The seeming relationship between sunspots and climate has been known about for around 200 years. I've just finished reading a book called "The Sun Kings" by Stuart Clark and learnt it was William Herschel who first noticed the relationship between sunspot numbers and the wheat prices.
For those not aware of it, a lack of sunspots correlates with cooler global climate and higher sunspot numbers with higher temps. It has been easy enough to trace the past history of sunspot numbers past recorded history with dendrochronology and the C13/C14 ratio in tree rings and for solar flare activity the amount of nitrates in snow in polar regions indicates strong auroral events caused by flares.
This topic is currently verging on being controversial. While on one hand there does seem a very clear relationship between sunspots and climate, no one has a good explanation of why. And this is only for long term climate, as in seasons, not daily weather. The last attempt to explain how cosmic rays encourage cloud formation was rubbished by the proposers scientific peers (times of low sunspot numbers lead to a quieter magnetic field around the earth and that allow more cosmic rays down to the ground).
For some calm, positive and pro-sunspot influence on weather discussion I would direct you here for starters. I find it a very interesting topic but I'm wary of jumping on any particular bandwagon until the hard proof is in the bag.
One of the reasons why there appears to be no good explanation for the link between sunspot activity and climate is that the answer is staring them in the face. It's this....what happens to the Sun during the sunspot cycle. What happens to the Sun's luminosity when it's active and there is a lot of activity sunspot wise?? It's luminosity increases. What happens to the Earth when the amount of light and heat reaching it increases. It gets hotter. Now, there is lag due to the differences in solar insolation between air, water and land. Plus you have to factor in how the oceans store and carry the heat around, changes in cloud cover, water vapour content in the atmosphere, greenhouse gas concentrations etc etc etc.
So when the Sun is less active, as in during long periods of quiessence like the Maunder Minimum, the reduction of solar insolation at the Earth's surface cause a consequential reduction in heat being input into the climate, hence the Mini Ice Age. Remember, there is still a time lag between the drop (or rise) in solar activity and it's follow on effects on the planet, for the simple reason you can't just throw the switch and it immediately goes off or on. It may take a few years to a decade or two, but the follow on effects will occur.
Yes, it is an extremely complicated system...however, sometimes scientist tend to either do one of two things. 1. Look for simple explanations where there isn't any, and 2. Over complicate processes which are either simple or complicated to begin with. It's not just a case of not seeing the forest for the trees, it's also a case of not seeing the relationships between the forest, the trees, the soil, the rocks, all the critters, the Sun etc etc, because they let themselve become overwhelmed by it all. You need to stand back and consider everything, including the big picture.
I've just finished reading a book called "The Sun Kings" by Stuart Clark and learnt it was William Herschel who first noticed the relationship between sunspot numbers and the wheat prices.
This is a great not too technical read and I would too highly recommend it for those interested in the sun and a bit more of the discoveries during the 19th Century. Thanks for mentioning it.
One of the reasons why there appears to be no good explanation for the link between sunspot activity and climate is that the answer is staring them in the face. It's this....what happens to the Sun during the sunspot cycle. What happens to the Sun's luminosity when it's active and there is a lot of activity sunspot wise?? It's luminosity increases. What happens to the Earth when the amount of light and heat reaching it increases. It gets hotter. Now, there is lag due to the differences in solar insolation between air, water and land. Plus you have to factor in how the oceans store and carry the heat around, changes in cloud cover, water vapour content in the atmosphere, greenhouse gas concentrations etc etc etc.
So when the Sun is less active, as in during long periods of quiessence like the Maunder Minimum, the reduction of solar insulation at the Earth's surface cause a consequential reduction in heat being input into the climate, hence the Mini Ice Age.
Without being rude... well yes, no and perhaps...
I strongly recommend you read R.J. Tayler's 1989 Quarterly Journal of the Royal Astronomical Society pdf article entitled "The Sun as a star".
Especially on pg.147, http://adsabs.harvard.edu/abs/1989QJRAS..30..125T which says;
"The excess radiance from bright faculae at solar maximum is greater than the loss from sunspots." If there were a correlation, it is the bright threads of faculae on the solar surface and not sunspots."
(This is graphically show on pg.148)
It is interesting that the output of the Sun is about 1367 Watts per square metre, whose variance during the solar cycle is no more than about 0.25%. Atmospheric conditions, especially cloud cover, ocean temperatures, etc., would cause far more influence than solar output.
When compared to long term climatic changes, like ice ages, the cause is more due to changes in the tilt of the Earth's axis (obliquity of the ecliptic) that varies roughly between 24.5 to 22 degrees every 50,000 years or so, and even changes in the Earth's distance from the sun or the shape of the orbit.
Whilst probably too detailed for this general thread, I've attached a graphic of the so-called Milankovitch Variation, which shows the historical variation between now and million years ago. (This shows the Earth is peaking at a warmer part of the Earth history.)
You are right in saying "Yes, it is an extremely complicated system..."
