Global warming

[iNow]

The earth will be fine. Humanity might not. What happens in the future depends largely on what we do today as a species.. a species which is increasing in population at an incredible rate. The earth will eventually find some sort of equilibrium, probably after a few hundred thousand years... but before that equilibrium is found there will likely be a great number of extinctions. The real question is whether or not one of those extinctions will include humanity, or if it's just going to be one ginormous mass extinction event.

 

A lot of it depends on what we do... right now... and how quickly/profoundly we change our ways.

[swansont]

Do you think the Earth is going to cool down? I mean... the Earth does cycle, and it WILL eventually cool down. (Hasn't the Earth been cooling lately anyways?) (And DON'T bash me for saying that. I don't know ANYTHING, that's y i'm here.) What do you think is going to happen in the long run?

 

The long run isn't the pressing issue. How we deal with what happens over then next generation or two is of a more immediate concern.

[PoWn3d_0704]

I'm pretty sure that some will survive at least. We're not going to just allow ourselves to become extinct. We will build shelters (such as the vaults in Fallout 3) and use the vast seed-banks to keep us alive. We won't go extinct, but if it gets to an unbearable point for humanity, many will die.... not all. Then we just repopulate. Think... they will probably charge to reserve a spot in these vaults... which means all the rich hot babes will be there. re population shouldn't be a problem

[JohnB]

Sorry for the delay, I've been away for the weekend.

 

Which period are you discussing, recent or deep history? You’re aware of global dimming after WW2?

Any of the previous cycles. If CO2 is a strong forcing agent, then what causes the temps to drop in the previous cycles? Something causes the temp to drop, even though CO2 continues to rise. Where is the large negative forcing? See what I'm getting at?

 

If however, CO2 is a weak feedback then in previous cycles it piggybacked on the Malenkovitch cycles. this would mean that when the forcing CO2 was "riding" disappeared the temps drop even though the oceans were still releasing CO2 allowing the amount to rise. (At least I think that's where the CO2 was supposed to come from, sounds reasonable to me.)

 

How ‘strong’ is strong? I’m strong compared to my 6 year old girl, but not so strong compared to a weight lifter.

Good question. The current AGW argument centres around this to a degree. (I think:-)) If CO2 is the primary forcing agent, then it must by definition, be stronger than any current negative forcings. The argument is that since it is a "strong" forcing we need to do something about it. If it were a "weak" forcing, then reducing CO2 would have only minimal effect on temps.

 

By analogy, if 40% of car accidents are caused by drunks and 1% by vehicle defects, then you do something about the drunks as that is the "strong" forcing. Doing something about the defects will have minimal effect on accident rates.

 

Your deep history Co2 graph is REALLY fascinating! If only I had more time for reading this stuff... it has sparked all sorts of questions. For instance, at the beginning of the graph the Co2 is off the Richter scale!

It is fascinating. Care should be taken in two areas though. Firstly, notice the shaded "estimate of uncertainty" area which gets huge as you go back in time. Secondly, (and this doesn't actually help my argument:D) I don't think that going back more than maybe 10 million years is a good idea. Even if everything else remains the same, continental drift must come into play by changing the pattern of ocean currents.

 

For example, I'm sure the ocean currents were far different in the Triassic period when the continents were arranged in this fashion.

 

Even at a "mere" 50 million years ago

currents would have been different. Notice that North and South America have yet to join and India is still in the middle of the ocean having yet to collide with Asia.

 

So I think going back too far is a mistake. Too many other factors are liable to mess up the picture.

 

As to the more recent past. Royer et al 2001 say;

a CO2 reconstruction based on fossil Ginkgo and Metasequoia cuticles for the middle Paleocene to early Eocene and middle Miocene. Our reconstruction indicates that CO2 remained between 300 and 450 parts per million by volume for these intervals with the exception of a single high estimate near the Paleocene/Eocene boundary. These results suggest that factors in addition to CO2 are required to explain these past intervals of global warmth.

(Emphasis mine)

Federov et al 2006 maje the comment in their abstract;

During the early Pliocene, 5 to 3 million years ago, globally averaged temperatures were substantially higher than they are today, even though the external factors that determine climate were essentially the same.

 

(You know, I'm really starting to hate paywalls.)

 

Presumably they include CO2 in their "factors".

 

Crowley and Berner 2001 say;

CO2 concentrations over the past 65 million years appear to have reached low levels well before the most recent phase (the past 3 million years) of Northern Hemisphere glaciation. This is especially true for times of elevated temperatures at about 50 to 60 Ma and 16 Ma, when CO2 was apparently low.

