knocker

I believe there was a quiet (in intensity) La Nina in 1907 following a fairly long Nino) before the decline in both the frequency and intensity of warm events from 1925 until 1958.

That's odd, comes up okay with me.

I thought it was the other way around. Ozone traps shortwave radiation (UV at certain wavelengths) which causes the warming of the stratosphere. One of the problems in the arctic stratosphere in recent years is that it has become colder (GW) allowing the formation of PSCs which act as a catalyst for the destruction of ozone. I just wondered whether it was about greater transport of ozone into the arctic stratosphere. I vaguely see your point about the vortex but the role of ozone still illudes me. Not to worry.

I'm no doubt being very thick here but could you go into a little more detail as to how ozone aids blocking. Ta.

That is true but isn't the tipping point the point in time when the process you describe actually accelerates due to increasing positive feedbacks? In black and white terms, when any process is irreversible.

If for simplistics sake we take the incoming extraterrestrial short-wave radiation to be 100 the figures break down thus. Forgetting the absorbtion fsctors, twenty units are reflected back to space from clouds, which cover about 62% of the earths surface, on average. A further 8 units reflected from the surface and 3 units are returned by atmospheric scattering. The planetary albedo is 31%. The decrease in the albedo in the Arctic I feel has been ably demonstrated by GW and many scientific studies and I feel that a tipping point has been past. Certainly one can't be definitive about this and I wonder whether possible increased cloud cover may mitigate against significant changes in the planetary albedo. On the other hand signicant changes in circulation patterns in the arctic way well outweigh those considerations.

Rather supports the theory that we are passed the 'tipping point'. Had a quick look at the full report but it obviously requires a pot of coffee and an hour or three.

Another time when lightning triggered a disaster in a coal mine. This time in Canada in a mine near Sparwood & Elkford in 1916. Twelve men were all killed in series of explosions which occurred shortly after the start of the night shift on August 8, 1916. At the time there was a bad lightning storm taking place. It is thought that the lightning struck near the portal and travelled into the mine either on the signal wire (bells used to communicate in the mine), the cable used to pull coal cars, or along the track itself. The main entry way was constructed of 18 to 24 inch diameter timbers which were smashed and strewn all about in front of the portal.

Seems a reasonable definition from Clive Hamilton, Requiem for a Species. ISBN 978-1-84971-081-7 Since 2005 a number of scientific papers have described the likelihood of the climate system passing significant 'tipping points' beyond which the warming process is reinforced by positive feedback mechanisms-small peturbations that cause large changes.This new understanding has upset the comforting idea of a 'dose-response' relationship between the amount of greenhouse gases we put into the atmosphere and the amount of global warming that follows. That idea has allowed us to believe that, although we may be slow to respond, once we decide to act we will be able to rescue the situation. In truth, it is likely that in the next decade or so, beginning with the melting of the Arctic's summer sea-ice, the Earth's climate will shift onto a new trajectory driven by 'natural processes that will take millenniums to work themselves out. I have an idea that this might be near the mark.

New space research published this week (Thursday 21 October) in the journal Nature, has settled decades of scientific debate. Researchers from the University of California (UCLA) and British Antarctic Survey (BAS) have found the final link between electrons trapped in space and the glow of light from the upper atmosphere known as the diffuse aurora. The research will help us understand ‘space weather’, with benefits for the satellite, power grid and aviation industries, and how space storms affect the Earth’s atmosphere from the top down. http://www.antarctic...ase.php?id=1312 To save people the bother if they want to read the full paper. ftp://ftp.nerc-bas.ac.uk/pub/photo/Nature-diffuse-aurora/documents/PDF%20Nature%20paper.pdf

Interesting. Perhaps the mechanism that caused the Wilkins Ice Shelf collapse. Elephant seals recruited as field researchers have uncovered new evidence of what may have caused the dramatic collapse of an Antarctic ice shelf two years ago. Wearing tracking tags, the deep-diving mammals mapped the seabed near the Wilkins Ice Shelf, which is the size of Jamaica but recently began to disintegrate. They discovered channels that deflect warm water towards the ice. http://www.thetimes.co.uk/tto/environment/article2775724.ece

