Solar Activity - Not CO2 - Could Cause Global Warming, New Paper Says
The impact of carbon dioxide on climate change may have been overstated, with solar activity giving a better explanation of changes in the Earth's temperature, according to Chinese scientists.
A new paper published in the Chinese Science Bulletin has found a "high correlation between solar activity and the Earth's averaged surface temperature over centuries," suggesting that climate change is intimately linked with solar cycles rather than human activity.
The paper, written in Chinese, says that there is also a "significant correlation" between solar activity over the past century and an increase in Earth's surface temperatures over the same period. The correlation between solar activity and water temperature is even higher than the correlation between solar activity and land temperature.
The paper, by Dr Zhao Xinhua and Dr Feng Xueshang, adds that a peer-reviewer said the results "provide a possible explanation for the global warming".
In a press release, posted on the Hockey Schtick blog, The researchers say:
The Intergovernmental Panel on Climate Change (IPCC) claimed that the release of the anthropogenic greenhouse gases contributed to 90 percent or even higher of the observed increase in the global average temperature in the past 50 years.
However, the new paper casts doubt on the IPCC's assertion:
Research shows that the current warming does not exceed the natural fluctuations of climate. The climate models of IPCC seem to underestimate the impact of natural factors on the climate change, while overstate that of human activities. Solar activity is an important ingredient of natural driving forces of climate. Therefore, it is valuable to investigate the influence of solar variability on the Earth's climate change on long time scales.
Indeed, the study says that the "modern maximum" – a peak in solar activity that lasted much of the last century – corresponds very well with an increase in global temperatures.
There has been increasing evidence in recent years that global warming is linked with solar activity. In 2009, Professor Henrik Svensmark from the Danish National Space Centre, said that the last time the Earth experienced unusually high temperatures, in the later Medieval period, there had also been an increase in solar activity. When this activity dropped, it led to the "little ice age" of the seventeenth century.
In 2011, three further papers suggested the Earth could be heading for a new "little ice age" as solar activity drops once again. Frank Hill of the National Solar Observatory in New Mexico said: "The fact that there are three separate lines of evidence all pointing in the same direction is very compelling."