There is a lot of very very good stuff on that blog. Always taken step by step and always thorough.

Also how is it measured now? I see the figures, incredibly high, deeply worrying, but this seems to be from one measuring station? Mauna Loa, is that right, which sounds as if it is in Hawaii somewhere.

Having just had my eyes opened as to the dizzying heights the CO2 levels are reaching, I wish to find out more about it, and it is surely the key issue, all we hear about is CO2, isn't it?

I just keep finding the same charts, though, and wondered if anyone had dug up some other info.

Many thanks

Actually I have found the mauna loa website, which seems a good place to start....forgive my total ignorance of, apparently, even how to do a web search!

So total atmospheric CO2, currently running at 389 ppm, works out as 0.0389 % of the atmosphere? Just feeling my way through here, but 4 tenths of a percent? Does it really have this massive impact?

Off to do more reading :)

The important thing about CO2 levels is that they have doubled due to industrial emissions. As a proportion of the whole atmosphere greenhouse gases may not constitute much but the way the physics works means that they are an important constituent of the atmosphere.

A useful explanation of the history of the science can be found here

http://www.aip.org/history/climate/co2.htm

Thankyou very much for that link. It answers a lot of questions, and I was glad to see that the questions I have been asking have actually been asked by scientists, and answered. This stuff never gets as far as the papers, though, does it? I was quite the fence-sitter before, but now I see why people are so deeply worried by this.

I was looking at the Milankovitch cycles, too, to try and see where we are on them, but it is pretty difficult to figure out - not one page says "we are at x,y,z points on these cycles and therefore the globe should currently be cooling/warming. It looks as if we should broadly be at or approaching peak temperatures as a result of the Milankovitch cycles, and at some point in the next 10,000 ought to start to cool down again. That is quite a long time, though, and with the unknown effect of the high CO2 levels in terms of whether they might counter that cooling cycle, or whether we will still be around by then due to having boiled ourselves off the planet, it is rather difficult to say what will actually happen.

The problem is most people are pretty parochial at the end of the day, and simply can't worry about global effects, or effects in even 100 years, let alone 10,000, which is partly why it's so difficult to get this message across. There is also the question of whether we can actually make any difference now, or if it's too late. Quite a lot of people I know say things like, "this global warming business is highly debateable, and besides if those greenies are to be believed it's too late to change it now so what's the point?" So the one message that did reach the public consciousness is the one that leads to the most apathy, sadly.

Anyway, that's an extremely useful link you have there, very in depth, but really readable. Thankyou.

Thank you.

The best thing about reading the scientific history is that it is free of modern political agendas since the science was largely written before it became a 'hot' issue.

Science is based on predicates just like Law. If you have not studied the case history, making pronouncements about the outcome is unwise.

Minor quibble is that it's still some way short of doubling. Pre-industrial ~280ppm, to current ~390ppm. The big picture is most important of course but it's good to get the details right.

Yep the absolute concentrations may be low but essentially they make the atmosphere opaque to most wavelengths of infrared. That is, if you fired a beam of infrared radiation towards Earth from the moon, the vast majority of that beam would not reach the surface - it would be absorbed and then re-radiated by the GHGs in the atmosphere.

Yes, accepted. Just me being lazy.

It's still a good idea to get the background, and this particular history of climate science does come up quite close to the present. Starting to take an interest in only the last 10 years, and finding opinion so divided, and everything having been discussed so much that people won't answer your questions because they've been over it before so many times, it is useful to see the background all written down so well.

Ulric raises a very important key issue there - Modern political agendas!

Thankyou in advance 🙂

Without going into all this in great detail, the recent changes in direct solar input have been very small, far too small to cause significant warming on Earth or Mars. The sun does have other indirect effects on the Earth's atmosphere which can influence atmospheric circulation and regional weather (this is not so on Mars). The changes in global temperature on Mars are caused by a much bigger effect the amount of dust in the atmosphere. Mars has periodic dust storms which sometimes cover the whole planet. These are the major regulator of global temperature there.

"The sun does have other indirect effects on the Earth's atmosphere which can influence atmospheric circulation and regional weather."

Thank you Tom. We are getting there.

Now, how about those circulation changes altering cloudiness and albedo for an amplified energy budget response ?

