RedShift

Well, for 125 kyr ago the Earth’s tectonic plates were largely in the same position as they are today. But going back further in time they were obviously different which makes comparisons of the present ice age to previous ones like chalk and Wensleydale. Tectonics do play a big role in the Earth’s climate, and with the right combination of suitable tectonics and Milankovitch cycles you get an ice age. Some of the tectonic ingredients which probably kicked off this ice age are; 1) It seems to have an ice age you need a large isolated landmass over a Pole. A few (can’t remember exactly when for now) millions years ago Antarctica separated from South America, forming Drake’s Passage – this isolates Antarctica and allows cold circum-Polar water currents. 2) The rise and rise of the Himalayas (and to a lesser extent, the Alps) these ‘new’ mountains exposed a huge amount of silicate rocks to the atmosphere. As these rocks chemically weather they draw down CO2 from the atmosphere via reactions like CaSiO3 (a pyroxene if anyone is interested) + CO2 = CaCO3 (calcite) + SiO2. The Himalayas also kicked off the monsoon, which creates more rainfall, which creates even more rock weathering, which lowers CO2 in the atmosphere…..etc. There are also some ideas about sea-floor spreading rates. Large amounts of CO2 are generated at mid-ocean ridge volcanism sites. At the start of the break up of the super-continent Pangea which started sometime in the Jurassic, volcanism on earth was far higher than now. Continents were splitting up quickly by large sea floor spreading rates – which raises sea levels too (if you generate a large amount of new crust at an ocean ridge – the water has to go somewhere, it goes up). So during the Cretaceous, sea levels were way higher as a result of both lots of CO2 and the water being ‘pushed up’ by active mid ocean spreading. Since then, the continents have taken on their present position and volcanism has died down a little. The Earth is relatively quiet. It all goes to show the Earth as one big system - tectonics, biosphere, atmosphere - they all infuence each other. It never ceases to amuse me how some on here reckon we are arrogant to think we are capable of altering the composition of the atmosphere - hence climate. Why, for example, is there oxygen in the atmosphere? It wasn't there in the very early Earth's atmosphere and without it life (or photsnththetic life anyway) wouldn't be there at all as all the rocks on the earth's surface would eat it up. It seems that a bunch of bactaria - the cyanobacteria put oxygen there in the first place. So if a population of photosynthetic bacteria can alter the atmosphere.....we sure can. How Lovelockian of me!

Re: Solanki and solar output infuence on climate. Solanki & Krivova (2003) estimate the Sun to have contributed ~30% to the temperature increase since about 1970. Lean et al., (2005) conclude "When the contemporary empirical relationships are extended to the past 120 years, the solar influence on global surface temperature, consistent with current understanding of plausible secular irradiance change, is likely an order of magnitude smaller than the net warming from increasing concentrations of greenhouse gases and tropospheric aerosols." And from Bard and Frank (2006) whilst acknowledging that the Sun does play a significant role on the Earth's climate, a fairly neutral, but similar(ish) conclusion: "Overall, the role of solar activity in climate changes—such as the Quaternary glaciations or the present global warming—remains unproven and most probably represents a second-order effect.Althoughwe still require evenmore and better data, the weight of evidence suggests that solar changes have contributed to small climate oscillations occurring on time scales of a fewcenturies, similar in type to the fluctuations classically described for the last millennium: The so-called Medieval Warm Period (900–1400 A.D.) followed on by the Little Ice Age (1500–1800 A.D.)." The lean et al paper is bigger than the 2Mb allowed here....you'll just have to take my word for it.

This is a perennial net weather favourite…Yes, there did appear to be a cooling episode for the Norse in Greenland to contend with, but it isn’t quite as simple as ‘It got cold and then they died’ Why didn’t the local Inuit die out? Archaeological evidence seems to point to a number of factors why life got tough for the Norse. They seemed to lose a lot of trade from the ‘homeland’ – less material to work farms. Their diet has been reconstructed showing the animals they took with them (sheep pigs and cattle) were exactly the same as on farms from Scandinavia, they had this ancestral image of how a ‘homeland’ farm should work. They didn’t appear to eat a lot of fish or seals. Their clothes followed French and Dutch fashions, their Church owned a lot of the land, and they didn’t adopt the ‘stone-age’ technologies of the Inuit. In short they saw themselves as being too European, they didn’t adapt to life in Greenland. The Inuit did fine.

MS, I can concur with you, up to a point, here. NERC have recently gone a bit ‘climate change’ mad…I am currently applying for funding to have some rocks Ar/Ar dated for my research in Turkish Cretaceous tectonics…to stand a better chance of getting this I have to link my proposal to climate change!?! That said, the NERC has just altered its ‘priorities’ a bit and are encouraging more ‘geo’ earth science. All this though, against a backdrop (here at Edinburgh at least…don’t know about where you are) of ever less NERC funds being available. A few years ago we had about 7 or 8 for geology and geophysics alone, now we have 4 for all the Earth Sciences. It always makes me laugh when I see the ‘Scientists in it for the money’ type rants on here…it really isn't that simple.

