New Global Cooling?

Here is an article by Henrik Svensmark, director of the Centre for Sun-Climate Research at the Danish Space Research Institute that appears on the Watt's Up With That web site. The original Danish version is here and was published in the Jutland Post. This is a machine translation of the Danish, so it is a bit rough. I've made a few corrections and bolded key bits:

While the sun sleeps

Henrick Svensmark, Professor, DTU, Copenhagen

Indeed, global warming stopped and a cooling is beginning. No climate model has predicted a cooling of the Earth, on the contrary. This means that projections of future climate is unpredictable, writes Henrik Svensmark.

The star which keeps us alive, has over the last few years almost no sunspots, which are the usual signs of the sun’s magnetic activity.

Last week, reported the scientific team behind the SOHO satellite (SOlar and Heliospheric Observatory) that the number of sunspot-free days suggest that solar activity is heading towards its lowest level in about 100 years. Everything indicates that the Sun is moving into a hibernation-like state, and the obvious question is whether it has any significance for us on Earth.

If you ask the International Panel on Climate Change IPCC, representing the current consensus on climate change, so the answer is a reassuring ‘nothing’. But history and recent research suggests that it is probably completely wrong. Let us take a closer look at why.

Solar activity has always varied. Around the year 1000, we had a period of very high solar activity, which coincided with the medieval warmth. It was a period when frosts in May was an almost unknown phenomenon and of great importance for a good harvest. Vikings settled in Greenland and explored the coast of North America. For example, China’s population doubled over this period. But after about 1300, the earth began to get colder and it was the beginning of the period we now call the Little Ice Age. In this cold period all the Viking settlements in Greenland disappeared. Swedes [were surprised to see Denmark to freeze over in ice], and the Thames in London froze repeatedly. But more serious was the long periods of crop failure, which resulted in a poorly nourished population, because of disease and hunger [population was reduced] by about 30 per cent in Europe.

It is important to note that the Little Ice Age was a global event. It ended in the late 19th century and was followed by an increase in solar activity. Over the past 50 years solar activity has been the highest since the medieval warmth for 1,000 years ago. And now it appears that the sun returns and is heading towards what is called ‘a grand minimum’ as we saw in the Little Ice Age.

The coincidence between solar activity and climate through the ages have tried explained away as coincidence. But it turns out that almost no matter what time studying, not just the last 1000 years, so there is a line. Solar activity has repeatedly over the past 10,000 years has fluctuated between high and low. Actually, the sun over the past 10,000 years spent in a sleep mode, approx. 17 pct of the time, with a cooling of the Earth to follow.

One can wonder that the international climate panel IPCC does not believe that the sun changed activity has no effect on the climate, but the reason is that they only include changes in solar radiation.

Just radiation would be the simplest way by which the sun could change the climate. A bit like turning up and down the brightness of a light bulb.

Satellite measurements of solar radiation has been shown that the variations are too small to cause climate change, so this has closed our eyes for a second much more powerful way the sun is able 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 of exploded stars, the cosmic radiation, are helping to form clouds.

When the Sun is active its magnetic field shields better against the cosmic rays from outer space before they reach our planet, and by regulating the Earth’s cloud cover the sun can turn up and down the temperature. High solar activity obtained fewer clouds and the earth is gets warmer. Low solar activity inferior shields against cosmic radiation, and it results in increased cloud cover and hence a cooling. As the sun’s magnetism has doubled its strength during the 20th century, this natural mechanism may be responsible for a large part of global warming during this period.

This also explains why most climate scientists are trying to ignore this possibility. It does not support the idea that the 20th century temperature rise is mainly due to human emissions of CO2. If the sun as has influenced a significant part of warming in the 20 century, it means that CO2’s contribution must necessarily be smaller.

Ever since our theory was put forward in 1996, it has been through a very sharp criticism, which is normal in science.

First it was said that a link between clouds and solar activity could not be correct because no physical mechanism was known. But in 2006 after many years of work we managed to conduct experiments at DTU Space, where we demonstrated the existence of a physical mechanism. The cosmic radiation helps to form aerosols, which are the seeds for cloud formation.

