Climate Change

Future changes in ultraviolet radiation in the Arctic

This is Section 5.7 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

 

While there are early signs that the Montreal Protocol and its amendments are working, a return to normal ozone levels is not likely to occur for several decades. Scientists primarily concerned with chemical contributions may be interested in the earlier signs of ozone recovery (for example, a reduction in the downward trend in ozone levels), while those studying UV radiation and its effects are likely to focus on an overall recovery from depleted values. Delayed recovery of total column ozone in the polar regions implies the possibility of increased UV irradiance at northern latitudes for another one to five decades. Although there are many uncertainties in the models, current projections indicate that ozone depletion over the Arctic is likely to continue for 50 years or more[1].

Because ozone depletion at polar latitudes is expected to persist, and possibly worsen, over the next few decades[2], UV radiation reaching the surface is likely to remain at levels greater than those observed in the past. Using ozone projections from the GISS chemistry–climate model, which projects the most severe, longest-lasting ozone depletion of any of the models,Taalas et al.[3] estimated that the worst-case spring erythemal UV radiation doses averaged over the period from 2010 to 2020 will increase by up to 90% relative to average 1970–1992 conditions. By comparison, the annual UV radiation dose increases for the entire Northern Hemisphere are estimated to be 14% for 2010 to 2020, and 2% for 2040 to 2050. Ultraviolet radiation projections depend on future ozone levels, which are highly uncertain. Future UV radiation levels will also be complicated by changes in snow and ice cover and albedo and are likely to vary locally as well as regionally. Reuder et al.[4] simulated ozone levels using various CFC emissions scenarios, as well as changes in future temperatures and dynamics and used these results to project UV radiation conditions over central Europe. Their results indicate a slight increase in spring UV radiation levels between the present and 2015, and the potential for continued above-normal late winter and spring UV radiation levels through approximately 2050, although future climate-induced forcings of arctic ozone recovery still need to be better explored.

Continued increased UV levels are likely to have profound effects on human health. Slaper et al.[5] estimated that reaching minimum ozone levels around the year 2000 (based on the Copenhagen Amendments to the Montreal Protocol) would be likely to result in a 10% increase in skin cancer 60 years later. While these results were based on analyses at mid-latitudes, they illustrate the long-range effects of increased UV radiation levels on human health. These human health effects are discussed in more detail in section Section 15.3.3. While humans can choose clothing, sunglasses or goggles, and other protection to reduce their exposure to UV radiation, plants and animals in the Arctic must adapt to their environment through slower, biological means or by migrating or seeking shelter to reduce their exposure. Section 7.3.2 describes plant and animal adaptations to UV radiation exposure in greater detail. These adaptations include thick leaves and protective pigments in plants and reflective white feathers and fur in arctic animals. Sections 8.6 and 9.4 also address potential adaptations and protections for organisms experiencing increased UV radiation exposure. If UV radiation levels in the Arctic remain high into the 21st century, the relative incidence and time frame of effects on human health and on plants and animals would also be extended.

Ozone levels and future changes in these levels are not the only factors affecting anticipated UV irradiance in the Arctic; aerosol concentrations and cloud cover also play a role (see section 5.4). These factors are likely to change, at least on a regional basis, in the future. A more active hydrological cycle in the Arctic, projected to occur as a result of climate change[6], is likely to result in changes in cloud cover. In general, increases in cloud cover will reduce UV irradiance at the surface, except in certain conditions when multiple reflections between clouds and a snow-covered surface may enhance the UV radiation dose. Current model projections suggest that cloud cover over the Arctic is likely to increase in some areas and decrease in others. Uncertainties in projections of future aerosol or cloud changes and in the understanding of aerosol–cloud–UV radiation interactions complicate projections of future surface UV irradiance.

