In a surprising discovery, a new study has found the impact of the Sun on Earth’s climate has greater significance when our planet is cooler.
An international team of researchers discovered that during the last 4,000 years, there appears to have been a close correlation between solar activity and the sea surface temperature in summer in the North Atlantic, The Economic Times reported.
Since the end of the last Ice Age about 12,000 years ago, the Earth has generally experienced warmer temperatures. However the climate has not been stable during the past 12,000 years, when temperatures have varied for long durations.
The Earth has generally had a slightly cooler climate the past 4,000 years, and the ocean currents in the North Atlantic have been weaker, the Economic Times reported.
“We know that the Sun is very important for our climate, but the impact is not clear. Climate change appears to be either strengthened or weakened by solar activity,” said Professor Marit-Solveig Seidenkrantz from Aarhus University in Denmark.
“The extent of the Sun’s influence over time is thus not constant, but we can now conclude that the climate system is more receptive to the impact of the Sun during cold periods – at least in the North Atlantic region,” said Seidenkrantz.
Researchers studied the sea surface temperatures in summer in the northern part of the North Atlantic the past 9,300 years.
Direct temperature measurements were only found for the last 140 years, when they were taken from ships, however by examining studies of marine algae found in sediments deposited in the North Atlantic sea bed, it was possible to use the species distribution of these organisms to reconstruct fluctuations in sea surface temperatures dating much further back.
The study made it possible to draw comparisons with records of fluctuations of solar energy bursts in the same period, and the results indicate a clear correlation between climate change in the North Atlantic and variations in solar activity during the last 4,600 years.