Archive for the ‘Climate Change’ Category

Groundwater depletion rate accelerating worldwide

Friday, September 24th, 2010

Here is a connection that may not be so obvious – accelerating ground water depletion worldwide is adding to sea level rise. That is the finding of a forthcoming study – A Worldwide View of Groundwater Depletion by Dr. Marc Bierkens of Utrecht Universityslated for publication in Geophysical Research Letters, a journal of the American Geophysical Union.

How might that be possible? Well, the water has to go somewhere. Once its pumped out of the ground and used for its intended purpose, much of it ends up in the oceans, either through evaporation and precipitation or direct flow into the seas. Yes, some of it does infiltrate back into the soil and recharges underlying aquifers. Yet, according to the study, as much as 25% of annual sea level rise can be attributed to ground water withdrawn by human ingenuity.

Dr. Ramón Llamas, Emeritus Professor of Hydrogeology at the Complutense University of Madrid, Spain, has termed the growing global exploitation of ground water resources a silent revolution for its stealthy expansion and the lack of attention in both national and international water law and policy. It is high time that governments and policy-makers begin focusing on both domestic and transboundary aquifers and their sustainable management, not only to protect these dwindling and threatened sources of fresh water, but also to consider the global impact that their utilization is having on communities, dependent ecosystems, and now sea level.

You can read more about this forthcoming study in the press release AGU just issued. Here is an excerpt:

In recent decades, the rate at which humans worldwide are pumping dry the vast underground stores of water that billions depend on has more than doubled, say scientists who have conducted an unusual, global assessment of groundwater use.

These fast-shrinking subterranean reservoirs are essential to daily life and agriculture in many regions, while also sustaining streams, wetlands, and ecosystems and resisting land subsidence and salt water intrusion into fresh water supplies. Today, people are drawing so much water from below that they are adding enough of it to the oceans (mainly by evaporation, then precipitation) to account for about 25 percent of the annual sea level rise across the planet, the researchers find.


Applying these techniques worldwide to regions ranging from arid areas to those with the wetness of grasslands, the team finds that the rate at which global groundwater stocks are shrinking has more than doubled between 1960 and 2000, increasing the amount lost from 126 to 283 cubic kilometers (30 to 68 cubic miles) of water per year. Because the total amount of groundwater in the world is unknown, it’s hard to say how fast the global supply would vanish at this rate. But, if water was siphoned as rapidly from the Great Lakes, they would go bone-dry in around 80 years.


The new assessment shows the highest rates of depletion in some of the world’s major agricultural centers, including northwest India, northeastern China, northeast Pakistan, California’s central valley, and the midwestern United States.


Most water extracted from underground stocks ends up in the ocean, the researchers note. The team estimates the contribution of groundwater depletion to sea level rise to be 0.8 millimeters per year, which is about a quarter of the current total rate of sea level rise of 3.1 millimeters per year. That’s about as much sea-level rise as caused by the melting of glaciers and icecaps outside of Greenland and Antarctica, and it exceeds or falls into the high end of previous estimates of groundwater depletion’s contribution to sea level rise, the researchers add.

Climate Change and the Spread of Disease

Wednesday, April 29th, 2009

As swine flu continues to wreck havoc in the life of Mexico City residents and threatens to escalate to a global pandemic, the question of whether climate change might have a role in spread of disease seems appropriate. The short answer is “YES,” climate is likely to have a significant effect on the proliferation and geographic distribution of diseases.

Many of the world’s most notorious and persistent diseases, for example, are directly related to the lack of clean water and proper sanitation. The UN, in its 3rd World Water Assessment Report, attributes nearly three million deaths annually to such maladies. As temperatures rise, vector-borne diseases like malaria and dengue fever are expected to expand their range into regions that previously had been inhospitable to them. Likewise, where climate change causes precipitation to increase, water-borne pathogens including bacteria, parasites and algal blooms will flourish. The result will be a significant geographical shift in the range and proliferation of various diseases.

In the case of swine flu and other diseases originating in animals, changing climates could disrupt normal geographic movements and distributions of animals harboring such diseases. These disruptions could bring the pathogens into closer contact with other animals and pathogens, as well as humans, and could result in alternate transmission routes and, possibly, alternate mutations.