Sea ice  and snow cover are also likely to be affected by climate change, and can have major effects on incident UV radiation, both by reflecting radiation and by protecting organisms buried beneath it. Almost all climate models project increases in precipitation in the Arctic[7]. Model projections indicate that overall temperatures in the Arctic are likely to be warmer, suggesting that for late spring through early autumn, much of the precipitation increase is likely to be in the form of rain, or of rain falling on existing snow cover, possibly enhancing the rate of snowmelt. The extent and duration of snow cover in the Arctic is important in part because of its relation to UV radiation doses. In the polar regions, UV radiation doses affecting biological organisms depend greatly on the local surface albedo. Reflection off snow, for example, can increase the amount of UV radiation reaching an organism’s face, eyes, or other surface. These amplified doses can be particularly pronounced at low solar elevations, or in the presence of increased multiple scattering by non-absorbing aerosols. Any shift in the extent or duration of snow cover, particularly during the critical spring months, is likely to amplify the biologically effective UV radiation doses received by ecosystems potentially already stressed by climate change. In areas normally covered by snow, early spring snowmelt, such as has been observed by Stone et al.[8], is very likely to leave organisms at ground level vulnerable to increased UV irradiance during periods of spring ozone depletion.

UV radiation exposure can have a range of effects on humans and on the overall arctic environment. Human health concerns include skin cancers, corneal damage, cataracts, immune suppression, and aging of the skin. Ultraviolet radiation can also have deleterious effects on both terrestrial and aquatic ecosystems, and is known to affect infrastructure through damage to plastics, wood, and other materials. Many of these effects require increased study.The combination of future climate change and the likelihood of prolonged increases in arctic UV radiation levels present a potentially challenging situation for the people and environment of the Arctic. These effects and some of their expected consequences are discussed in greater detail in sections 7.3, 7.4, 8.6, 9.4, 14.12, 15.3.3, 16.3.1, and 17.2.2.3.

Chapter 5: Ozone and Ultraviolet Radiation

5.1. Introduction
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

References

  1. ^ WMO, 1999. Scientific Assessment of Ozone Depletion: 1998.WMO Ozone Report 44,World Meteorological Organization.
    --WMO, 2003. Scientific Assessment of Ozone Depletion: 2002. Global Ozone Research and Monitoring Project – Report No. 47.World Meteorological Organization Geneva, 498pp.
  2. ^ WMO, 2003. Scientific Assessment of Ozone Depletion: 2002. Global Ozone Research and Monitoring Project – Report No. 47.World Meteorological Organization Geneva, 498pp.
  3. ^ Taalas, P., J. Kaurola, A. Kylling, D. Shindell, R. Sausen, M. Dameris, V. Grewe, J. Herman, J. Damski and B. Steil, 2000. The impact of greenhouse gases and halogenated species on future solar UV radiation doses. Geophysical Research Letters, 27:1127–1130.
  4. ^ Reuder, J., M. Dameris and P. Koepke, 2001. Future UV radiation in Central Europe modeled from ozone scenarios. Journal of Photochemistry and Photobiology, 61:94–105.
  5. ^ Slaper, H., G.J.M.Velders, J.S. Daniel, F.R. deGruijl and J.C. vanderLeun, 1996. Estimates of ozone depletion and skin cancer incidence to examine the Vienna Convention achievements. Nature, 384(6606):256–258.
  6. ^ IPCC, 2001. Climate Change 2001: Impacts, Adaptation, and Vulnerability. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. J.J McCarthy, O.F. Canziani, N.A. Leary, D.J. Dokken and K.S. White (eds.). Cambridge University Press, 1032pp.
  7. ^ IPCC, 2001. Climate Change 2001: Impacts, Adaptation, and Vulnerability. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. J.J McCarthy, O.F. Canziani, N.A. Leary, D.J. Dokken and K.S. White (eds.). Cambridge University Press, 1032pp.
  8. ^ Stone, R.S., E.G., Dutton, J.M. Harris and D. Longenecker, 2002. Earlier spring snowmelt in northern Alaska as an indicator of climate change. Journal of Geophysical Research, 107(D10): 10.1029/2000JD000286.

 

 

 

 

Glossary

Citation

Committee, I. (2013). Future changes in ultraviolet radiation in the Arctic. Retrieved from http://www.eoearth.org/view/article/51cbedd47896bb431f694385