes have been observed, as shown below.
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Cerveny and Balling (1998) reported weekly variation in rainfall on the eastern cost of the U.S. with a 22 per cent increase on Saturdays and the lowest days being Sunday to Tuesday.
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For the three days after 9/11, night-time temperatures across the U.S. dropped to near pre-modern levels, and water use also dropped for those days, as nuclear, industrial and agricultural activity dropped to minimum levels, lower than what happens every weekend.
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Reducing river flows into the Gulf of Mexico or coastal regions of California reduces mass flow through those regions, and allows the surface waters to warm, even with no change in net solar input, and should reduce the mass flow in the Gulf Stream.
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The major ecological disaster of the Aral Sea drying up is due to increased irrigation not global warming impacts. Visit http://enrin.grida.no/aral/aralsea/english/arsea/arsea.htm#top.
Conclusion
Greater efforts should be directed to studying water fluxes, both natural and
anthropogenic, to allow a more complete assessment of this question, and what
it can tell us about global and regional climate changes. Meanwhile, engineers
should honour the “precautionary principle” for both theories, and
work towards sustainable reductions in emissions of water vapour and other GHGs
to mitigate the potentially disastrous effects of climate change.
Bruce Peachey, P.Eng., has over 30 years’ experience in the upstream oil and gas industry, mainly on projects related to energy efficiency, water conservation and sustainable recovery of hydrocarbons. He received his bachelor of science degree in chemical engineering from the University of Saskatchewan in 1976, is a member of various technical and other groups, and is a founding member of the Petroleum Technology Alliance Canada. Mr. Peachey has often presented the human enhanced water evaporation concept and is preparing a paper to present at the 2006 Engineering Institute of Canada Climate Change Conference in Ottawa.