How changes in the sun’s energy have affected European climate in the last 1000 years
David Thornalley in Cardiff study
A team of scientists, including Dr David Thornalley from UCL Geography, has studied seafloor sediments to determine how the temperature of the North Atlantic and its localised atmospheric circulation have altered over the past 1,000 years.
They used seafloor sediments, taken from south of Iceland, to study changes in the warm surface ocean current by analysing the chemical composition of fossilised microorganisms that once lived in surface waters. These measurements were then used to reconstruct the past seawater temperatures and salinity of this key current.
Analysis of the atmosphere component in a climate model also reveals that during periods of solar minima a high-pressure system is located west of the British Isles. This is often referred to as atmospheric blocking, and brings harsh winters to Europe, such as those recently experienced in 2010 and 2013. Such a combined ocean-atmospheric response to solar output minima may help explain the notoriously severe winters experienced across Europe between the 16th and 18th centuries.
The study found that changes in the Sun’s activity can have a considerable impact on ocean-atmospheric dynamics in the North Atlantic, with potential effects on regional climate.
Predictions also suggest that a prolonged period of low sun activity will occur over the next few decades, although any associated temperature changes will be much smaller than those created by human carbon dioxide emissions. The effects of solar output on the ocean and atmosphere should nevertheless be taken into account when making future climate projections.