Climate Change Emissions

The effect of cutting CO2 emissions to zero by 2050

Guest Post by Dr Tom M. L. Wigley. Tom is a a senior scientist in the Climate and Global Dynamics Division of the US National Center for Atmospheric Research and former Director of the CRU. He is an adjunct Professor at the University of Adelaide. For his list of papers and citations, click here (his h-index is 70!). Tom is also a good friend of mine and a strong supporter of the IFR.

What would happen to CO2 concentrations, global-mean temperature and sea level if we could reduce total CO2 emissions (both fossil and net land-use change) to zero by 2050? Based on the literature that examines possible policy scenarios, this is a virtually impossible goal. The results presented here are given only as a sensitivity study.

To examine this idealized scenario one must make a number of assumptions. For CO2 emissions I assume that these follow the CCSP MiniCAM Level 1 stabilization scenario to 2020 and then drop linearly to zero by 2050. For the emissions of non-CO2 gases (including aerosols and aerosol precursors) I assume that these follow the extended MiniCAM Level 1 scenario (Wigley et al., 2009). The extended Level 1 scenario provides emissions data out to 2300. Note that the Level 1 scenario is the most stringent of the CCSP stabilization scenarios, one that would almost certainly be very costly to follow using traditional mitigation strategies. Dropping CO2 emissions to zero is a much more stringent assumption than the original Level 1 scenario, in which total CO2 emissions are 5.54GtC/yr in 2050 and 2.40GtC/yr in 2100.

For modeling the effects of this new scenario one must make assumptions about the climate sensitivity and various other model parameters. I assume that the sensitivity (equilibrium warming for 2xCO2) is 3.0C, the central estimate from the IPCC AR4. (Note that the 90% confidence interval for the sensitivity is about 1.5C to 6.0C – Wigley et al., 2009.)

For sea level rise I follow the AR4 and ignore the possible effects of accelerated melt of the Greenland and Antarctic ice sheets, so the projections here are almost certainly optimistic. All calculations have been carried out using version 5.3 of the MAGICC coupled gas-cycle/climate model. Earlier versions of MAGICC have been used in all IPCC reports to date. Version 5.3 is consistent with information on gas cycles and radiative forcing given in the IPCC AR4.

The assumed CO2 emissions are shown in Figure 1.

The corresponding CO2 concentration projection is shown in Figure 2. Note that the MAGICC carbon cycle includes climate feedbacks on the carbon cycle, which lead to somewhat higher CO2 concentrations than would be obtained if these feedbacks were ignored.

Global-mean temperature projections are shown in Figure 3. These assume a central climate sensitivity of 3.0C. Temperatures are, of course, affected by all radiatively active species. The most important of these, other than CO2, are methane (CH4) and aerosols. In the Level 1 scenario used here both CH4 and aerosol precursor (mainly SO2) emissions are assumed to drop substantially in the future. CH4 concentrations are shown in Figure 4. The decline has a noticeable cooling effect. SO2 emissions drop to near zero (not shown), which has a net warming effect.

The peak warming is about 0.9C relative to 2000, which is about 1.7C relative to pre-industrial times. This is below the Copenhagen target of 2.0C – but it clearly requires a massive reduction in CO2 emissions. Furthermore, the warming peak could be significantly higher if the climate sensitivity were higher than 3.0C. For a 3.0C sensitivity, stabilizing temperatures at 2.0C relative to the pre-industrial level could be achieved with much less stringent CO2 emissions reductions than assumed here. The standard Level 1 stabilization scenario, for example, gives a 50% probability of keeping below the 2.0C target.

Figure 5 gives the sea level projection for the assumed scenario. This is a central projection. Future sea level is subject to wide uncertainties arising from uncertainties in the climate sensitivity and in parameters that determine ice melt. As noted above, the projection given here is likely to be an optimistic projection. Note that sea level roughly stabilizes here, at a CO2 concentration of about 320ppm. Less optimistic assumptions regarding the emissions of non-CO2 gases would require a lower CO2 concentration level. Given the unrealistic nature of the assumption of zero CO2 emissions by 2050, this is a graphic illustration of how difficult it would be to stabilize sea level – even at a level more than 20cm above the present level.