Then came the criticism that the mechanism we have found in the laboratory was unable to survive in the real atmosphere and therefore had no practical significance. But the criticism we have just emphatically rejected. It turns out that the sun itself is doing, what we might call a natural experiment. Giant solar flares can cause the cosmic radiation on earth to dive suddenly over a few days. In the days after the solar eruption, cloud cover falls by about 4 per cent. And the content of liquid water in clouds (droplets) is reduced by almost 7 per cent. Indeed, you could say that the clouds on Earth originated in space.

Therefore we have looked at the sun’s magnetic activity with increasing concern, since it began to wane in the mid-1990s.

That the sun could fall asleep in a deep minimum was suggested by solar scientists at a meeting in Kiruna in Sweden two years ago. As Nigel Calder and I updated our book “The Chilling Stars” therefore, we wrote the provocative passage “we recommend our friends to enjoy global warming while it lasts.”

Indeed, global warming stopped and a cooling is beginning. Last week, it was argued by Mojib Latif from the University of Kiel at the UN World Climate Conference in Geneva that cooling may continue through the next 10 to 20 years.

His explanation was natural changes in North Atlantic circulation and not in solar activity. But no matter how it is interpreted, the natural variations in climate then penetrates more and more.

One consequence may be that the sun itself will show its importance for climate and thus to test the theories of global warming. No climate model has predicted a cooling of the Earth, on the contrary.

This means that projections of future climate is unpredictable. A forecast that says it may be warmer or colder for 50 years, is not very useful, for science is not able to predict solar activity.

So in many ways, we stand at a crossroads. The near future will be extremely interesting and I think it is important to recognize that nature is completely independent of what we humans think about it. Will the Greenhouse Warming theory survive a significant cooling of the Earth? Not in its current dominant form. Unfortunately, tomorrow’s climate challenges will be quite different from the greenhouse warming theory’s predictions, and perhaps it will again become popular to investigate the sun’s impact on climate.

Professor Henrik Svensmark is director of the Center for Sun-Climate Research at DTU Space. His book “The Chilling Stars” has also been published in Danish as “Climate and the Cosmos” (Gads Forlag, DK ISBN 9788712043508)

This is one scientists viewpoint. It isn't the majority view, but if you look at sites like NASA's daily solar data site you can see recent activity, the Belgian Solar Influences Data Analysis Center provides graphs of activity over decades, and NOAA Solar Cycle Progression site has its own graph of the current solar cycle with its prediction of future activity (which has had to be trimmed down and pushed out in time).

The Wikipedia site on solar insolation provides background info. The hostile viewpoints on Svensmark's research can be seen here.

My personal viewpoint is that if sunspot activity (the sun's magnetic field) does have the impact that Svensmark claims, it will be very obvious within the next five years because we are on a once-in-a-hundred-years and maybe once-in-a-couple-of-millenia excursion from the recent sunspot activity, so climate effects should be obvious very shortly. How does it feel to be part of a "scientific experiement"? Exciting, but worrisome. I prefer dull and boring times. But a little intellectual excitement is fun. Living through a "Little Ice Age" would not be fun.

In another posting on the WattsUpWithThat web site, the same Danish institute has another researcher worrying that all the CO2 has caused plants to kick into a higher gear increasing O2 in the atmosphere which can cause global cooling. Yet another reason to worry about "global cooling". The following is from a news release by the University of Copenhagen:

Using a completely new method, researchers have shown that high atmospheric and oceanic oxygen content makes the climate colder. In prehistoric times, the earth experienced two periods of large increases and fluctuations in the oxygen level of the atmosphere and oceans. These fluctuations also lead to an explosion of multicellular organisms in the oceans, which are the predecessors for life as we know it today. The results are now being published in Nature.

Everybody talks about CO2 and other greenhouse gases as causes of global warming and the large climate changes we are currently experiencing. But what about the atmospheric and oceanic oxygen content? Which role does oxygen content play in global warming?

This question has become extremely relevant now that Professor Robert Frei from the Department of Geography and Geology at the University of Copenhagen, in collaboration with colleagues from Departamento de Geologı´a, Facultad de Ciencias in Uruguay, Newcastle University and the University of Southern Denmark, has established that there is a historical correlation between oxygen and temperature fluctuations towards global cooling.