GLOBAL CLIMATE CHANGE

[From CHGE Newsletter (Vol. 2., No. 1, March 3, 1997)]

a) Health Impacts

DENGUE FEVER AND CLIMATE

Scientists in New Zealand have found that outbreaks of the tropical disease dengue in some South Pacific islands are directly related to climate change in the region, raising fears that "global warming could lead to outbreaks of tropical disease in new locations." Simon Hales and his colleagues at the Wellington School of Medicine in New Zealand, publishing their findings in the medical journal The Lancet (``Dengue Fever in the South Pacific: driven by El Niño Southern Oscillation?'' 1996;348:1664-65), attributed the mosquito-borne disease, which generally occurred after floods in tropical zones such as Southeast Asia, China and Cuba, to climate change caused by the El Niño Southern Oscillation. El Niño is a pattern of currents and weather that affect world climate.

Hales compared data from previous studies on dengue to El Niño and its effects, which demonstrated that the higher the Southern Oscillation Index the greater the instances of dengue fever. "The result is consistent with other studies and is biologically plausible, since the mosquitoes that transmit dengue are sensitive to temperature and rainfall," the scientists wrote.

"These findings suggest that dengue will be an increasing problem if the global climate continues to warm, as predicted by the Intergovernmental Panel on Climate Change," the report said.

CHOLERA: MONITORING ENVIRONMENTAL CHANGE

A combination of data from oceanography, ecology, microbiology, epidemiology, medicine, marine biology, and satellite imagery would enable scientists to better understand cholera, and ultimately prevent global epidemics. So argues Professor Rita R.Colwell, from the University of Maryland Biotechnology Institute and past president of the American Association for the Advancement of Science in her presidential lecture, the text of which was published in Science (``Global Climate and Infectious Disease: the Cholera Paradigm'' 1996;274:2025-2031).

In her talk, she used the history of cholera epidemics to illustrate the effect of environmental changes on infectious disease, tracing the history of seven cholera pandemics, which began in 1817 and continue today on six continents.

Cholera thrives in salty waters, but can grow in water with low salinity if the water temperature is relatively high and there is a high concentration of organic nutrients. The cholera bacteria attach themselves to certain types of plankton, in particular a zooplankton known as copepods. Water systems with agricultural and industrial waste provide the nutrients cholera need to flourish, creating the potential for epidemics and pandemics, "especially in developing countries having poor sanitation, lack of hygiene, and crowded living conditions," Dr. Colwell said.

Also, the El Niño climatic event, an unusual warming of the central Pacific region, brings an influx of warmer surface water and nutrients, which trigger the plankton blooms that carry the disease The plankton may then be ingested in a glass of water, in areas where there are no proper water treatment facilities. Evidence suggests that cholera cases occur following a rise in ocean surface temperature.

Colwell noted that between 1991 and 1995 the El Niño lasted for over three years, the longest period since monitoring began in the 1870s, and suggested that models to predict cholera outbreaks can be developed by using remote sensing to measure plankton blooms, and computer processing to integrate ecological and epidemiological data. "Because phytoplankton blooms can be measured by satellite imagery, and zooplankton blooms quickly follow phytoplankton blooms, conditions associated with a cholera outbreak or epidemic can be measured by satellite."

MALARIA MAKING A COMEBACK

In the first of a two part article, N.D. Kristof (``Malaria Makes a Comeback, and is More Deadly Than Ever'' NY Times 1/8/97, P. 1) discusses the resurgence of malaria, which is becoming resistant to medications and is expanding into new areas. Between 300-500 million people worldwide get malaria each year. In 1996, there were 1-3 million malaria deaths. As noted in the WHO/WMO/UNEP report Climate Change and Human Health (1996) [see last Newsletter, Vol I, No 1 ], global climate change, by increasing the range of the mosquitoes that carry malaria (perhaps even into Southern Europe and Southern U.S.), would result in an extra 80 million cases of malaria by the year 2100.

