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II. ENVIRONMENTAL MONITORING OBJECTIVES

Introduction

A new and important objective of Earth Sciences is to obtain sufficient understanding of the causes and future course of global change so that it can be predicted and managed for the benefit of humanity. The tasks is immensely complex -- it may be the most challenging scientific initiative of the next 50 to 100 years. It is thus appropriate for the ISY to focus on a mission to Planet Earth -- including extensive space-based and surface observations, careful analysis and verification of data, and the development of innovative models for assimilating data and placing them in a meaningful context.

The ISY is timed perfectly for initiation of a global commitment to such a Mission to Planet Earth. In 1992, the space agencies of the world will have in orbit, or under active preparation, an unprecedented number and variety of Earth science missions. Meanwhile, the international scientific community will be in the process of launching its most comprehensive activity ever - the International Geosphere-Biosphere Programme (IGBP), dedicated to the prediction and management of global change, which will extend into the 21st century. The ISY can unify the efforts of the IGBP just as they are taking shape and thus initiate a Mission to Planet Earth that would directly address global issues of immediate concern such as ozone depletion, the greenhouse effect, deforestation, and desertification. Careful and rigorous environmental monitoring is the key to detecting and understanding the evolution of planet Earth and the environmental changes and hazards yet to come. The IGBP can achieve its objectives of understanding global change only if the many disparate activities are coordinated worldwide. Thus the ISY can contribute significantly through:

• the initiation of prototype projects that establish standards and organizational mechanisms for eventual worldwide application; and

• through the development of long-term data sets, beginning with the organization of data accumulated through the last two decades, so that it can be applied in a focused manner to the problem of global change.

Scientific and Technological Challenges

Greenhouse and deforestation pilot projects, and a related data organization project, are proposed. Together, they will bring us much closer to diagnosing two major environmental problems. The first project will be to detect and verify, with environmental data taken from satellites and on the ground, the global and regional changes that have been predicted as a consequence of the intensified greenhouse effect of carbon dioxide and other gases being added to the atmosphere. The second prototype project will be to study, again using actual satellite and ground data, the climatic impacts of large-scale deforestation in the tropics. Is the decreasing forest cover accelerating the process of desertification as many scientists have predicted? Can these predictions be checked by documenting the exact change?

Both these projects will require a third -- the assemblage and coherent organization of existing data from satellites of different nations and from surface observations around the globe that will make an excellent ISY project in its own right.

Together these three projects, two scientific and one technological, are the centerpieces of environmental monitoring activities we are recommending for ISY.

Greenhouse Effect Detection Project

An essential global experiment is to determine whether we can detect unambiguously the enduring effects of increasing greenhouse gases on the climatic regimes of the earth. The immediate task will be to ascertain changes in global and regional averages and compare with model prediction.

This task will require creating global data sets of temperature, pressure, wind velocity and humidity both near the surface and in the atmosphere. Any long-term trends thus established should be compared and checked against other indicators of global change. These include the changing rainfall patterns and their impact on the ecosystem, the changing oceanic cloud cover because of increasing sea surface temperatures, the heating of the poles and its manifestation on permafrost and on snow lines in the northern hemisphere, on the lake levels in the Antarctic and on the global sea ice volume. It had also been predicted that increased greenhouse effects should affect the intensity of spring-bloom in the North Atlantic and the stratospheric temperatures over the poles, and cause increased inundation of the coastal areas.

It is by studying these diverse signals that we will be able to determine whether a long term global change is really underway and if so whether an increased greenhouse effect is the cause.

Deforestation Pilot Study

Regional experiments to check on the hypothesis that deforestation leads to desertification are now feasible by using a combination of multi-satellite and ground based data over Brazil and Africa. Such experiments will involve measurements over large areas (1000 x 1000 km) from satellites, aircraft and surface networks, assimilation of the data into models and checks of model prediction by observations. Several such experiments are currently being planned by a 

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