DESERTIFICATION:

Global Climate Shift Feeds Spreading Deserts

NEW YORK, New York, June 17, 2002 (ENS) - Over the next 20 years some
60 million people in northern Africa are expected to leave the
Sahelian region if desertification there is not halted, United Nations
Secretary-General Kofi Annan said today. June 17 is the day set aside
each year by the UN as World Day to Combat Desertification and
Drought, twin problems that must be solved if world hunger is to be
relieved, Annan said.

"The fight against desertification is fundamentally a fight against
poverty," said Hama Arba Diallo, executive secretary of the eight year
old UN Convention to Combat Desertification and Drought.

Desertification, environmental degradation and poverty are closely
linked, and now an Australian scientist has found that air pollution
may also play a role in the Sahel drought, by hampering the northward
movement of the tropical rain belt.

Desertification and land degradation are worldwide phenomena with most
severe effects on communities in the poorest rural areas. More than
110 countries are affected, and the livelihood of over 1.2 billion
people are threatened by desertification, with 135 million around the
world at risk of being displaced.

In northeast Asia, "dust and sandstorms have buried human settlements
and forced schools and airports to shut down," Annan said, "while in
the Americas, dry spells and sandstorms have alarmed farmers and
raised the spectre of another Dust Bowl, reminiscent of the 1930s." In
southern Europe, "lands once green and rich in vegetation are turning
barren and brown," he said.

"Every year, an estimated $42 billion in income and six million
hectares of productive land are being lost because of desertification,
land degradation and declining agricultural productivity," Annan said
today.


Hama Arba Diallo, executive secretary of the UN Convention to Combat
Desertification and Drought (Photo courtesy ENB)
The secretary-general urged countries to support the UN Convention to
Combat Desertification and Drought - the only legally binding treaty
to address desertification and drought with a focus on sustainable
development.
Diallo said that most of the 179 countries that are Parties to the
convention are hosting activities today such as roundtable
discussions, field trips and media campaigns at the national and local
levels and involving government and nongovernmental organizations, the
media, and other stakeholders.

But raising awareness of the problems is not enough - funds are needed
to solve them. Diallo called on the international community to make
financial commitments to enable countries affected by land degradation
to implement the treaty.

"In order for the convention to move from preparation to the
implementation of national action programmes, predictable financial
resources are imperative," he said from the secretariat's office in
Bonn, Germany.

He urged leaders of the international community who will be meeting at
the Johannesburg World Summit for Sustainable Development in August
and September to back up their pledges made 10 years ago at the UN
Earth Summit in Rio de Janeiro.

Drought air pollution link found

Australian government researcher Dr. Leon Rotstayn has evidence that
air pollution is likely to have contributed to the what he terms the
"catastrophic drought in the Sahel," a region of northern Africa which
borders the fringe of the Sahara Desert.

Tiny atmospheric particles, known as sulfate aerosol, have contributed
to a global climate shift, he says.

"The Sahelian drought may be due to a combination of natural
variability and atmospheric aerosol," says Dr. Rotstayn. "Cleaner air
in future will mean greater rainfall in this region.


Dr. Leon Rotstayn (Photo courtesy Australian Academy of Science)
The majority of sulfate aerosol comes from the burning of fossil fuels
and metal smelting. Smaller amounts come from the burning of
vegetation in the tropics, and natural sources such as marine
plankton.

Atmospheric aerosol concentrations are far greater in the northern
hemisphere, cooling the atmosphere there more than in the southern
hemisphere. It is this imbalance that affects the tropical rain belt.

"Global climate change is not solely being caused by rising levels of
greenhouse gases. Atmospheric pollution is also having an effect,"
says Dr. Rotstayn, who is affiliated with CSIRO, the Australian
government's research branch.

CSIRO's research into aerosol and climate is in part supported by the
Australian Greenhouse Office and involves collaboration with the
University of Michigan in the USA and Dalhousie University in Canada.
The findings on air pollution and the tropical rain belt have just
been published in the international "Journal of Climate."

The researchers ran sophisticated global climate simulations on a
supercomputer. They found that sulfate aerosol particles, which are
concentrated mainly in the northern hemisphere, make cloud droplets
smaller. This makes the clouds brighter and longer lasting, so they
reflect more sunlight into space, cooling the Earth's surface below.

As a result, the tropical rain belt, which migrates northwards and
southwards with the seasonal movement of the sun, is weakened in the
northern hemisphere and does not move as far north.

The main impact of the weaker rain belt is in the Sahel. Since the
1960s, this region has experienced a devastating drought. Rainfall was
20 to 49 percent lower than in the first half of the 20th century,
causing widespread famine and death.

Scientists also believe that air pollution over China has affected
their summer monsoon rainfall belt. Northern China had successive
droughts in the summers of 1997, 1998 and 1999.

A reduction in the severity of the Sahelian drought during the 1990s
may be linked with emission controls in Europe and North America that
lowered atmospheric aerosol concentrations during that decade, Dr.
Rotstayn says.

Tropical and eastern Australia have experienced an increase in
rainfall over the 20th century, and this may be related to the same
effect.

"We are not yet seeing reductions in aerosol emissions in Asia," says
Dr. Rotstayn. "It is possible that other forms of aerosol in the air,
such as black soot emitted from Southeast Asia, could affect
Australia's climate."

Copyright Environment News Service (ENS) 2002. All Rights Reserved.