Key reference:
T. M. L. Wigley, L. E. Clarke, J. A. Edmonds, H. D. Jacoby, S. Paltsev, H. Pitcher, J. M. Reilly, R. Richels, M. C. Sarofim and S. J. Smith (2009) Uncertainties in climate stabilization. Climatic Change 97, 85-121, DOI: 10.1007/s10584-009-9585-3.


By Barry Brook

Barry Brook is an ARC Laureate Fellow and Chair of Environmental Sustainability at the University of Tasmania. He researches global change, ecology and energy.

96 replies on “The effect of cutting CO2 emissions to zero by 2050”

Quote: “Given the unrealistic nature of the assumption of zero CO2 emissions by 2050, this is a graphic illustration of how difficult it would be to stabilize sea level – even at a level more than 20cm above the present level”

This was actually demonstrated about a thousand years ago in England by King Canute.


Tom’s assumption for 2050 is that we begin reducing CO2 much earlier, around 2020, which is not going to happen in my opinion, so right off the bat we are assuming something that is probably too optimistic. I had hoped to see the response for a linear growth in CO2 levels through 2050, i.e. that would be a CO2 level of 470 ppm, and then hold the CO2 level at 470 ppm indefininitely. That was my assumption in Tom’s test is far less CO2 than my assumption. However there is every indication that the fossil fuel industry will continue to grow, making even my forecast too low. The other important item here is the Greenland Ice melting rate versys CO2 level. Its currently accelerating but no one can explain why – at least in a model, although it seems obvious that we should expect an acceleration to occur for a constantly rising level of CO2. Not being able to explain this cause and effect realationship is a serious shortcoming of Tom’s model. As far as I know there is no climate model that correctly reproduces what we are currently seeing in the acceleration of Greenland and Antartica ice melting .


What I don’t understand is how warming can cease while pCO2 remains above pre-industrial levels.

Surely if we started warming at 280-290ppmv we must keep warming at least until we get back there, albeit at a slower rate than if we kept adding to concentrations?

Can someone who knows the relevant physics comment on this?

I’m also wondering about the point at which we lose serious quantities of permafrost and the CH4 trapped underneath.

It seems clear to me that we absolutely do need to have an early and rigorous look at the geoengineering options (both active and passive) especially given the improbability of the optimistic scenario sketched above.


From The Australian article TerjeP referenced:

“Rather than succumbing to gay marriage and other Green exotica at Labor’s next national conference, Gillard can take control of a real reform agenda by championing the nuclear option.”

Wow. That type of reasoning is brilliant. Really goes down well with most of the public. Great PR for the nuclear industry.

Is it possible to find a newspaper somewhere in Australia that is not so full of idiotic doctrinaire like Green Left Weekly or The Australian?


Pending expert comment, note that the temperature plotted is relative to year 2000, when we had 370 ppm CO2. In the model, that level is recovered in ~2110, with lower methane but presumably also lower (cooling) aerosols, and less ice, and the climate 0.8C warmer than today. A warmer world will radiate more heat to space than a cooler one, all else being equal. With more heat going out than sunlight energy being absorbed, the planet will cool, slowly.

A long-standing question (for me) on climate basics, is what happens to the underlying natural trends? I thought that the Milankovitch cycle prediction was for slow cooling over centuries, leading to ice-age conditions in a few millennia. This trend is too slow, by at least an order of magnitude, to make any difference to what happens over the next century, but the projection in this article goes out to 2300. Do modern models still support the prediction of a cooling climate, if we hadn’t intervened? How long before the if-we’d-never-been-here climate gets to (say) 1C below pre-industrial baseline? What does -1C ( Milankovitch) + +1C (AGW) look like?



We’re not saying this is any kind of real scenario. This is a system response test. If we went along with business as usual until 2050 and then suddenly stopped all CO2 how would the earth respond. At least that is the original question. Tom tried to make it semi real by introducing a transition period of declining CO2 for about a 20 year period. Problem with that assumption is that its not based on any plan at all. I would like to see the scenario rerun with CO2 increasing and even escalating up through 2050 and then take a step function drop to zero emissions at that point and see how the earth responds. This is just a system response test so we can see the effects and time constants more clearly. In this test we treat the earth like a black box (pun intended) and do modeling tests to see how it responds. You guys trying to second guess how we will acutually cause a CO2 reduction are missing the point of this analysis.


