This is Section 5.8 of the Arctic Climate Impact Assessment Lead Authors: Betsy Weatherhead, Aapo Tanskanen, Amy Stevermer; Contributing Authors: Signe Bech Andersen, Antti Arola, John Austin, Germar Bernhard, Howard Browman,Vitali Fioletov,Volker Grewe, Jay Herman, Weine Josefsson, Arve Kylling, Esko Kyrö, Anders Lindfors, Drew Shindell, Petteri Taalas, David Tarasick; Consulting Authors: Valery Dorokhov, Bjorn Johnsen, Jussi Kaurola, Rigel Kivi, Nikolay Krotkov, Kaisa Lakkala, Jacqueline Lenoble, David Sliney
Four key areas of research activity will improve the ability of the scientific community to assess the changes in and effects of ozone depletion and UV radiation in the Arctic: addressing unanswered scientific questions concerning variability and long-term changes in both ozone levels and UV irradiance; ensuring accurate and comprehensive monitoring of ozone and UV radiation levels; improving analysis of emerging data and incorporating this new understanding into modeling efforts; and undertaking crossdisciplinary studies to determine the effects of changes in UV irradiance. All four areas are important both to improve scientific understanding and to provide relevant information for policy decisions.
There are a number of unanswered scientific questions concerning the sources of variability in ozone and UV radiation levels in the Arctic. Improved knowledge is needed to quantify the effects of trace gases, dynamics, and temperature on arctic ozone levels. The influence of climate change on both ozone and UV radiation levels needs to be better understood. Understanding the controls on and interactions between various processes will greatly improve projections of future ozone levels. In addition to ozone levels, several other factors, including cloud conditions, aerosol concentrations, and surface albedo, affect surface UV irradiance. The interactions between and overall influence of these factors are still the subject of much uncertainty, but future changes in any one parameter – for example, in cloudiness or snow melt timing – could substantially affect UV radiation levels in the Arctic. Quantifying these factors across the Arctic will provide opportunities to more realistically assess changes in UV irradiance and their effects.
Although many of the questions regarding the cause of ozone depletion have been addressed and confirmed in a number of studies both within and outside the Arctic, questions still remain concerning the future of ozone and UV radiation levels in the Arctic. Current model projections vary widely in terms of future ozone and UV radiation levels, with the large differences due mainly to uncertainties regarding the roles of dynamics, temperature, and trace gases. Because of these uncertainties, continued monitoring of both ozone and UV radiation levels in the Arctic is important. Ozone levels and the stratosphere are also known to play a key role in influencing and modulating climate. Monitoring efforts are necessary both to document the evolution of ozone and UV radiation levels over time and to validate model projections. Past monitoring of ozone and UV radiation levels has shown that changes occur on a regional basis even within the Arctic, indicating that regional observations are critical for assessing the overall status of the Arctic. Satellite monitoring of the Arctic for most times of the year has been ongoing for the past few decades, but continued observations will be necessary to understand the evolution of arctic ozone. The continuation of ground-based monitoring of ozone levels depends on available funding and is highly uncertain at this time. Adding UV radiation monitoring in the Russian Arctic and coordinating the existing surface UV radiation and ozone level monitoring throughout the Arctic would allow for a more accurate assessment of the changes that are occurring. Analyses of emerging ozone and UV radiation data continue to reveal new information concerning the relative importance of trace gases, dynamics, and temperatures in the Arctic. Continued studies are likely to add to the understanding of UV radiation levels in the Arctic. Campaigns with intensive measurements of a variety of parameters as well as detailed monitoring of trace gases and vertically resolved ozone concentrations are important for advancing this understanding. Analyzing these measurements and using the available information in conjunction with model results will help achieve the best possible insight into future ozone and UV radiation levels, as well as the impacts of specific changes in these levels. Recent studies support the idea that advanced three-dimensional models will be fundamental for obtaining improved projections of future ozone levels over the Arctic.
One of the most important issues to address in the Arctic is determining the impacts of increased UV irradiance, particularly as levels are likely to remain higher than normal in the coming decades.This work requires coordinated cooperation between the UV radiation monitoring community and the biological and impacts communities. Few cross-disciplinary efforts have been implemented so far, but the collaboration that has taken place has resulted in many of the impact studies cited in other chapters of this assessment. Many questions remain concerning the impacts of UV radiation on individual species, ecosystems, and human health. Because the Arctic is likely to have elevated spring UV radiation levels for some time, understanding the magnitude of potential impacts will be critical for future policy decisions. Because of projected future changes in emissions and atmospheric concentrations of various trace gases, future arctic ozone levels are highly uncertain, not only for the next few decades but throughout the rest of the 21st century. Policy decisions regarding trace gas emissions are likely to directly influence ozone levels in the Arctic, and should be based on not only improved understanding of how ozone and UV radiation levels are likely to evolve, but also on increased knowledge of how the ecosystems, infrastructure, industries, and people of the Arctic will be affected.
In addition to the scientific requirements outlined above, there is ongoing concern about maintaining the existing international legislation to protect the ozone layer. Most developed countries have ratified the Montreal Protocol and its amendments, but economic and political pressures have led some countries to suggest that they cannot meet their obligations under the current agreements. The atmospheric concentrations of most ozone-depleting substances are decreasing due to compliance with the Protocol and its amendments, but future compliance is uncertain and requires vigilance and cooperation. In addition, because arctic ozone and UV radiation levels are strongly influenced by climate change, including the effects of changes in temperature, trace gas concentrations, and dynamics, international legislation regarding climate change is likely to directly affect arctic ozone levels in the coming decades. Any climate change policies need to be considered in light of the impacts both on arctic climate and on arctic ozone and UV radiation levels.
Chapter 5: Ozone and Ultraviolet Radiation
5.2. Factors affecting arctic ozone variability
5.3. Long-term change and variability in ozone levels
5.4. Factors affecting surface ultraviolet radiation levels in the Arctic
5.5. Long-term change and variability in surface UV irradiance
5.6. Future changes in ozone
5.7. Future changes in ultraviolet radiation
5.8. Ozone and Ultraviolet Radiation in the Arctic: Gaps in knowledge, future research, and observational needs