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Is global warming just about CO2?

Thu, 8th Aug 2013

Dominic Ford

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Dominic - Now, a paper which really caught my eye came out in the journal of Ozone holeClimate this week, looking at the environmental impact of chlorofluorocarbons or CFCs. Now, if you were following the news about 25 years ago, you may remember hearing quite a lot about the damaging effect that CFCs have on a layer of the atmosphere called the ozone layer, which is a layer of the atmosphere in the stratosphere which is opaque to the sun’s ultraviolet radiation. It means that we on the surface of the earth are exposed to much less of this damaging radiation. So, it makes it possible to go sunbathing without getting sunburnt. Potentially in the past, might actually have made life possible by making sure that complex chemistry needed for life was able to occur without being broken apart by those ultraviolet rays.

Hannah - And I remember when I was a child that the refrigerators suddenly, they weren’t allowed to emit these CFCs that were damaging the ozone layer. There was a big call to make sure that refrigerators complied with the new CFC legislation.

Dominic - That's right. What happened in 1980s was that people realised that CFCs were used as a refrigerant in fridges in people’s homes. In 1987, the Montreal Treaty banned the use of those because they had this damaging environmental impact. That was ratified by 200 countries, although it has taken a very long time for the CFCs that had already been emitted in the atmosphere to breakdown.

Now this is often held up as being a great triumph of international legislation in solving environmental problems. But what this paper in the journal Climate is saying this week is that CFCs are also really very strong greenhouse gases. Now, we hear about CO2, carbon dioxide and the effect that that has in causing global warming. But CFCs are actually 10,000 times more powerful as a greenhouse gas than CO2. And so, what this paper is saying is that because we had this spike of CFCs in the atmosphere in the 1980s, that was causing a strong greenhouse effect historically, and over the past 20 years or so, that's tailed off.

So in fact, the global warming that may have been caused by carbon dioxide in the last 20 years, we may not have seen the effect of that in full because it’s been offset by this diminishment in the number of CFCs in the atmosphere. So, the argument is really that we mustn’t just look at carbon dioxide,we need to look at the full suite of molecules that can cause global warming to really understand the effect that these gases can have.

Hannah - So, there's no cause to celebrate yet about decreasing CO2 levels because actually, we’re measuring CFC effects on global warming.

Dominic - That's right. I mean, in the 1980s, we has this wonderful success with the Montreal Treaty that really does seem to have solve the problem with CFCs, we haven’t had a similar treaty with carbon dioxide, the Kyoto protocol was not ratified in the end. The data is extremely complicated to analyse because there's all of these different molecules, all causing the greenhouse effect and it’s not just carbon dioxide.


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"So, there's no cause to celebrate yet about decreasing CO2 levels because actually, we’re measuring CFC effects on global warming. "


CO2  hasn't been going down at all? yor_on, Wed, 21st Aug 2013

This may shed some light on the question. Nuccitelli et al. (2012) Show that Global Warming Continues.

And 4 Hiroshima bombs worth of heat per second.

I do not honestly expect this trend to be reversible in human terms, geologically I'm sure it is, but those guys labors with hundred of thousands of years, or millions, we don't. Saw a image that got stuck in my mind. discussing it from Sydney's harbor, if I remember right. The heat accumulated each day was equivalent to drying out the entire harbor, each day. You leave in the morning seeing the sea, when you go home there is no more sea. Although the surface area of Earth is large, this heat accumulation in its sinks, as our oceans, must have a impact.

"Oceans cover approximately 70.8% or 361 million square kilometers (139 million square miles) of Earth’s surface (Table 8o-1) with a volume of about 1370 million cubic kilometers (329 million cubic miles). The average depth of these extensive bodies of sea water is about 3.8 kilometers (2.4 miles). Maximum depths can exceed 10 kilometers (6.2 miles) in a number of areas known as ocean trenches. The oceans contain 97% of our planet's available water. The other 3% is found in atmosphere, on the Earth's terrestrial surface, or in the Earth's lithosphere in various forms and stores." from Introduction to the Oceans.

But it is also a question of how the oceans store and transport this heat (laterally and vertically).

