From a surprisingly even-handed article in The Guardian:
... recent studies have suggested part of the West Antarctic ice sheet is indeed unstable, triggered by warm water flowing onto the continental shelf for at least a few decades. We don’t yet know if humans have made this more likely, and until now we also haven’t had confidence in predictions of how much sea level rise could result from this region and others that could become unstable from climate change.
The Intergovernmental Panel on Climate Change decided in 2013 there was insufficient evidence to make an assessment any more precise than “it would not exceed several tenths of a metre” this century. We predict Antarctic ice sheet instability will most likely contribute 10cm sea level rise by the end of the century but is extremely unlikely to contribute more than 30 cm. So ‘several’, for us, is ‘about three’.
The author goes on to say "Does this mean climate sceptics should be dancing in the aisles, because our study rules out these very high contributions? Not at all."
If we are dancing, some will be dancing barefoot, obviously, because that extra 10cm of water will have made their shoes and socks wet.
Nope - it was ridicule
53 minutes ago
35 comments:
50:50 chance it will exceed 12cms though!
The overall sea level rise due to all sources is reckoned at 42-80cms. Enough to require a complete change of garments.
That's quite a lot. " More than 1 million people living in the Ganges- Brahmaputra, Mekong and Nile deltas will be directly affected simply if current rates of sea-level rise continue to 2050 and there is no adaptation. "
In fact certain places already are being affected.
http://www.grida.no/graphicslib/detail/population-area-and-economy-affected-by-a-1-m-sea-level-rise-global-and-regional-estimates-based-on-todays-situation_d4fe#
And then, to use a different analogy there's the Syrian civil war, which may well have been set off by a drought, exactly the expected sorts of effects.
... Exactly the sorts of effects that are expected.
Anyway, it's not particularly news that ice melt and sea level rise should take a long time, so perhaps we can invent something in time for that. But it aint the only effect. I'm guessing that we'll in the end have to pump the CO2 back out of the atmosphere again and if we do it will be seriously pointless use of energy (it's much more energy required to get it back and make coal or co2-in-rocks again than there was in the first case.
Anyway we should stop using oil to stop giving Saudi loads of cash. QED. No further argument needed.
Antibiotic resistant bacteria will save us: they'll wipe out half the human race, which will halve energy consumption.
Yours cynically . . . .
Perhaps, but humans are good at solving problems. We've got some environmental problems to solve. As for antibiotics, it's the same sort of problem - plenty of innovation in the private sector, but not enough in the public sector..... We simply need to find a way of putting well focused money into collective problems. The scientists are doing their bit, better public policy needs to do its bit too. Sorry to sound a bit wide-eyed but surely, it's simple; there are problems that need fixing and we need technology and good policy to solve them, no?
As for population, to the degree dto which modernism is taking over, there's a massive change in fertility -- look at South America - amazing change in children per adult. Africa, India and the Arab world are the main major flies in the ointment another need for ideology change. As for ecological impact take a big number (world energy consumption) you 'just' need to make sure you multiply it with a number close to zero (impact per J of energy). Nuclear energy and solar in deserts are the big ones. Financial incentives across the board, massive energy, think big. It's only Saudi Arabia and their friends in the corporate world and the American Right that are stopping this by all sorts of means, some foul some fouler.
Anyway, I think most people don't understand economics properly. They tend to conflate social profit, economic activity and efficiency. Economists costs are opportunity costs, whereas the media actually cares about activity, whereas what we should really care about is social profit. You are both (Ralph and Mark) super smart people from what I read, so I won't explain myself right now since I've got to get to Oxford to talk about the link between money issuance and Land Value Tax..... More soon!
Oh and the greens. They are the worst enemies of real realistic action to tackle climate change. Absolute nightmare. Don't live in the real world of who has what interest.And care more about warm fuzziness. Clowns to the left, jokers to the right.... :((
We know that the climate is changing, and that's about all we know. We don't even know, overall, if the Earth is getting warmer, and we certainly don't know what's causing it if it is. We have some theories, and they appear to fit some of the facts but, to quote Voltaire, "Whilst doubt may be uncomfortable, certainty is absurd".
Well it depends what you mean by doubt. There's certainly a large degree of risk to our actions, that's for sure. But it's a complex picture best summarised by the relevant experts.
I think what many people fail to realise is the difference between a small change in termperature (e.g. from one day to the next) and a whole shift in all the distributions caused by a huge additional quantity of energy being put in the distribution. Shifting the mean of a whole series of distributions can make what seem like extreme weather events normal.
