An inconvenient coincidence?
The Maunder Minimum coincided with the middle — and coldest part — of the so-called Little Ice Age, during which Europe and North America, and perhaps much of the rest of the world, were subjected to bitterly cold winters. Whether there is a causal connection between low sunspot activity and cold winters is the subject of ongoing debate.
The Spörer Minimum was a period of low solar activity which lasted from about 1420 to 1570 (some say 1450 to 1550). It occurred before sunspots had been directly observed, and was discovered instead by analysis of the proportion of carbon-13 in tree rings, which is strongly correlated with solar activity. It is named for the German astronomer Gustav Spörer.
Like the subsequent Maunder Minimum, the Spörer Minimum coincided with a time when Earth's climate was colder than average. This correlation has generated hypotheses that low solar activity produces cooler than average global temperatures, though a specific mechanism by which solar activity results in climate change has not been established.
The Dalton Minimum was a period of low solar activity, lasting from about 1790 to 1820. Like the Maunder Minimum and Sporer Minimum it coincided with a period of lower than average global temperatures. Low solar activity seems to be strongly correlated with global cooling, although the mechanism by which solar activity causes climate change is not well understood.
Well, just a coincidence? What I will say is that regardless of who is right or wrong. This is actualy an incredable intresting subject once you start to do a little digging for yourself.
Answer:
http://en.wikipedia.org/wiki/global_warm...
you're right, very interesting.
Yes
No, it's probably not a coincidence. There was very little human greenhouse gas emission back then, so solar variations would have a much larger relative impact on global warming than now, when greenhouse gas emissions dominate.
If you'll examine the following climate model graph, solar variations were playing a larger effect than greenhouse gas emissions until almost 1960
http://en.wikipedia.org/wiki/image:clima...
Coincidentally, 1960 is when scientists started to directly measure atmospheric CO2 concentrations:
http://en.wikipedia.org/wiki/image:mauna...
You might want to read this, by scientists who have been studying the sun for years. They say global warming is not caused by the sun.
http://solar-center.stanford.edu/sun-on-...
Solar radiation is of course considered by global warming scientists. The peer reviewed data shows it's about 10% of the problem.
http://www.globalwarmingart.com/wiki/ima...
Good question. NASA data has shown the cooler period was caused by changes in the sun.
Well done. There is also some evidence that CO2 levels are a result, not a cause, of temperature changes that could result from changes in solar activity. Also, the effect of water vapor in the atmosphere is seldom taken into account, because it is so variable. Bottom line: it is entirely possible that the sky is not falling, and Gore's Chicken Little imitation is just that -- an imitation.
You notice that Bob's example in the Chart starts at 1850 or so even though they mentioned the cold period before. There is a pretty interesting theory that the sun spots mess with the Earth's magnetosphere which results in more cosmic rays hitting our atmosphere. The cosmic rays have recently been shown to cause water vapor to condense. It seems we get warmer when our magnetosphere is lessened. This is interesting to me since I am a geologist and have studied the earth's magnetosphere. We seem to be entering a period with weakening magnetic strength and nearing a pole reversal. I wonder if that might result in warmer temperatures since there will be an extended period with very little to no magnetosphere based on previous reversals. It is a complex situation. I doubt if the climate scientists have even taken this into account. I seem to remember hearing about the earth's magnetic strength weakening (not sure how much) and seems like this might also be responsible for some of the recent warming. I have never put this together before. Hmmm?
There is no place for things like truth and common sense in the GW debate. Please stop
The Little Ice Age has been more closely linked to environmental conditions on the Earth rather than conditions on the sun. There were a series of major eruptions of volcanoes during that time including but not ONLY the MAJOR eruption of Krakatoa which covered the Earth in an enormous "blanket" of fine dust particles. In a way that was a fortuitous event for the world's climate. Sunspots are areas of cooler temperatures on the sun. Cooler temps means LESS energy than from surrounding areas is radiating out to space. During the time of the Maunder Minimum there would have been MORE warming rather than less warming. The reflective nature of all that volcanic dust in the upper atmosphere tended to mitigate the effects of the sun's INCREASED energy output during that time and not ONLY eliminated that "extra solar heating but further reduced the level of incoming solar radiation at the Earth's surface.
the effects of the magnetosphere of the Earth on climate are minimal at best. Most of the effects tend to be in the electro-magnetic spectrum and the changing of the polarity of the Earths magnetic poles would tend to raise havoc on radio, telephone and electric grids, and sensitive electronic equipment, maybe even unprotected computers but climatic changes will tend to be minimal if noticeable at all.