I was talking to someone the other day and tried to make an analogy for how the sun would effect circulation. If you put a saucepan on the gas but so only the edge of it touches the flame, it will still eventually boil because of convection. Obviously global and solar system physics is way more complex than that, but still if you heat something unevenly it creates convection, and we are heated unevenly by the sun so this must contribute to the circulation of air around the globe. That is, of course, not the only thing that effects the climate.

And of course if you add salt to the water it boils at a higher temperature, so continuing the analogy shows that adding a little of something can make differences.

Stephen, clouds are complicated too, aren't they? They stop things getting too cold at night, but also stop things getting too warm during the day. Do these effects balance each other out, or is there an imbalance, so they cool more than they warm (or vice versa)?

Questions, questions....

:)

http://www.skepticalscience.com/global-warming-on-mars-intermediate.htm 

Cheers - John

We now have sat's that can 'see' the impacts of mid level clouds and though new , so small data set, it looks like the 'mid level clouds' will only add to the warming (by the way they are 'reacting' to a warmer planet?) and not offset it?

Check out the 'NASA' news page?

See  -

http://www.eurekalert.or...010-11/tau-cat112310.php

Clouds play a major role in the climate-change equation, but they are the least-understood variable in the sky, observes a Texas A&M University geoscientist, who says mid-level clouds are especially understudied. The professor, Shaima Nasiri, is making those "in-between" clouds the focus of her research, which is being funded by NASA.

Mid-level clouds are so understudied, Nasiri says, that scientists have yet to develop a common nomenclature for them. "We do not have a unified definition, so the scientific community can't look at the statistics with a shared level of understanding. Also, because mid-level clouds are formed either from water droplets or ice crystals or a combination of both, they can be more difficult to model.

"Only in the past few years have we focused on the physical properties of mid-level clouds. This means that previous climate models are incomplete," Nasiri says. "All cloud formations are important tracers in the climate-change equation. But we must accurately define and measure the middle layer before we can have a complete picture."

Nasiri credits recent satellite technology for being the vehicle that gives scientists the facts and figures needed to fold the essence of clouds into climate-change formulas.

"NASA satellites launched over the last few years have helped us identify height and base, and temperature and pressure of mid-level clouds. This has revolutionized atmospheric studies," she says. Called the A Train, a formation of six satellites collects and relays an unprecedented amount of atmospheric data, giving scientists such as Nasiri the ability to see all the way through clouds around the globe.

and.......

Thankyou for your replies, folks. I will look at the links etc when I have a chance, but my son's proposed statement of sen turned up on Wednesday and is going to need a lot of work, so my own interests have to go on hold for a bit. Just didn't want to disappear for possibly weeks without letting you know your answers are appreciated

Good luck with that!!! our son is profoundly disabled so we had no issues (rubber stamped) but I know how hard sorting folk's 'needs' can be (esp. in a 'cut ,cut .cut. world!!!).

A little break in the battle with the LA, so I can ask my next question, which arises from the things I have been reading about CO2. I may have misunderstood, so clarification would be a great help.

Okay, here goes....I am sure I read that there is little mixing between the northern and southern hemisphere, which is why the effects of climate change are greater in the NH (eg Arctic is melting, Antarctica seems not to be), as there is more CO2 being pumped into the atmosphere in the NH. So if this is the case, why do El Nino and La Nina have such a great effect on the weather (ie short-term climate effects), when they are largely SH phenomena?

Answers on a postcard....

It is true that cross hemisphere mixing takes longer but you can't treat the two hemispheres as separate. The reason for the slower warming in the Southern Hemisphere is the large area of ocean compared to the Northern Hemisphere which gives a lrger thermal lag. The main difference comparing the arctic and antarctic arises because we have a glaciated land mass in the antarctic and rather seasonal sea ice in the arctic

On the Arctic/Antarctic score, there is a whole raft of differences, such as the angle and distance from the sun having an effect as well as the land/sea difference. Never mind the hemispherical land mass difference on top of that. I knew it was more complicated than that, it is just a handy example, as it is partly influenced by the CO2 thing (well, wholly, if you believe in AGW, obviously, but not in a directly linear fashion).

So there are lags in the system then? There seem to be question marks over how long the lags are, but at least the fact of their existence seems now to be accepted (which didn't appear to be the case several years ago when I last had time to think about AGW).

Thanks Tom :)