Center Associate Director Dr. Paul Epstein's recently published letter in the NY Times, 1/13/96, p. A16) discusses the possible relationship of malaria to climate change.

b) The Physical and Biological Evidence

1996 STILL ONE OF THE WARMEST ON RECORD

W.K. Stevens ``Global Climate Stayed Warm in 1996, with Wet, Cold Regional Surprises'' NY Times, 1/14/97, p. C1

1996 saw marked temperature fluctuations around the globe, with cold spells in parts of Central U.S. and Canada, and in Europe, and warmer temperatures in other regions. Overall, mean global surface temperatures show that 1996 ranked among the 10 warmest years since records were first kept in the 19th Century (NASA Goddard Institute for Space Studies ranked it the 5th warmest, while the British Meteorological Office placed it 8th). By contrast, 1995 was the warmest year on record. The 1990's are shaping up as the warmest decade on record, with the 1980's being second. According to greenhouse climate models, the warming is not expected to be smooth and continuous, "owing to natural variation" as explained by David Parker, a climate analyst at the British Meteorological Office, but the warming trend is still clear. This past year had all-time record precipitation in the Northeastern U.S. and Pacific Northwest (it was the 7th wettest year in more than a century in the contiguous 48 states, even including the prolonged drought in the Southwest). Researchers believe that the warming that has occurred so far in this century has led to a 20% increase in heavy precipitation in the U.S. As Thomas R. Karl, senior scientist at the National Climatic Data Center in Asheville, N.C. explains, moisture increases in the atmosphere at a faster rate than the warming itself, accounting for the increases in precipitation.

MORE EVIDENCE OF HUMAN INFLUENCE ON GLOBAL CLIMATE CHANGE

In another study supporting the findings of B.D. Santer et al. ``A Search for human influence on the thermal structure of the atmosphere'' Nature 1996;382:39-46--[see last Newsletter (Vol I, No 1 )], S.F. B. Tett et al. ``Human influence on the atmospheric vertical temperature structure: detection and observations'' Science 1996;274:1170-1173 have found that the observed changes in atmospheric temperatures (in the vertical temperature structure) match those predicted, taking into account the contributions from greenhouse gases, sulfate aerosols, and stratospheric ozone concentrations.

Mark Cane et al (Science ``Twentieth-Century Sea Surface Temperature Trends'' 1997; 275:957-960 suggest that long-term cooling of sea surface temperatures may account for some of the modulation of atmospheric temperatures over the past century.

N.B. The world's oceans -- the main memory for the climate system -- may turn out to be the repository for global warming.

PAST EVIDENCE OF DROUGHTS

In a report by Kathleen R. Laird of Queen's University, Kingston, Ontario and her colleagues [tel +1-613-545-6000 x5541,fax +1-613-545-6617,email-lairdk@biology.queensu.ca] in Nature ``Greater drought intensity and frequency before A.D.1200 in the Northern Great Plains, USA'' 1996;384:552-554) [N.B. One can find Nature articles on the web:www.america.nature.com], analysis of salinity fluctuations inferred from fossil diatoms in lake-bed sediments in North Dakota showed that the climate of the past 500 years has been unusually stable.

The drought that caused the 'Dust Bowl' in the American Midwest during the 1930s was a rare event according to modern standards. But our perspective may be dangerously narrow, according to Dr. Laird. Droughts were more frequent and more extreme before 1200 AD. A return to the climate variability seen then could have devastating consequences for agriculture and for the availability of drinking water supplies. An increased severity and frequency of droughts is one possible consequence of increasing CO2 atmospheric concentrations.

LARGE CRACKS FOUND IN ANTARCTIC ICE SHELF

According to Kalee Kreider of Greenpeace's Climate/Energy Campaign, researchers from Greenpeace found large cracks in the Antarctic's Larsen B Ice Shelf on February 5, 1997, providing further evidence that global warming may be resulting in a melting of Antarctic ice.

Also reported in Nature (Anon. ``Rifts found as Antarctic ice breaks apart'' 1997; 385:566), the rift was predicted by scientists from the British Antarctic Survey last year, who said that a neighboring ice shelf, Larsen C, "may behave in a similar way" (Nature 1996;378:328). The researchers have found that five Antarctic ice shelves out of the nine they have studied have disintegrated in the past 50 years, corresponding to a 2.5°C. rise in atmospheric temperatures over the same period, the most rapid warming observed anywhere in the world.

Scientists blamed a recent steady warming of the Antarctic Peninsula region when the 4,200 sq. km northern most part of the Larsen Ice Shelf, known as Larsen A, collapsed suddenly in January of 1995. British Antarctic Survey glaciologists argue that the behavior of ice shelves in the Antarctic Peninsula indicates the existence of an abrupt thermal limit on ice-shelf viability, which has been driven progressively downwards by the regional atmospheric warming. They have concluded that "ice shelves appear to be sensitive indicators of climate change."

Greenpeace climate change specialist Erwin Jackson on board the MV Arctic Sunrise in the Antarctic Peninsula region said: "It has taken centuries to millennia for these ice shelves to form and in a few short decades they are crumbling into nothing."

