Solar Influence

Some say the sun causes global warming. Well, I don't think anyone is arguing that. The better question is what is causing this global warming, especially since the climate forcing is now clearly outside of natural cycle forcing.

Scientists are attempting to derive methods to examine long term solar activity. Currently reasonable knowledge of solar cycles and activity is limited to sunspot observations for the past 400 years and satellite observations since 1979.

It is clear in the observations that sunspot numbers and temperature rise do not correlate.

The sun is our main energy provider. However, it alone does not determine how much heat energy is retained in our atmosphere. It provides energy, and our atmosphere captures and holds some of it. This is due to green house gases. If there were no greenhouse gases in our atmosphere, earth would be a frozen ball in space.

Below is a comparison of sunspot activity done with satellite measurements since 1979 compared to sunspot counts from Greenwich Observatory. When sunspot activity is low we lose approximately .2W/m2 of solar energy and regain that at a sunspot peak. It has been shown that these increases and decreases are related to weather on earth.

Source: http://www.nasa.gov/centers/goddard/images/content/93620main_sun5m.jpg

Sunspots

Sunspots have been observed since the time of Galileo. Since the Schwabe sunspot cycles average 11.1 years, we have limited data to see long term solar cycles clearly. But the short term Schwabe cycles are quite clear in the sunspot record.

These cycles range from 9 to 14 years in lengths with an average length of 11. years. As of early 2009 we are in an extended solar minimum, similar to the one noted around 1913. We are entering Solar Cycle 24 and you can monitor the entry to the new solar cycle with the links below.

• http://solarcycle24.com/
• http://sohowww.nascom.nasa.gov/data/realtime-images.html
• http://earthobservatory.nasa.gov/Features/SolarMax/
  

The solar variance between solar maximum and solar minimum accounts of a change in total solar irradiance of around 0.2 W/m2. The current forcing above natural cycle is 1.6W/m2, all major forcings considered. This clearly illustrates that our current global warming event can not be attributed to solar forcing from the sunspot cycle.

There is also a slight irradiance increase in solar output that has been noticed by NASA, but that also does not provide nearly enough forcing to account for current forcing above natural cycle. The only attribution possible is industrial greenhouse gases which are easily calculated quantitatively and the amount of forcing this provides in the system matches the amount of climate forcing we are observing.

Links

• http://solarscience.msfc.nasa.gov/SunspotCycle.shtml
  
• http://earthobservatory.nasa.gov/Features/SolarMax/
  
• Current View of the Sun: http://sohowww.nascom.nasa.gov/data/realtime-images.html
  
• Current Solar Trends: http://solarcycle24.com/
  
• http://www.hao.ucar.edu/Public/education/bios/schwabe.html
• http://earthobservatory.nasa.gov/Features/SolarMax/solarmax.php
• http://earthobservatory.nasa.gov/Features/SolarMax/solarmax_2.php
• http://istp.gsfc.nasa.gov/Education/whsun.html
• http://science.nasa.gov/headlines/y2008/11jul_solarcycleupdate.htm
• http://www.swpc.noaa.gov/SolarCycle/
  

Solar forcing - RealClimate:

• Recent Warming But No Trend in Galactic Cosmic Rays
• A critique on Veizer’s Celestial Climate Driver
• The lure of solar forcing
• Did the Sun hit record highs over the last few decades?
• Another study on solar influence
• The trouble with sunspots
• How not to attribute climate change
• Taking Cosmic Rays for a spin
• Nigel Calder in the Times
• 'Cosmoclimatology' - tired old arguments in new clothes () ()
• Cosmic rays don’t die so easily