 

Bottom line, the record appears to show that temp and CO2 are not as closely coupled as we think.

 

The records also appear to show that in the last few million years, CO2 has crossed the 300 ppmv mark without a climate catastrophe occurring.

 

Thy system is nonlinear.

I'm aware of that, however CO2 concentrations and temps can be shown together on a linear graph. The graph is a generalised way of showing that temps can remain high even when CO2 levels drop. (But we should always bear in mind the second point I made to POL above.)

[swansont]

Bottom line, the record appears to show that temp and CO2 are not as closely coupled as we think.

 

The records also appear to show that in the last few million years, CO2 has crossed the 300 ppmv mark without a climate catastrophe occurring.

 

 

I'm aware of that, however CO2 concentrations and temps can be shown together on a linear graph. The graph is a generalised way of showing that temps can remain high even when CO2 levels drop. (But we should always bear in mind the second point I made to POL above.)

 

Bearing in mind that things were different in the past needs to be applied to all of the argument, though. I can imagine a feedback forcing haveing a different value if e.g. the albedo were different, which is probably the case when you rearrange the continents. Which means that showing that "CO2 are not as closely coupled as we think" is an invalid statement. It would mean that CO2 was not as strong a forcing in the past. Has anybody studied this and come up with a number? But if it is different, then all arguments based on the past values are moot.

 

Showing a logarithmic relation on a linear graph is deceptive. Yes, it can be done, just like showing a linear relation on a log plot can be done. But it shouldn't be done — it's misleading.

[JohnB]

It would mean that CO2 was not as strong a forcing in the past.

Interesting point. I'm operating on the basis that the CO2 forcing in "definitive" terms is a function of ppmv. As in the forcing of 500ppmv is the same whether now or 500,000 years ago.

 

The claim ATM is that CO2 forcing is very strong, I'm exploring for times when CO2 forcing might also have been defined as "strong". (Accepting of course that "strong is a relative term.)

[swansont]

Interesting point. I'm operating on the basis that the CO2 forcing in "definitive" terms is a function of ppmv. As in the forcing of 500ppmv is the same whether now or 500,000 years ago.

 

The claim ATM is that CO2 forcing is very strong, I'm exploring for times when CO2 forcing might also have been defined as "strong". (Accepting of course that "strong is a relative term.)

 

Well, alternately your model would have other forcings present, making CO2 less important. I'm not conversant enough with the details of the models.

[JohnB]

Well, alternately your model would have other forcings present, making CO2 less important.

I know I must come across as a "denier" at times, but it's simpler than that. If I'm told "If we cross 450 ppmv then... yada, yada, yada", the first thing I do is have a look at when similar situations occurred in the past.

 

To me, any theory that predicts disaster when a certain threshold is crossed must also explain why it didn't happen last time the threshold was crossed.

 

The further back we go, then the more likely that very different forcings come into play.

I ask questions, I read, I learn. So far I'm unconvinced. That's all. I'm not saying the pro side are wrong, simply that I'm unconvinced.

 

I honestly don't understand why the act of questioning seems to be a crime sometimes.

[Mokele]

I honestly don't understand why the act of questioning seems to be a crime sometimes.

 

Frustration / exhaustion. You may be genuinely interested in understanding at a deeper level, but 99% of those who "express skepticism" are doing so for partisan or economic self-interest with no real interest in actually learning anything. It's the same reason we're instantly suspicious of any sort of skeptical question about evolution.

 

We humans are inductive creatures - if the first 10 times we encounter something, there's a negative association, we assume that association is always there. In this case, we see so many shills for the oil lobby tossing about blatantly false claims that we become instantly suspicious of any skepticism.

[bascule]

I honestly don't understand why the act of questioning seems to be a crime sometimes.

 

You ask reasonable questions, unlike some people around here...

[GutZ]

I am wondering (based on the assumption that CO2 increase doesn't cause GW) is it something that can affect us in other ways? If it's not global warming is there something esle.

 

Also are we capable especially as growth of world population increase and other parts of the world start to industrialize....

 

How much pollution power do we have overall?

 

I am not skeptical of GW, If we predict to be a great possibility of happening, even if there is missing fact or something was done wrong and an tiny error cause us to look at it different.....

 

 

Is it just better overall to just stop polluting? Do we really need GW to motivate us? Or is it more that no matter what we do the earth will adjust for our activities?