The Greenpeace vessel will be in the Antarctic Peninsula region for a month to document signs of climate change there. It successfully circumnavigated James Ross Island, a passage previously impassable due to an 200 meter thick ice shelf that joined the island to the Antarctic continent until 1995. It is believed this is the first time that the island has ever been circumnavigated.

[N.B. For aerial footage and photographs of the cracks in the ice-shelf contact Anke Scheib 00-44-171-865 8168]

Contacts on the Arctic Sunrise 874-130 2577:

Erwin Jackson - English

Martina Krueger - German, Dutch

Emiliano Ezcurra - Spanish, Portuguese, French, Italian.

THE COMPLEXITY OF GLOBAL CLIMATE CHANGE SCIENCE

Four separate studies demonstrate the enormous complexity of global climate change science:

  1. J.L. Sarmiento and C.L. Queve ``Oceanic CO2 uptake in a model of century-scale global warming'' Science 1996; 274:1346-1350 (1996) have looked at the influence of ocean circulation and temperatures in determining the ability of the oceans to act as sinks for the main greenhouse gas, CO2. They have concluded that global warming would have a significant effect on ocean circulation and temperatures and that prior predictions, which assumed both would remain constant, have over-estimated the capacity of the oceans to take up CO2, meaning that atmospheric CO2 concentrations may be even higher than have been estimated [these calculations did not take into account the effect that biological processes in the oceans may have on oceanic C02 uptake].

    N.B. Most climate models assume that biological systems will remain unchanged with global warming, This article suggests that biogeochemical cycles themselves may be altered.

  2. R.A. Kerr ``A New Driver for the Atlantic's moods and Europe's weather'' Science 1997; 275:754-755 (1997) discusses decade-long swings in the North Atlantic Oscillation, a complex current of warm and cold water which interacts with the Gulf Stream affecting weather in the North Atlantic, and which may complicate temperature signals from greenhouse warming.

  3. D. Menemenlis et al. ``Basin-scale ocean circulation from combined altimetric, tomographic and model data'' Nature 1997; 385:618-621(1997) have cautioned that direct observations of global oceanic circulation and its transport properties over time, in addition to modeling, are necessary to understand the Earth's climate and biosphere. They note that the ocean stores and transports vast quantities of heat, fresh water, carbon, and other materials that play important roles in determining both climate and fundamental biological processes.

  4. And L.D. Keigwin ``The Little Ice Age and Medieval Warm Period in the Sargasso Sea'' Science 1996; 274:1504-1508(1996), in examining radiocarbon dated samples of marine organisms in sediment of the Sargasso Sea, has demonstrated that sea surface temperatures were around 1°C cooler than today around 400 years ago (the Little Ice Age) and 1700 years ago, and around 1 °C warmer than today 100 years ago (the Medieval Warm Period). Such oscillations, he believes, need to be understood in determining the anthropogenic effects on climate change.

c) Extreme Weather Events and Climate Variability

"Most of the damage due to climate change is going to be associated with extreme events, not by the smooth global increase of temperature that we call global warming," Bert Bolin, chair of the Intergovernmental Panel on Climate Change warned fellow scientists at an international conference in Geneva in 1994.

RECORD PRECIPITATION IN NORTHWEST AND IN CALIFORNIA

D. Johnson ``As the Northwest Dries Out, Residents Prepare for Recovery'' NY Times, 1/6/97, p. A15--40 inches of rain fell on the Northwest during the lst week of 1997, killing about 2 dozen people and forcing 125,000 Northern Californians from their homes.

J. Christensen ``California Floods Change Thinking on Need to Tame Rivers'' NY Times, 2/4/97, P. C4--Floodwaters in California covered 250 square miles, destroyed or damaged 16,000 homes, killed 8 people, and caused an estimated $1.8 billion in damage [updated estimate Anon. NY Times, 2/15/97, p. 12]. This article talks about the need to adopt new land use and flood control measures to prevent future flooding, but neglects to mention that the historic flooding may have been caused by the "greenhouse effect"!

One of the major human health consequences of flooding comes from the effect on drinking water quality from contamination of surface waters by toxic substances (e.g. in the Mississippi Valley flooding of 1993). Such contamination was also seen in the California flooding, but this time, the mechanism was quite different. High levels of water in the Sacramento-San Joaquin Delta washed away low lying islands, letting salt water from the San Francisco Bay push upstream, contaminating the drinking water from the Delta (20% of the drinking water for L.A. comes from the Delta). (Anon. ``California Crews Bolster Levees; Drinking Water Faces Peril'' NY Times, 1/7/97, p. A10)

EXTREME WEATHER EVENTS OUTSIDE THE U.S.

