SCIENCE CLIMATE: Huge sigh of relief as sunspot appears

Huge sigh of relief as sunspot appears
Published: 10 Oct 08 - 0:00
A sunspot has just appeared on the sun and many people are breathing a sigh of relief. Why?

Well firstly, what is a sunspot? A sunspot is actually a huge magnetic storm on the sun, which, when one looks at the sun, appears as a darker spot on the bright surface.

Do not look at the sun with binoculars or a telescope, as doing that will probably destroy your eye – there are ways of projecting the sun's image.

The sun has a well-known 11-year cycle, during which it moves from Solar Max to Solar Min; this means from a state of many sunspots, or solar storms, to few.

Sunspot data has been collected since 1749, and 100 or more ‘spots' can occur during a single month of the maximum portion of the cycle.

We have just been through Solar Min, and the return of sunspots is late. During the last few months, there have been virtually no spots, and a month with no spots at all is very rare.

It has been found that there is a direct correlation between the number of sunspots and global warming, and, consequently, the state of the climate.

The last time the sun was as quiet as it is now was 400 years ago, and that signalled the onset of a period of global cooling, the coldest point of which is known as the Maunder Minimum. At that time, New York harbour froze to such a degree that people could walk from Manhattan island over to the island on which the Statue of Liberty stands today. In London, the Thames froze, and ice fairs were held on the river.

There has been no global warming since 1998; in fact, there has been a slight cooling. In 2005, Russian astronomer Khabilullo Abdusamatov predicted that the state of the sun could trigger a rapid cooling if it stayed this way. So it is with relief that the current sunspot has made its appearance – maybe more will follow.

Dr Timothy Patterson, director of the Geosciences Centre at Carleton University, has found "excellent correlations" between solar fluctuations and global temperature, whereas he says there are no such correlations with the carbon dioxide content of the atmosphere. Patterson says there is no surprise in this, since "the sun is the ultimate source of energy on this planet".

Sunspot climate research dates back to 1991, when the Danish Meteorological Institute (DMI) released a study showing that world temperatures over the last several centuries correlated very closely with solar cycles.

Further research, led by the DMI's Dr Henrik Svensmark, has revealed what appears to be happening. The temperature of the planet is related to how much cloud cover there is. Fewer clouds mean a warmer planet, since sunlight strikes the earth and warms it up. More clouds mean that the tops of the clouds reflect the sun's heat back into outer space.

The amount of cloud cover is related to the quantity of cosmic rays coming into the atmosphere. Cosmic rays are energetic nuclear particles that originate in the stars and constantly hurtle through space. While you read this article, a few cosmic rays will pass through your body.

As the cosmic rays race through the atmosphere, they strike atoms and molecules in the atmosphere, and this gives rise to nucleation points, which induce clouds to form, from the water vapour in the air.

This is the same mechanism that drives the formation of the long trails of cloud that appear behind the engines of high-flying jet aircraft. The specs of soot and ions in the jet exhaust provide the nucleation sites for droplets of water to form, which are then seen as the familiar ‘contrails'.

But the earth has protection. This protection is provided by the magnetic field around the planet. This field extends out a great distance, and its effects are seen half way to the moon.

The earth's magnetic field acts as a shield, preventing many cosmic rays from getting through to our atmosphere. Then there is another phenomenon, which is known as the Solar Wind. The sun blasts out a huge stream of nuclear particles, including charged particles, which race away from the sun and impact the earth.

The charged particles interact with the earth's magnetic field, giving rise to, besides other effects, the awe-inspiring northern and southern lights, which look like gossamer curtains of coloured lights in the polar skies.

As the magnetic storms on the sun's surface vary in number, which we see as the sunspot count, so the intensity of the Solar Wind alters. As the wind alters, so it alters the magnetic protection around the earth.

When there are many sunspots, a stronger magnetic field develops around the earth, and this shields the planet from the cloud-forming cosmic rays. The result is less cloud cover and so a warmer planet. A quiet sun, like we have now, results in more clouds covering the earth, and so a cooling climate results.

During the Little Ice Age of 400 years ago, the Solar Minimum stayed for years, and one could walk across New York harbour. Dr Kenneth Tapping, a solar researcher at Canada's National Research Council, has said that if we do not get some sunspots soon, we could be heading for an extended chilly period.

http://www.engineeringnews.co.za/article.php?a_id=144110