[Mark620]

July 18, 2004
Sun Energy Output At Over 1,000 Year Peak

Sami Solanki, Professor at the Federal Institute of Technology in Zurich Switzerland, says the Sun has been burning more brightly over the last 60 years than over the previous 1090 years.

“We have to acknowledge that the Sun is in a changed state. It is brighter than it was a few hundred years ago, and this brightening started relatively recently – in the last 100 to 150 years. We expect it to have an impact on global warming,” he told swissinfo.

The sun's brightness hasn't changed much over the last 20 years. But it has been brighter for the last 60 years than it has been at any time in the last 1,150 years.

According to scientists, the Sun’s radiance has changed little during this period. But looking back over 1,150 years, Solanki found the Sun had never been as bright as in the past 60 years.

The team studied sunspot data going back several hundred years. They found that a dearth of sunspots signalled a cold period - which could last up to 50 years - but that over the past century their numbers had increased as the Earth's climate grew steadily warmer. The scientists also compared data from ice samples collected during an expedition to Greenland in 1991. The most recent samples contained the lowest recorded levels of beryllium 10 for more than 1,000 years. Beryllium 10 is a particle created by cosmic rays that decreases in the Earth's atmosphere as the magnetic energy from the Sun increases. Scientists can currently trace beryllium 10 levels back 1,150 years.

Sunspots have been increasing in number as the Earth has been getting warmer.

Over the past few hundred years, there has been a steady increase in the numbers of sunspots, a trend that has accelerated in the past century, just at the time when the Earth has been getting warmer.

Variations in sunspot activity are probably behind the increases and decreases in solar radiation and consequence changes in Earth's climate.

During the Medieval maximum of 1000-1300 there was an extremely large Sunspot which is believed to have warmed the Earth higher than normal. There were no accurate measurements of the weather to call upon during this time but the discovery and colonization of Greenland by Eric the Red supports this hypothesis. Eric was exiled from Iceland for manslaughter and sailed west discovering Greenland. He then led many ships, filled with people who wanted to make a fresh start, to this new land. For 300 years Greenland flourished, new communities settled, trade with other countries grew, and the population increased. Around 1325 the climate cooled down considerably, people started to abandon the northern settlements. By 1350 glaciers covered the northern settlements, and the southern most settlements were dying out as well.

The Sporer minimum of 1400-1510 and the Maunder minimum of 1645-1715 were each known as a "little ice age." They were both droughts in Sunspot activity, and a link to a time of abnormally cold weather on Earth. In addition to finishing off the Greenland colonies, the Sporer minimum showed increased rates of famine in the world, and the Baltic Sea froze solid in the winter of 1422-23. Some of the more notable effects of the Maunder minimum included the appearance of glaciers in the Alps advancing farther southward, the north sea froze, and in London there was the famous year without a summer where it remained cold for 21 consecutive months.

The evidence supports the effect of Sunspot activity on the Earth's climate, but that is only one of many areas that effects us on Earth. On March 13,1989 a large Sunspot ignited powerful flares that tripped the circuit breakers a generator station. The started the collapse of the Quebec power system and left people without power for hours to days. These same flares damaged several man made satellites, and caused smaller outages all over the U.S and Canada. There are countless other times when large Sunspots have effected similar damage to various electrical systems on Earth.

The Sun could start going through a down trend in sunspot activity at any time. We could find ourselves back in a state similar to the Maunder Minimum with decades of much colder weather. Or sunspot activity could increase to an even higher level and temperatures could rise more than the amount some models project as a consequence of higher atmospheric carbon dioxide.

My guess is that the chances are greater for a reduction in sunspot activity than for an increase. Why? Most of the time the planet Earth is in an ice age. This is suggestive of the possibility that the Sun just doesn't put out enough heat to keep the Earth out of ice ages most of the time. Also, the higher sunspot activity reported above is at the high end of an over 1,000 year period. Therefore the odds seem greater that we will have more future years with lower sunspot activity than with higher sunspot activity.

My further guess is that a reduction in sunspot activity would cause more harm to humans than a further increase in sunspot activity. A decrease could put large amounts of farm fields out of production and would reduce the useful length of the growing seasons for other fields. The freezing over of rivers and seas along with snows and ice would interfere with transportation more than higher temperatures would.

Also, my guess is that it would be easier to reflect away excessive sunlight than to try to replace the heat lost in another cold period like the Maunder Minimum. For example, to reduce the sunlight hitting the Earth during high sunspot periods we could genetically engineer plankton to produce more of the chemicals they generate to make clouds. We could also try to engineer more snowfall around glaciers to increase the areas covered by reflective white snow. We could also paint more human structures white to reflect back sunlight.

But imagine trying to generate enough energy to make up for a reduction in solar radiation during a period of low sunspot activity. We could take some steps to compensate for reduced solar radiation. For instance, we could paint all human structures black to make them absorb more light to raise ground temperatures. Also, we could try to develop some really large scale methods for coating ice sheets with dark coverings. It may also be possible to reduce cloud cover by seeding clouds to cause rains to fall in areas where the water is needed.

One option for a period of reduced sunspot activity would be to increase the release of green house gasses. But it is not clear that the planet contains enough fossil fuels to make that possible. We'd probably have to shift heavily toward the use of coal. But even that might not generate enough greenhouse gasses to compensate for a period of no sunspots.
By Randall Parker at 2004 July 18 01:18 PM