There’s a new report from UNEP which looks at emissions scenarios designed to hit 2ºC and 1.5ºC (discussed here), which indicates that hitting something like 1.5ºC (as opposed to the 1.7ºC here) involves negative emissions after 2050. Now there’s a challenge…


Tom quoted the OO

Rather than succumbing to gay marriage and other Green exotica at Labor’s next national conference, Gillard can take control of a real reform agenda by championing the nuclear option.

Then continued:

Wow. That type of reasoning is brilliant. Really goes down well with most of the public. Great PR for the nuclear industry.

Indeed. This would be an excellent strategy if one opposed nuclear power. The idea of reinforcing the dominant view that only cultural conservatives, xenophobes and enemies of the environment support nuclear power would be just brilliant, for them.

That would allow us leftwing pro-human rights and pro-environmental people having to start every claim about nuclear power with a prefatory disclaimer like I’m no reactionary at all, but … or I’m totally OK with gay marriage and refugees but nevertheless … or Yes I know there are a lot of ufly characters around the pro-nuclear movement, but there are some quote reasonable people too …

This would split the ALP, cost them government and ensure that we again had both sides running away from being wedged on the matter.

Luke UK said:

I thought that the Milankovitch cycle prediction was for slow cooling over centuries, leading to ice-age conditions in a few millennia. This trend is too slow, by at least an order of magnitude, to make any difference to what happens over the next century,

AIUI the next glaciation was predicted in about 23,000 years, so definitely too slow to do that.

A warmer world will radiate more heat to space than a cooler one, all else being equal. With more heat going out than sunlight energy being absorbed, the planet will cool, slowly.

The first statement doesn’t entail the second. Yes a warmer world will radiate more heat to space than a cooler one, ceteris paribus but the question is the point at which equilibrium is achieved. We know that the equilibrium point was higher than 290ppmv because when we paassed that point the world started to heat and kept on heating as it passed 350 and 370. Unless a new equilibrium occurs at 420 then the world will keep warming, surely.

It seems to me that our aim ought to be to try to recreate the energy balance in incoming shortwave/outgoing longwave that applied in about 1890, if necessary by reducing the former, at least until the near-tropospheric forcings can be brought back to those apply in 1890.



My thoughts entirely. Adopting 2000 as a baseline appears to me to be overly optimistic. Maybe 1890 is unnecessarily far into the past.

Post-1970 or 1980, there should be sufficiently reliable atmospherical and ocean, etc data to plug into models to be able to say: Here is a post-1970 run of the model, indicating some sort of fit with the past 40 years, assumption of decline of CO2 emissions over the next 40 years and projections out to 2300. That will add context to the projection.

Still, the article achieves what it sets out to do, and that is to provide a lower bound of sorts to the atmosphere’s response to an optimistic CO2-e reduction scenario. Well done.


Next ice age – I’ve seen claims ranging from “it’s overdue” – on AGW-skeptic sites, highly dubious – out to “maybe not for 130,00 years” on the Wikipedia Milankovitch entry, which would break the long cold period, short warm period pattern of the last million years or so. Just curious

Radiative equilibrium – there is an equilibrium temperature for any CO2 value. The assumption stated is that doubling pCO2 from pre-industrial levels raises the equilibrium temperature by 3C. Looking at the plots, the model is giving +1.7C for 420ppm, or +0.9C above today’s already warmed climate. Once pCO2 (and pCH4) are falling, the equilibrium temperature will be falling. When the equilibrium temperature goes below the actual temperature, cooling begins – but it is slow, so that even in this drastic cuts scenario, we are warmer than today out to 2300.


Fran – IMHO a pro nuclear stance would not split the Labor party. Some individuals might quit but I think it would ultimately prove a useful point of differentiation with the Greens. At the moment the ALP risk looking like a less principled form of the Greens which is politically dangerous for them. They do need a stronger point of differentiation. They can’t afford to be too cozy with the Greens. I fully support gay marriage and I think the ALP (and Liberals) should too. However making it a centre piece of debate isn’t good in terms of securing their base. Their base is not the same higher income, university educated, left leaning idealists that gravitate to the Greens. If they forget their base then they will suffer the same ultimate fate as The Australian Democrats.