There's a massive lag (associated with the inertia of energy infrastructure), like having a car with brakes that don't work.
It's not just climate change. CO2 causes a reduction in the alkilinity of the oceans, with impacts on the marine food chain. This is a blue planet, so this is probably a big deal. And burning oil gives money to fundamentalists which destabilises our world. Indeed it's likely that drought is one of the causes of the current Syrian conflict, and climate change is likely to cause drought in exactly the same sort of regions as Syria (by extending the 'desert zone' north and south).
Assessing this and working out 'how bad' is not easy. But we can try. A realistic risk of a range of outcomes some very bad, some a small improvement, is not the same as fundamental uncertainty as to whether something is real or not.
By doubt, I mean a reasonable suspicion that we might be wrong, that what looks like causality could actually be coincidence or the causality could be in the opposite direction. Yes, we have been burning more fossil fuels and yes, until the end of the C20th the global temperature was rising and yes the amount of CO2 in the atmosphere was rising, too and yes, a mechanism that could explain how more CO2 might cause the temperature to rise was formulated, but nothing has been proved beyond doubt. Rising temperatures could be the cause of the additional CO2, not the other way around. Some other mechanism, like for instance, the sun giving out more energy could be causing the warming.
Doubt is an essential part of all science. If you want certainty, you need religion, not science.
"And burning oil gives money to fundamentalists which destabilises our world."
I don't think the Christian fundamentalists in the USA who have done so much to destabilise our world since the second world war would have been much better if the USA didn't produce so much oil. OTOH they couldn't really have been much worse.
You just have to look at history - climate change scaremongering first took off about the same time that the Soviet Union collapsed. Everyone realised that the promise of wealth under communism was bogus, so the statists had to find a new mantra and they switched to "the state must control consumption for our own good".
I'm not even a "denier". I suspect the models aren't very accurate yet, but at worse, less people will die in 100 years from climate change than from malaria or dysentery. Yeah, we might lose Tuvalu, but so what? Is it worth spending billions to protect 10,000 people, or cheaper to just re-home them? Even if we lost a couple of miles of coastline, it would be irrelevant. It would be the Lex Luthor situation - people living 5 miles from the coast in LA would find their land values rising. There's plenty of land in the world.
This weekend is the first in the new Ice Age.
Nah, you've just got our weather. It's unseasonably warm for the time of year here in Calgary. We should be feet deep in snow by now. But hardly a flake.
So I understand 'sceptics' typically think that climate change and the greenhouse was invented in the 1970s and that it's basically about looking at graphs showing (alegedly) that the climate is warming (like the 'hockey stick'). And your not convinced by that line of argument - is that a fair assessment?
To repeat, the assumption is that this is a whole set of bogus science based on some interpretation of temperature records foisted on an unsuspecting public. And because you think the whole thing is bogus, and especially the IPCC, then you won't really be interested in reasoning about it.
Broadly speaking this is a complete straw man, but I understand why you hold this view. The greenhouse effect is physics. Without it the average temperature would be about 14C below zero rather than around 14 above. CO2 keeps heat in, and a warmer world holds more water vapour, which is also a greenhouse gas. That's not uncertain. If you deny the greenhouse effect I suggest going to Venus for a summer holiday. Good luck!
I'm very keen to talk to and engage with Skeptics. If some of you are around in London sometime, I'd love to socialise. I could present my opinions on the science from a semi-educated perspective (1st class degree in physics from Cambridge; spent a couple of years on the issueing). Blog commenting is a poor use of time, but very happy to engage in person after Christmas. You can get me at info@stephenstretton.co.uk
Cheers and enjoy Venus!
SS, I used to believe in global warming, but once I started looking into actual explanations, the whole thing seemed to be made up.
We have discussed this face to face. The extra 28C of temperature at earth's surface is of course down to the atmosphere, namely atmospheric pressure. The earth's surface is warmer than otherwise but the top of the atmosphere is cooler than otherwise,
But that atmospheric pressure is down to the sheer weight of the air pressing down. it makes not much difference whether it is N, O or CO2 pressing down.
Also, when it's a cloudy night, it's warmer than a clear night. We have all observed this and it can be easily and plausibly explained.
These effects are more or less instantaneous.
Now, to C02….
