Mars melt and Global Warming

[Brian the Snail]

Thanks. More questions:

I notice under "stages of glaciation" that we're in a current peak that seems to follow cyclically with what's been going on before. A lot of GW people make a big deal about glaciers in Greenland and Antarctica melting and being lost; but shouldn't we expect that given this particular graph?

Is there any way to see better-resolved data for this graph over the last, say, 1000 years?

The "peak" that you refer to is the current interglacial (the Holocene), which are the warm periods that intersperse the colder glacial periods. The current interglacial has lasted about 10 000 years, and the temperature changes over various intervals can be found here.

I'm not sure why we should be expecting glaciers to be melting now, based on the glacial/interglacial cycles. If anything, we should be heading for another glacial period, but according to this, not for another 50 000 years (if ever, our CO2 emissions will probably change things).

 

[CapelDodger]

From what I understand, it is a potent feedback mechanism though (i.e. warmer air can hold more water vapour, more water vapour can make for warmer air, which can hold more vapour, etc.). And it is mentioned as such in the AR4 SPM. So if shanek would want to read up on water vapour's effect on the warming trend, its feedback properties are probably what are of interest in that context.

This is a point worth stressing : the world isn't getting warmer because the air suddenly got wetter. The air gets wetter in a warmer world. Something else has to cause the warming.

It's a simple enough point. That has to made over and over and over again ...

 

[CapelDodger]

I'm not sure why we should be expecting glaciers to be melting now, based on the glacial/interglacial cycles. If anything, we should be heading for another glacial period, but according to this, not for another 50 000 years (if ever, our CO2 emissions will probably change things).

I doubt the human race will ever see a good reason for another glaciation, and we know how to stop one now, don't we ?

 

[jimecallaw]

I have so many questions about global warming it's untrue, they may all have very good explanations, to start with one. Living in England we know that the climate has been warmer than it currently is twice before in the last 2,000 years. once around 0 and again around 1,000 England was a big wine producer in those days and is starting to produce wine again now. Now what was the cause of the warming in those days, and more importantly those times seem to be a relatively good time for human life, with no mention of increased storm activity or raised sea levels. I'm not sure how this information fits in with current theories, but I am always reminded of Einstein who said something along the lines of no experiment can ever prove one of my theories, but it only takes one experiment to disprove them.

 

[joe1347]

This is a point worth stressing : the world isn't getting warmer because the air suddenly got wetter. The air gets wetter in a warmer world. Something else has to cause the warming.

It's a simple enough point. That has to made over and over and over again ...

Sorry, I don't have a good source. But from 'academic' memory. I recall that CO2 in the atmosphere absorbs long wavelength incident sunlight and converts it to heat. Hence, the more CO2 in the atmosphere, the more the earth is 'heated'. Therefore, any man-made (or natural) CO2 emissions that increase the ppm CO2 content in the atmosphere will cause the earth to warm up. I would assume the scientists can measure (closely estimate) how much CO2 'man' is pumping into the atmosphere in ppm and then directly predict how much the earth will warm up.

To my simple mind, this doesn't seem to be a difficult concept to grasp. I would think that science can also make reasonable long range (decades out) predictions on atmospheric CO2 (ppm's) and then translate that directly to how much the earth will warm up over the next century.

I would think that the more complex and challenging part of the analysis would be to predict what are the overall effects from both increased CO2 concentation and a warmer earth.

 

[Shabaz]

I would think that the more complex and challenging part of the analysis would be to predict what are the overall effects from both increased CO2 concentation and a warmer earth.

What you're describing here is pretty much exactly what climate model science is all about. Which is indeed complex and challenging, and has to account for a lot of different forcings and cycles and feedback and other factors, and how they all interrelate to each other. But that is exactly what the modellers spend their time on doing, and while the models are not perfect, they have at this point a high enough predictive value to make meaningful statements based on them. RealClimate.org has some interesting articles on climate modelling, but you'll have to look them up yourself, since I can't link anything yet.

 

[Soapy Sam]

Absolute nonsense. The Martian ice caps are well-known for their variability. They're frequently barely even there.

So are Earth's. Longer cycle is all.

 

[jimecallaw]

hmm! the explanation I heard for greenhouse gases was they let through visible light radiation, but block infra red radiation. So we do not lose heat to space. however if they block infra red radiation, this would seem to imply that the sun doesn't send much infra red radiation our way, or the greenhouse gases would cool the planet, I have come across contradictory sources as too the extent of the infra red radiation hitting the earth.

But even given that only a small amount of infra red radiation came from the sun, and the greenhouse gases were trapping infra red radiation from earth, wouldn't this only be a temporary effect, similar to going outside with an overcoat on. In the long term surely the temperature must be dependant more on the suns output, our distance from it and the absolute zero of space.

grateful for any answers, as you can't ask these questions to textbooks or newspaper articles

 

[a_unique_person]

So are Earth's. Longer cycle is all.

Except it shouldn't be happening at the moment.