terje said

Fran – IMHO a pro nuclear stance would not split the Labor party

I don’t think it would either and indeed, within the Greens, I am seeking to effect a reconsideration of this question. And if the ALP adopted a pro-nuclear stance I don’t think The Greens would have any choice but to maintain their effective alliance with the ALP, particularly if the ALP cast itself as a party interested in liberal reform, humanitarianism and the Libs also got on board with nuclear (since it was now safe) but held out in the moral shibboleths and xenophobia etc…

My problem was with the wholesale attempt to make the ALP indistinguishable from the Liberals so as to differentiate from the Greens and bundling this with nuclear power. An even larger part of the the ALP’s base would jump ship, see them as corporate shills and make nuclear power wear the odium for that. If The Greens got to 30% then sections of the moderate liberals who are chafing at conservative control would have an alternative and could probably begin preferencing The Greens notwithstanding the anti-nuclear position. Some Liberals aren’t all that keen either, on nimby grounds, or because they think coal is a money spinner.

Nuclear would again become a wedge issue and entangled in broader left-right debates about social issues. If I were interested only in The Greens doing well electorally, I’d be OK with this, but as people know, I am very keen for The Greens to change their view on this, and that would not help.


Developing climate models is a worthwhile exercise in the long term as they may help us to understand which variables matter and which do not.

Unfortunately, people are too ready to believe the predictions of today’s climate models even though they cannot explain past climate variations except over brief periods of time.

The climate models available today are so fallible that it would be the height of folly to use them to justify spending huge sums of money.


Thanks Tom. This result looks consistent with Hansen’s “Target CO2 paper” where he looks at
coal phase out by 2030 but continued use of current
reserves of oil and gas. It’s clear that both scenarios
are currently unthinkable … which is pretty


My problem was with the wholesale attempt to make the ALP indistinguishable from the Liberals so as to differentiate from the Greens and bundling this with nuclear power.

For better or for worse pro-nuclear is a right wing thing. I think the ALP should move right on this issue and left on things like same sex marriage. If they just move on the left issues the Greens will cream them. They need to move both ways at the same time as a form of political neutralisation.


@Dappledwater and others above, I just got back from a talk by the President of Geological Society, Brad Pillans (an expert on climate change in the Quaternary) which covered this subject, amongst other things. He sees good evidence for Ruddiman’s idea that Earth’s departure from Milankovitch climate control actually began some 5000 years ago, when the onset of widespread agriculture (particularly submerged-field rice growing technology) began to drive up methane concentrations. Milankovitch had our descent to an ice age starting around then (5000 yrs BP), and this obviously hasn’t happened. My understanding of a slide put up is that the next Milankovitch insolation nadir is ‘only’ a few centuries from now, certainly within this millennium. But the screen was a fair way away, and I couldn’t make out the axis numbers too well.


I agree the climate models need improvement, however they seem to me to be consistently under predicting the climate change response, not over predicting. Therefore it is folly to take no climate change action at this time because to do so is likely to lead to a disastrous energy shortage, climate runaway, and world financial collapse in just a few short decades. Yes, I have trouble sleeping at night worrying about this. I would sleep much better knowing we had real solutions.


the event described in is said to have lasted 400k years. I think the climate models today are predicting recovery of the CO2 in about .001 amount of the time in this historical event. Therefore I would say the current models may underpredict the effect of CO2 by by having too fast a recovery time. Or did the volcanos last for 400k years and the Earth was continuously recovering all the time? If that is the case we have little to worry about with CO2 because we will run out of fossil fuels this century and the recovery will be shortly thereafter in the next couple of centuries. But if the current climate models are inaccurately predicting the CO2 removal, then we could be in for a more horrific warming event than being predicted in the models. So which way is it?


It is a big mistake to yet start making judgements on what’s “realistic”. Winning WWII was not at all “realistic” for Churchill. Cutting to net zero by 2050 is not just realistic but relatively easy, compared to say the collapse of the global economy if climate change accelerates out of control. I wrote a paper on this with Jorgen Randers including detail on how such cuts could be achieved. You can read The One Degree War Plan here


@Paul Gilding, it staggers me how anyone can invoke a WWII/climate analogy and still contrive to avoid nuclear power, as your ‘One Degree War Plan’ does. Of all the disruptions to the prewar economic order that the ODWP document mentions, one is conspicuously omitted: the Manhattan Project. The Allies did not eschew nuclear technology in pulling out all stops to win WWII – why do you?