If there were any sort of link between rising CO2 and higher temperatures, then it would have manifested itself by now.CO2 ppm have doubled or whatever over the past few hundred years or whatever, if it was going to do anything nasty it would have done it by now.
And don't give me this "tipping point" nonsense, the effect is the opposite, C)2, to the extent it can push up temperatures at all, would push them up "a lot" for the first incremental increase, then "a bit" for the next increase then "hardly at all|" for the next and then "effectively zero" for the next.
"You just have to look at history - climate change scaremongering first took off about the same time that the Soviet Union collapsed. Everyone realised that the promise of wealth under communism was bogus, so the statists had to find a new mantra and they switched to "the state must control consumption for our own good".
I think that it was not so much that, but, for the irreligious, there needed to be a new bogey-man, something that was causing our problems and that we, the little people, could do something about if we only believed, followed the right way of living and exhorted our leaders to do likewise. If it walks like a religion and it quacks like a religion....
"CO2 keeps heat in, and a warmer world holds more water vapour, which is also a greenhouse gas. That's not uncertain. If you deny the greenhouse effect I suggest going to Venus for a summer holiday."
CO2 has a relatively minor effect as a "greenhouse gas". As you say, the "greenhouse effect is physics". If you look at the physics, as explained in a handy little diagram put out by the IPCC, how the effect works is that the molecules of CO2 scatter the outgoing infra-red radiation, bouncing some of it back to earth. But only some of it. The more CO2 you have, the more radiation is scattered, but the more is likely to hit another CO2 molecule on the way down and be bounced back onto an outgoing path. Also, by far and away the biggest "greenhouse gas" is water vapour, which is why clouds keep in the heat.
Venus is a red herring, and an excellent example of coincidence not being causality. Venus is a lot closer to the Sun and has a completely different atmosphere. It is made up of 96% carbon dioxide. Oxygen can not be detected even as a trace element. At the surface the atmospheric pressure is 92 times that of Earth. That's about as different from Earth's atmosphere as the bottom of the ocean.
Anyway, the biggest argument, as far as I am concerned, against any global warming being caused by human activity, is that if that were the case, the Earth would now have to be warmer than it ever was any time since it was created, otherwise, how do we know that the same mechanisms that warmed it then aren't warming it now? Since we know that, even in relatively recent geological time, the Earth was a lot warmer than it is now, there has to remain the possibility that there is some other effect at play. Given that NASA has reported that the polar icecaps on Mars shrank as the Earth warmed up, that suggests that it might just be that the Sun was giving out more heat.
Mark, yes the temperature goes down as you go up in the atmosphere. http://www.atoptics.co.uk/highsky/htrop.htm
It would carry on decreasing all the way to absolute zero if there was nothing else going on (if we had a purely convective atmosphere without radiative transfer, which becomes dominant at higher altitudes). But it's not the top of the atmosphere that absorbs and re-emits radiative heat, but the surface. The atmosphere largely either reflects or transmits incoming radiation. (The incoming radiation is more high-energy (visible and UV) whereas when the Earth re-emits heat it's lower energy (IR dominant), and therefore gets captured by the IR bonds.)
Your argument would be fine so long as the earth had a black shell at the top of the atmosphere (with presumably no greenhouse effect above that). That would then be the point of black-body equilibrium, rather than the surface. Then we'd expect the surface to be a higher temperature according to the standard adiabatic lapse rate. But clearly we don't have a black top of atmosphere.
Anyway, this is all old news: Joseph Fourier worked it out in 1820: https://en.wikipedia.org/wiki/Joseph_Fourier#Discovery_of_the_greenhouse_effect
Arhhenius quantified it in 1900: https://en.wikipedia.org/wiki/Svante_Arrhenius#Greenhouse_effect
There was even a period of 'scepticism' in scientific circles between 1900-1940 -- there's a potted history here: https://www.aip.org/history/climate/co2.htm#Sk
This stuff is hard, but it's science -- and one of the hardest parts of science at that. But most of the sceptic talking points are just bullshit. I'm very open to any real arguments - I'm 99th percentile in open mindedness, including to unopen ideas!!! - But I still haven't seen any scientific arguments that pass scrutiny of 1st year university Physics.
