Tuesday 18 June 2019

Why outer space’s rays could be to blame for climate change

Supernovae are now being linked to the Medieval Warm Period
Supernovae are now being linked to the Medieval Warm Period

Sarah Knapton

Cosmic rays flung out from exploding stars have an impact on our weather, a study has shown for the first time.

New research from the Technical University of Denmark has found that supernovae release ions which rain down through our atmosphere, seeding clouds.

As more clouds form, the climate cools, which can have a major impact on the long-term weather.

The researchers claim that cosmic rays, coupled with the activity of the Sun, were linked to the Medieval Warm Period around 1,000AD and the Little Ice Age between the 13th and 19th centuries, when London’s River Thames regularly froze over during the winter, allowing frost fairs to be held.

“Finally, we have the last piece of the puzzle explaining how particles from space affect climate on Earth,” said Dr Henrik Svensmark, lead author of the study. “It gives an understanding of how changes caused by solar activity or by supernova activity can change climate.”

The study involved two years of observations into the effects of cosmic rays on a simulation of Earth’s atmosphere, which was recreated inside a cloud chamber – a sealed lab which mirrors the pressure and moisture of the upper atmosphere.

It showed that the high energy particles emitted from exploding stars knock electrons off air molecules to produce ions – positively or negatively charged particles.

The charged particles draw water and sulphuric acid together to form clusters in such a way that they do not evaporate, a process known as nucleation. As the clusters grow, they attract more water, and if they get large enough, will form clouds.

The study also showed that the Sun’s magnetic activity alters the influx of cosmic rays on to Earth. When the Sun is quiet – like at present – more cosmic rays can enter the atmosphere and the planet cools. When it is active, its magnetic emissions prevent so many rays reaching Earth, causing fewer clouds, and allowing the climate to warm.

Dr Hamish Gordon, from the Institute for Climate and Atmospheric Science at the University of Leeds, UK, said: “This is an interesting and plausible result, and if it stands up to more detailed scrutiny it may prove an important contribution to aerosol microphysics.”

The research was published in ‘Nature Communications’.

© Daily Telegraph, London

Irish Independent

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