I'm quite well aware of all that you have written there. I did climatology/meteorology as part of my first degree...along with remote sensing. The problem is that this question is too large for any one branch of science to tackle on it's own. I can give you all the lowdown on the astronomical side of things concerning what you have written there (i.e. I've read many of the papers), however, you also need to know it from a geological (my area of specialty), climatological, biological and physical point of view as well. There are just so many factors that come in play it's near impossible to account for them all and that's why this sort of study should be multidisciplinary right from the start.
Actually, the last 2.5-3 million years has been the coldest period in Earth history for the last 680 million years. Even during cold snaps in the Devonian and Permian Periods, the overall global temps were higher than what they are now. The big deterioration occurred about halfway through the Oligocene when there was a massive fall in sea levels and temps declined by more than 15-20 degrees from the Paleocene-Eocene Climatic Maximum.
The correlation between obliquity, eccentricity and precessional drift of the semi-major axis of the Earth's orbit and long term climate is reasonably well documented, but not entirely nailed down, yet. But what ultimately effects the climate is that big heat engine in the sky...in other words the change in solar insolation at the Earth's surface over time. Like I said, there are various lag effects which means any change in solar insolation at the Earth's surface won't necessarily mean an immediate shift in climate, but it is the principle driving force behind the changes which may or may not occur rapidly or slowly.
Last edited by renormalised; 30-01-2009 at 10:42 PM.
Like I said, there are various lag effects which means any change in solar insolation at the Earth's surface won't necessarily mean an immediate shift in climate, but it is the principle driving force behind the changes which may or may not occur rapidly or slowly.
Agreed.
Quote:
Originally Posted by renormalised
The correlation between obliquity, eccentricity and precessional drift of the semi-major axis of the Earth's orbit and long term climate is reasonably well documented.
My general response was more to do answering "interstellar" question and the given NOAA's article. There is of course much debate on weather is based on climate change, but there does seem to me a particularly large void in explaining natural variations against possible manmade ones. Whilst I agree with your quoted statement above, it is quite surprising that many novices actually have not learnt about this at all.
The sunspot debate on climate is a trick one to openly discuss, as it can set the typical trap for the layperson that the science for this is absolute known. Previous influencing Australian forecasters, say like, Indigo Jones and Lennox Walker (and now Hayden Walker) profess being able to predict long-range weather patterns using sunspots. Many among the general population accept this correlation as a scientific fact rather than towards its more speculative nature. (It does appear that much of there presumed knowledge or experience is more based on "pseudo-statistical means" from the physical cyclic observation of the sun, sunspots or planets, say, like Jupiter, which also has an 11-odd year cycle.)
Historically, these forecaster's views have held much sway on climate debate in Australia. (Others like Ken Ring and his generally debunked moon theory on weather seem to have more influence these days.)
I was unaware of your background or knowledge here, so sorry if I sounded too condescending! My sole aim was offer general astronomical explanations as other contributing factors.
Between the years 1645 and 1715 sunspot activity disappeared completely. At the same time, Earth went through a "Little Ice Age". Where the summer months were cold and winter was exceptionally cold.
To me this is proof enough that some how, the Solar Cycle does affect the Earth's weather.
Yeah, you have to be careful when taking these more esoteric ideas into account. Much of it is like reading tealeaves or licking your finger and holding it up in the air to test the wind
Although, some "hard" science is like that too. It's not all cut and dried like many seem to think it is...and despite what a lot of "experts" say.
No mate, you weren't being condescending at all. I just pointed out where I was coming from by stating what I had previously done
Between the years 1645 and 1715 sunspot activity disappeared completely. At the same time, Earth went through a "Little Ice Age". Where the summer months were cold and winter was exceptionally cold.
To me this is proof enough that some how, the Solar Cycle does affect the Earth's weather.
And, it's not the first time the Sun has gone through cycles like that. There is evidence both in ice cores and from glacial lake sediments (varves) of previous minima occurring in the past. I can't remember the exact periodicity, but the Sun seems to have a long period magnetic/sunspot cycle that ranges on the order of several thousand years, maybe longer.
Much of our current information of the climate data for the last six million years has come from mainly core samples taken from the deep ocean floor. An interesting graphic from the Precambrian to Today appears at the webpage; ICE HOUSE or HOT HOUSE?
However, regarding the earlier debate in this thread, I think an article "Earth’s Atmosphere" that appears in the "Encyclopaedia of Astronomy and Astrophysics" (2001), which summaries the important period of climate activity - and the causes of it as;
"These long-term variations modify the spatial and seasonal sequences of solar energy deposition at the surface of our planet, resulting in variations of Earth’s climate. For example, at the end of the last glacial period, about 10 000 years ago, the inclination of the Earth’s rotational axis relative to the ecliptic plane was
about 24.5 degrees (at present 23.5 degrees) and the closest approach of the orbiting Earth to the Sun occurred in July (at present January). This past condition resulted in about 8% more solar radiation reaching the northern hemisphere in the summer and about 8% less in winter time. Although the astronomical effects are weak by themselves, they are relayed by strongly nonlinear feedback effects which result in large-amplitude climatic variations. Besides, the climate is also thought to exhibit large variations by itself, without any changes to astronomical effects."
