On the 25th anniversary of the Montreal Protocol
Recently published research for the first time examines changes in ultraviolet (UV) radiation in Australia over a period of fifty years (1959-2009). The research found that there has been an overall annual increase in UV levels of 2% to 6% since the 1990s, for locations throughout Australia.
Dr Lilia Lemus-Deschamps, Scientist at the Bureau of Meteorology, said: "The data shows that during the 1970s and early 1980s, clear-sky UV Index levels for the three Australian regions (North, Central and South) were fairly stable. But over the last twenty years, there has been an overall annual increase in UV levels across the country from to 2% to 6% above the 1970-1980 levels, corresponding to ozone depletion."
"When ozone levels are depleted, the atmosphere loses its protective filter resulting in more solar UV radiation reaching the Earth's surface."
The Montreal Protocol, which came into force 25 years ago today, was specifically designed to phase out the use and production of substances that were known to deplete ozone in the stratosphere.
The Protocol has been very successful, and new modelling research shows that without it, about two million more people per year would have developed skin cancer by the year 2030 world-wide, 16% more than current estimates of skin cancer incidence. However, it will still take time for the ozone layer to fully recover, as is reflected in the higher UV levels over the past 20 years.
The data also shows seasonal variations in UV increases, with winter increases from 1970-1980 almost twice those recorded in summer, and higher average UV levels observed in more southerly latitudes.
The implications of these seasonal increases in UV and temperature vary for each state, Dr Lemus-Deschamps explains.
"For the southern parts of Australia, summer increases in UV are concerning because when temperatures are warmer, more people are outside exposed to the sun and therefore at greater risk of over-exposure to UV radiation and skin cancer."
"In contrast, the increases observed in winter UV levels are of particular concern for central and northern Australia. Pleasant winter temperatures in these regions lead to more outdoor activities and extended exposure to damaging UV."
Ms. Jen Makin, SunSmart Manager, said: "Given that Australians are already living in a high UV environment, the study serves to reinforce the importance of the SunSmart message at this time."
"Overall skin cancer rates have increased over the past 20 years, despite reductions in melanoma incidence rates for younger generations who grew up with the SunSmart messages. The impact of the current higher UV levels on skin cancer rates will take 20-25 years to become apparent, given the time lag that exists for skin cancer to develop, however our message is that prevention is better than cure."
Ms. Makin advises everyone not to rely on temperature as a guide, but to check the sun protection times daily at bom.gov.au/uv/index.shtml , sunsmart.com.au, or on the free SunSmart app. The sun protection times show when the UV is forecast to be 3 or above. During these times, use a combination of the 5 SunSmart steps - Slip on clothing, Slop on broad-spectrum, water resistant SPF 30+ sunscreen, Slap on a hat, Seek shade and Slide on sunglasses.
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About the study
The study calculated clear-sky UV radiation over a fifty year period (1959-2009) for Australia using two long-term ozone data sets derived from surface and satellite measurements, a radiation code and atmospheric meteorological fields .
Lemus-Deschamps L, Makin J. Fifty years of changes in UV Index and implications for skin cancer in Australia. International Journal of Biometeorology 2012; 56(4): 727-735. http://rd.springer.com/article/10.1007/s00484-011-0474-x