A new scientific study has overturned a widely-held belief that awkward periods of warm and cold weather on earth in the past might have been caused by periodic fluctuations in solar activity.
The findings show that periods of low sun activity should not be expected to have a large impact on temperatures on earth.
"Until now, the influence of the sun on past climate has been poorly understood. We hope that our new discoveries will help improve our understanding of how temperatures have changed over the past few centuries, and improve predictions for how they might develop in future," said Andrew Schurer of the University of Edinburgh's School of GeoSciences.
Scientists at the university carried out the study using records of past temperatures constructed with data from tree rings and other historical sources. They compared this data record with computer-based models of past climate, featuring both significant and minor changes in the sun.
They found that their model of weak changes in the sun gave the best correlation with temperature records, indicating that solar activity has had a minimal impact on temperature in the past millennium.
So what is causing climate change on earth?
Blame it on greenhouse gases that have been the primary cause since 1900. Before that, research has shown that the key driver of periodic changes in climate was volcanic eruptions. These tend to prevent sunlight reaching Earth, causing cooler, drier weather.
The findings of the study have been published in the journal Nature GeoScience.
--IANS (Posted on 23-12-2013)