In March 1989, a major solar eruption disrupted satellite and radio systems, completely shutting down the electricity supply in Quebec, Canada. Smaller eruptions regularly disrupt GPS signals and radio traffic. The KNMI studies this so-called space weather and warns of possible disruptions during solar eruptions. Fortunately, large eruptions are rare. Old wood can shed light on major eruptions from the past, as recent research at the University of Groningen shows.
Space Weather and Carbon
The unstable isotope of carbon (14C) is continuously produced in the upper layers of the atmosphere by cosmic radiation, which consists of charged particles with very high energy. Such particle radiation mainly comes from supernovae in our galaxy and beyond, but also from massive solar eruptions (SEP, solar energetic particle events).
Once produced, 14C spreads through the Earth system via the carbon cycle (see Figure 1), eventually ending up in the biosphere, and thus in trees. With a half-life of about 5730 years, we can use the 14C stored in trees for dating, but also to determine the historical production of 14C in the atmosphere, and thus the intensity of cosmic radiation.