``Tropical Storm Kills 100 in Eastern Malaysia State'' Reuters. NY Times, 12/26/96, P. A6--a tropical storm in eastern Malaysia killed at least 106 people (in addition, 100 people were still missing at the time of this report); and left 3000 people homeless in the state of Sabah. It was described as one of the worst storms ever to hit the state.

``Heavy Rains and Floods Drench Much of Bolivia'' AP, NY Times, 2/10/97, p. A7--The Bolivian government declared a national emergency as heavy rains, the heaviest in nearly 30 years (3 times its annual totals in just the first 6 weeks of the year), leaving at least 20,000 farmers homeless, destroying large areas of soy bean, corn, and cotton crops, and drowning thousands of cattle. Health officials reported sharp increased in cases of malaria and yellow fever, as the mosquito vectors for these diseases thrive in the water-soaked regions. In addition, people were coming into greater contact with snakes which had been displaced by the flooding into inhabited regions.

``Hundreds Feared Killed by Peruvian Mudslide'' NY Times, 2/21/97, p. A9--Torrential rains in the Andes, the worst of the decade, resulted in mudslides that covered entire villages, killing as many as 300, and sweeping away homes, livestock, and crops.

1996 HURRICANE SEASON VERY ACTIVE

A. MacSwan ``96 Hurricanes Claimed Heavy Toll'' The Boston Globe 11/29/96, p. A3

In its annual report, the Colorado State University Department of Atmospheric Science, a hurricane watching center, said "the 1996 hurricane season was characterized by very high activity." There were 13 named storms, 9 of them hurricanes from June 1 to the end of November [average is 10 named storms, and 6 hurricanes]. Hurricane Hortense killed at least 22 people in Puerto Rico and the Dominican Republic in September. Hurricane Fran, one of the strongest storms to hit the southeastern U.S., killed 34 people, and caused $1.6 billion in property damage and $616 million in agricultural losses.

References

S. Hales, Lancet, 1996

R. Colwell, Science, 12/20/96

N.D. Kristof ``Malaria Makes a Comeback, and is More Deadly Than Ever'' NY Times 1/8/97, P. 1

P. Epstein's ``Look to weather for clues to malaria comeback'' NY Times, 1/13/96, p. A16

W.K. Stevens ``Global Climate Stayed Warm in 1996, with Wet, Cold Regional Surprises'' NY Times, 1/14/97, p. C1

B.D. Santer et al. ``A Search for human influence on the thermal structure of the atmosphere'' Nature 1996;382:39-46

S.F. B. Tett et al.``Human influence on the atmospheric vertical temperature structure: detection and observations'' Science 1996;274:1170-1173

K. R. Laird Nature 1996; 384:552-

Anon. ``Rifts found as Antarctic ice breaks apart'' Nature 1997; 385:566

Nature 1996;378:328

J.L. Sarmiento, C.L. Queve ``Oceanic CO2 uptake in a model of century-scale global warming'' Science 1996; 274:1346-1350

R.A. Kerr ``A New Driver for the Atlantic's moods and Europe's weather'' Science 1997; 275:754-755

D. Menemenlis et al. ``Basin-scale ocean circulation from combined altimetric, tomographic and model data'' Nature 1997; 385:618-621

L.D. Keigwin ``The Little Ice Age and Medieval Warm Period in the Sargasso Sea'' Science 1996; 274:1504-1508

D. Johnson ``As the Northwest Dries Out, Residents Prepare for Recovery'' NY Times, 1/6/97, p. A15

J. Christensen ``California Floods Change Thinking on Need to Tame Rivers'' NY Times, 2/4/97, P. C4

Anon. ``California Crews Bolster Levees; Drinking Water Faces Peril'' NY Times, 1/7/97, p. A10

Reuters ``Tropical Storm Kills 100 in Eastern Malaysia State'' NY Times, 12/26/96, P. A6

AP. ``Heavy Rains and Floods Drench Much of Bolivia'', NY Times, 2/10/97, p. A7

Anon. ``Hundreds Feared Killed by Peruvian Mudslide'' NY Times, 2/21/97, p. A9

A. MacSwan ``96 Hurricanes Claimed Heavy Toll'' The Boston Globe 11/29/96, p. A3