A new study showed that global warming may have slowed down recently due to small volcanic eruptions that dimmed sunlight and offset a rise in emissions of heat-trapping gases.
Since 1998, the pace of the rising temperature has slowed down, encouraging those who doubt the urgency to counter global warming by switching from fossil fuels to renewable energies.
Until now, climate change scientists have been ignoring the sun-blocking effects of sulphur ejected from at least 17 volcanoes since 2000, including Kasatochi in Alaska,Nabro in Eritrea, and Merapi in Indonesia.
Benjamin Santer of Lawrence Livermore National Laboratory in California told Reuters, as reported by Sidney Morning Herald, "Volcanoes are part of the answer but there's no factor that is solely responsible for the hiatus".
An explanation for this slowdown could help gain support for a U.N. climate deal which is to be agreed by almost 200 governments at a summit in late 2015 in Paris. This is to prevent more floods, heat waves, droughts and rising sea levels.
Big volcanic eruptions that can dim global sunshine for years are unpredictable just like the 1991 eruption of Mount Pinatubo in the Philippines.
According to Santer, other factors could also explain the recent slowdown in global warming like the decline in the sun's output, associated to a natural cycle of sunspots, or the riseof sun-blocking emissions from China.
Volcanoes can explain up to 15 percent of the difference between the predicted and observed warming, according to the study. Temperatures should rise due to continuous rising of greenhouse gas emission while all things remain equal.
The U.N. Intergovernmental Panel on Climate Change conducted a survey last year which suggested that extra uptake of heat by the oceans and other natural variations in the climate could also explain the slowing down of global warming.
Since the 1950s, human activities are still the main cause of global warming. According to the World Meteorological Organisation, with this ongoing slowdown, temperatures are still rising with 13 of the 14 warmest years recorded were in this century.
This study was published in the Feb. 23 issue of Nature Geoscience.