Last October (2008), the Wildlife Conservation Society (a US organization based at the Bronx Zoo that operates in 60 nations to save wildlife and habitats worldwide), issued its “deadly dozen” list of diseases that could spread into new regions and become more virulent as a result of climate change. Among others, the list included avian flu, one of the three genetic components of the Mexico swine influenza. The complete “deadly dozen” list includes [in alphabetical order]:

  1. Avian influenza
  2. Babesia
  3. Cholera
  4. Ebola
  5. Intestinal and External Parasites
  6. Lyme Disease
  7. Plague
  8. Red Tides
  9. Rift Valley Fever
  10. Sleeping Sickness (trypanosomiasis)
  11. Tuberculosis
  12. Yellow Fever

A Reuters article discussing the Society’s report can be found here. The Society has brochure that describes the “deadly dozen” diseases and their interaction with climate change here.

Global River Flows Decline

Thursday, April 23rd, 2009

The Christian Science Monitor Discoveries Blog has an interesting article on the global decline of river flows.  Too many ’straws’ sucking water out of the Colorado River” describes how by 2050, the Colorado River be unable to live up to its current allocation scheme 60-90 percent of the time; even absent climatic changes, scheduled deliveries would be unmet 40 percent of the time.  This news is based on a recent study by scientists at the Scripps Institution of Oceanography and published in the April 20 edition of the journal Proceedings of the National Academy of Sciences.

According to a forthcoming study by the National Center for Atmospheric Research and the College of William and Mary, the Colorado is not alone in suffering such shortfalls.  The study reveals that over the past 60 years, some 300 of the world’s largest rivers have experienced significant changes in flow rates.  While some rivers have gained volume, the rivers with reduced flow rates outnumbered the ones with higher flow rates by 2.5 to 1.  As for the culprit, the study suggests that large dams and diversion projects have certainly caused their share of water problems. However, they place greater burden on global climate change, which is altering precipitation patterns and increasing the rate of evaporation.

This study, which represents the most comprehensive data base yet assembled to track river flows (assessing the flows of 925 of the planet’s largest rivers), is scheduled for publication in the May 15 issue of the American Meteorological Society’s Journal of Climate.  You can download the research paper here, or view a simplified description of the study’s findings here.

Changing Climate, Changing Borders

Wednesday, April 15th, 2009

A recent article in New Scientist reported on how climate change could effect changes in political geography. The article – “Climate changes Europe’s Borders – and the world’s” – related how “Italy and Switzerland are planning to redraw their shared alpine border, as global warming is melting the glaciers that originally guided the line.”


While the article focused on borders in glaciated regions, it got me thinking about other ways in which climate change could impact international boundaries. The most obvious may be through the expected impacts on various transboundary rivers and lakes that form such boundaries. Flooding, for example, could have considerable impacts on the natural flow routes of rivers, sometime in sudden avulsive alterations, but often in gradual accretive changes.


While the international law applicable to changes by avulsion and accretion may be fairly settled (namely, that abrupt changes due to storms and other natural phenomena do not move the boundary, which remains in the old channel; while gradual and natural changes can legally increase or decrease a state’s territory notwithstanding sovereignty), it may be an entirely different matter where the changes are induced by climate change. If climate change is indeed a product of human action, there may be grounds to question whether climate change-induced changes to rivers routes constitute accretion. On the one hand, the changes may be described as gradual and natural; on the other, they have an unnatural, albeit indirect, source. Similarly, abrupt climate-induced changes may not constitute avulsion where they too have a human origin.


In a similar vein, droughts also could impact international boundaries where they deplete waters in a transboundary river or lake. The case of Lake Chad is illustrative. Between human withdrawals and climate change, the lake has been drastically reduced in size and volume.  Moreover, it continues to fluctuate with changing seasons. Because the boundary here is demarcated in relation to the tripoint in Lake Chad where the frontiers of Cameroon, Chad and Nigeria meet, any change to its geographical size, can change its tripoint location. This lack of a definitive and stationary border has witnessed citizens from neighboring countries cross the border, often inadvertently, to fish and forage for resources, which in turn, has resulted in a number of disputes.


At the January 2008 World Economic Forum at Davos, Switzerland, UN Secretary General Ban Ki-moon cautioned that water scarcity could spell increased conflicts in the future, and added that “[p]opulation growth will make the problem worse. So will climate change. As the global economy grows, so will its thirst.  Many more conflicts lie just over the horizon.” I can’t help but think that some of those conflicts may include border disputes.