WEEKLY WATER NEWS

WES WEEK ELEVEN: 16-20 April 2001

Water in the News:

• Increased hurricane awareness -- The National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service (NWS) have announced that the week of 21-25 May 2001 as Hurricane Awareness Week. A new hurricane awareness website also will be created. [NOAA News]
• Link between human activity and ocean warming -- Two recently released studies in Science indicate that the increase in ocean temperatures in the planet's major ocean basins within the last 50 years appears to be related to human activities, especially those which produce the so-called "greenhouse gases". [EurekAlert! and Scripps Institution of Oceanography]
• An orbital anomaly affects earth climate -- A team of researchers from the University of California at Santa Cruz reports that a particularly rare combination in the variations of the earth's orbital elements (known as the Milankovitch cycles) between 25 million and 20 million years ago may have been responsible for a change in the planetary climate at a time known as the boundary between the Oligocene and Miocene epochs. At this time a large ice sheet spread across Antarctica [UC Santa Cruz]
• An unusual ocean eddy discovered -- Using satellite data collected by the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) satellite, scientists from several institutions have discovered a long-lasting whirlpool-like eddy off the Hawaiian Islands that have led to an increase in marine food supply. [NASA GSFC]
• Plant growth driven by global heat engine -- NASA scientists have assembled a long-term global data set that appears to indicate that changes in the patterns of plant growth on land appear to be related to changes in sea surface temperatures. [NASA GSFC]
• Earth diary - A summary of the week's major environmental events on Planet Earth. [CNN]

Concept of the Week: Desertification

Desertification is one of the world's most pressing environmental issues, threatening the existence of more than a billion people who depend on the land for survival. In 1992, the United Nation's Conference on Environment and Development defined desertification as "land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climate variations and human activities." Through desertification, arable land is transformed into desert-like land, greatly reducing or eliminating the land's capacity to produce food. Desertification's impact on people dependent on subsistence farming and herding is food insecurity, and often their only option to avoid famine is migration to urban areas.

According to U.N. estimates, desertification affects about 130 million hectares (320 million acres) of land worldwide, equivalent to the areas of France, Italy, and Spain combined. Portions of some 110 nations are impacted, including parts of the North American Great Plains, the Pampas of South America, the steppes of Asia, the "outback" of Australia, and the edges of the Mediterranean. But by far the most widespread and severe impact is in Africa where two-thirds of the continent's land area is desert or dry land. Almost three-quarters of Africa's dry-land agricultural area is degraded to some extent. Desertification is a very serious problem in Sub-Saharan Africa with its considerable year-to-year variability in seasonal rainfall and frequency of long-term drought (described on pages 81-82 of the WES Textbook).

The systems approach is valuable in understanding desertification in that the process involves interactions of the climate system, Earth's land surface, the water cycle, and human activity. Desertification of dry lands accelerates during prolonged drought. Climate change can alter the frequency and intensity of drought and thereby contribute to soil desiccation. Although climate change may play an important role in desertification, a key factor is human mismanagement of the soil resource. Poverty and subsistence agriculture drives people to over-cultivate the land, quickly exhausting the soil's fertility. Overgrazing by livestock and deforestation exacerbate an already bad situation by removing the protective vegetative cover and exposing the topsoil to erosion by wind and running water. Winds can transport fine topsoil thousands of kilometers and sandstorms strip the leaves from plants and bury crops under dunes.

Land mismanagement also impacts the local climate and water budget, speeding up desertification. Without a vegetative cover, the soil surface temperature rises, accelerating evaporation of water, depletion of soil moisture, and build up of salts in the soil. Less soil moisture means that more of the available heat is used for raising the air temperature through conduction and convection (i.e., sensible heating). In this way heat stress combines with moisture stress to cut into crop yields.

Concept of the Week: Questions

1. Through desertification, crop productivity [(declines)(increases)].
2. Human mismanagement of the soil resource [(is)(is not)] a key factor in desertification.

Historical Events:

• 16 April 1851...The famous "Lighthouse Storm" raged near Boston Harbor. Whole gales and gigantic waves destroyed the 116 foot Minot Ledge Light at Cohasset, MA with the loss of its two keepers still inside. The storm coupled with a spring tide resulted in massive flooding, great shipping losses and coastal erosion. (David Ludlum)
• 16 April 1854...A furious storm that produced two feet of snow at New Brunswick, NJ also caused approximately 18 shipwrecks along the New Jersey coast. The immigrant ship Powhattan beached 100 yards from the shore. With rescue impossible, 340 people on board lost their lives. "The shrieks of the drowning creatures were melancholy indeed." (Accord's Weather Guide Calendar)
• 16 April 1987...A slow moving storm system produced heavy rain over North Carolina and the Middle Atlantic Coast States. More than six inches of rain drenched parts of Virginia, and flooding in Virginia claimed three lives. Floodwaters along the James River inundated parts of Richmond, VA. (The National Weather Summary) (Storm Data)
• 17 April 1942...A deluge of 8.35 inches in two hours dampened West Palm Beach, FL. (Intellicast)
• 17 April 1953...One of the few severe hailstorms accompanied by snow, sleet, glaze, and rain, pelted parts of Kay, Osage, Creek, Tulsa, Washington, and Rogers Counties in northeastern Oklahoma late in the day. Nearly 10,000 insurance claims were filed. (The Weather Channel)
• 17 April 1965...The Mississippi River reached a flood crest at Saint Paul, MN four feet higher than any previous mark. During the next two weeks record levels were reached along the upper Mississippi between Saint Paul and Hannibal, MO. Flooding caused more than 100 million dollars damage, but timely warnings kept the death toll down to just twelve persons. (David Ludlum)
• 17 April 1997…The Red River of the North crested at Fargo, ND, with a record crest of 39.6 feet, which is 22.6 feet above flood stage. This record flood, produced by several major winter storms, heavy spring rain, rapid snow melt, and ice jams, was responsible for at least 11 deaths (7 in North Dakota and 4 in Minnesota) and tremendous property damage along with large scale evacuations of residents from the Grand Forks metropolitan area. Overall damage and cleanup costs have been estimated to range from 1 to 2 billion dollars in Grand Forks, where a portion of the downtown burned as firefighters had a difficult time reaching the buildings due to the flood. [NCDC]
  Editor's Note: "History repeats!" The spring flooding of rivers across the Upper Midwest is reaching historic proportions. The USGS hydrograph for the gauge on the Red River at Grand Forks shows that the river stage there at the end of last week was at 45 feet, or approximately 17 feet above flood stage and about 7 feet below the top of the levee. In 1997 this gauge reported a record 54.35 feet. [EJH]
• 20 April 1952...The tankers Esso Suez and Esso Greensboro crashed in a thick fog off the coast of Morgan City, LA. Only five of the Greensboro's crew survived after the ship burst into flame. (David Ludlum)

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Prepared by AMS WES Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
ã Copyright, 2001, The American Meteorological Society.