Lotta talk on the internet about a solar something-or-other concerning sunspots, or rather the lack of them. Some in climate "science" are claiming that a sunspot drought will save us from Global Warming.
Doubtful. Sunspots have been observed for some 400 years. They wax and wane on an 11 year cycle, and they do effect high frequency (2-30 MHz) radio communication. During sunspot maximum radio amateurs can work stations all over the world. During sunspot minimum they may have trouble working a friend in the next town.
Needless to say, amateurs pay a good deal of attention to sunspots. Right now we are at sunspot minumum, and it's the lowest minimum on record. Like zero spots visible, and we are late coming out of it. We should have a lot more sunspots right now than we do. Based on this sunspot drought some people are predicting an abnormal sunspot cycle. This has happened before, and no reason to believe it won't happen again.
There is little reason to believe that sunspots have anything to do with Global Warming. No weatherman will say that sunspots effect the weather, and climate is just long term weather forecasting. The climate "scientists" will say almost anything, you gotta watch them carefully.
We have about 30 years of satellite data on "the solar constant", i.e. the amount of sunlight falling on the earth. The satellites show about 1350 watts per square meter. If you look hard at the plots of satellite data, you can see the 11 year sunspot cycle, it's about plus/minus 1 watt/sq meter, that's a variation of like 0.1%. Weathermen and most reasonable people feel that is way too small to make any difference in weather.
But expect to see a good deal of talk about it on slow news days.
5 comments:
It must be remembered that luminosity is not the only factor affecting insolation. There's also the Sun's magnetic field, the solar wind, and radiation outside the visible spectrum, all of which have an effect.
And while I agree we can't make a case for sunspots=weather, there is plenty of data that shows a correlation between them. (Yes, I know. Correlation does not imply causality.) It will be interesting to see what happens if we do indeed enter an extended minimum (decades long) after Cycle 24, as some solar scientists are predicting.
Perhaps, but 1350 watts per square meter is real energy, so strong you can feel it on your skin without instruments. The solar magnetic field is not strong, in fact it is weaker than the earth's magnetic field, that's why magnetic compasses point to the earth's magnetic pole rather than the sun's. I don't have figures on the strength of the solar wind but it is far far less than 1350 watts per square meter. Most of the sun's output is visible light. Our eyes have evolved to use the strongest part of sunlight, Granted there is some energy outside of the visible band. We don't see ultra violet or infra red, but the reason we don't see them is that they are not very strong compared to visible sunlight. In short, the luminosity is much stronger than the second order effects. I expect luminosity to dominate any climate change.
The satellite data is remarkably flat, going back to the launch of the first satellite about 30 years ago. I cannot see a long term tilt in the data. In fact I am impressed that the sensors are sensitive enough and quiet enough to show the 11 year sunspot cycle. As far as long term, the satellite data says the sun hasn't changed luminosity at all.
Ah, but the sun's magnetic field has quite a bit of an effect, particularly on the amount of cosmic radiation making it into the Earth's atmosphere. Cosmic radiation has an effect on lower level cloud formation. As the sun's magnetic field 'calms' during solar minimums, the amount of cosmic radiation making it into the atmosphere increase, in turn increasing lower level cloud formation. This in turn cools the Earth as more solar radiation is reflected back into space.
Take a look at the work of Dr. Henrik Svensmark of the Danish Space Research Institute. His work ties in the sunspot cycle, cosmic radiation, carbon-14 dating, and the Earth's climate. So far his hypothesis is holding up, even as others have looked over his data and methodology. That's more than can be said about Mann's or Hansen's work.
I'd never heard of Svensmark before. I googled and read the first few hits. His point that cosmic rays can trigger cloud condensation is well taken, a Wilson cloud chamber demonstrates this effect.
On the other hand, it remains to be seen if additional nucleation makes much difference. Way back in the 1940's there was much talk of cloud seeding and local governments even paid aviators to fly around seeding clouds, hoping to increase rainfall. They don't do that today, possibly because seeded clouds didn't rain much more than plain old natural clouds.
Then to clinch the cosmic ray theory, you have to show that cosmic ray intensity varies over time. I never heard anyone claim that it did, and Svensmark did not present a graph of cosmic ray intensity over the last fifty years or more.
Svensmark did make another very important point, namely clouds have great effects upon climate, greater than CO2 does. Anyone standing on a beach can tell you it gets chilly when a cloud covers the sun.
Some of Svensmark's other work as well as follow on work by others used a proxy to indicate the amount of cosmic radiation hitting the Earth's surface, that being carbon-14 ratios.
Apparently the level of cosmic radiation can be calculated using the ratio between carbon-13, carbon-14, and carbon-14's decay products. The more cosmic radiation reaching the Earth's surface, the more carbon-13 and carbon-14 there is. Depending upon the amount of time that passes, both the date of the cosmic irradiation and its intensity can be derived. I believe Svensmark used peat bogs as his original source for the organic materials used for his calculations (I'm doing this from memory, so excuse me if I get this wrong). Others have used similar and non-similar sources to do the same and have come up with the same answers he did. (At least his results are repeatable!)
Does this prove the theory? No, not in the least. But it doesn't disprove it either.
Another question that must be asked: How much change in insolation must there be to see the effects as climate change? Some have suggested that it's less the 0.2%. (No, I don't recall where that came from) Over a short term, we probably wouldn't see much of an effect. But if it were a long term change, meaning decades, then the effects might become quite apparent.
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