Oh and back to the sea level rises: http://uk.businessinsider.com/cities-exposed-to-rising-sea-levels-2014-4?r=US&IR=T
And will we really be able to stop it, if the 4-5m from Greenland and a similar amount from West Antarctica. I know we can potentially pump stuff out of the atmosphere, but stuff that starts slowly is also hard to stop. A lot of the historical places would be eventually swamped. What
And all the scepticism relies on the notion that it would be dreadful giving up fossil fuels. But anyway, burning fossil fuel involves giving vast quantities of money to terrorist-supporters/sympathisers.
But of course, a few fired up weather bloggers and their media supporters know better than people who actually study this for a living, right? Just sow doubt on the scientists and science will go the way of economics.
"Imagine that the natural sciences were to suffer the effects of a catastrophe. A series of environmental disasters are blamed by the general public on the scientists. Widespread riots occur, laboratories are burnt down, physicists are lynched, books and instruments are destroyed. Finally a Know-Nothing political movement takes power and successfully abolishes science teaching in schools and universities, imprisoning and executing the remaining scientists. Later still there is a reaction against this destructive movement and enlightened people seek to revive science, although they have largely forgotten what it was.."
@Bayard, I'm glad we agree (a) that CO2 is a greenhouse gas and (b) so is water vapour. Of course, then we agree that a warmer atmosphere holds more water vapour, (an amplifying process). (The remaining question (if we try to model climate change) is clouds - do they hold heat in, or do they reflect more?)
(Very) broadly speaking, then, we are on the same page on the underlying physics.
Then it's just a debate about how bad it will be(both in physical, biological and economic terms), which is a vast difficult question beyond the scope of a single comment, but that others have attempted to estimate. E.g. IPCC, Stern review. We can all argue the toss on this stuff, but my perspective is that we should be using technology and taxes to fix this problem. Coal and oil are old technologies and should be made obsolete asap.
There's already some tipping points potentially reached (e.g. West Antarctica perhaps); but a 'tipping point' should not be seen as a runaway to a ultra hot world. Remember that the underlying Stefan-Bolzman law emits radiation at temperature to the fourth power. This is a pretty powerful driver to avoid us getting a 'runaway' effect.
I mentioned Venus because it's warmer than Mercury despite being much further from the sun, thus showing the effect of Venus's greenhouse effect - I wasn't trying to compare it to Earth. It was simply to show that obviously, there is such a thing as the greenhouse effect! Otherwise the temperature of Venus would be between Mercury and the Earth's moon, not hotter than Mercury all day long.
We care about hurricanes and droughts more than a small change in average temperatures. A small shift in the mean of a distribution can lead to a much greater change in the frequency of two- or three-standard deviations extreme events. That's the worrying thing. And the Syria conflict is exactly the sort of thing that we might predict when occasional events become regular.
SS, just because CO2 and water vapour are both greenhouse gases doesn't mean to say that CO2 has any effect in the concentrations in which it exists in the earth's atmosphere. For all we know, it might be water vapour doing all the work. Thus it is not certain whether an increase in air temperature is the result of an increase in CO2, nothing to do with an increase in CO2 or the cause of an increase in CO2. All we know is that, by and large, as air temperatures have increased, so have the CO2 levels. So we are not on the same page on the underlying physics.
Re Venus, yes it is warmer than Mercury, but then it has an atmosphere, which Mercury doesn't (well not significantly) and not only that , but it has a lot more atmosphere than we have, almost 100 times, so it would be very surprising if it was not a lot hotter on the surface of Venus than that of Earth or Mercury, regardless of what its atmosphere consisted of.
One thing we do know for sure is that the climate is changing. We know this, because it always has changed and, presumably, always will. Things may get a lot hotter, or they may get a lot colder. They could easily get a lot more hostile for the human race. That is a distinct possibility and thus a distinct risk. People don't like that sort of risk, therefore there is a very strong temptation to believe that there is something that we can do about it. Once you have that, then there will always be people coming forward to feed that need. When there is an incentive to make things up, things will be made up, especially in these days of the internet, when a lie really can be half way round the word before the truth has got its boots on.
B. " Venus is a lot closer to the Sun and has a completely different atmosphere."
As SS already explained the distance is not itself relevant here in comparing the principle of possible runaway greenhouse effect. Nor is the fact that no free Oxygen is found in today's Venusian atmosphere. Earth had none either for over a billion years until the early photosynthesisers got going.
Then this: "Anyway, the biggest argument, as far as I am concerned, against any global warming being caused by human activity, is that if that were the case, the Earth would now have to be warmer than it ever was any time since it was created, otherwise, how do we know that the same mechanisms that warmed it then aren't warming it now?"
