The trouble with scientific history is that it is out of date. Science moves on.

 

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.

 

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.

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

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I have been doing a lot of reading in the last few days, and it leads to a question for me, just wondering if there is a site with the answer put in reasonably simple terms. There is obviously, obviously a link between CO2 levels and temperature levels. What is the proof that the current warming is caused by the CO2 increase? Other factors, like the sun having had a higher baseline of activity in the second half of the 20th century than it did in the first half, for example, could well have an effect. Also the news that the ice caps on Mars are melting is interesting and would imply that there is a solar-system wide increase of temperature, which surely cannot be caused by our CO2 emissions, can it? Or can it?

Thankyou in advance 🙂

I have been doing a lot of reading in the last few days, and it leads to a question for me, just wondering if there is a site with the answer put in reasonably simple terms. There is obviously, obviously a link between CO2 levels and temperature levels. What is the proof that the current warming is caused by the CO2 increase? Other factors, like the sun having had a higher baseline of activity in the second half of the 20th century than it did in the first half, for example, could well have an effect. Also the news that the ice caps on Mars are melting is interesting and would imply that there is a solar-system wide increase of temperature, which surely cannot be caused by our CO2 emissions, can it? Or can it?

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.

TomC said:

"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 ?

Thankyou TomC. It's not simple, is it? So coincidentally the surface of Mars it warming at the same time as the surface of earth is?

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....

:)

Hi AspieMum,

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?

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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?

Yes, we have a thread on it. You seem very confident about these cloud adding to the warming. After reading this, I don't think I would.

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.......

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Thanks for that Polarwind!

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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

 

 

 but my son's proposed statement of sen turned up on Wednesday and is going to need a lot of work,  

 

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!!!).

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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....

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

Well I did think that what I was reading was a bit odd, really. There isn't a big glass wall at the equator, is there? I wish I could remember where it was - it was a site on the pro-AGW side of the fence, too...

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 :)

Well I did think that what I was reading was a bit odd, really. There isn't a big glass wall at the equator, is there? I wish I could remember where it was - it was a site on the pro-AGW side of the fence, too...

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 :)

I will pick you up on one point, I don't think that understanding of the role of greenhouse gases in the atmosphere means that nothing else affects climate. They are going to be dominant on the timescale of a century or several decades but there are lots of processes that also alter regional and global climate on all timescales. These tend to be dominant over months and years up to say a decade.

Isn't that the point of the debate? Everyone now accepts that there are a whole host of climate drivers. There are some disagreements about what some of those are, but the biggest disagreements are over just how much influence any one driver has, the main bone of contention being whether CO2 is the major driver at present or if there is something else going on (solar variation seeming to be a main contender).

As I said, looking at the figures for CO2 I can see why the pro-AGW lobby are so concerned about it, and if they are correct about its effects on climate we are pretty much doomed because there is no way China is going to slow down, stop or reverse its massive coal-burning power station building programme (10 a week going up at one stage weren't there?)

It's all a bit lot worrying and I can see why so many people don;t want it to be true. I don;t want it to be true either.... but that is why I need to find out the answers to my questions. I never just accept what I'm told.

 

 

 

Isn't that the point of the debate? Everyone now accepts that there are a whole host of climate drivers. There are some disagreements about what some of those are, but the biggest disagreements are over just how much influence any one driver has, the main bone of contention being whether CO2 is the major driver at present or if there is something else going on (solar variation seeming to be a main contender).

As I said, looking at the figures for CO2 I can see why the pro-AGW lobby are so concerned about it, and if they are correct about its effects on climate we are pretty much doomed because there is no way China is going to slow down, stop or reverse its massive coal-burning power station building programme (10 a week going up at one stage weren't there?)

It's all a bit lot worrying and I can see why so many people don;t want it to be true. I don;t want it to be true either.... but that is why I need to find out the answers to my questions. I never just accept what I'm told.

Another way to think about this is to remember that all of the natural cycles have been impacting climate for millenia and, to a reasonable extent, their effects can be demonstrated.  What is different now is that we are changing one of the key parameters (i.e. GHGs).  You may have seen my question elsewhere in this Forum as regards the sensitivity of the climate system to CO2 increases.   There seems to be a reasonable case that quite small changes in solar output have disproportionate effects on our climate system - IIRC the variation in solar is less than 0.5% between peak and trough.  In which case increasing CO2 by ca. 0.5% every year must be taking a risk with the climate system: it is a mistake to assume that the relationships are linear.  Sceptics tend to react to suggestions of tipping points or step changes but it is a fact of the natural world and IMHO we are tampering with a complex system without understanding the potential effects.

As for your comment about China, might I ask you to think about why has increased it's GHG emissions so much in the last 10-20 years?  Have a look at all the goods you buy and see where they are made.  We are responsible for a significant proportion of those emissions because we buy their manufactured goods. 

Sadly your comment "we are pretty much doomed" is about right.  It will require a complete re-engineering of our entire socio-economic systems and our assumptions about how we live on this planet - and that isn't going to happen pro-actively.  It will happen in response to any changes we inflict on our planet - whether that be climate change or wholesale degradation of the eco-system through pollution and loss of species.

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Ah, the relationship are definitely not linear or there would be no debate, would there? It would be easy and clearly demonstrable.

However, I would suggest that the sun has to be our major climate driver - after all, it is our distance from the sun that enables the planet to have the life-sustaining temperatures it has in the first place. 0.5% variance of solar radiation could conceivably be a far bigger influence than 0.5% variance in the levels of a gas that only makes up, what, 0.04% of the atmosphere? I am not saying that is the case, but you can see how it looks to a great many people.

Of course, to put it in perspective you could start telling people exactly how big a flu virus is. They might realise, then, that tiny things can have a huge effect....

Ah, the relationship are definitely not linear or there would be no debate, would there? It would be easy and clearly demonstrable.

However, I would suggest that the sun has to be our major climate driver - after all, it is our distance from the sun that enables the planet to have the life-sustaining temperatures it has in the first place. 0.5% variance of solar radiation could conceivably be a far bigger influence than 0.5% variance in the levels of a gas that only makes up, what, 0.04% of the atmosphere? I am not saying that is the case, but you can see how it looks to a great many people.

Of course, to put it in perspective you could start telling people exactly how big a flu virus is. They might realise, then, that tiny things can have a huge effect....

I like the last comment - I'll remember that one, thanks.   We had that discussion here some time back, i.e. how can something that is only ca 390 parts per million matter.....

As for your opening point, then yes clearly the sun is the major climate driver.  But this plays back to the previous point - the sun is a constant plus or minus 0.5%.  What has adding, so far, 110 parts per million, or 40%, to CO2 levels done to the balance in the system.  The issue is how this is manifesting itself and how that effect is measurable above the noise of the underlying climate variability. 

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