"During El Niño heat builds up in the surface layers where it is able to interact with the atmosphere, and therefore raises global surfaces temperatures. During La Niña much more heat is transported to deeper ocean layers and, with the surface layers cooler-than-normal, global surface temperatures are cooler-than-average. This can be seen in Figure 2 - using observations from the global system of ARGO floats....

Though not strictly true, it's easier to think of  the ocean circulation  as two distinct but interconnected processes - the wind-driven ocean circulation which warms and ventilates (mixes air into) the surface-to-deep ocean (down to about 2000 metres), and the thermohaline circulation which warms and ventilates the deep-to-abyssal ocean (2000 mtrs to ocean floor), and which is mainly driven by changes in the bouyancy and density of seawater. The wind-driven ocean circulation can be described as a pool of warm salty surface ocean sitting on top of a cold fresh (less salty) abyssal ocean. .

During the late 1970's global surface temperatures changed so quickly (Graham ) that  some researchers labelled this a 'climate shift' (Miller , Wainwright ). It was later shown that this climate shift was simply the human-caused global warming trend combining with the positive (warm surface ocean) phase of the Interdecadal Pacific Oscillation (Meehl ). With both driving forces moving in same (warming) direction, they combined to nudge global surface temperatures sharply upwards. 

The late 1970's climate shift is an appropriate analogue for the near-future because, based on the modelling in Meehl (2013) and other peer-reviewed scientific papers not discusssed here, the current negative IPO (cool surface ocean-warm deep ocean) trend is likely to come to an end sometime soon. The NCAR climate model suggests that these phases can last up to 15 years, but are generally around a decade in length. This climate model-based IPO cycle length is shorter than the IPO cycle length observed during the 20th century, however the reasons for this disparity are not yet clear.

Whenever this phase reversal does kick in there are likely to be significant changes in global rainfall patterns (Dai ), drought, mass coral bleaching and fish catches (caused by change in the wind-driven upwelling of nutrients in key areas of the ocean). Just how significant this is will depend on how much heat remains in the surface ocean during the next positive phase of the IPO..." from A Looming Climate Shift: Will Ocean Heat Come Back to Haunt us?

This one makes for a somewhat easier digested presentation
Diving deep into ocean data uncovers ‘missing heat’ treasure

Also The answer is blowing in the wind: The warming went into the deep end.

And Retrospective prediction of the global warming slowdown in the past decade.

But it's using several, and different, processes, all mixed up and non-linearly as I understands it. You can't think of it as a even layer of heat meeting the water surface, sinking, then getting evenly assimilated and mixed through the water volume, although that is what first comes to mind. It has to do with winds, streams, the suns output as well as the geological location where it happens, different depths, salinity, density etc etc. And there guaranteed are more things to find out about it. yor_on, Wed, 21st Aug 2013

The problem with all the predictions is that when one looks at the temperature charts, there has been little or no warming from about 1998, or 2001 to present.

Which is now coming up on a decade and a half without more "warming" all starting about the time when interest in global warming was becoming more widespread.

At the same time, global fossil fuel consumption has steadily increased despite all efforts to curb the usage, at least through political speeches.

So, the question is why we're not seeing more peak temperatures???

One notes that the temperatures seem to go up in spurts, with a massive increase from about 1985 to 1998.  So, more temperature jumps could be just around the corner. 

However, there are a few things that may well be affecting the temperatures.
Chlorofluorocarbons (CFCs) hit a peak about a decade ago, and have been declining.  They could have contributed to the increase in temperatures in the late 80's and 90's.
In many communities, smog also hit a peak in the 80's or so, and has been decreasing since.  The theory I read was that SMOG should decrease global warming, so a decrease in smog should mean more warming.  Perhaps cleaning the smog in the 80's and 90's contributed to the earlier increases.  Now, the USA and Europe have relatively low smog, but 3rd world nations may have increasing levels, thus less "warming", or perhaps cooling.
Low solar activity.  We likely are in one of the lowest solar cycles in a century.  At the peak now, it should be decreasing again for the next few years.  The decade solar cycles seem to affect at least the step-wise increases in temperature.  With a low cycle, we may not see any jumps up for at least 5 to 10 more years.
Other "Climate Cycles", not man caused.  We may be at a peak of a natural, long-term climate cycle.

