greenhouse effect is actually a natural and useful phenomenon. The earth's
atmosphere contains water vapour, carbon dioxide, nitrous oxide and
methane. These gases form a transparent layer that acts like the glass
in a giant greenhouse. Light from the sun can get through to warm the
earth, but the heat has difficulty getting out again. Just as the inside
of a greenhouse gets hot on a sunny day, the earth's atmosphere is also
warmed. Without the greenhouse effect, our planet would be so cold we
could not exist.
In the last 150 years, we have burned increasing amounts of coal, oil
and natural gas. The vast quantity of carbon dioxide that we have released
into the atmosphere has gradually increased the greenhouse effect. Most
scientists believe that this is raising the average temperature of the
earth's atmosphere. The mean annual temperature across Europe, for example,
has increased by about 0.5°C since 1900. If this trend continues, it
could have a huge impact on the world's climate and the environment.
the last 15 years, the European Union has supported dozens of projects
to increase our understanding of the link between the greenhouse effect
and global warming. The EU's Environment, Climate, and Marine Science
research programmes have convinced the world that man's ability to change
the global environment is a major challenge for the future, and in 1997,
at the Kyoto Conference in Japan, Europe backed international policies
that will reduce emissions of greenhouse gases.
We know a lot about the human activities that give off carbon dioxide
and methane, but we don't yet understand enough about the natural processes
that release, absorb and store these important greenhouse gases. The
way the earth transfers carbon between natural reservoirs - the carbon
cycle - is very complex; learning more about it will help us to decide
how best to reduce emissions. European researchers are busy investigating
the earth's natural capacity to deal with excess greenhouse gases. How
much carbon dioxide, for example, can the forests and oceans mop up?
Can we do anything to enhance these 'carbon sinks'?
Managing our methane emissions
Methane is the most important greenhouse gas after carbon dioxide.
It is given off by all biological decay. In Western Europe, several
projects are quantifying the huge volumes of methane released by intensive
cattle breeding, landfill, sewage, and more. These emissions could
be greatly reduced by appropriate environmental management.
Forest 'carbon sinks' reduce the greenhouse effect
Through photosynthesis, plants store carbon, which they take from carbon
dioxide in the atmosphere. They therefore play an important role in
reducing the global warming it causes via the greenhouse effect. The
EUROFLUX measurement network estimates that European forests constitute
a carbon sink able to absorb 10% to 40% of carbon dioxide emissions
related to human activities in Europe.
Understanding the role of the oceans
Several European projects are underway to study the little-understood
mechanisms of carbon dioxide exchanges between oceans and the atmosphere
- exchanges which are very important for absorbing human emissions of
this greenhouse gas. Scientists on the ASGAMAGE project are using measurement
platforms to investigate the processes involved.