Researchers at the University of Edinburgh contend that climate change has not been strongly influenced by variations in heat from the sun.
Their findings overturns a widely held view that lengthy periods of warm and cold weather are caused by periodic fluctuations in solar activity, according to a press release.
In their study, scientists found that until the year 1800 the key driver of periodic changes in climate was volcanic eruptions. Ash and debris from these eruptions resulted in cool, drier weather. They also found that since 1900, greenhouse gases have been the primary cause of climate change.
Based on their findings, researchers conclude 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," Andrew Schurer of the University of Edinburgh's School of GeoSciences said in a statement. "Links between the sun and anomalously cold winters ... are still being explored."
Researchers 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.
According to a press release, they found that their model of weak changes in the sun gave the best correlation with temperature records. This indicates that solar activity has had a minimal impact on temperature in the past millennium.
Researchers believe their findings will improve scientists' understanding and help climate forecasting.
The study was published in the journal Nature GeoScience.