 

[CapelDodger]

Sorry, I don't have a good source. But from 'academic' memory. I recall that CO2 in the atmosphere absorbs long wavelength incident sunlight and converts it to heat.

That's a very minor contribution. Most of the incident solar energy is at short wave-lengths, the Sun has one damn' hot body. Just look at it (but don't stare) and you'll see. The planet surface absorbs most of that, it just zips through the atmosphere as if it wasn't there. Not so easy to ignore a planet.

Hence, the more CO2 in the atmosphere, the more the earth is 'heated'.

The Earth is no way near as hot as the Sun, so that's where the long-wavelengths come in (or go out).

Therefore, any man-made (or natural) CO2 emissions that increase the ppm CO2 content in the atmosphere will cause the earth to warm up.

Will tend to cause the Earth to warm up. Other, cooling influences could be dominant so actual warming might not occur. Other factors being equal, the higher the proportion of CO2 in the air the higher the global temperature will be.

I would assume the scientists can measure (closely estimate) how much CO2 'man' is pumping into the atmosphere in ppm and then directly predict how much the earth will warm up.

Scientists can (and do) measure the CO2 concentration, and it's rising at about 2ppm per annum, and is 380ppm for round numbers. What they can't predict is how that's going to pan out over the next few decades. Will growth stall in China and India, or not? What about Brazil? What about Western economies, the Middle East, Indobloodynesia, all the rest of it. And climate change going on at the same time. Science can provide extrapolations in some cases, but extrapolating through that lot is too much to ask.

To my simple mind, this doesn't seem to be a difficult concept to grasp. I would think that science can also make reasonable long range (decades out) predictions on atmospheric CO2 (ppm's) and then translate that directly to how much the earth will warm up over the next century.

See above. How can climate scientists be asked to make predictions about Chinese coal-consumption in ten years time? Compared to Europe and the US, those guys are just getting going. They still have mountains of the stuff. Or perhaps Chinese growth will be revealed as a paper tiger and those mountains will stay where they are. Science can't help us there.

I would think that the more complex and challenging part of the analysis would be to predict what are the overall effects from both increased CO2 concentation and a warmer earth.

The feedbacks from any climate forcing do present the great challenges.

 

[CapelDodger]

So are Earth's. Longer cycle is all.

The Earth's ice-caps haven't melted for millions of years, Martian "ice-caps" have been and gone in the few centuries we've been observing them. So a vastly longer cycle, that can have no bearing on current events. On this planet. Where stuff is very visibly happening. And CO2 is at 380ppm. Uncharted territory.

 

[rockoon]

But then again, there hasn't been 380ppm of CO2 in the atmosphere until very recently so it's hardly surprising that this cycle is bucking the trend.

Liar.

Need a source?

Stop making things up!

 

[Shabaz]

Liar.

Need a source?

Stop making things up!

Where did that come from?

Far as I know he's absolutely right in the claim that there wasn't a C02 concentration of 380ppm until fairly recently. I suppose if you take his statement as him saying that 380ppm is absolutely unprecedented in the history of the planet and then go far back enough it might've happened before, but with a more common sense interpretation of what he was saying he really wasn't misrepresenting the data we have on atmospheric CO2 concentrations.

To copy-paste another IPCC AR4 SPM chart:

 

[rockoon]

Where did that come from?

Far as I know he's absolutely right in the claim that there wasn't a C02 concentration of 380ppm until fairly recently.

Well its absolutely demonstrably wrong. He has a track record of taking a small bit of narrow factual information and blowing it up into a big fat lie -> Drawing a much much (much) greater conclusion than the evidence permits. Converting a period smaller than an eon into an eternity is just one example.

Would it suprise you to know that during some ice ages, there has been more CO2 in the atmosphere?

Would it suprise you to know that in the past the atmosphere was at least 50% CO2 (a lower limit for the period, based on evidence .. btw, 50% = 500,000 PPM)

Facts such as these begs the question of how significant the 380 PPM figure is.

The story CapelDodger tells is that 380 PPM is unprecidented; that humans have pushed the atmosphere into new and dangerous territory. The facts are different. This isnt "uncharted territory" as he puts it. This is infact charted territory.

While 380 PPM is certainly higher than it was 500,000 years ago, we do have evidence of what the planet was like when it was much higher than it is. We know that the green house effect did not 'run away' with itself due to a mere 380 PPM, or 1000 PPM, or 10,000 PPM, or even 100,000 PPM. This is Earth, not Venus.

A rational debate on the subject would consider similar circumstances in the past. This is especialy important when we cannot directly test the theories on the table. The past holds a record of repeated tests for us.

While computer models have been developed that correctly mimick some of the climate in the past, we cannot conclude that they will correctly predict the future. It is dangerously similar to a "self-weighting strategy." There is more than one set of tunable parameters that mimick the data that they are trying to mimicked. More than one solution. More than one conclusion.

We have actual data to work with and we shouldn't ignore it (or declare that it doesnt exist.)

