New study finds that a Carrington class solar event could cause global cooling of more than 3C

A paper recently published in Atmospheric Chemistry and Physics finds that “a solar proton event, if it took place in the near future with an intensity similar to that ascribed to the Carrington Event of 1859”. Based on the results of the study it would be expected to have a major impact on atmospheric composition throughout the middle atmosphere, resulting in significant and persistent decrease in total ozone, resulting in a “significant [global] cooling of more than 3C”.

From the paper: Solar energetic particle events, frequently referred to solar proton events (SPEs), occur when protons and other particles emitted by the active Sun are accelerated to very high energies (for protons up to 500 MeV) either close to the

Sun’s surface during a solar flare or in interplanetary space by magnetic shock waves associated with coronal mass ejections (Reames, 1999). They typically last for a few days. The high energy protons are deflected, when they enter the Earth’s magnetic field, and upon penetrating the atmosphere can cause massive ionization including significant production of HOx and NOx (Sepp¨al¨a et al., 2004; Jackman et al., 2009).

Based on the modeling done here, and while the Carrington Event of 1859 lasted only 2 days, the proton event caused persistent changes in atmospheric ozone lasting up to several months, the authors predict such an event could cause a “cooling of up to 5 K in eastern Europe and Russia to a somewhat smaller decrease of about 3 K for the Southern Hemisphere in Argentina.” as shown in figure 9 below:

Influence of a Carrington-like event on the atmospheric chemistry, temperature and dynamics

M. Calisto, P. T. Verronen, E. Rozanov, and T. Peter

Abstract: 

We have modeled the atmospheric impact of a major solar energetic particle event similar in intensity to what is thought of the Carrington Event of 1–2 September 1859. Ionization rates for the August 1972 solar proton event, which had an energy spectrum comparable to the Carrington Event, were scaled up in proportion to the fluence estimated for both events. We have assumed such an event to take place in the year 2020 in order to investigate the impact on the modern, near future atmosphere. Effects on atmospheric chemistry, temperature and dynamics were investigated using the 3-D Chemistry Climate Model SOCOL v2.0. We find significant responses of NO_x, HO_x, ozone, temperature and zonal wind. Ozone and NO_x have in common an unusually strong and long-lived response to this solar proton event.

The model suggests a 3-fold increase of NO_x generated in the upper stratosphere lasting until the end of November, and an up to 10-fold increase in upper mesospheric HO_x. Due to the NO_x and HO_x enhancements, ozone reduces by up to 60–80% in the mesosphere during the days after the event, and by up to 20–40% in the middle stratosphere lasting for several months after the event. Total ozone is reduced by up to 20 DU in the Northern Hemisphere and up to 10 DU in the Southern Hemisphere.

Free tropospheric and surface air temperatures show a significant cooling of more than 3 K and zonal winds change significantly by 3–5 m s⁻¹ in the UTLS region. In conclusion, a solar proton event, if it took place in the near future with an intensity similar to that ascribed to of the Carrington Event of 1859, must be expected to have a major impact on atmospheric composition throughout the middle atmosphere, resulting in significant and persistent decrease in total ozone.

…

From the concluding remarks:

Comparing the outcome for temperature and dynamics modeled with SOCOL with results of Jackman et al. (2007), who investigated the SPE of October/November 2003 using

their 3-D TIME-GCM, we see that these results are in good qualitative agreement. They show that shortly after the event happened, the southern hemispheric polar region has a decrease in temperature throughout the entire mesosphere, similar to our results for the northern hemispheric polar region.

The difference between their results and ours is in the intensity of the changes. For the temperature a decrease of more than 3K is shown in this work while Jackman et al. (2007)

depict a decrease of up to 2 K. The fact that our results show a larger effect can be due to the intensity of the solar proton event. The Carrington-like event presented in this paper

represents an event that is more intense than the SPE of October/ November 2003.

The qualitative agreement of our results, modeled with the 3-D CCM SOCOL, for the changes in NOx, ozone, temperature and dynamics, with those obtained by Thomas et

al. (2007) and Jackman et al. (2007), corroborates the finding that solar proton events of this strength have intense atmospheric interactions in a broad altitude range starting from

80 km down to 30 km, with repercussions for surface air temperature.

The latter range from a cooling of up to 5K in eastern Europe and Russia to a somewhat smaller decrease of about 3K for the Southern Hemisphere in Argentina. Therefore

it is important to analyze the impact of energetic particles with a 3-D CCM to ensure that the dynamical and transport aspects are properly taken into account. In this paper,

the solar proton event was placed during equinox. We think that the impact could even be larger if it would happen during earlier winter because the polar vortex prevents the exchange of fresh air from the mid-latitudes with the polar region.

Final Revised Paper (PDF, 1740 KB)   Discussion Paper (ACPD)

H/t to The Hockey Schtick