Solar output and climate change

QuestionEdit

Hello,

I have recently been having a debate with co-workers about the issue of climate change. My co-workers claim that Earth is getting warmer because the Sun has started to put out more energy over the last few years, and that in fact ALL the planets in our solar system are heating up at exactly the same rate as Earth. They further claim that their argument is supported by data from NASA. I can accept that a system as complex as a star can vary in its output, but in the absence of real data concerning the output of the Sun, that concept means little. The research that I've done on this subject indicates that this theory is widely viewed as having been soundly discredited--that while the output of our Sun may go through cycles there is no cycle which would appear to explain global warming. However, I've been unable to locate hard data from what I would consider to be a reputable source. Is there any merit to this argument, and where can I find hard data regarding solar output and the average global temperatures of the other planets in our solar system?

Thank you for any time that you expend on this question, and any insight that you can provide.

--Tom

AnswerEdit

Hello,

You are correct that the claim of a warmer Sun has been discredited. Having just returned from the 40th Meeting of the Solar Physics Division of the American Astronomical Society (at which I also presented a poster paper) I can tell you emphatically that the Sun is not the culprit in the warming piece.

One particular sequence of three lectures on Tuesday morning, June 16th, dealt with the current interphased (23 and 24 ) solar cycles. The lectures included a Parker Lecture ('Cycle 23's Long Decline- Quiet But Not Dull') by Janet Luhmann, and also:

'A Helioseismic Comparison of the Solar Minima Preceding Cycles 23 and 24' from Frank Hill, and

'A Shallow Solar Dynamo' - by Kenneth H. Schatten

In her Parker Lecture, Luhmann noted that with 286 total spotless days accumulated in 2008, and 128 so far this year - we are in a prolonged period of solar activity minimum. This has been since 2000. (When technically, Cycle 24 commenced)

At the same time, it is also true that we currently have the lowest solar wind pressure since cycle 15, as well as the lowest irradiance in the modern (space observation) era. Since irradiance is tied to warming (solar and terrestrial) your coworkers cannot be correct. Right now, the jury is still out on whether cycle 24 will be overall weaker than cycle 23, and hence portend significantly colder temperatures (which would help immensely to mute the anthropogenic warming increases from enhanced CO2 concentrations projected)

On the other hand, cycle 24 could actually turn out to be very active cycle with higher solar irradiance that actually reinforces man-made global warming as opposed to cancelling it.

Why do fewer spots portend less solar irradiance and cooler temperatures, more spots higher ones? (Which appears at first glance counter-intuitive since spots are darker, cooler areas).

The lecture by Schatten on the shallow solar dynamo touched on this. (Including making the case for why a shallow dynamo is needed- meaning its origin lies much closer to the solar surface than currently supposed)

As Schatten pointed out - and as we know from the standard (sunspot) theory of (Eugene) Parker, the "inverse ion hurricane" represented by a large sunspot enables the basis for the latent energy (embodied in the reaction: H + (energy) -> H+ + e(-) ) to translate into a convective collapse process so the solar luminosity can flow out and around the periphery of spots. Basically, the spot blocks normal convective dynamics inside it, so the convective flow - upwelling must be re-directed around it, which then emerges at greater intensity.

The larger the spot the greater the escaping luminosity and heat discharged.

This is why the more spots there are in a cycle, the higher the solar irradiance, and the higher the mean global temperature of Earth. (One can get variations up to 0.21 K or more, which was pointed out by Thomas N. Woods in his own lecture Wednesday morning. But this is still significantly lower than the 0.6C = 0.6K increase in global mean temperatures arising from the human-caused greenhouse effect.)

The claim that "ALL the planets in our solar system are heating up at exactly the same rate as Earth" is total nonsense. This is patently clear on the face of it simply using the inverse square law for radiation: e.g. that the intensity of radiation from a source decreases as the inverse square of the distance. Thus, a planet four times as far away from the Sun as the Earth, would only receive:

(1/4)^2 = 1/16

the heat energy from the Sun

So obviously this nonsense is disproven by merely using this basic principle

Apart from that, since each planet has a distinct agglomeration of chemicals in its atmosphere, and many may be frozen (for the outer planets, Jupiter, Saturn etc.) it is plain balderdash to insist all planets heat at the same rate. They cannot, because there are different heat capacities, specific heat capacities applicable to the differing components of the atmosphere.

Re: the data, I will provide links but there is no certainty that you will be able to interpret the data therein properly. What I will do is give the simplest, most straightforward data link first, then the more complex one which you can peruse and perhaps learn to parse while exploring it.

Basically, the data you want are associated with the TSI or 'total solar irradiance' (This is just the solar radiance - in watts per square meter per steradian - integrated over the full solar disk. "Steradian" denotes a solid angle measure- which you can google to learn more about how measured)

The first set based on a plot (graph) for a composite database (1978099) is found at:

ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SOLAR_IRRADIANCE/COMPOSITE.v2.PDF

Note in the preceding that most of the variations in the TSI are within +/- 0.1% of the mean value. Beyond 1999 is not shown (data not integrated into the total and normalized yet) but as I said earlier the irradiance is on a decline, since all the other solar markers (solar wind pressure, etc.) are in decline during an interphase minimum.

The SORCE data (Solar Radiation and Climate Experiment) from Univ. of Colorado are here:

http://lasp.colorado.edu/sorce/data/tsi_data.htm#summary_table

The avg. global temperatures of the other planets will not do you any good, unless you are able to acquire data that reflects a comparative study *over different decades* to show local (at the planet) increases or decreases in temp. (and the reference points at which taken) that are of a significant amount and *can be traced* to solar irradiance data.

I am unaware that any such database has ever been compiled. Indeed, I would bet that the probability is a near certainty none has. (Since there are no known space craft or instruments within vicinity of *all the other planets* capable of detecting solar irradiance and planetary temperature variations in situ over decades!)

I hope you find this information useful!