EUROTRAC (the European Experiment on Transport and Transformation of Environmentally Relevant Trace Constituents in the Troposphere over Europe) is a co-ordinated research project within the EUREKA Initiative framework. (The EUREKA Initiative is a partnership of European countries and the Commission of the European Communities). At its peak, EUROTRAC comprised some 250 research groups in 24 countries. It achieved remarkable scientific success during its eight year life, which officially finished at the end of 1995. This undoubted success led to a desire, both on the part of the participating scientists, and from the supporting governments, for a follow-on project: EUROTRAC-2. The purpose of the present article is to describe the features of the first project that provided the basis for the success and to indicate how these are being utilised in the development of the new project.

Successes of EUROTRAC in science, infrastructure, and policy development
EUROTRAC had a number of major scientific successes. It has shown beyond doubt that the ozone concentration in the lower atmosphere over Europe and much of the northern hemisphere is now at least twice the level at the beginning of the century. Studies of ice cores from the high Alps further revealed that the bulk of the increase in deposition of acidity and heavy metals has occurred over the last fifty years. The perturbation from the natural state in the lower atmosphere is much larger than that observed for ozone in the stratosphere and there are consequences for both climate change and for plant damage throughout Europe. The cornucopia of new results from EUROTRAC is being presented in a ten volume final report.

The project has also left a legacy of measurement stations across Europe from Ireland to Turkey and from Spitzbergen to Tenerife. In addition a variety of instruments and techniques were developed or improved which have led to substantial improvements in the quality of the science being done.

The contacts built up between EUROTRAC and the agencies responsible for environmental protection in Europe has resulted in a better appreciation of the current scientific view in policy development. In addition the project has contributed directly towards the development of better measurement techniques and quality assurance in the national and international monitoring networks.

Perhaps the most substantial achievement is the formation of groups of European scientists, bound by common scientific interests, who represent both for Europe and for the countries a substantial resource and a source of advice on policy matters. The crucial point here is that to tackle regional environmental problems, a shared and agreed scientific understanding is required before expensive regulation can be attempted. These groups and their work provide that necessary commonality.

Organisation of EUROTRAC
The success of EUROTRAC owed much to its simple organisational structure. There were two committees, the International Executive Committee (IEC) in which the funding agencies from the participating countries were represented, and the Scientific Steering Committee (SSC). Central co-ordination was provided by the International Scientific Secretariat (ISS) in Garmisch-Partenkirchen.

In a EUREKA project each country must fund its own participants: there are no central funds as such. The ISS was initially funded by the German Government alone although later other countries and the European Commission (EC) helped with co-ordination costs.

It is generally true to say that funds made available to EUROTRAC participants would probably have been spent on national research projects anyway. The advantages that the countries appeared to find in EUROTRAC were (a) that the national work was given an international dimension together with the possibility of contributing to policy development on a regional scale, and (b) there was additional confirmation that their investigators were performing well by international standards. For the PIs there was the confirmation that one's work, often in a narrow field, had a genuinely wider utility and that, in a modest way, one was able to contribute to the understanding and possible solution of a large interdisciplinary environmental problem.

EUROTRAC-2: the new project
EUROTRAC-2 was accepted into EUREKA in February 1996. The overall objective of EUROTRAC-2 is:

"to support the further development of abatement strategies within Europe by providing an improved scientific basis for the quantification of source-receptor relationships for photo-oxidants and acidifying substances".

It is also now realised that pollutants cannot be dealt with separately; there are undoubtedly synergistic effects between pollutants and the reduction of one pollutant can lead to changes in another. Thus a reduction in ammonia emissions is likely to increase the transport distance of sulphur dioxide.

Another complication is the potential feedbacks and interactions between systems which, for convenience, are often regarded as independent. When plants are exposed to pollutants they do not act as simple passive receivers; they can be expected to respond actively and in doing so change the environment in which they find themselves. These interactions are little studied and less well understood, but as more detailed forecasting is required it will not be possible to neglect them.

Finally a better scientific understanding is demanded by the present directions in policy development themselves. The latest protocols to the Geneva Convention on the Long-Range Transport of Air Pollution (LRTAP) are based on the concept of critical loads to eco-systems. In much of Europe the particular eco-systems occupy numerous relatively small areas and so, in the future, the models used to determine deposition or exposure will have to cope with additional detail on smaller scales.

Organisation: a scientific programme with strong links to policy development
The organisation envisaged for the new project is similar to that in the first phase. It should ensure that the community and expertise in Europe continue to develop and that the quality of the science remains high.

However to ensure that the new project maintains a strong link to policy development, EUROTRAC-2 is to have an Environmental Assessment Group (EAG) which is intended to act as an interface between EUROTRAC-2 and agencies responsible for environmental management in Europe. It should ensure that the scientific uncertainties in policy development are addressed in the new project and that new results actually reach those responsible promptly.

It is not intended that EUROTRAC-2 should act in isolation from other developments. It is hoped that there will be links with the International Global Atmospheric Chemistry Programme (IGAC) and with NARSTO, a programme involving the United States, Canada and Mexico, that is concentrating on the scientific understanding of the tropospheric ozone problem in support of policy development in North America.

EUROTRAC-2: the scientific programme
To meet the objectives the project description specifies twenty substantial scientific tasks, which range over the whole subject but concentrates on the areas where the understanding needs to be most improved. As in the first phase there will be a number of subprojects to undertake these tasks. So far some fifteen groups have submitted suggestions, and from this alone is clear that is no shortage of principal investigators wishing to engage in the co-ordinated research required or colleagues enthusiastic enough to undertake the scientific co-ordination.

The work, of evolving a coherent and viable scientific programme, seeing that the subprojects and principal investigators have realistic and achievable aims, and of fitting EUROTRAC-2 into the existing programmes and initiatives, both national and international, are what will occupy the project in the coming months. When successfully completed, as it should be with the experience from the first phase, we can look forward to a further six years of worthwhile and exciting science, coupled with a genuine contribution towards the development of soundly based environmental policy in Europe.

Peter Borrell
Executive Secretary
IFU Garmisch-Partenkirchen