[CaptainPanic]

I am wondering (based on the assumption that CO2 increase doesn't cause GW) is it something that can affect us in other ways? If it's not global warming is there something esle.

 

Also are we capable especially as growth of world population increase and other parts of the world start to industrialize....

 

How much pollution power do we have overall?

 

I am not skeptical of GW, If we predict to be a great possibility of happening, even if there is missing fact or something was done wrong and an tiny error cause us to look at it different.....

 

 

Is it just better overall to just stop polluting? Do we really need GW to motivate us? Or is it more that no matter what we do the earth will adjust for our activities?

 

You need motivation?

Check how much oil is being imported into whatever country you live in. (I know where Ontario is, but I write to a wider audience than GutZ ).

 

The money that goes to countries in the Middle East is enormous. In the Netherlands, at the current price of about 70 dollar / barrel, we pay 10-15 billion euro per year (all that money goes to other countries!). Coal and gas imports aren't included either, so the fact that the Netherlands has gas reserves is irrelevant for that number.

 

Money is a great motivation, and although I think that ecology in general is a fantastic motivation for sustainable energy, it is more important to stop giving money away. In stead, we should invest this enormous amount of money in our own country, or at least make sure that it's being spent usefully.

 

That is also one reason why I dislike bio-fuels from biomass: for many European countries, this would involve an import of biomass. Bad idea.

[GutZ]

lol no I don't need other motivations. I would think that polluting with earth with other chemicals and such might cause an effect later on, so regardless of the debate of GW I was seeing if it was point to argue because there are potential other life threatening problems that could come about as well...

 

More the fact that it's just a GOOD idea not to pollute. I know NOTHING about this subject so I mean I was see if that were the case or not, assuming GW is wrong (which it probably and most like is not) Does it really matter if we pollute.

 

example: Maybe at our current level there are no visiable affects other than GW, but say like acid rain or something but it becomes so strong that it's becomes harmful....I dont know you can see the lack of knowledge already coming out here.

 

That's more my point.

 

P.S.

 

You are from Nederlands by chance? I was born there and have a dutch name (Jeroen) but I am more Canadian than anything. I do drink nothing but grolsch does that mean anything?

[Tolmosoff]

Before we go into a global cool down then ( Global Warming ) would be a blessing like thousand of years ago. Our earth has a way of recycling itself back to normal temp.

Forget the Nuclear Winter syndome as said by global sience models.

Warm ocean water is what we desperatlly need to achieve Global Freeze.

 

I do believe that all fish will migrate to the actic and antarctic areas to survive.

Warm oceans cause lots of moisture and result in worldwide cloud cover to block off our sun to cause a global freeze, the weather never seen before like the days of Noah. After the flood and rain threw our world into a global freezer.

Oceans then lowered so man was able to cross the bering see land bridge.

 

I think the Nuclear Freeze proponents is stupid but a hot ocean will cool our earth with a mile thick Glasier on USA soil.

[Tolmosoff]

No global warming I'm just going by past Climate evolutionary times. After the dinosaur extintion.

Global warming has always created a Global freeze with Glasiers a mile thick of ice on USA that created our grand canyon.

With the ice age caused lowering of oceans and human migration across the berring land bridge.

Man has taken steps to prevent a Nuclear Winter proposed by global scientists of an all out war and sward rattling.

But a hot ocean can kill fish and ecco systemes under our ocean. Thats why I think that fish specie would migrate to cold water to servive its specie been put in to them by nature.

 

After the dinosaur extintion our world went into a deep freeze mode.

 

As for Co2 carbon emissions that will be a blessing to reverse our climate on global warming.

Our human activity can speed up our warming will be good. Well our oceans will rise and good by hawai and much of San Joaquin> Vallys agriculture.

 

I say there will not be a ( Nuclear Winter ) or asteroid headed to earth but our Ocean warming as before Noahs time of the great flood threw our earth into a global freezer and the two earth ends that are farthest from our sun will be unliveable in ice homes of the north and south thats farthest from the sun.

NO !!! Global imissions and global warming is good. For our earth can become a cool giant planet with ice again.

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Merged post follows:

Consecutive posts merged

Lets not pray for the shy to fall on us.

 

I'm just a scientist that has become a radicle in our ideas.

[iNow]

After the dinosaur extintion our world went into a deep freeze mode.