 

[Texastwister]

Living in England we know that the climate has been warmer than it currently is twice before in the last 2,000 years. once around 0 and again around 1,000 England was a big wine producer in those days and is starting to produce wine again now. Now what was the cause of the warming in those days, and more importantly those times seem to be a relatively good time for human life, with no mention of increased storm activity or raised sea levels.

This is one of the kinks in their armor, so your not likely to get an answer. They will ignore it or say it didnt happen.

 

[a_unique_person]

Kink in what armour? The scientific debate is still going on about the details of the hisotry, but we know the temperature is going to keep rising well past those levels, this will be uncharted territory.

 

[Shabaz]

Well its absolutely demonstrably wrong. He has a track record of taking a small bit of narrow factual information and blowing it up into a big fat lie -> Drawing a much much (much) greater conclusion than the evidence permits. Converting a period smaller than an eon into an eternity is just one example.

OK, I'm new here, and I don't know your posting history or his. But you seem to be doing a lot of interpreting on just a couple of words from him, where it seemed obvious to me what he was referring to, and putting a lot of words in his mouth. I dunno, maybe you expect him to say such things as "380ppm is unprecedented in all eternity" based on past experience with him, but I didn't see him making such overstatements in this thread.

Would it suprise you to know that during some ice ages, there has been more CO2 in the atmosphere?

Would it suprise you to know that in the past the atmosphere was at least 50% CO2 (a lower limit for the period, based on evidence .. btw, 50% = 500,000 PPM)

Facts such as these begs the question of how significant the 380 PPM figure is.

Well, they raise the question, if you want to be pedantic.

And to answer the question to the best of my knowledge: it's pretty significant. I'm not quite sure what you're saying here, that the rise to 380ppm is not because of us, but because of natural processes? That CO2 won't have the amount of climate forcing it is said to have? Because far as I know neither are true, and I'm not sure in exactly what way you're suggesting that the rise to 380ppm isn't as significant as it is made out to be. Maybe you could help me out here?

The story CapelDodger tells is that 380 PPM is unprecidented; that humans have pushed the atmosphere into new and dangerous territory. The facts are different. This isnt "uncharted territory" as he puts it. This is infact charted territory.

Just to be clear, he didn't use the word unprecedented, that was me. And the type of very rapid introduction of a massive amount of CO2 as we're doing now, I think that could be validly described as moving us into uncharted territory. I don't really want to debate by way of analogy, but I didn't think it was a terrible way to put it. And it isn't necessarily that we're pushed into dangerous territory as much as that there is a push, and that the change the push is precipitating is large enough and fast enough that it could be dangerous.

While 380 PPM is certainly higher than it was 500,000 years ago, we do have evidence of what the planet was like when it was much higher than it is. We know that the green house effect did not 'run away' with itself due to a mere 380 PPM, or 1000 PPM, or 10,000 PPM, or even 100,000 PPM. This is Earth, not Venus.

I guess I missed where someone said or implied that the green house effect would run away or that earth would turn into Venus in this thread. I'm not trying to wilfully ignore things here, honestly, but I'm again left with the feeling that you're putting words in people's mouths. Please help me see where someone either said this, implied this, or argued something that could only be valid if this was true.

A rational debate on the subject would consider similar circumstances in the past. This is especialy important when we cannot directly test the theories on the table. The past holds a record of repeated tests for us.

While computer models have been developed that correctly mimick some of the climate in the past, we cannot conclude that they will correctly predict the future. It is dangerously similar to a "self-weighting strategy." There is more than one set of tunable parameters that mimick the data that they are trying to mimicked. More than one solution. More than one conclusion.

Why can we not conclude any predictive power from models? Which models have been shown to be dangerously close to a "self-weighting strategy"? And why are you implying that the tests that are held in the past records are not exactly what is used to validate or falsify GCMs? Or has it been shown that their methods of validation are in error? Sorry to reply with so many questions, but your point seem predicated on a lot of what I know about GCMs to have been proved wrong when I wasn't looking, and maybe you can point out what I'm missing here.

We have actual data to work with and we shouldn't ignore it (or declare that it doesnt exist.)

I don't think that's being done.

 

[Alan Heap]

i've found a correlation between pet ownership and global warming. so please, slaughter kittens and pups, save planet earth! the possible causes are endless. if you said it was caused by santas increased delivery load, it would get scientific recognition. though at least other theories are cropping up, maybe a few more alternative theories will prevent loud mouths jumping to conclusions.

 

[Diamond]

Nobody is saying that there's a sole cause for global warming on Earth. Certainly not the climate scientists, anyway. They're saying that the dominant cause over the past few decades is greenhouse gas emissions from human activity.

Then they're a long way from proving it. Greenhouse gas emissions don't account for the 1940-1977 cooling, nor the cooling of Antarctica over the last 50 years, nor the delayed reaction of greenhouse gases to climatic warmth seen in the ice cores.

 

[a_unique_person]

That's because it wasn't the greenhouse gases causing the cooling, but pollution. The cooling over antarctica is caused by the disappearing ozone layer, which acts as a greenhouse gas.