It has long been known that the Earths land mass has changed dramatically due to ongoing continental drift and that during the Cretaceous period we had one huge southern land mass [Gondwanaland] and Pangea before that and land masses at both poles. That accounts for the much warmer temperatures. That's not a valid argument at all and if it's the 'biggest' argument as you claim then you really haven't considered it in much depth at all. Hardly surprising unless you were a full time scientist.
Fact is there are something like one in ten thousand papers in climate related peer reviewed journals [2011-13] which reject anthropomorphic warming. So no certainties just overwhelming evidence in favour of AGW that is supported by 99.99% of scientists working in the climate related field.
Is there a greenhouse effect on Venus? If the atmosphere is virtually opaque, how would it work? The greenhouse effect requires SW radiation to be absorbed by the surface and emitted again as LW radiation. How does the SW radiation reach the Venusian surface in the first place?
Whenever someone advances the alleged " 99% consensus" as a serious argument in the climate debate, you know they feel they are losing the argument. Here is an interesting blogpost about what happened to the drafting of the Second IPCC Report. In the prior reports, the scientists had been very cautious about attributing warming to any human influence. It was only in 1995 that any attribution statement was made and even then it was hotly debated. If there has been any real advance in climate science since 1995, it is not clear to me. The consensus estimate of climate sensitivity to CO2 has not changed. The "consensus" is just a political construct designed to keep the IPCC going.
P156, So what you appear to be saying is that a fluid containing 98% of a single gas behaves in the same way as one containing a few parts per million of that gas, that if atmospheric pressure on Earth was 92 times what it is at present, things would still be broadly similar and the difference between the temperatures of the atmospheres of Venus and Earth is entirely due to there being more CO2. Also that water vapour, at ten times the concentration in our atmosphere of that of CO2, has no real effect compared with that of CO2.
"during the Cretaceous period we had one huge southern land mass [Gondwanaland] and Pangea before that and land masses at both poles. That accounts for the much warmer temperatures."
How does it?
"When I've said it three times it's true" (Lewis Carroll). I am afraid that outside the "Hunting of the Snark", it make no difference how many people say the same thing and how many of them agree with each other, it doesn't make it any truer than if only one person says it. You only have to look at the sheer volume of words written about any of the world's major religions over the centuries to see that. You have no way of knowing if anything that has been written on AGW is true. It is impossible to trust anything you read 100%. There are only two options, doubt and faith. If you have the latter, you are not dealing in science, you are dealing in religion.
Paulc156,
Interested in the debate.One small point. You say:It has long been known that the Earths land mass has changed dramatically due to ongoing continental drift and that during the Cretaceous period we had one huge southern land mass [Gondwanaland] and Pangea before that and land masses at both poles
My understanding was that by the end of the Cretaceous the continents were practically in the positions they are in now. Give or take some land bridges.
B, well said.
If these scientists were so sure of themselves, why don't they tell us what the explanation is in such a way as a open minded person can understand it and accept it as true?
Nobody disputes for example that
thicker atmosphere = warmer surface temperatures
clouds at night = warmer surface temperatures
volcanic eruptions = cooler temperatures.
The explanations for these are fairly straightforward, the impact is fairly direct and fast and you can experience them yourself (OK, I have never been to the moon or to venus but am happy to accept that they are cooler and warmer respectively).
I used to believe in global warmening until I looked at the actual explanations and realised they were hokum, or at least wildly exaggerated.
AKH, that's the thing.
The way I understand it, some scientist worked out centuries ago that thicker atmosphere = warmer surface temperature, and this effect was referred to - for whatever reason - as the greenhouse effect. So in that sense, there very much is a greenhouse effect on Venus (and none of the Moon and very little on Mars).
M.Antarctica wasn't isolated until 35mya. That alone had a major cooling effect.
MW. Antarctica was only isolated 35mya. Hence only then a circumpolar current. That alone had a major cooling effect
PC, nice one!
We were actually discussing how likely it is and whether there is any evidence for the simplistic equation, hand made CO2 => global warming.
Now you've managed to drag this round to a side show about continental drift.
MW. 'simples innit'? Erm, no. Sorry but I was replying to Bayard's simplistic assertion that the Earth must have been cooler in the past if AGW were true ...but surely!!!
