How greatly do you believe solar cycles affect global warming?

Question

The solar cycle is the eleven-year cycle of the solar activity of the sun, first determined in 1843 by astronomer Heinrich Schwabe. Solar variations in output have been measured from satellites. Climate scientists are trying to determine how much the variations effect the temperature of Earth's atmosphere.

What do you think, and please provide a link or two if you have them.

Thanks for the link, Doc! Through your link I found an article titled, "How to Fight Global Warming."

How do you fight the sun?

http://www.livescience.com/environment/070131_GW_tips.html

Answer 1

Almost all scientific studies show that the Sun is responsible for 5-10% of the current warming.

A recent study by Lockwood showed that essentially all solar factors which effect the climate have been going in the wrong direction to have caused the planet to warm over the past 30 years.

http://news.bbc.co.uk/2/hi/uk_news/6290228.stm
http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf

Basically the ways the Sun has been proposed to effect our climate through total solar irradiance (TSI), sunspots, and indirectly through galactic cosmic rays (GCRs).

The TSI trend has at most been increasing 0.008% per decade since 1980, depending on which measurement you accept. This is a very small increase. If you take the absolute greatest TSI trend estimate possible (this includes using the ACRIM composite and using the 2-sigma error), it could only account for a warming of 0.062°C since 1980, when the total global warming has been 0.5°C. At the very most, TSI would account for 12.4% of the recent warming.

http://tamino.wordpress.com/2007/07/24/pmod-vs-acrim/
http://answers.yahoo.com/question/index;_ylt=An9utGUjDUqDHOorAbGsaGnty6IX;_ylv=3?qid=20071030091957AAMwreQ

And there are some very good reasons to accept the PMOD over the ACRIM composite.

http://answers.yahoo.com/question/index;_ylt=AkrpFY07cYlN4lwS07hKFgXty6IX;_ylv=3?qid=20071030092346AABWrzY

The PMOD composite actually shows a 0.006% decrease in TSI per decade since 1980.

http://www.acrim.com/Senior%20Review%202007/earth_obs_fig14.pdf

Sunspots show virtually no correlation to the current warming trend:

http://solar-center.stanford.edu/sun-on-earth/600px-Temp-sunspot-co2.svg.png

And Svensmark's GCR theory has been thorougly disproven by several different studies, and has several fundamental flaws.

http://answers.yahoo.com/question/index;_ylt=AmRC4woki.QadIUY2fk7kLPty6IX;_ylv=3?qid=20071030112550AA7AXSu
http://answers.yahoo.com/question/index;_ylt=AvbtgI1im3pK.PoH1Qb02YkAAAAA;_ylv=3?qid=20071029182557AAwlqQv
http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf

Given all this evidence, I agree with the IPCC, which concludes that the solar forcing only accounts for ~5% and at the very most ~15% of the current warming (page 4 in the link below)

http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf

Answer 2

As Jimz pointed out there are many solar cycles, even though the 11 year cycle is the most obvious because it modulates the sun's brightness and magnetic field over an 11 year period, it is a forgone conclusion that over longer cycles the suns background energy level increases and decreases as well. The generally accepted theory that is backed up by proxy data that the sun increased it's output by as much as 3 watts meter^2 over the last three centuries allowed the world to climb out of the little ice age. This increase in solar output was not associated with a change in Earths orbit, so obviously there are longer term solar cycles at work. The vast majority of climate scientists agree that the sun is primarily responsible for the warming up until the mid 70's. That also happens to magically coincide with the point at which we began measuring the sun's output outside the Earths atmosphere via satellites.

There are two basic versions of the satellite data, one called ACRIM and one called PMOD. From the mid 70's until present, ACRIM shows an increase and can account for as much as 30% of the 1980 to present warming, and PMOD however shows no increase over the same period.

A link to a discussion about ACRIM and PMOD.

http://www.warwickhughes.com/agri/solar_daleo_Lockwood_and_Frolich_Review.pdf

The analysis generally performed on the solar data vs. climate are usually very simplistic and assumes that total solar irradiance (TSI) and temperature have a linear relationship, which is a naive assumption. If the sun increases it's output level, (which it has over the last century) the earths temperature will increase allowing evaporation to occur at a faster rate, which causes more water vapor to exist in the atmosphere, which is the most effective greenhouse gas. This simple positve feedback mechanism caused by increased solar output is beyond the scope of most solar/climate relationship studies.

Answer 3

Solar cycles have about an 11 year sun spot cycle but the amount of increase varies from one cycle to another. According to IPCC, the amount of variance is not great. Some scientists have postulated a natural "solar amplification," active especially at the polar regions that is different from greenhouse gases but increases the effect of Total Solar Irradiance. It is an interesting hypothesis, but without much support just yet.