Anyway, I have no doubt we should continue to monitor the global climate, but there may be several things working together to make it seem like we haven't had continued warming for the last decade and a half. CliffordK, Thu, 22nd Aug 2013

Yeah, a sweet illusion, before that war that will come, assuming we keep up this stupidity. Either a war or a slow decline into poverty. But I think that will lead to a war too, between those that have and those that are without. yor_on, Thu, 22nd Aug 2013

"Prediction is very difficult. Especially about the future." (Niels Bohr)

It's made more difficult if you ignore what you already know, which is the starting point of most global warmists. alancalverd, Fri, 23rd Aug 2013

If you're referring to climate models Alan I totally agree, they're just as good as the programming and the assumptions made will make them. And climate science is not a settled field in any way. But you have models that attacks the problem statistically too, as that British one using simpler models, on home computers, tweaking them somewhat differently to then look at outcomes getting probable statistics. You can naturally question those models too, but they are interesting to me. As for my pessimism that has to do not only with global warming, it's about the way we're naturally 'set up', looking at way we behave, and have behaved, historically. Global warming is only the icing on the cake there. Doesn't mean I will be right though, I hope I'm not. yor_on, Fri, 23rd Aug 2013

AFAIK most climate models are self-serving.

You start with an assumption, say that CO2 has a significant effect on global temperature.

You do not define "global temperature", but pick some reasonably selfconsistent data without asking what its inbuilt biases might be (75% of the globe is covered with oceans, for which we have no reliable data. Most of the rest is collected from populated areas, which account for about 10% of the landmass, and there is no reliable data before about 1920 anyway.) 

You use this to calculate the "forcing function" of CO2 that fits the data

You then extrapolate....

and it doesn't work! (see this thread) 

So you review some unequivocal historic data....

and it doesn't work! (the Vostok ice cores show that temperature leads CO2, not the other way around)

So you admit that your entire career has been fraudulent, and hand back your peerage. Fat chance.

alancalverd, Fri, 23rd Aug 2013

You seem very sure on your assumptions here Alan :)
Don't know what to make of that. What evidence do you have of climate science being bogus? yor_on, Fri, 23rd Aug 2013

No suggestion that climate doesn't change. I'm sitting in a part of East Anglia that used to be a hot swamp, if the hippopotamus bones in the Sedgwick Museum are to be believed.

The bogusity is the assertion that  the change is driven by carbon dioxide, that it is largely man-made, that it is controllable, that things are a lot hotter now than ever in human history, that it will inevitably get a lot hotter in the near future, and that "global mean temperature" is defined and measured.

You may recall the announcement a few weeks ago of viable bryophytes discovered under a retreating glacier. Interesting botany, but all the press reports burbled on about unprecedented global warming, completely ignoring the obvious fact that it must have been a lot hotter 400 years ago in order for the bryophytes to grow there in the first place. And 400 years is well within recorded history.

Climate change is an inevitable fact. Anthropogenic global warming is a bogus, unscientific con trick. alancalverd, Fri, 23rd Aug 2013

I agree, it is important to realize that CO2 levels, and temperatures have varied significantly over the life of the planet.  We may be approaching a local high temperature for the Holocene, but it certainly isn't close to the Eocene maximum temperatures. 

I think the most likely explanation is that the current temperature changes are the result of both human driven AND natural cycles.  We should be able to better understand the influence of different factors over the next few decades. 

Some of the future temperature projections were based on the maximum slope of the temperature increases.  This was likely an overestimate. 

A warming environment may not necessarily be bad, although inundating the coastlines would be hard on some communities.  I think it is more a fear of the unknown, and unleashing poorly understood consequences of our actions. CliffordK, Tue, 27th Aug 2013

The rediscovery of viable bryophytes under a retreating Canadian glacier reminds us that things were a lot hotter in the pre-industrial Holocene, never mind the Eocene. 400 years ago my old school was celebrating its 40th anniversary, homo sapiens walked upright, the woolly mammoth had left the building, and there was a flourishing sub-arctic flora in what is now a frozen wasteland.   