"There are also three significant Milankovitch cycles: the eccentricity of the Earth’s orbit varies from more elliptical to more circular with a period of the order of 100 000 years; the obliquity of the Earth’s axis oscillates between two extremes with a period of 41 000 years; and the spin axis precesses with a 23 000 year cycle."
From the same source, is the article entitled "Solar–Terrestrial Connection: Long-Term and Short-Term Climate Variability", which is very very useful.
One point also should be raised, that is not in this rather interesting discussion thread, is volcanism and the junk tossed up in to the atmosphere can accelerate climate change as well. If I remember my geology, there was a volcanic activity about 20 to 23 million years ago west as south of Brisbane. Known as the Mount Warning Shield Volcano, this volcanic mountain rose 2 km., the highest point anywhere on the Australian continent in the last 250 to 500 million years. The size extended 100 kilometres, spreading from Byron Bay, Mount Tamborine and Lismore. The caldera is known as the Tweed Volcano, whose size is 40 km. across and about one kilometre deep. It remains one of the biggest volcano we know of!
Such volcanic activity would have catastrophic influence on the southern climate, especially as the latitude of Australia was closer to just south of where Tasmania is today.
One point also should be raised, that is not in this rather interesting discussion thread, is volcanism and the junk tossed up in to the atmosphere can accelerate climate change as well. If I remember my geology, there was a volcanic activity about 20 to 23 million years ago west as south of Brisbane. Known as the Mount Warning Shield Volcano, this volcanic mountain rose 2 km., the highest point anywhere on the Australian continent in the last 250 to 500 million years. The size extended 100 kilometres, spreading from Byron Bay, Mount Tamborine and Lismore. The caldera is known as the Tweed Volcano, whose size is 40 km. across and about one kilometre deep. It remains one of the biggest volcano we know of! http://www.iceinspace.com.au/forum/....s/scared14.gif
Such volcanic activity would have catastrophic influence on the southern climate, especially as the latitude of Australia was closer to just south of where Tasmania is today
Yep, know all about Mt Warning. Nice place to hike and the geology is spectacular. However, volcanism such as the one that is represented by Mt Warning isn't as deleterious on the climate as you might think. Volcanoes like Mt Warning are not as violent nor as immediately influencing as your typical volcanoes such as Krakatoa, Tambora etc. The reason why Mt Warning was as big as it was (it was quite a bit taller than Mt Kosciusko) is because the mountain is made up of vast sheets of basalt that were made up of many lava flows. The volcanism you see there is the same as the volcanism you get in Hawaii. It's very extensive, can last a long time for each individual eruption (many years, in fact), but is relatively quite. Most of the emissions from a shield volcano are water vapour, with some CO2, CO, H2S and other gases. A lot is put up into the atmosphere, but it occurs over a long period of time.
The volcanism we have to be really worried about is the type that is present in areas such as Yellowstone, Snake River, Lake Toba etc. This type of volcanism is similar to your more typical volcanoes, Acidic and Calc-Alkaline, and the explosion in these volcanoes is rather abrupt and can be extremely violent. They tend to pour out vast quantities of volatiles in a short period of time, along with vast quantities of ash. However, unlike your typical volcano, these ones are on a vastly larger scale. The whole Mt Warning volcano would disappear inside the caldera at Yellowstone. When these fella's erupt, it's goodnight starlight time. Your typical supervolcano (as they are called) can erupt anywhere from 2500 to 20000km^3 of rock and ash, most of it blasted into the atmopshere and trillions of tons of volatiles. Last time Yellowstone erupted (650Ka....and now we're overdue by some 40000 years), it blasted 2500km^3 of ash and rock into the sky....covered the US right out to the distance of Phoenix, Az, in a metre of ash!!!!. In that same eruption, a complete range of mountains, over 80kms in length, many over 7000 feet high, disappeared in a few seconds...they slipped into the caldera. Lake Toba (on Sumatra) was even more important to us, as it's effects may have nearly sent our species into oblivion. It blasted 2000km^3 of dust and ash into the atmopshere about 75Ka ago. It's been estimated that the eruption reduced us down to about 500-2000 individuals...however, there is still some controversy about this.
If Yellowstone or another supervolcano erupted today, we'd be in for a very rough time....it would kill many millions with it's immediate and after effects....more so with its after effects. An eruption like that would drastically change the climate, and almost overnight. By the time the northern winter came along (if it erupted in the early to mid summer), it would already be pretty cold and it would only make things worse. The USA would just be a memory...they'd be FUBAR. Canada and Mexico would also be in quite a lot of trouble as well. The rest of us would also be in for some very heavy going too. So, let's hope we never see such an eruption.
"The Sun Kings" : Highly Recommended