This line of thought has been canvassed before, here. There is much wisdom in the comments ;-)

Barry, this has the potential to run and run. How about upgrading Paul Gilding’s contribution to a guest post in its own right? Apart from Mr Gilding’s general eminence, the One Degree War Plan certainly deserves…close scrutiny, shall we say.


Thanks for the links, very informative both on the state of current knowledge and on where the various predictions have come from.

You may be interested in the ‘moveable trigger’ link. Using a simplified climate model, they predict that a major CO2 injection (burn all the available fossil fuels – 5000 GT carbon) disrupts the climate for the next 400,000+ years. Push hard enough, and the system never recovers.


Paul Gilding

I just read through your plan. Much of it sounds intuitively reasonable and even admirable, but whole swathes of what you are saying sound impracticable on one ground or another.

In particualr, your reliance on CC&S seems greatly at odds with any strategy one could call sustainable, given that these stores are themselves a finite resource and that the CO2 one would be storing will have to be stored forever in circumstances where the CO2 would be under sufficient pressure to keep it in liquid form.

I can’t but think that storing radioactive hazmat for a few hundred years would be a hell of a lot easier technically, and far cheaper. If we are on a war footing, what is the problem?

Why replace only the 1000 dirtiest coal-fired plants? Why not replace them all and the gas plants too? Even the best are about 70% as bad as the typical bog standard plant, Let us also bear in mind that this also ignores the CO2 (and human) footprint of harvest of coal.

Cash for clunkers is also a very cost-ineffective way way to cut emissions — estimated here to deem carbon at about $400 per tonne — about four times your imputed figure. If you are going to ration fuels and tyres, then you probably don’t need this anyway. A suitable price on carbon and people will self-ration. This cuts compliance costs. eventually, people will surrender their inefficient cars. If the cars are on the grid and the grid is net zero carbon, then this is not as much of a problem.

It seems to me one low tech way of removing CO2 from the atmosphere might be through industrial-scale alage farms. Dry the biomass and stabilise it in some cheap inert material (salt, charcoal, fly-ash) and bury it deep in disused mines or at the sea floor.

I can’t see why you’d burn plantation timber though. Once again, it would be simpler just to dry it and bury so much of it as wasn’t needed in furniture or construction.

(Note spelling error in heading p16 “Adapation”)


Current sea level rise is about 3 cm/decade, so it’s a bit strange to see this projection a rate less than 2/3 of that. As Dr. Wigley said, the AR4 SLR numbers are almost certainly an underestimate, with more recent estimates running factor of 3 or so higher.


I expect some serious emissions reduction sooner than the rest here seem to. My reason: climate disruption in the forms of floods & droughts and storms. I think the implication: possible crop losses in too many places in a single year (and ocean acidification will hurt that food supply as well) will spark big changes.

But climate disruption will still come. This isn’t going to be a walk in the park.


Ms. Perps,
Thanks for the link to an interesting paper although I don’t think it has much relevance to the issue of GCM forecasting skills.

The real problem with studies of the Eocene is time resolution. Without good time resolution it is difficult to separate cause from effect.

The initial Vostok ice cores showed a strong correlation between CO2 concentrations and Antarctic temperatures.

It was only when the time resolution was improved that it became evident that CO2 lags temperature by about 600 years.

The Vostok ice cores go back only 700,000 years so you can imagine how difficult it is to get comparable time resolution for events that took place 40 million years ago.


Gene Preston,
I think you are losing sleep for the wrong reasons.

While I strongly support Barry Brook’s arguments for building large numbers of nuclear power plants which is in the long run inevitable, the scenarios for a rapid build during this century are pipe dreams.

Much more likely is an extended dependence on fossil fuels based on technology that already exists. For example:


GC I’d go more on reports from The Oil Drum than from Forbes. Here’s a less optimistic view of shale gas fracking that says it will extend US gas reserves by only 7 years

I think what will prolong fossil fuel use is high prices and declining net energy, more so than increased recovery.


Ms. Perps,
Like you, I appreciate “Skeptical Science”. While I usually disagree with John Cook, his blog is excellent in many ways; certainly far better than the CAGW echo chambers such as Joe Romm’s “Climate Progress” and Tim Lambert’s “Deltoid”.


