Ozone and UV over Europe: no sign of improvement

“The occurrence of ozone mini-holes over Europe increases and any ozone layer recovery could only become measurable around 2010 at the earliest” concludes an assessment report, released today, on European research in the stratosphere. The report concerns loss of ozone, increases in ultraviolet radiation as well as the impact of aircraft on the atmosphere. It covers European research efforts during the period 1996-2000 including the Third European Stratospheric Experiment on Ozone – THESEO, which is the biggest EU-supported campaign ever to study the ozone layer.

Commissioner for Research Philippe Busquin said: “The assessment results shows once more how important studies such as THESEO are in order to understand ozone loss and the resulting increase in harmful sunlight radiation. An international campaign like THESEO also clearly demonstrates that a close integration of European and national programmes provides great benefits for science and for carrying forward the EU`s policies. When properly organised at a European scale, our research can play a major role in solving environmental problems of a global dimension.”

Based on exciting new scientific findings, the assessment concludes that the possibility of severe ozone losses over the Arctic and Europe remains high, due to slow chlorine decreases and the current increase of bromine concentrations, which will ultimately contribute to this loss. The observed cooling of the stratosphere due to ozone depletion and greenhouse gas emissions further increase these ozone losses and changes in atmospheric circulation. The circulation changes are responsible for the increase of ozone mini-holes over Europe. Future UV radiation doses will depend on these ozone losses and additionally on cloudiness, snow and ice cover which are affected by climate change.

In contrast to previous estimations, however, nitrogen oxide emissions and line-shaped contrails from aircraft emissions seemingly play a less important role with respect to climate change.
It took almost two years and over 100 scientists to prepare this assessment which is based on European research efforts during the last few decades and the analysis of 40 years of atmospheric data. It provides a thorough review of the progress of the European research programme on stratospheric ozone, UV radiation and aircraft impact on the atmosphere during 1996-2000. The results of the assessment endorse the position of the EU concerning the international agreements on ozone depletion (Montreal Protocol) and climate change (Kyoto Protocol), as well as the International Civil Aviation Organisation’s regulation of the impact of aviation emissions.

The report goes further and identifies the environmental issues and areas for atmospheric research that will be most relevant for the future implementation of the European Research Area (ERA) and the Sixth Framework Programme 2002-2006.

Professor Gérard Mégie, chair of the EU Science Panel on Stratospheric Ozone and President of CNRS, France, said: “The experience of successful pan-European collaboration on atmospheric issues at scientific and research agency levels will prove of great benefit in tackling the ambitious goals set out in ERA and the future Framework Programmes. The stratospheric research programme and the THESEO experiment showed the advances in Europe’s research capability and the development of a coherent European community of researchers.”

Twelve new EU projects have recently been signed to address questions identified in the assessment, through experimental and modelling studies in the Antarctic, the Arctic, the Tropics and the Middle Latitudes over Europe. They are aiming to tackle open scientific issues (the ozone-climate interactions, the role of particles with respect to the climate and in the stratosphere, the tropical sources of stratospheric air, the impacts of a potential supersonic aircraft fleet, the interaction of UV radiation and atmospheric constituents, etc) and satellite validation needs.

The main findings of the report are summarised in the Annex, together with the list of the 12 new projects.

ANNEX

Main conclusions of the Assessment Report on European Research in the Stratosphere:

Large ozone losses (20-30% in the column, 40-70% at altitudes around 18 km) have occurred in the Arctic during each of the five last cold winters since 1993/94. Recent campaigns, including THESEO, have revealed a great deal about the role of halogen compounds (from CFCs and other ozone-depleting gases), particles, as well as the stratospheric meteorological conditions in general that lead to the large ozone losses in the Arctic and the subsequent reduced ozone amounts over Europe.

Stratospheric ozone amounts over mainland Europe started to decline in the 1970s, with bigger decreases (5-10% in the ozone column) occurring in winter and spring seasons. Biologically active UV has increased at the ground, in line with the reduced ozone amounts. The ozone decline has resulted from:

1. chemical processes resulting from the break-down of CFCs and other ozone depleting gases and,
2. changes in stratospheric meteorology over a decade, which are now much better understood. For example, the frequency of ozone ‘mini-holes’ over Europe has increased and is linked to climatic changes and atmospheric circulation in the north Atlantic and Europe.

Thanks to the existing international controls on ozone-depleting gases agreed through the Montreal Protocol process, chlorine amounts are now slowly decreasing in the atmosphere. However, the growth in bromine concentrations continues.

Full ozone recovery is expected when the chlorine amounts in the atmosphere return reach the to pre-ozone hole levels in about 50 years. Any ozone recovery could become measurable around 2010, at the earliest, due to the large atmospheric variability.