I think Earth's climate is affected mainly by internal climate variation from oceanic oscillations. The Pacific Decadal Oscillation is the most important. Each phase lasts about 30 years. The PDO was in a warm phase from 1905 to 1945 and global temps went up. The PDO was in a cool phase from 1945 to 1975 and global temps went down. The PDO began a warm phase in 1975 and temps started up again. The El Nino Southern Oscillation gets the most press because of annual variation is so great. When both the PDO and ENSO are in a warm phase, the Earth can get quite warm - as it did in 1998 and 2006. Since PDO just ended its warm phase, I am expecting cooler temps for the next 30 years or so.

Answer 4

It's not so much the 11 year cycle as long periods of low sunspot activity or high sunspot activity during several 11 years cycles.
Nor have they ruled out radiation in the ultraviolet and there are stll Questions about cosmic rays as effected by the suns magnetic field that expands or contracts depending on the amount of activity. Solar activity in the past can be measured in Stalagmites in cave systems.

Solar Force Naked Science National Geoghraphic TV

Since the Sun is the sole source of heat and energy for this planet I find it laughable when they claim that the sun has such a ridiculously low effect on climate on this planet. Maybe sell that to Pluto the now non planet

Answer 5

It's a few percent of the total, at most.

Here's a good, although highly technical, discussion.

http://tamino.wordpress.com/2007/07/24/pmod-vs-acrim/

Note that a big reason the 11 year cycle is not that important is the enormous thermal mass of the oceans which smooths things out. It takes a longer and larger cycle, like the Milankovic cycle, to make much of a difference.

The Sun changes in other ways. Most scientists think changes in the Sun are about 5% of the reason for climate change these days. This graph, from the source below, nicely shows the relativ contribution of the Sun.

http://www.globalwarmingart.com/wiki/Image:Climate_Change_Attribution.png

A few "skeptics" think the Sun is more important. But they dot that by either doing very strange things with the data or invoking some mysterious magic mechanism to make that happen.

While a few planets are warming (for different reasons), most are not, which is more data showing our problem is not changes in the Sun. More here:

http://environment.newscientist.com/channel/earth/climate-change/dn11642

Answer 6

They are two different things.

Global warming hasn't been proved but people are thinking that its real because of scientific evidence that has come through years of studying the climate, global currents and well the study of the earth. But solar cycles do affect the earth but solar output at the moment is normal so no it can't really effect "global warming" at the moment. And solar cycles only happen every 11 or 12 years so it would be permanent.

Answer 7

Yes, I have studied some of Heinrich Schwabe's work, and I honestly think that the sun is the real cause of the warming trend that we are seeing. But I also believe that it's nothing to worry about. I'm sorry, I don't have an exact link, but go to YouTube, and type in "The Great Global Warming Swindle." I think that video, which is great for combating the theory of manmade Global Warming, talks about this issue.

Answer 8

Most Paleoclimatologists will tell you that the evidence in the Earth points to the sun as the major climate driver of the past. The measured variation in intensity is not enough to cause the observed variation in past climates, but the fact is that the climate responds to those variations. The ice cores reveal that ice production varies with solar activity. The satellites that monitor the reflective properties of the Earth reveal that the Earth's albedo changes with solar activity. The 11 year solar cycle is just one of several.

Mechanisms that are not well understood are considered "magic" until they are understood. Scientists that propose "magic" theories are considered quacks until they are proven.

Tim Patterson, Paleoclimatologist
http://www.geocraft.com/WVFossils/Reference_Docs/The_Geologic_Record_and_Climate_Change.pdf

Nir Shaviv, Physicist
http://www.sciencebits.com/CO2orSolar

Henrik Svensmark, Physicist
http://www.spacecenter.dk/research/sun-climate/Scientific%20work%20and%20publications/resolveuid/86c49eb9229b3a7478e8d12407643bed

http://www.space.com/scienceastronomy/060926_solar_activity.html

http://www.warwickhughes.com/geol/img_LG51.htm

http://wattsupwiththat.wordpress.com/2007/10/17/earths-albedo-tells-a-interesting-story/

http://icecap.us/images/uploads/Solar_Changes_and_the_Climate.pdf

Answer 9

The Sun is the source for all of the planets warmth.

CO2 is 400ppm or just 1/2500 of the air. Man is blamed for increasing co2 by just 100ppm or a scant 0.001%. This is too insiganificant to have any impact on the Earth's climate at all.

Other Planets in the solar system are warming as well. These facts are causing more scientist to believe any warming on Earth is natural, and not caused by man.

Answer 10

Folks who can cut and paste better than me have already addressed this. However, I do believe that solar variations, oceanic and thermal currents and John Travolta's private jet collection have quite a bit to do with Earth's oscillating climate.

You're on the right track.