'Solar activity has always varied. Around the year 1000, we had a period of very high solar activity, which coincided with the Medieval Warm Period. It was a time when frosts in May were almost unknown – a matter of great importance for a good harvest. Vikings settled in Greenland and explored the coast of North America. On the whole it was a good time. For example, China’s population doubled in this period.
But after about 1300 solar activity declined and the world began to get colder. It was the beginning of the episode we now call the Little Ice Age. In this cold time, all the Viking settlements in Greenland disappeared. Sweden surprised Denmark by marching across the ice, and in London the Thames froze repeatedly. But more serious were the long periods of crop failures, which resulted in poorly nourished populations, reduced in Europe by about 30 per cent because of disease and hunger.
It’s important to realise that the Little Ice Age was a global event. It ended in the late 19th Century and was followed by increasing solar activity. Over the past 50 years solar activity has been at its highest since the medieval warmth of 1000 years ago. But now it appears that the Sun has changed again, and is returning towards what solar scientists call a “grand minimum” such as we saw in the Little Ice Age.
The match between solar activity and climate through the ages is sometimes explained away as coincidence. Yet it turns out that, almost no matter when you look and not just in the last 1000 years, there is a link. Solar activity has repeatedly fluctuated between high and low during the past 10,000 years. In fact the Sun spent about 17 per cent of those 10,000 years in a sleeping mode, with a cooling Earth the result.'There's science as well:
'You may wonder why the international climate panel IPCC does not believe that the Sun’s changing activity affects the climate. The reason is that it considers only changes in solar radiation. That would be the simplest way for the Sun to change the climate – a bit like turning up and down the brightness of a light bulb.
Satellite measurements have shown that the variations of solar radiation are too small to explain climate change. But the panel has closed its eyes to another, much more powerful way for the Sun to affect Earth’s climate. In 1996 we discovered a surprising influence of the Sun – its impact on Earth’s cloud cover. High-energy accelerated particles coming from exploded stars, the cosmic rays, help to form clouds.
When the Sun is active, its magnetic field is better at shielding us against the cosmic rays coming from outer space, before they reach our planet. By regulating the Earth’s cloud cover, the Sun can turn the temperature up and down. High solar activity means fewer clouds and and a warmer world. Low solar activity and poorer shielding against cosmic rays result in increased cloud cover and hence a cooling. As the Sun’s magnetism doubled in strength during the 20th century, this natural mechanism may be responsible for a large part of global warming seen then.
That also explains why most climate scientists try to ignore this possibility. It does not favour their idea that the 20th century temperature rise was mainly due to human emissions of CO2. If the Sun provoked a significant part of warming in the 20th Century, then the contribution by CO2 must necessarily be smaller.'Read the whole article and rest assured that the BBC won't be reporting this scientific paper any time soon.