A new study from the University of Waterloo claims that Chlorofluorocarbons (CFCs) and not carbon dioxide have been driving global warming since the 1970s.
According to Quing-Bin Lu, professor of physics and astronomy, biology and chemistry, at Waterloo's Faculty of Science, in a paper titled: "Cosmic-ray-driven reaction and greenhouse effect of halogenated molecules: Culprits for atmospheric ozone depletion and global climate change," published this week in the International Journal of Modern Physics B, CFCs, already known to deplete ozone, have been found after an in-depth analysis of statistical data from 1850 to the present time, to be the primary cause of global climate change phenomenon.
Quing-Bin Lu said: "Conventional thinking says that the emission of human-made non-CFC gases such as carbon dioxide has mainly contributed to global warming. But we have observed data going back to the Industrial Revolution that convincingly shows that conventional understanding is wrong. In fact, the data shows that CFCs conspiring with cosmic rays caused both the polar ozone hole and global warming."
He continued: "Most conventional theories expect that global temperatures will continue to increase as CO(2) levels continue to rise, as they have done since 1850. What's striking is that since 2002, global temperatures have actually declined - matching a decline in CFCs in the atmosphere. My calculations of CFC greenhouse effect show that there was global warming by about 0.6 degC from 1950 to 2002, but the earth has actually cooled since 2002. The cooling trend is set to continue for the next 50-70 years as the amount of CFCs in the atmosphere continues to decline."
Quing-Bing Lu explains (PDF) that his findings are based also on his cosmic-ray-driven electron-reaction (CRE) theory of ozone depletion and other research he had carried out previously into Antarctic ozone depletion and global surface temperatures.
He said: "It was generally accepted for more than two decades that the Earth's ozone layer was depleted by the sun's ultraviolet light-induced destruction of CFCs in the atmosphere. But in contrast, CRE theory says cosmic rays - energy particles originating in space - play the dominant role in breaking down ozone-depleting molecules and then ozone."
According to Lu, observations of cosmic ray, CFC, ozone and stratospheric temperature data over several 11-year solar cycles confirm his theory. He said: "CRE is the only theory that provides us with an excellent reproduction of 11-year cyclic variations of both polar ozone loss and stratospheric cooling. After removing the natural cosmic-ray effect, my new paper shows a pronounced recovery by 20% of the Antarctic ozone hole, consistent with the decline of CFCs in the polar stratosphere."
Lu said that linking CFCs, ozone depletion and temperature changes in the Antarctic make it possible to correlate global temperature trends with levels of CFCs in the atmosphere. He explains: "The climate in the Antarctic stratosphere has been completely controlled by CFCs and cosmic rays, with no CO(2) impact. The change in global surface temperature after the removal of the solar effect has shown zero correlation with CO(2) but a nearly perfect linear correlation with CFCs - a correlation coefficient as high as 0.97."
Lu claims that his study provides new understanding of the ozone hole and global climate change. He said that compared to the conventional "sunlight-driven ozone-driven ozone-depleting and carbon dioxide-warming models," his alternate theory improves our ability to predict the global temperature trend.
The researcher points out that available data from 1850 to 1970, a period before significant CFC emissions, show that although carbon dioxide levels increased significantly due to the the Industrial Revolution, global temperature remained nearly constant. This was in spite of the fact that conventional warming models of the greenhouse effect of carbon dioxide predict that global temperatures should have increased by about 0.6 degrees Celsius.
To support his claim in favor of CFCs as the primary cause of global climate change, he notes that in the period 1970-2002, global temperature rise of 0.6 degrees Celsius coincided with the period that significant quantities of CFCs were released into the atmosphere for the first time.
According to Lu, the empirical evidence supports his CRE theory. He also notes that data which suggest recent global cooling point to the success of the Montreal Protocol on Substances that Deplete the Ozone Layer.
He said: "We've known for some time that CFCs have a really damaging effect on our atmosphere and we've taken measures to reduce their emissions. We now know that international efforts such as the Montreal Protocol have also had a profound effect on global warming but they must be placed on firmer scientific ground."
Terry McMahon, dean of the faculty of science, said: "This study underlines the importance of understanding the basic science underlying ozone depletion and global climate change. This research is of particular importance not only to the research community, but to policy makers and the public alike as we look to the future of our climate."
Lu's study predicts that global sea levels will continue to rise for some years and ice melting in the polar regions will continue as the hole in the ozone recovers. He said: "Only when the effect of the global temperature recovery dominates over that of the polar ozone hole recovery, will both temperature and polar ice melting drop concurrently."