 

That also probably had something to do with that giant comet which struck the earth and caused said extinction. This is especially interesting since it illuminates how the cause of climate change back then is different from the cause of climate change now.

[JohnB]

POL, I haven't looked into that much and like you I keep hearing it's a long way off.

 

But, if we look at the record, (post #43) temps spiked sharply and then dropped. (The previous peaks appear to have lasted less than 1,000 years) On that basis, if anything I would have thought we were well overdue for cooling.

[Reaper]

But, if we look at the record, (post #43) temps spiked sharply and then dropped. (The previous peaks appear to have lasted less than 1,000 years) On that basis, if anything I would have thought we were well overdue for cooling.

 

 

Yes, it's supposed to be cooling right about now, with another ice age coming in the next few thousand years or so. BUT, it is not cooling down, it's warming up. It's warming up because of the large increase in CO2 over the past 150 years.

[SH3RL0CK]

Yes, it's supposed to be cooling right about now, with another ice age coming in the next few thousand years or so. BUT, it is not cooling down, it's warming up. It's warming up because of the large increase in CO2 over the past 150 years.

 

That response really does not address the question that JohnB brought up, which is: Why, in the past when CO2 levels greatly exceeded todays levels, the earth did not get correspondingly hotter; and also seemed to quickly cool down. As such, are there cooling forcing functions which we simply don't know about yet?

 

Also, is it really supposed to be cooling now? Or maybe not for another 3,000 years? The milankovitch cycles operate on geologic timescales...I don't think it is warranted to invoke these should the climate actually be cooling (or not warming as quickly as it should be). Just like I don't think it is warranted to assume (yet) global warming isn't happening because the warmest year (1998) is now over a decade ago.

 

http://en.wikipedia.org/wiki/Milankovitch_cycles

 

I think a big part of the answer to his question was presented in post # 46 by swansont:

 

So one problem here is that the values are presented on a graph with a linear scale, when the effects are not linear. A change from 200 ppm to 1000 ppm of CO2 is going to have the same effect on forcing as the increase from 1000 ppm to 5000 ppm. An ideal blackbody at 295K radiates almost 15% more energy than one at 285 K, even though that's only a 3.5% increase in temperature.

 

To play the devils advocate a bit, I'll ask: Would this imply there is a maximum temperature (22C) that the earth can realistically reach? Would this imply that there is no concern at all regarding global warming?

 

My short answers are 1) Yes there is obviously some maximum, and 2) No, there is certainly cause for concern (but not cause for panic). But I'm more interested in what others think about his question.

[CaptainPanic]

So one problem here is that the values are presented on a graph with a linear scale, when the effects are not linear. A change from 200 ppm to 1000 ppm of CO2 is going to have the same effect on forcing as the increase from 1000 ppm to 5000 ppm. An ideal blackbody at 295K radiates almost 15% more energy than one at 285 K, even though that's only a 3.5% increase in temperature. (from: post #46, by swansont)

My short answers are 1) Yes there is obviously some maximum, and 2) No, there is certainly cause for concern (but not cause for panic). But I'm more interested in what others think about his question.

 

I agree that there is a maximum.

 

Interestingly, the radiation might not be linear (it's a 4th order function) but many other processes are also not linear.

 

The evaporation of water (vapor pressure of water) is one example of a curve which follows a function that goes up faster than linear (they are often approached by higher order polynomials for a limited range). So, while radiation might be a 4th order function of the temperature, other aspects are also going up strongly.

 

A certain temperature increase might sounds insignificant, but it is significant when processes are not linear.

[bascule]

Why, in the past when CO2 levels greatly exceeded todays levels, the earth did not get correspondingly hotter; and also seemed to quickly cool down.

 

What specific time in the past are you talking about when "CO2 levels greatly exceeded todays levels"?

[SH3RL0CK]

What specific time in the past are you talking about when "CO2 levels greatly exceeded todays levels"?

 

JohnB provided this in post # 43. There were many times (albeit millions of years ago) when the ppm of CO2 were in the several thousands. On the same graph is the global temperature, which never exceeds about 23C as JohnB also pointed out.

[bascule]

JohnB provided this in post # 43. There were many times (albeit millions of years ago) when the ppm of CO2 were in the several thousands. On the same graph is the global temperature, which never exceeds about 23C as JohnB also pointed out.

 

You're talking about this graph:

 

 

and JohnB's associated comments:

 

This graph says maybe not. Even with CO2 in the thousands of ppm we idn't get greatly increased warming. This would tend to reinforce the idea that CO2 is not more than a "weak" feedback at best.