Luke_UK, on 25 November 2010 at 12:09 AM & Dappledwater, on 25 November 2010 at 4:14 PM — Orbital forcing began to turn more positive (less likely to trigger a stade) about 2000 years ago. The next possible chance is about 50,000 years from now (IPCC AR$ says at least 30,000 years). Study the orbital forcing graph in the Archer & Ganapolski paper quite, quite closely.


Even such an agressive diminution of anthropogenic CO2 may not be enough to prevent to collapse of agriculture:
“This is very alarming because if the drying is anything resembling Figure 11, a very large population will be severely affected in the coming decades over the whole United States, southern Europe, Southeast Asia, Brazil, Chile, Australia, and most of Africa.”


We should invest more money into new technologies to help predictions to be more accurate. There are o lot of side effects that can happen unexpectedly. We still know almost nothing about an Earth´s core and that could be a major aspect which can have an influence on more weather changes that can happen in the future.


@Pete Dunkelberg and @Paul Gilding re trigger events for serious emissions reduction, I vaguely recall a discussion on this topic in the very early days of BNC. Something like a ‘top ten’ or ‘top twenty’ list of climate impact events, yet to transpire, that might lead to a rapid change in political will. I can’t find it now, even though I think I contributed to it. Can anyone else recall and/or point me to this?


Ms. Perps,
I was ready to concede the last word to you when you invoked the relatively reasonable arguments of “Skeptical Science”.

Then you spoiled it by quoting a delusional post by Professor Jeff Severinghaus on the vapid “Real Climate” blog. You should be aware that blog is the echo chamber for Gavin Schmidt and Michael Mann.

No matter what those lunatics say, the Vostok and Greenland ice cores show that in the long term there is a relationship between temperatures and atmospheric CO2 concentrations. Temperature is the “cause” and CO2 is the “effect”.

While CO2 affects climate, solar radiation, cosmic radiation, Milankovitch cycles, water vapor, clouds and changes in albedo due to ice coverage appear to be much more important.


” Temperature is the “cause” and CO2 is the “effect” ”

Rubbish. It is very well documented in the palaeoclimate record that CO2 acts as a strong positive feedback mechanism. If it is capable of driving further temperature change due to temperature perturbations, it is certainly capable of driving change when other factors influence its abundance.


David B. Benson Our planet produces 500,000 billion tons of water vapor per year as well as 5.9 billion tons of natural co2 and 2.6 billion tons of man made co2! Which natural system besides AGW has the positive feed backs in it to make such a small driver have control of such an enormous system?


Water constantly evaporates and then condenses and falls back down again, in a few days and often on the same day. What system keeps it all going nicely? 280 ppm CO2. The feedbacks work “in reverse” too. Remove all CO2 and allow no elevated levels of other non-condensing GHGs and planet earth becomes an ice world. Stick that in your water pipe and smoke it.

What’s up with you and gallopingcamel anyway? Why make rhetorical arguments against science? Or did I misunderstand you?


David Benson,
I am fascinated by Richard Alley’s work and particularly his analysis of the GISP2 data (central Greenland). If I find myself at Penn State, I would want to meet Richard Alley rather than Michael Mann.

While Alley’s initial interest was in the “Younger Dryas”, more recent events such as the Minoan Warm Period, Roman Warm Periods, Dark Ages, Medieval Warm Period and the Little Ice Age are all clearly shown in his data.

The GISP2 data starts about 70,000 years before present (BP) and ends around 1905. Within a few weeks I hope to link this data with the present day as this should shed some light on the issue of how temperatures during the MWP compare to today.

Here are a couple of links that discuss the GISP2 data that Alley used in the presentation you quoted:



The argument that climate has changed before is extremely tedious as is the tired old stuff about about medieval temperature in Greeenland. If these know-it-alls have something new to add then get it published.

The median value of around 3C for climate sensitivity has been derived through decades of research by many, many scientists and is broadly accepted. A bit of the old “doubt and confusion” is not going to make any difference at all.


15 people killed so far by cold snap in Europe! I guess that is due to Catastrophic man-made Global Warming :)

Funny how every time we get some warm weather somewhere in the world it is evidence of ‘Catastrophic man-made Global Warming’ but all the Alarmist go quiet when a cold spell occurs.

