New study confirms Sun/Cosmic-Ray climate connection 

This looks like progress, although more research will be needed to try to better understand how the relevant effects work in practice.
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A new study published in Nature Scientific Reports by researchers at the Danish National Space Institute at the Technical University of Denmark (DTU) and The Hebrew University of Jerusalem suggests that the Sun’s activity in screening cosmic rays affects clouds and, ultimately, the Earth’s energy budget with concomitant climatic effects, says David Whitehouse @ NetZeroWatch.

This research, by Henrik Svensmark, Jacob Svensmark, Martin Bødker Enghoff, and Nir Shaviv supports 25 years of discoveries that point to a significant role for cosmic rays in climate change.

In particular, it connects observable variations in clouds and Earth’s energy budget to Copenhagen laboratory experiments and theory, showing how cosmic rays help make aerosols and accelerate their growth to become cloud condensation nuclei and ultimately clouds.

Eruptions on the Sun screen the Earth from galactic cosmic rays – energetic particles raining down on our planet from exploded stars. “The Sun carries out fantastic natural experiments that allow us to test our ideas about cosmic ray effects on the atmosphere,” professor Henrik Svensmark, lead author of the study told the GWPF.

Solar explosions produce magnetised gas that sweeps past the Earth reducing the cosmic ray flux reaching us. These events are called Forbush decreases taking their name from the American physicist Scott E. Forbush, who first noticed them more than 80 years ago.

They lead to a temporarily lower production of small aerosols – molecular clusters in the air – that normally grow to seed the water droplets of low-level clouds. This, in turn, reduces the cloud cover which is known to affect climate.

The recent breakthrough is that the effect on the Earth’s energy budget has been quantified using satellite observations from the CERES instrument on NASA’s Terra and Aqua satellites.

The observational data indicate that the Earth absorbs almost 2 Watts per square metre additional energy within 4 to 6 days of the cosmic-ray minimum. Such a large effect is a major surprise…

Full article here.