The Sun plays a crucial role in climate change. A new study conducted by an international team of scientists shows that the impact of the Sun on the climate system is not constant over time. Instead, it has a greater impact when the Earth is cooler. For decades, there has been a lot of discussion as to whether variations in the strength of the Sun have played a role in climate change in the past.
Close correlation between the activity of the Sun and sea temperature
But more and more studies show that the Sun impacts how the climate varies over time. Now researchers led by Professor Marit-Solveig Seidenkrantz of Aarhus University have found that, over the last 4,000 years, there has been a correlation between solar activity and ocean surface temperature in summer in the North Atlantic. Researchers did not see any correlation in the preceding period.
The Earth’s climate has generally been warm since the end of the Last Ice Age about 12,000 years ago. But the climate was not stable during this year as temperatures varied for long periods. Professor Marit-Solveig Seidenkrantz said that the solar activity either strengthens or weakens the climate change. But the latest study has made one thing clear: the climate is more receptive to the impact of solar activity during cold periods, Seidenkrantz said.
Marine algae provides clue about climate change
To conduct the study, scientists looked at the ocean surface temperatures in summer in the northern portion of the North Atlantic over the last 9,300 years. Direct measurement data is available only for the last 140 years. So, researchers examined marine algae (diatoms) present in sediments deposited on the North Atlantic sea bed. The species distribution of marine algae helped them reconstruct fluctuations in ocean temperatures much further back in time.
Results show a close correlation between variations in solar activity and climate change in the North Atlantic over the last 4,000 years. Professor Seidenkrantz says our climate is very, very complex. By gathering knowledge piece by piece about how individual elements influence each other can help us get the overall picture of the climate change mechanisms.
Findings of the study were published in the latest issue of the journal Geology.