This is an excellent question! I doubt that all the various scientific factors are being combined and evaluated properly due to "political" science which has a political agenda. The more I study this the more that conclusion is validated. Man has only an infinitismal influence on Climate Change. If we disappeared tomorrow, the Earth would still warm up, perhaps reaching the same temperatures as in the 7,500 years following the last Ice Age.
Real pollution with poisonous gases and particulates is far more important than CO2. We would be better off trying to find ways to cope with Climate Change than trying to stop it, which is like trying to stop the tides.
The environmentalist nuts cry about the polar bear becoming extinct. Where were the polar bears when Greenland was warm enough to grow wheat for the Vikings, about 1000 yrs ago? It was warmer than now. Did the polar bears evolve in only the last 3500-1000 yrs of somewhat cooler climate than the preceding 7,500 yrs?
The fact is that no one is sure about the causes of Climate Change. Consensus means nothing. It was once the consensus of all educated men that the Earth was flat and the sun revolved around the Earth. Consensus has often been wrong, especially when politically driven, because it feeds itself by suppressing the opposition.
Stuff Gore's head where the sun doesn't shine and he will still talk out his behind.
Good information, jb.
And an interesting condition I had not given a lot of thought, jim z. Even if it is not THE reason, it is still one of the MANY factors that have to be considered before committing massive resources towards fixing a problem that may not have a significant man-made cause.
Raji - Krakatoa's major eruption was in 1883, more than 30 years after the end of the Little Ice Age. That must have been one hell of an eruption to disrupt the space-time continuum, altering weather patterns hundreds of years in the past. Also, dismissing Jim's hypothesis about the magnetosphere by saying that it only has an effect on the electromagnetic radiation - whew! Good thing the sun doesn't radiate em waves! Oh...wait...ALL of the sun's radiation is in the form of electromagnetic waves. Your witchcraft fu is not good.
Finally, Dana, before you or Bob wheel out that same lame Wikipedia Mauna Loa graph again, do a little quality check:
The reason given for the ANNUAL CO2 fluctuations is the seasonal uptake by plants. Uhh...no. The bulk of Hawaii's plantlife photosynthesize year-round. Ever been to Hawaii? If you compare the CO2 fluctuations to those in land-locked monitoring stations, you'll find that the land-locked fluctuations are considerably less - despite the fact that those stations have better defined seasonal differences. And if the Big Island were serving as an example of limited carbon emissions and optimal plant growth - AND IT IS STILL FAILING!! - then it's gameover. We could never achieve that ideal in our lifetimes.
If you care about the science vs the hype in deciphering your Mauna Loa graph - look at the annual variations of sea surface temperatures vs annual fluctuations of CO2.
If you look at the study below, you will see that there is a good correlation between sun spots and temperatures. http://www.geocraft.com/wvfossils/refere...
Global warming theorist say that the mid century drop in temperatures were due to high sulphate levels in the atmosphere which block the sun's ray and act as a cooling agent. Now look at the chart that Dana provided. You have high levels of sulphates, low levels of co2, but temperatures still rose during the early part of the century. Now find the graph in the site that I listed above that shows temperatures and sun spots. Notice how in 1910 when sun spot activity started to rise so did the temperatures. Is that coincidence?
A recent paper by Dr. Jan Veizer of Ottawa, Canada, based on dozens of studies and his own research of 40 years, concluded that solar activity has been the “climate driver” for billions of years. While the climate can be affected by the many factors , it is the sun and its effects that have caused changes in climate for 4 billion years. Dr Veizer first set out to prove that CO2 was historically what caused changes in climate, but noted, “Personally, this last decade has been a trying period because of the years of internal struggle between what I wanted to believe and where the empirical record and its logic were leading me.”
It very interesting what gets left out of debates. Am I right in thinking we also currently at/very near a high of predicated solar activity?
Geologically speaking we are still in an ice-age, due to there still being polar ice.
Deforestation of Europe about 4000 BC probably due to Dutch Elm disease, not climatic in origin.
The North West Passage might have been easily traversibly prior to these minimii.
http://en.wikipedia.org/wiki/northwest_p...
The Romans reported that Britain was getting colder towards the end of their "occupation". Ancient people/The Romans did have large scale manufacturing industry. The ancient Greeks also reported that people were "using black rocks which burned to provide heat" (ie coal)
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