However, future stratospheric ozone and UV levels will depend not only on the successful control of chlorine and bromine concentrations, but also on the impact of climate change and other trace gases such as nitrous oxide (N2O), water (H2O) and methane (CH4) on the stratosphere. A continuation of the observed cooling of the stratosphere may extend the period in which severe springtime depletion of ozone over the Arctic can occur. Changes in climate are also likely to affect the stratospheric ozone distribution over mid-latitudes such as Europe.

The atmospheric impact of the present fleet of aircraft has been thoroughly studied. The role of nitrogen oxides in producing ozone and methane is now much better quantified and a great deal of progress has been made in the evaluation of the climate effects of aircraft line-shaped contrails. The contribution of both to climate change is found to be smaller than previous estimations.

Achieving a similar understanding of the aviation influence on cirrus clouds is a major challenge for future research.

Twelve new EC research projects on ozone, UV radiation and aviation impacts:

12 new EU projects worth a total of € 19.4 million have recently been approved, which will study the emerging issues during the coming 2-3 years. To date a total of 31 projects related to stratospheric research have been funded through the EU Environment and Sustainable Development Programme. The large amount of Member State’s research projects is closely coordinated with the EU projects through 5 research clusters.

In exciting new developments, the chemical and physical composition of the tropical stratosphere will be given additional emphasis in projects involving the high-flying aircraft and long duration balloons. What happens in this region of the atmosphere is important in determining ozone amounts at higher latitudes and it is also an important component of the Earth’s climate system. At the same time, there is a maintained commitment to study the Arctic region, which each spring is at risk to loose large amounts of ozone: a large field campaign will study critical aspects of the ozone loss in the winter 2002/03. These activities will greatly help the validation and exploitation of measurements from European earth observation satellites such as those from GOME on the European Space Agency (ESA) ERS-2, the Swedish led ODIN and the soon to be launched ESA ENVISAT. Moreover, the benefits derived will be enhanced through international collaboration, e.g. with satellite validation programmes in the USA (NASA SAGE III), Japan (NASDA ADEOS 2) and Canada (ACE/SCISAT).

New research projects to be supported during the coming 2-3 years in the Area of “Stratospheric ozone depletion” under the Key Action Global Change, Climate and Biodiversity of the EC Environment and Sustainable Development Programme

Upper tropospheric ozone processes involving HOx and NOx. The impact of aviation and convectively transported pollutants in the tropopause region (UTOPIHAN-ACT). Partners: 3 D, F, B, GR, NL, UK

Civil aircraft for regular investigation of the atmosphere based on an instrument container (CARIBIC 3). Partners: 4 D, UK, NL, S, F

Particles in the upper troposphere and lower stratosphere and their role in the climate system (PARTS). Partners: 3 D, CH, 2 UK, F, 2 S, I

Impact of tropical convection on the upper troposphere and lower stratosphere at global scale (HIBISCUS). Partners: 3 F, 3 UK, DK, 2 I, N

Scenario of aircraft emissions and impact studies on chemistry and climate (SCENIC). Partners: 2 UK, 4 F, NO, 2 D, I

Tropical convection, cirrus and nitrogen oxides experiment (TROCCINOX). Partners: 3 D, 2 CH, 2 UK, 2 RU, 2 I, F

Chemical and Dynamical Influences on Decadal Ozone Change (CANDIDOZ). Partners: FIN, CH, UK, F, GR, 2 CZ, DK, 2 D, N

Towards the Prediction of Stratospheric Ozone III: The Partitioning of the NOy Components (TOPOZ III). Partners: 5 D, ES, N, 2 UK, NL, F, I

Quantitative Understanding of Ozone losses by Bipolar Investigations (QUOBI). Partners: 3 D, RU, 4 UK, F, DK, FIN, ES, N, GR

Influence of clouds on the spectral actinic flux in the lower troposphere (INSPECTRO). Partners: 3 D, 3 UK, A, 2 N, GR, I

European Polar Stratospheric Cloud and Lee Wave Experiment (EUPLEX). Partners: 5 D, 2 CH, 3 I, 2 RU, 2 UK, N

Coordination of Research into Understanding of Stratospheric Ozone over Europe II (CRUSOE II). Partner: UK

EC and national projects are being coordinated in the following currently running European research clusters

Stratospheric Ozone Loss (SOLO)

Atmospheric Ultra-Violet Radiation (ATUV)

Ozone-Climate Interactions (OCLI)

Coordination of Research for the Study of Aircraft Impact on the Environment (CORSAIRE)

Global Atmospheric Observations (GATO)