Boston (MA) - Harvard astrophysicist Dr. Willie Soon tells us that Earth has seen a reduced level of sunspot activity for the past 18 months, and is currently at the lowest levels seen in almost a century. Dr. Soon says "The sun is just slightly dimmer and has been for about the last 18 months. And that is because there are very few sunspots." He says when the sun has less sunspots, it gives off less energy, and the Earth tends to cool. He notes 2008 was a cold year for this very reason, and that 2009 may be cold for the same.
As of today, there have been 15 days in a row without any sunspots. In 2008 there were 266 days scattered throughout the year without sunspots, and in 2007 there were 163 days without sunspots. These are the #2 and #9 fewest sunspots years seen since 1911.
Dr. Soon's field of specialty is the sun. He explains that sunspots are planet-sized pockets of magnetism with much greater energy output and matter expulsion, some of which strikes the Earth's atmosphere as extra energy from the sun. He says when sunspots are present, the temperature goes up, when they are not present the temperature goes down. He also told a reporter at WBZ, CBS TV 38 (http://wbztv.com/video/?id=75101 @ wbz.dayport.com -- remove spaces), that beginning in 1645 and continuing through 1715, there were no observed sunspots. This is the period known as the Little Ice Age.
He also explains that sunspots go in cycles, which are around 11 years. There are periods of maximum activity (called the Solar Max) and periods of minimal or no activity (called the Solar Min).
Around the year 2000, the current cycle had reached its maximum. As of right now in 2009, it is at a period of zero sunspot activity. Still, he explains that no one knows for sure how long the cycles will last, and there are precedents that sunspots can persist for long periods of time, or there can be few or none for long periods of time (as happened between 1645 and 1715 during the Little Ice Age).
So far in 2009, the sun has had no sunspots for 88 out of the 99 days so far this year. Dr. Soon calls what we are seeing "the first deep solar minimum of the space age", and "In fact, this is the quietest [fewest sunspots] Sun we have had in almost a century".
In a separate video interview (http://wbztv.com/video/?id=75103 @ wbz.dayport.com -- remove spaces), he explains some possible scenarios which align with global temperature changes relating to sunspot activity, as the increased or decreased energy output from the sun affects the Earth's climate.
He explains in that interview:
"When the energy input to the Earth from the sun is lower, you can easily imagine then what the first effect would be -- heating less of the ocean's surface. This promotes less evaporation of water vapor from the ocean, reducing what we all know to be the major green house gas, water vapor, in contrast to atmospheric carbon dioxide. Then, you would say that if the sun provides less energy to warm the ocean's surface, and there is less of this water vapor and less of the water vapor greenhouse effect, then the Earth begins warming less so than you would normally have during the normal sunspot activity maximum when the sun gives off more light-energy to the planetary system.
"The second way to think about this is if the sun is giving less light to the ocean's surface, then you will also give less energy to transfer the heat, or even the material itself, from the surface to the upper atmosphere. The connection between the surface and the upper atmosphere is less than it would be, including the circulation patterns of the weather and the oceans.
"And then one can think about it another way, if you give less energy to transfer energy from the surface to higher up in the atmosphere, as high as 5 or 8 kilometers, then the chance for the system to produce these so-called thin high-cirrus clouds is less. These are the clouds that are very, very effective as a greenhouse blocker, these thin high-cirrus clouds. This is the idea that Professor Dickenson from MIT has suggested, that the Earth system may act like an iris. If it's too warm, then the iris opens, if it's too cold it closes, so that this fixture can trap heat, providing a very efficient way to warm or cool the Earth system.
"During a solar activity minimum, imagine that you produce less of these high-cirrus clouds, then the ability of the Earth to shed heat itself is a lot easier, therefore the system cools. And then continuing, when you don't have enough energy to bring all of this water vapor and the currents more than a few kilometers up, then it all accumulates at the bottom of the system, producing more of the low clouds. And on low clouds we know that they are very effective at reflecting sunlight. So again, it's another way that the Earth system can cool.
"And even another way to think about it is less energy intercepted in the tropical region, from say 20 or 30 degrees north and south latitudes, then you are able to transfer less heat energy to the polar regions, resulting in the arctic regions getting slightly cooler in that sense as well.
"So these are some of the possible scenarios that we've reached which in sort of a low-sunlight scenario would affect the Earth's weather."
He says, "If this deep solar minimum continues and our planet cools while CO2 levels continue to rise, thinking needs to change. This will be a very telling time and it's very, very useful in terms of science and society in my opinion".