Solar Forcing

The Solar Forcing Working Group was launched in 2011 with the main goal to quantify the role of solar forcing in climate change. The group finished in 2015.

By organising two workshops in Davos in 2013 and 2014 with FUPSOL (Future and Past Solar Influence on the Terrestrial Climate), leading scientists from the solar physics, climate modeling and paleoclimate data communities discussed strategies to detect, attribute, and quantify solar forcing in the past.

It become clear that none of these three communities can tackle the problem by itself. However, by joining forces and concentrating on selected time intervals and regions there is good hope to make progress in the near future. A synthesis paper summarising the problems and describing potential solutions is in preparation and should be released in 2016.

Solar Forcing background

Background picture - The Sun emitting electromagnetic radiation and hot plasma (solar wind) carrying magnetic fields. While the radiation reaches the Earth directly solar particles are partly shielded by the geomagnetic field.

Graph - Sunspot numbers reflect the solar magnetic activity which is dominated by the 11-year Schwabe cycle. The reconstructed smoothed total solar irradiance (TSI) follows the envelope of the sunspot record with minima at 1645-1715 AD (Maunder Minimum) and at 1790-1830 AD (Dalton Minimum) and a maximum in the second half of the 20th century.

The Sun is the main driver of the climate system. However, its contribution to climate change is still highly uncertain despite the considerable scientific advances made in recent years. A large number of new paleoclimate records with high temporal resolution have been produced. Simultaneously, high precision measurements of the solar total (TSI) and spectral (SSI) irradiance have been performed using satellite bound radiation monitors.

Attempts have been made to use proxies of solar activity to extend the instrumental records of TSI and SSI back in time for the past 10 ka. In order to link the solar forcing with the observed climate response, climate models have been improved to simulate dynamical couplings between stratosphere and troposphere, the effect of UV changes on the ozone, and the influence of solar energetic particles and cosmic rays on the upper atmospheric chemistry (Gray et al. 2010; Wanner et al. 2008). In spite of these significant efforts, many open questions remain; some of which will be addressed by this working group on solar forcing.

The Solar Forcing Working Group was formed in July 2011. Read more about the launch here.

It aimed to bring together scientists from the solar physics, climate modeling, and palaeoclimate reconstruction communities and contribute to a better mutual understanding and a closer collaboration.

Find out more about the two workshops from 2012 and 2014.

Further information

For more information about the Solar Forcing Working Group, contact Jürg Beer.