The Sago disaster produced a massive investigation and one of the research teams came up with this. “Current from a surface lightning strike can generate electromagnetic fields that can readily propagate through the earth, as opposed to current being driven into conductors entering a mine such as metal rails or power lines,†Schneider said in a news release. “The correlation between our field measurements and analytical models is quite impressive. Significant energy can be transmitted deep into the mine without physical conductors being present on or near the surface. This has profound implications.†http://www.miningtopnews.com/sandia-team-researches-cause-of-sago-mine-disaster.html

In September 1908, during a violent thunderstorm, Lightning flashed down a Pennsylvania coal mine and killed three miners 1,300 feet underground. The miners were working at the bottom of the shaft and the lightning apparently travelled down a steel rail that acted as a conductor. There have actually been a number of occasions when lightning has been linked to explosions in mines, the latest being the disaster in the Sago Mine in West Virginia where twelve miners died. The tragedy was compounded by the fact that is was announced that all the miners were safe and this wasn't corrected for three hours. It has not been completely established how the lightning travelled and triggered the explosion. One can't help wondering whether any of the many coal mine explosions in Britain were caused by lightning strikes although I haven't come across any evidence to confirm this. Anyone come across any bizarre strikes that ended in tragedy? On a similar vein apparently rapid changes of atmospheric pressure at coal mines could be very dangerous, but that's another topic.

That is very true but unfortunately you are missing the point of the post. And the explanation that you quote was an attempt at trying to be helpful in repsonse to a direct question. Even I, in my ignorance, appreciate there is a difference.Time for me to make my exit from these climate discussions methinks but a final thought ,although this wasn't the point of the original post. AGW tends to make the stratosphere colder which in turn leads to the increse of PSCs whis act as a catalyst in ozone destruction. Ergo the chalk and cheeze tend to be in closer proximity.

Inez Fung is on a mission to find and account for every gram of heat-trapping carbon dioxide on the planet. And she knows where most of it is hiding. Fung is the director of the Berkeley Institute of the Environment at the University of California-Berkeley. Her work has led to a more complete understanding of the current and future role played by Earth's so-called "carbon sinks" -- features such as oceans and forests that suck carbon dioxide out of the air. Fung's research shows that when the role of these carbon-absorbing mechanisms is taken fully into account, global warming is likely to accelerate even faster than scientists previously believed. http://www.grist.org/article/2010-07-30-carbon-hunter

Was there ever?

Are you not creating problems for yourself here? Blizzard-like conditions could be construed by some as a ground blizzard. No snow actually falling.Or indeed this is exactly what you mean.

Super typhoon Megi has swept key agricultural areas in northern Philippines on Monday, and may significantly reduce the country's rice output in the current harvest season, reports China's Xinhua news agency. http://www.bernama.com/bernama/v5/newsworld.php?id=536419

I think I'll keep the long johns in the draw a wee bit longer. http://www.ncdc.noaa.gov/sotc/?report=global&year=2010&month=9

The year 1608 also marked the twelve year truce with the war with Spain which was probably just as well. The Reverend Johan van de Sande wrote the following about this frosty period, which saw the beginning of the Twelve Years' Truce. There was such a severe frost in the full two months of January and February in the year , 1608 as had never been seen in living memory, with all the waters, streams and marshes, aye even the Zuider Zee, covered in ice, so that all the frontiers of the United Provinces lay open, an occasion which the enemy had so often desired that it might attack the interior of the country, so it was a special dispensation from God Almighty that arms were laid down just when this frost came. One can’t help wondering whether the use of ‘frosty period’ is a reflection on how they considered these events at the time. I’m not sure ‘frosty period’ would be my description today.

Okay some background. Interest in atmospheric ozone began with O. M. B. Dobson, a British meteorologist. Studies of meteor trails led to the discovery of a region in the stratosphere at a height of about 50 km which owed its high temperature to absorption of ultraviolet radiation by ozone. Dobson invented a spectrophotometric method of measuring its total amount in the air column and in the 1930s set up a chain of ozone measuring stations. Systematic measurements using the Dobson instruments at Argentine Islands (Faraday) and Halley Bay (Halley), were begun in 1957. Measurements were also made at other lGY Antarctic stations including Little America. The interest was that ozone, being produced photochemically at heights of between 20 and 50 km, mostly at low latitudes or, in the summer only, at high latitudes, could be used as a tracer of atmospheric circulation at high levels. It was found that a major increase in total ozone occurs in the course of breakdown of the Antarctic winter stratospheric vortex. Long-term trends, however, seemed to be small, less than those at lower latitudes. Meanwhile concern had been growing about effects of human activities on the ozone layer which might result in penetration of damaging amounts of ultraviolet radiation to ground level. The science behind the causes of the depletion I’ll leave to Wiki. http://en.wikipedia....Ozone_depletion Wondering about whether it has happened before is irrelevant. IMHO that is.