Preaching doom and disaster without evidence, blaming sinful Man for every natural crop failure, and using fear of the unknown to extract money from the proletariat, is the province of politics and religion, not science.

Costal communities recognise the risk of hurricanes, tsunami, solitons, erosion, recession, flash floods, tourism, etc., and balance it against the benefits of an easy life. Since the sea level will initially decrease as the icecaps melt, I don't think they will be much inconvenienced by a bit of climate change.      alancalverd, Tue, 27th Aug 2013


Please clarify

Most measurements indicate that the sea levels are increasing by a few mm a year (and have been generally increasing since the beginning of the Holocene). CliffordK, Tue, 27th Aug 2013

There's a general problem about the definition of sea level anyway. Where do you measure it in order to determine the global value, and why should it remain constant if, as we know, the seabed and continents are all moving anyway? Within 100 miles of each other, and in recent history, Dunwich has disappeared beneath the North Sea whilst once-thriving ports on the north Norfolk coast are now high and dry, five miles inland from the beach - nothing to do with intentional reclamation, just natural forces. So try to define sea level around East Anglia! Nevertheless, if we ignore all we know about tides, winds and geology, let us assume that the icecaps are melting in an otherwise static world.

Now ice is less dense than water, and water at 0 deg C (in contact with freshly melted ice) is less dense than at 4 deg C, so to the first order of approximation the floating arctic ice cap and the antarctic ice shelves will not alter the level of the oceans as they melt, and to the second order, since melting the ice will cool the surrounding sea, the sea level will actually decrease as the circumpolar water gradually warms from 0 to 4 deg C.

For as long as there is any floating ice surrounding them, the Antarctic and Greenland continental surfaces must be below 0 deg C, so will not be relevant to the question.    alancalverd, Tue, 27th Aug 2013

That's a interesting take on sea levels Alan, and one I haven't considered. It should have a impact assuming that continents are wandering away form each other, but then you would need more water to measure a same sea rise, as it seems to me? To measure a sea rise from continents wandering we then need to assume that they either press up the sea bottoms, although leaving dry land at a same elevation, or that the continents are coming closer together creating a smaller volume for the same amount of water to exist in. yor_on, Wed, 28th Aug 2013

Clifford, myself I think the problem isn't one in where we don't know that we have a global warming. We can prove a global warming statistically, also excluding external sources as the suns variations, that as we know them too statistically. What we don't know, and can't predict though, is all the ways a earth can react to it. That's what climate models are to me, 'best predictions' based on what people think are most important 'forcing's' of a climate at the moment they present it.

What we can see geologically isn't that clear cut to me, as it's most often about variations over centuries, millenniums etc, although you might want to argue otherwise. But to me it's geological forensics, or deductive guesswork, as we wasn't there measuring, year from year, that last time a global warming happened. What worries me isn't how the heat 'disappear', or 'hides' for now, but ocean acidity. That one seems more worrying as it discuss some of the first food chains existing on this planet, and their survivability.

Here are some of the evidence collected, of Anthropogenic (made by man) CO2, stored in ocean sinks.  The Oceanic Sink for Anthropogenic CO2.

Personally I think NOA is doing invaluable work there,  assembling information and research from all over the world. And this one is about the North Atlantic specifically. Not as easy to digest though, from 2012. Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean.

If one read the the abstract it says "Here, we show the longest continuous record of ocean CO2 changes and ocean acidification in the North Atlantic subtropical gyre near Bermuda from 1983–2011." 1983 to 2011, right? When it comes to measuring acidification statistics are fairly new. Climate science is overall a fairly new science and, as in all types of science, there are no set truths, only what we can know at that moment. No one here demands a instant TOE from physics, but when it comes to climate science all seems to expect it? yor_on, Wed, 28th Aug 2013

An interesting question in itself. There seems to be a general upwelling in the Pacific, and subduction in the Atlantic, so whilst the eastern coasts of the Americas are approaching the western coasts of Eurasia and Africa, the opposite coasts are drifting apart!

And the situation is complicated by volcanic activity within the continents, which increases the overall amount of dry land and therefore makes the effective sea level decrease. alancalverd, Wed, 28th Aug 2013

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