So with all due respect , away 'your' simplistic. ;)
Bayard. When one starts a post "so you appear to be saying..." and then go on to fill in the sentence I patently have not been saying it usually constitutes a nice big fat straw man is about to emerge, one which you batted down admirably. Even MW congratulated you.
Nooooo. You pointed out your big factoids in disqualifying the potential analogy of Venus and an earlier runaway greenhouse effect with that of Earth based on; no O in the atmosphere of Venus and Venus being much closer to the sun. i merely pointed out that the former was the case with Earth [no O for over a billion years]. End of. If you keep data mining skeptic websites for bits and pieces of info to support your argument you will get pulled up occasionally on the paucity of such arguments.
Furthermore, your self claimed "biggest" argument against AGW was that the Earth should not have been warmer in the past if AGW were true, yet it clearly has been been warmer. Therefore AGW is presumably wrong. QED!
Sorry but that is a joke and none the less so for MW's complaint about me muddying the waters [no pun intended]by referring to continental drift over the last 40-200 million years in particular to explain why the Earth is thought to have been warmer in the past.
So to summarise your argument, provided we ignore tectonic plate movements and subsequent Ocean formation etc the Earth should have been cooler in the past, and it wasn't, therefore AGW is falae ...
Graeme. Why did you reduce my statement that little more than one in ten thousand peer reviewed papers [99.99%] opposing the AGW argument to one in a hundred [99%]? You misquoted by a factor of one hundred.
Mike W. Actually the Atlantic was something like half as big at the end of the cretaceous and the antarctic was no isolated until as little as 35mya. Before that time no Antarctic circumpolar current and no ice sheet. so pretty major implications for global climate therein.
P156,
You have still failed to explain how an atmosphere that contains 97% of a single gas is in any way comparable to one that contains 397ppm (0.0397%) of the same gas, nor how an one atmosphere is comparable to another that has an atmospheric pressure 92 times greater. So Venus has no O2 in it's atmosphere? In what way is that relevant to the argument? You have also not addressed AKH's point about the clouds on Venus preventing short wave radiation reaching the surface in the first place, nor said anything about the role of water vapour.
Why is there all this concentration on CO2, when there is little dispute that H2O acts in almost exactly the same way and there is ten times as much of it in the atmosphere. Surely I may be forgiven for having the tiniest of suspicions that H2O is self regulating and doesn't fit the "Big bad oil" narrative, and there's no money to be made in trying to cut back on H2O production, compared to the multi-billion pound anti CO2 crusade.
Anyway, getting back to your comment, how are my facts about the composition of Venus's atmosphere factoids? Which one do you dispute and since when is Wikipedia a "sceptic website"? If you dispute what Wikipedia says about Venus, why don't you go and edit the article?
You still haven't explained how tectonic drift warms the Earth, apart from a bald assertion "it does". Please read before putting finger to keyboard. Nowhere did I say "Therefore AGW is presumably wrong. QED!" What I actually said was "how do we know that the same mechanisms that warmed it then aren't warming it now?" You then brought up the interesting theory that tectonic drift caused warming in the past. Yes, I'm interested in that, I've not heard it before, that was the sort of thing that I was referring to. Tell me more! Explain how tectonic drift warmed the Earth, or was it to do with the shape of the continents? I'm interested to hear a reasoned argument, but I'm very unimpressed with "it does".
PS Oh and when I saw "what you appear to be saying" I mean how it comes across to me and, possibly, others. I'm quite prepared to believe that what I said you appeared to be saying was not what you intended to say, but only you know that. I can only go by my own impressions.
Paulc156,
Above My question to you about the Cretaceous period period was a direct, honest question.Unfortunately, Google decided to ask security question and it was sent 24 hours later.So the discussion had shall we say moved on! By 'Little'I did not mean it sacastically. I am 'Agnosit',not a deniar, over the important question discussed in the whole thread. I replyed because I feel that you are perfectly correct to seek to incorporate Earth Science, broadly understood in the discussion. I also take your geology as a given fact:'southern land mass [Gondwanaland] and Pangea before that..'However,these are events are of 200 million years +.So I stand by what I asserted; the continents (given or take a few miles!)are pretty much where they had moved to by 65million years ago.So, I think your case is sound, for the last 65 million years it is a fact the Earth temperature on average has moved up and down and the location of the 'modern'oceans and land mass is central to this. Certainly for animal populations that once lived in a swamp but have to adapt to desert or ice sheets!My point is,but would a climate sceptic worry about this fact. Surely they take this as a given background too?
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