The depletion of stratospheric ozone may well be halted, although if your 'natural cycle' continues and the stratosphere carries on cooling causing an increase in Polar Stratospheric Clouds, this may well slow down considerable, but this wasn't reallly my point. That being that a molecule of such minute concentrations can be so vitally important. Plus it's difficult to see how natural cylcles are the cause of the increase in tropospheric ozone unless you count millions of cars as being 'natural'. Just for the record I don't think anyone is denying the existence of natural cycles, just that a society obsessed by consumerism can adversely affect them.

Despite its relatively small overall concentration in the atmosphere, CO2 is an important component of Earth's atmosphere because it absorbs and emits infrared radiation. The present level is higher than at any time during the last 800 thousand years http://news.bbc.co.uk/1/hi/sci/tech/5314592.stm If you want another example of man interfering with disastrous consequences (working both ways) take ozone. Ozone is very rare in our atmosphere, averaging about three molecules of ozone for every 10 million air molecules. In spite of this small amount, ozone plays a vital role in the atmosphere. Stratospheric ozone plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight , allowing only a small amount to reach the Earth's surface. The absorption of ultraviolet radiation by ozone creates a source of heat, which actually forms the stratosphere itself . Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface. And we nearly managed to destroy it! And then of course there is the other angle. At the Earth's surface, ozone comes into direct contact with life-forms and displays its destructive side . Because ozone reacts strongly with other molecules, high levels of ozone are toxic to living systems. Several studies have documented the harmful effects of ozone on crop production, forest growth, and human health. The substantial negative effects of surface-level tropospheric ozone from this direct toxicity contrast with the benefits of the additional filtering of UV-B radiation that it provides. Being perverse we actually manage to increase levels of tropospheric ozone. Size isn't everything!

To continue in a little more detail the possible correlation between many severe winters in the Little Ice Age and snow and ice in paintings. In particular The Dutch Winter Landscape in the Golden Age which we can extend slightly to 1565 – 1700. Systematic measurements of temperature, rainfall and snowfall only really began after the 17th century so how to get an idea of the weather during the period of interest. Fortunately a historical study of the climates of the Low Countries has been carried out by the historical geographer Jan Buisman. The sources he used included chronicles, diaries and journals, letters pamphlets and weather diaries. A brief summation of his findings. It can be said that two out of three winters in the 17th century brought prolonged periods of freezing weather, snow and ice thus becoming a norm rather than an exception. One such winter has already been noted in the previous post but there were also severe winters in 1607-08, 1620-21, 1621-22. The second quarter of the century was mild by comparison but the last half of the century was severe with 1684 being perhaps the coldest month ever in the Netherlands. This can now be looked at from another angle. Meteorological understanding of climatic variations during the Little Ice Age is increasing through use of the North Atlantic Oscillation (NAO), which is now available from 1500. These seasonal values were also constructed using proxy data. The graph shoes that the NAO from 1550-1700 showed a negative index but it must be remembered that this data is smoothed and obviously there would have been periods of a positive index, maybe in the second quarter of the century. This negative index can possibly be construed as likely to produce more prolonged ice conditions than a positive when perhaps snow would be more likely. But as the NAO figures are seasonal averages one should be somewhat careful about drawing conclusions. What is inescapable is that during the period there were many periods of prolonged freezing weather and Dutch landscape painters depicted them as a matter of course. There are many examples one could use but to stick to two that have become icons. Peter Bruegal the Elder, Hunters in the Snow, 1565 (© Kunsthistorisches Museum, Vienna) and Hendrick Avercamp, A Winter Scene with Skaters near a Castle, c. 1608. (© The National Gallery, London). Actually the Bruegal throws up another question. It was painted towards the end of the Spörer minima when there was a very low level of solar activity. References. The Cambridge Encyclopedia of the Sun, Kenneth R. Lang. Holland Frozen in Time. Ice and Snow in Paintings of Little Ice Age Winters, Peter J. Robinson,Weather, February 2005, Vol. 60, No.2

If the sun died you would have no photosynthesis. Ergo no life. In any case if the sun died, in the process it would envelope the earth.