Crap joke time....Mount Ararat, the classic arc volcano!! Snigger.

Ocean warming - yup, the energy required to heat an ocean by even one degree is quite mind boggling. Take the Arctic Ocean, its area is around 14,056,000km2. It's a shallow ocean, with an extremely approximate average depth of 1.5km. This means its volume is 2,108,400 km3, let's say ~ 2.1 x10^6 km3...so the Arctic Ocean weighs ~2.1 x 10^18 kg. The specific heat of a substance is the energy required to raise an amount (unit mass here) by one degree. Now for even more simplifications - the heat capacity of seawater varies with temperature (which varies with depth...and density etc) but let's say it takes 3900 joules to raise a kilogram of seawater by 1 degree. Apply that to the Arctic Ocean and you need something in the order of 8 x 10^21 joules (or 8 zetta joules!) To put this into context, the Hiroshima bomb released around 8.4 x 10^13 joules of energy. Mount St. Helens in 1980 released 1.9 x 10^18 joules...so you need about 400 volcanic eruptions of the size of Mt. St. Helens to warm the Arctic Ocean alone by 1 degree. As Roo and SF point out, the locations of underwater volcanism are fairly well known. Besides, volcanoes are usually associated with seismic activity wich can be pin-pointed very accurately. Hawaii is one example of a 'hotspot'....Iceland lies on both a rift and a 'hotspot'....lucky Icelanders.

Well, north of the fun and games today some light/moderate wet snow showers in Edinburgh. ~2.2 C. Light east wind.

Moderately heavy snow in Edinburgh for now.

Some celestial bodies… Moan (n.) – Forget the Sun, or even the Un, as being the primary driver of our weather, the Moan decides our weather by sucking the heat (or was it the cold?) out of the clouds, just like a giant fan on an iceberg...or something. It is a law after all. Not to be confused with the noise made by many members here when some of our more excitable Antipodean contributors post. Murkury (n.) – A small grey planet that receives plenty of Unshine, but just on one side. Its magnetic field is in a transit van this winter…so expect plenty of no here in Britain. Penus (n) – A larger orangey-red object in the sky…where women are from. Probably an example of the ‘Ran Away Greenhouse Affect’ (RAGA) – whereby the Greenhouse Affect, erm…..ran away. Quite why its surface temperatures are so high is hence a mistery. Lars (n.) – A small red planet, named after a famous Swedish astronomer. Its atmosphere is ~95% carbon dioxide and yet is colder than the Earth. Firm evidence, according to some visionaries, that carbon dioxide is not a warming agent here on Earth. Its green canals are inhabited exclusively by men.

21°C Light NE wind. Sunny intervals between the haar rolling in off the sea.

I'd never heard of the Scientific Alliance before. But after a bit of searching...one of its co-founders was Robert Durward (along with a former Downing street civil servant), a businessman from Lanarkshire with some erm....interesting views. His latest project is to launch a new political party in Scotland called the New Party (it may be coincidental that this was also the name of Oswald Mosley's first party) David McLetchie, the ex-Tory leader in Scotland claimed the party was "fascist and undemocratic". Some Robert Durward quotes; "It is time for Tony Blair to try the "fourth way": declare martial law and let the army sort out our schools, hospitals, and roads". Durward is "'a businessman who is totally fed up with all this environmental stuff... much of which is unjustified, such as the climate change levy. We also have the aggregates tax, which will put the UK quarry industry out of business." He is also opposes the 'witch-hunt' against drink drivers. See...gmwatch.org gaurdian.co.uk scotsman.com scotsman.com Maybe it's just me, but I wouldn't trust anything found on the Scientific Alliance website.

Absolutely Dawlish. On this site you often see 'scientists' written in inverted commas or even pre-fixed with 'so called'...pretty patronising really. Re the Gulf Stream, yes I remember the furore here after that Nature paper last december. The paper mentioned that the Gulf Stream was doing just fine, but one deep water returning current had possibly slowed, and there was, perhaps, a reorganisation of deep water circulation, over a single line of latitude, at least, that was my understanding of it (I'm no oceanographer). There were also some fairly large uncertainties. I mentioned this here but few, if any, paid any attention. A quote from the Bryden et al. paper.... "Whereas the northward transport in the Gulf Stream across 25° N has remained nearly constant..." The only way to 'close' the Gulf Stream is to shut off the Atlantic wind system, or stop the Earth turning...or both. As TWS mentions, it's the media representation of science that mucks things up.

Daniel.......... oh never mind.

Light to moderate snow in Edinburgh city centre....1 to 2 cm so far.

I'm going to be in Cyprus, which I think is just off the 100% eclipse track...but it should be fun...I hope.

Currently heavy snow in Edinburgh city centre...'sticking' too.