There is a growing evidence that solar variability influences the Earth’s climate in various intricate ways. Prolonged periods of reduced solar radiation in the past coincide with periods of extremely cold weather in the northern hemisphere and massive outbursts of solar energy alter the chemistry of the atmosphere. Understanding the Sun’s role in past and present regional climate variability is required to narrow uncertainties of future regional changes in climate warmed by greenhouse gas emissions.

At the Department of Geoscience we are following a very interdisciplinary approach to study the solar influence on our climate by combining:

• Direct observations of the Sun
• Historic observations of the Sun
• Reconstructions of solar activity using cosmogenic isotopes
• Observations of Sun-like stars
• Modelling solar influences to the Earth’s climate

• That the Walker circulation slows down at solar cycle maximum (Misios et al. 2019, PNAS, in review).
• That the chemical composition of Sun-like stars can change their dynamo (Karoff et al. 2018).
• That radiocarbon in tree rings can be used to reconstruct solar activity with sub-annual resolution (Fogtmann-Schulz et al. 2017).
• That the Sun might be capable of hosting monster solar storms (Karoff et al. 2016).
• Understanding the relation between the Atlantic Multidecadal Oscillation, the Northern Hemisphere climate and the Sun (Knudsen et al. 2011, Knudsen at al. 2014).

• Villum Experiment grant to Stergios Misios entitled “Environmental consequences of solar cosmic rays”
• Villum Young Investigator grant to Christoffer Karoff entitled “Solar Connections”
• Villum Young Investigator grant to Mads Faurschou Knudsen entitled “Solar variability and North Atlantic climate during the last 1500 years”
• The Danish Council for Independent Research | Natural Sciences to Mads Faurschou Knudsen entitled “Deciphering the history of solar activity”
• Carlsberg grant to Christoffer Karoff entitled: “The Sun in Time – Impacts on Climate”

Our work on solar influence on our climate is part of iClimate Pillar 1 led by Marit-Solveig Seidenkrantz and the Stellar Astrophysics Centre led by Jørgen Christensen-Dalsgaard.