Slowing Global Warming -- A Life or Death Issue?
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Subject: NCAR News - "No Doubt" Human Activity Is Affecting Global
2003-49 FOR IMMEDIATE RELEASE: December 2, 2003
"No Doubt" Human Activity Is Affecting Global Climate,
Top Scientists Conclude
Cheryl Dybas, NSF
BOULDER-Two of the nation's premier atmospheric scientists, after
reviewing extensive research by their colleagues, say there is no longer
any doubt that human activities are having measurable-and
increasing-impacts on global climate. Their study cites atmospheric
observations and multiple computer models to paint a detailed picture of
climate changes likely to buffet Earth in coming decades, including
rising temperatures and an increase in extreme weather events, such as
flooding and drought. The study appears December 5 in Science as part
of the journal's "State of the Planet" series.
The coauthors-Thomas Karl, director of NOAA's National Climatic Data
Center, and Kevin Trenberth, head of the Climate Analysis Section at the
National Center for Atmospheric Research (NCAR)-conclude that industrial
emissions have been the dominant influence on climate change for the
past 50 years, overwhelming natural forces. The most important of these
emissions is carbon dioxide, a greenhouse gas that traps solar radiation
and warms the planet.
"There is no doubt that the composition of the atmosphere is changing
because of human activities, and today greenhouse gases are the largest
human influence on global climate," they write. "The likely result is
more frequent heat waves, droughts, extreme precipitation events, and
related impacts, e.g., wildfires, heat stress, vegetation changes, and
sea-level rise which will be regionally dependent."
Karl and Trenberth estimate that, between 1990 and 2100, there is a 90
percent probability that global temperatures will rise by 1.7 to 4.9
degrees Celsius (3.1 to 8.9 degrees Fahrenheit), because of human
influences on climate. Such warming would have widespread impacts on
society and the environment, including continued melting of glaciers and
the great ice sheets of Greenland, inundating the world's coasts. The
authors base their estimate on computer model experiments by climate
scientists, observations of atmospheric changes, and recorded climate
changes over the past century.
However, there is still large uncertainty in understanding the global
climate and how it will change, says Karl. If temperatures rise 1.7
degrees, the expected changes would be relatively small, whereas a
4.9-degree increase could bring drastic impacts, some of which may be
Carbon dioxide levels in the atmosphere have risen by 31 percent since
preindustrial times, from 280 parts per million by volume (ppmv) to over
370 ppmv today. Other human activities, such as emissions of sulfate and
soot particles and the development of urban areas, have significant but
more localized climate impacts. Such activities may enhance or mask the
larger-scale warming from greenhouse gases, but not offset it, according
to the authors.
If societies could successfully cut emissions and stabilize carbon
dioxide levels in the atmosphere, temperatures would still increase by
an estimated 0.5 degree C (0.9 degree F) over a period of decades, Karl
and Trenberth warn. This is because greenhouse gases are slow to cycle
out of the atmosphere. "Given what has happened to date and is projected
in the future, significant further climate change is guaranteed," the
If current emissions continue, the world would face the fastest rate of
climate change in at least the last 10,000 years. This could potentially
alter ocean current circulations and radically change existing climate
patterns. Moreover, certain natural processes would tend to accelerate
the warming. For example, as snow cover melts away, the darker land and
water surface would absorb more solar radiation, further increasing
Karl and Trenberth say more research is needed to pin down both the
global and regional impacts of climate change. Scientists, for example,
have yet to determine the temperature impacts of increased cloud cover
or how changes in the atmosphere will influence El Ni�o, the periodic
warming of Pacific Ocean waters that affects weather patterns throughout
much of the world. The authors call for multiple computer model studies
to address the complex aspects of weather and climate. The models must
be able to integrate all components of Earth's climate system-physical,
chemical, and biological. This, in turn, will require considerable
international cooperation and the establishment of a global climate
monitoring system to collect and analyze data.
Because of the broad range of potential change in temperature, it's
extremely important to ensure that we have a comprehensive observing
system to track unforeseen changes and variations, says Karl.
"Climate change is truly a global issue, one that may prove to be
humanity's greatest challenge," the authors conclude. "It is very
unlikely to be adequately addressed without greatly improved
international cooperation and action."
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160,000 Said Dying Yearly from Global Warming
MOSCOW - About 160,000 people die every year from side-effects of global
warming ranging from malaria to malnutrition and the numbers could almost
double by 2020, a group of scientists said yesterday.
The study, by scientists at the World Health Organization (WHO) and the
London School of Hygiene and Tropical Medicine, said children in
developing nations seemed most vulnerable.
"We estimate that climate change may already be causing in the region of
160,000 deaths...a year," Professor Andrew Haines of the London School of
Hygiene and Tropical Medicine told a climate change conference in Moscow.
"The disease burden caused by climate change could almost double by
2020," he added, even taking account of factors like improvements in
health care. He said the estimates had not been previously published.
Most deaths would be in developing nations in Africa, Latin America and
Southeast Asia, which would be hardest hit by the spread of malnutrition,
diarrhea and malaria in the wake of warmer temperatures, floods and
"These diseases mainly affect younger age groups, so that the total
burden of disease due to climate change appears to be borne mainly by
children in developing countries," Haines said.
Milder winters, however, might mean that people would live longer on
average in Europe or North America despite risks from heatwaves this
summer in which about 15,000 people died in France alone.
Haines said the study suggested climate change could "bring some health
benefits, such as lower cold-related mortality and greater crop yields in
temperate zones, but (that) these will be greatly outweighed by increased
rates of other diseases."
Russia is hosting a World Climate Change Conference this week to discuss
how to rein in emissions of gases like carbon dioxide from factories and
cars that scientists blame for blanketing the planet and nudging up
Russian President Vladimir Putin, who opened the conference on Monday,
suggested in jest that global warming could benefit countries like Russia
as people "would spend less money on fur coats and other warm things."
But Putin also backed away from Russia's earlier pledge to swiftly ratify
the key Kyoto pact on curbing global warming, a plan that will collapse
without Moscow's backing.
He told 940 delegates to the conference Russia was closely studying the
issue of Kyoto. "A decision will be taken when this work is finished," he
said, giving no timetable.
Haines said small shifts in temperatures, for instance, could extend the
range of mosquitoes that spread malaria. Water supplies could be
contaminated by floods, for instance, which could also wash away crops.
Story by Alister Doyle
Story Date: 1/10/2003
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