 

Well, let's see what a scientist has to say in response to the same graph:

 

http://rst.gsfc.nasa.gov/Sect16/Sect16_2a.html

 

The four major glaciations are shown on this plot at the same time as on the previous plot. What is especially interesting is the high CO2 content in the past. Assuming this is a generally reliable estimate' date=' the obvious point to be made: Carbon dioxide seems to have been much higher in the distant geologic past than at present - BUT LIFE SURVIVED AND EVEN THRIVED. (Also note: natural interglacials and alternating glacial advances both influenced life forms in each time span; some species disappeared and new species and even higher taxonomic levels emerged; thus, the current trends of loss of some life forms - cited as calamities induced by global warming - may in fact be natural consequences.

 

The above plot is too "coarse" to show one major temperature event that may be a precursor model to the projected rises due to global warming. At the end of the Paleocene - start of the Eocene, about 50 million years ago, there was an increase of about 10°C (18°F) over a span of about 10000 years. During this the Paleocene-Eocene Temperature Maximum (PETM), in North America tropical vegetation (e.g., Palmetto trees) spread as far north as today's Wyoming and Minnesota. A spurt in mammalian evolution resulted. The cause(s) are not precisely known but there was a notable increase in CO2, as recorded in the rocks. In the scenario so far reconstructed, life on Earth was affected but on the whole in a positive way. After about 80000 years, average temperatures began to drop and eventually in the last few million years polar ice formed and survived, leading to glaciation. Whether PETM implies that mankind can survive, and perhaps prosper, such changes, has not been settled to scientists' satisfaction. At first glance this would seem to score one for the anti-global warmers who say "don't worry". [b']But, keep in mind the time frame: over 10000 years, the averaged rate of increase is only 0.18° F per 100 years - far slower than the present and forecast rates that are now several degrees in the 21st century.[/b]

 

This paper implicates CO₂ as the forcing responsible for "Earth's only recorded icehouse-to-greenhouse transition" during the late Paleozoic, and the forcing responsible for "turnover to a permanent ice-free world".

Edited July 2, 2009 by bascule

[Reaper]

Reaper, is it really supposed to be cooling? Who said?

 

It was mostly from hearsay. I know it's not the most rigorous of sources, but from what I've heard, the ice age cycle is supposedly still ongoing. The figures I've seen for the occurrence of this future ice age ranges anywhere between the next 3000 to the next 8000 years....

 

Regardless of what the actual evolution of Earth's climate was supposed to be, it is clear that humans have had a significant impact in the last 10,000 or so years.

 

I know Tim Flannery said that the climate was very "fragile" and on a knife's edge, slipping into and out of glacial periods every few thousand years before we invented agriculture. That change seems to have created the "holocene" a human geological time frame in which we influence climate. Some papers (quoted in "Weather Makers") suggest it was the worldwide increase in methane as various bogs and rice paddies and even aboriginal water-practices that lead to the climate not so much "warming" as stabilising.

 

I'm not to familiar with those papers, do you mind linking to them?

[JohnB]

A few points.

 

SH3RLOCK.

 

One should always be careful when using graphs. The one I posted showing CO2/ Temps over millions of years was for 2 reasons.

 

1. It illustrates that an increase in CO2 even to very high concentrations would not appear to result in Earth becoming like Venus. Hence a terminal runaway greenhouse effect is not on the cards.

 

2. To illustrate the apparent "limit" of temp rise. Because of the long timeframe, it would appear that the limit is independent of CO2, continental drift or other variables.

 

However there are caveats to this. Firstly due to the long timeline, resolution is lost so comparison to modern records except in general, would perhaps not be a good idea. Secondly, the "limit" may be an artifact and not a true reflection of the temps way back then. I"m not fully conversant with the techniques used, but it is at least possible that the techniques simply do not recognise temps above 23 odd degrees over the timeperiod.

 

My observation of the apparent "limit" is nothing more than that, an observation that I find interesting.

 

For the above reasons and as demonstrated in post #63 forcings in the far distant past were so different from modern times that (again except in wide generalities) meaningful comparisons could probably not be inferred.

 

Peak Oil Man,

The way I read the graph in #43 is that the temp peak (blue line) has been very short (and some degrees above current temps) lasting for only 1,000 years or so followed by a drop to a 100,000 year glacial period. (give or take)

 

The current cycle is different though. Firstly the glacial was longer than usual by 10-15,000 years. Secondly the temps stopped rising some 12,000 years ago and have stayed remarkably level, moving up and down over about a 4⁰C range.

