Press
Release No.2002-34
A NEW GLOBAL
STRATEGY FOR EARTH OBSERVATION
Paris, June 3 - Global initiatives
to monitor climate change and the health of the planet took a
major step forward with the establishment of a unique alliance
between space agencies and scientific communities, which met at
UNESCO Headquarters from May 30-31.
The meeting set new parameters
to improve satellite observation of the environment, through the
Integrated Global Observing System (IGOS), which is the only forum
to link space and land-based scientific organizations. Created
in 1998, IGOS is an umbrella organization for hundreds of research
organizations, with a main decision-making body consisting of
14 partners, including diverse UN agencies and scientific organizations,
like UNESCO and the World Meterological Organization as well as
the Committee on Earth Observation Satellites (CEOS), which represents
23 space agencies.
"The space race has entered
a new phase," said Walter Erdelen, co-chairman of IGOS and
UNESCO Assistant Director-General for Science. "No longer
is it a mere playing field for superpower rivalry, dominated by
military concerns and national pride. Today, the race to space
is fuelled by a far more critical goal than that of Cold War politics--the
quest to understand the planet's life-support systems."
Since the end of the Cold War,
space agencies have increasingly focused on environmental security
by launching an expanding constellation of satellites equipped
with optical, infrared and radar sensors to monitor the Earth.
These satellites are often the only way to obtain suitable data
to understand and predict both man-made and natural changes to
the atmosphere, land and oceans.
Countries of diverse financial
means - from the United States, Japan and France to India, China,
Brazil and Argentina - have invested in Earth observation satellites.
Yet over the past several years, many space agencies have experienced
steep budgetary constraints. While the cuts appear to have stabilized,
agencies are trying to optimize scarce resources with tailor-made
missions for the end-users, land-based scientists. IGOS enables
them to consult directly with these communities to plan new missions.
"There are several global
initiatives to observe the climate or the oceans, for example.
But no single agency or organization can afford to implement one
of these systems alone," said Dr. Tillman Mohr of CEOS. IGOS
has begun by identifying several critical issues, notably: the
ocean currents and climate change, the state of the world's water
resources, the global carbon cycle, atmospheric chemistry and
geo-hazards such as volcanic eruptions and landslides. Scientists
specializing in these areas work in committees to develop strategies
in the form of reports, which begin by identifying the type and
duration of satellite data which might fill the gaps in current
knowledge.
For example, there are fairly regular
and accurate measurements of air-pollution levels for wealthy
capitals. Satellites might provide a global monitoring system,
necessary for understanding atmospheric chemistry.
Yet satellites alone cannot answer
most of the critical questions facing scientists today. Satellites
alone cannot measure the amount of carbon dioxide absorbed by
forests or the rate of coastal erosion. IGOS is also developing
strategies to integrate land and space based data. Satellite images
of coastal erosion can transform the studies of a marine biologist.
At the same time, space agencies need information from the field
to interpret the signals sent by satellites.
"This marks a paradigm shift
for both the space and land-based scientific communities,"
says Colin Summerhayes, who works closely with IGOS through UNESCO's
Intergovernmental Oceanographic Commission. "Both are shifting
to long-term research and blurring the boundaries between fundamental
and applied science through remote sensing."
Oceanography offers a classic example
and was the subject of the first IGOS report released in January
2001. Although it is too soon to evaluate the report's impact,
there is one concrete result: the U.S. and European agreement
to jointly launch Jason-2 in 2005. This satellite will follow
in the footsteps of the Jason-1 and Topex/Poseidon, Franco-American
satellites that revolutionized our understanding of oceanography.
Circling the Earth every 112 minutes,
Topex/Poseidon was the first satellite (launched in 1992) capable
of measuring the height and temperature of sea waves as well as
related wind speed. This kind of data is the only way scientists
can observe the major ocean currents that regulate our climate
by shifting heat around the world. For the first time, scientists
could watch major events unfold, like El Nino in which unusual
wind conditions bring warm waters to the equatorial Pacific and
disrupt normal weather patterns around the world.
The Topex/Poseidon was so successful
that the U.S. and France launched a follow-up mission, Jason-1,
in 2001. The satellite has just begun to send the most precise
measurements of sea surface ever recorded, with an accuracy of
a centimetre. Jason-1 should be operating for about ten years.
But a decade of data is just a
drop in the bucket in scientific terms. "We now know that
events like El Nino and the North Atlantic Oscillation (an atmospheric
see-saw driving winter storms west to east across the ocean) don't
simply occur on a year-to-year basis but follow decadal cycles,"
said Summerhayes. "With longer-term data, weather forecasters
might provide practical information for agricultural planning,
especially in arid regions."
IGOS is preparing a similar report
on the world's water resources. We take for granted the satellite
images shown by weather forecasters on television. A string of
meteorological satellites followed the first U.S. mission launched
in 1960. However, there are still gaping holes in scientists'
understanding of the basic water cycle. Precipitation is notoriously
difficult to evaluate: it has been estimated that only one to
four percent of the globe's area is covered at any time by rainfall.
And the intensity of that rainfall can vary widely in a matter
of minutes or even seconds.
Yet scientists will soon have unprecedented
quantity and quality of water-related data thanks to a new generation
of satellites: Terra and Aqua (USA), Envisat (Europe) and Adeos-II
(Japan). The challenge lies in harmonizing the different kinds
of equipment and models used to interpret the data.
IGOS is weaving a global network
to collect, compare and synthesize the data of the various satellites
with land-based observations. The aim is to finalize the system
within the next two years to prepare for what promises to be a
technological milestone. In 2007, the U.S. and Japan will launch
a constellation of nine Global Precipitation Measurement (GPM)
satellites, which will be able to measure the rainfall at any
spot on the globe every three hours.
IGOS is developing a similar strategy
to study the impact of rising carbon dioxide (CO²), emissions.
This is the most dangerous greenhouse gas because it can stay
in the air for tens and even thousands of years, trapping heat
in the atmosphere. To predict how atmospheric CO² levels
and climate may change in the future, we must understand where
and how it moves between the land, oceans and atmosphere in what
is known as the global carbon cycle.
For example, the oceans absorb
an estimated 30 to 50 percent of the CO² produced by burning
fossil fuels, thanks mostly to microscopic plants, known as phytoplankton
which live within the first 50 metres of the sea surface. Most
of the carbon that the plants absorb through photosynthesis is
released from the ocean within about a year. Yet some of it sinks
deep in the ocean as the plants die. It can take centuries and
even millennia before most of this dissolved carbon dioxide is
released back into the atmosphere.
By studying satellite images of
ocean colour, scientists can gauge phytoplankton levels globally.
But to verify these estimates, they need more specific information
provided by samples taken aboard ships and from special buoys.
This verification is essential to develop models on how the carbon
absorbed and released by the ocean interacts with the atmosphere
and land.
"Today there are several models
but the results they give can vary by as much as 50 percent,"
said Philippe Ciais of the French Atomic Energy Commission, leader
of the IGOS strategy for the carbon cycle, which will be finalized
within the next year. "These models will probably improve.
But if we don't improve our current observations, we won't have
a reference point to measure the extent to which the carbon cycle
has changed between now and the next decade."
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