 

Tim Flannery loses me when he speaks of "balance". The Earths climate and ecosystems never have been, are not now and never will be in "balance". His basic assumption is incorrect.

 

Reaper,

I see where you're coming from and would be inclined to agree except for the fact that this cycle is different from the others and I've yet to see a good explanation why. On the basis of previous cycles it should be cooling now, yes. But also on the basis of previous cycles, it should not have stopped warming some 12,000 years ago.

 

There is an argument going around that human agriculture over the last 10,000 years or so has effected climate to prevent the cooling. I would call this wishful thinking at best.

 

When we look at a population graph

 

It strikes me that for the idea to have credence, then the effect of some 30-50 million subsistence farmers in 10,000 BC would have to be roughly the same as 200-300 million people in 1,000 AD. I think we can call this "unlikely". For those subsistence farmers to have such a great effect (stopping the cooling cycle) then the climate would have to be extremely sensitive to such things. If this were the case, then we would have seen far greater impacts in the past 4-5,000 years.

 

We do not, therefore the climate is not extremely sensitive and therefore the change to farming did not prevent the start of the cooling cycle.

 

I would add that the hypothesis that early agriculture prevented the cooling does not address in any way the fact that warming stopped at around the same time. How would subsistence agriculture act to stop both a warming and cooling cycle?

 

But then is not now, is it? The debates in these pages are not about whether CO2 can cause warming, because of course it can. The question is better phrased as "How much of the current warming is attributable to CO2?" A totally different question.

 

When we model or project the future we make certain assumptions. Specifically the IPCC and (AFAIK) modellers make a basic assumption that climate will not change appreciably except as a result of exernal forcings. We test models in this fashion, if we don't vary the external forcings and the model runs stay roughly level (trendless) then we view the model as reasonable.

 

I believe, but cannot prove (except logically) that this assumption is false. The climate can change by only internal forcings and it can do so on a short time scale.

 

It's easy to demonstrate on a long time scale. Referring back to this graphic;

 

We can see that the Americas have yet to join. What many people don't realise is that now, the sea level on the US East coast is substantially higher than that on the west coast. The reason is that the world turns and the water bulges up on the east coast. As we can see from the illustration, with the Americas separate, the water can flow through the gap. Once they join however, the Pacific and Atlantic become separate oceans with an obvious vast change in circulation patterns.

 

This of course happens on geological timescales and the effect is over millions of years. The point is though, that even if every external forcing remained exactly the same, there would be a major shift in ocean currents and a resulting major shift in the Earths climate.

 

Could this happen quickly? Easily. A volcanic island can be born in a matter of days. To think that this doesn't disrupt the currents is fanciful. In turn this might effect cloud formations and lead us to cross one of James Hansens "tipping points" leading us to abrupt climate change. Again all through internal forcings only.

 

bascule,

 

All respect to Dr. Mitchell K. Hobish, but I think he is being misleading at best.

The above plot is too "coarse" to show one major temperature event that may be a precursor model to the projected rises due to global warming.

This translates to me as "My proof relies on something you can't see because the graph is "too coarse"." I don't see that as much of an argument. Would any scientist accept the argument "The proof is there, but the graph just doesn't show it"?

 

But, keep in mind the time frame: over 10000 years, the averaged rate of increase is only 0.18° F per 100 years - far slower than the present and forecast rates that are now several degrees in the 21st century.

There are a couple of problems with this comment.

 

Firstly it gives the impression that previous climate changes were slow and spread over thousands of years. This is totally false and frankly he should know that.

 

The changes connected to the YD period were faster and greater than the changes in the last century. (Some 3⁰C over 40 odd years IIRC.) Anybody who has looked at temps over the Holocene knows this, it's basic. So why is it misrepresented?

 

Secondly, note the mix. He compares known temp changes in the past with theoretical predictions in the future. This is knowingly comparing apples and oranges to give a misleading result.

 

I note in passing that he also seems quite reliant on broken hockey sticks.

 

Also since we now have a 30 year record from the satellites, it might be worth seeing what they say.

http://www.junkscience.com/MSU_Temps/UAHMSUglobe-m.html

 

Would you say that the UAH MSU is showing "unprecedented" warming over the last 30 years? For that matter, would you say that they show even "unusual" warming?