I couldn’t miss the opportunity to point out a bit of hypocrisy.


Peter Lang- weather extremes of all kinds are entirely consistent with the science. Perhaps, to enable you to understand that, you should think “Climate Change” and not “Global Warming”. The climate is changing because there is far more energy in the weather systems (because of the warming atmosphere) and thus we have more intense El Ninos and La Ninas. In Australia we are seeing the shifting patterns of rain. Rain for Melbourne is now coming from the north, as the normal weather systems move south dropping their moisture over the Southern Ocean so also do the cyclones extend further south, and the climate is changing from Mediterranean to a sub-tropical. Increased precipitation causes heavy rain and flooding or increased snowfall as in Europe at present. Surely it is not TOO difficult for anyone to comprehend.


Barry there seems to be an awful lot of mis information being posted here. In our local newspaper there is a truth-o-meter gauge where each speaker is given a rating by the paper. You may want to adopt your own gauge of how true each statement is so the readers can see how you feel about their “contributions.” When Tom Wigley gets back from Cancun I do wish he would run a less rosy scenario for CO2 reduction, ie no CO2 reduction through 2050, and see what the results of that simuation produce. I’m afraid the climate modelers are way underestimating the ability of the fossil fuel industry to keep on going and going and a run with no reductions would probably be a better forecast than to think the world is actually going to stop emitting CO2. It isn’t in my opinion.


Gene there are many who think man made CO2 will be in decline by 2020 let alone 2050
The unknown is whether delays to man made CO2 will enable trapped methane to take over as a driver of warming. The irony is that every year of inaction is a year closer to economic depletion of fossil fuels that give adequate net energy after extraction. It’s as if we are passengers on a runaway train that must either slow down or crash.


There is a curious inconsistency in the Royal Society paper. It bases the 4C rise on the highest emissions scenario A1FI but early on it acknowledges that global emissions declined in 2009, falling in the west but nearly made up in China and India. What if emissions permanently fall everywhere ( Chindia and the west) so A1FI is no longer valid? Was the recent emissions downturn a temporary blip or a crucial change in trend?

This is what people like Aleklett are trying to point out. The obvious triggers are global oil peaking and China coal peaking. Suppose despite best efforts Australia can’t supply enough coal to meet China’s coal deficit. China and India no longer want our iron ore. Meanwhile the price of petrol skyrockets and we’ve left it too late to make petrol from coal. We’re stuffed because we don’t have enough export income and the cost of everything like food and transport goes up.

Therefore I think that IPCC emissions scenarios themselves should model economic feedbacks. As fossil fuels decline they undercut their own demand. In the paper an emissions timeline like B1 looks more realistic which I would guess produces warming of well under 4C.


Temperature proxies that deny the historical and archaeological record are dubious at best. This is why tree rings do not pass the laugh test.

The Vostok, Greenland and Chinese ice cores on the other hand are consistent with instrumental, historic and archaeological records. You should have more respect for ice cores even though they show CO2 lags temperature.

With regard to “getting it published”, NOAA beat me to it ten years ago:


Peter Lang, bad news. When a cold blast blows out of the Arctic, the Arctic does not become a giant vacuum. Warmer air is blowing into it from some other angle, hastening future problems.


Pete Dunkelberg,

So, I guess, the reverse is also true. When Adelaide has a few hot days, cold air is blowing somewhere else and causing some problems, eh? Like killing crops.

I am just trying to get the Alarmists to tone it down a bit and become a bit more realistic and balanced. The extremist Alarmism, foir ever talking about danger, catastrophe, appocalypse, armageddon scenarios turn most people off, including me – big time!

Changing some words in Quokka’s statement in his post above:
The [extreme Alarmist claims about catastrophic man-made climate change] is extremely tedious as is the tired old stuff”


Climate Change is seen by many as an excuse to push a whole raft of other agendas. Many people don’t want the agendas that the climate change Alarmist are pushing.

I’d suggest separating off all the other agendas that the advocates of catastrophic climate change are pushing (carbon tax, ETS, renewable energy, world taxing powers, world government, wealth redistribution, and a host of others).

If you are prepared to offer:

– reliable, high quality electricity
– energy security
– lower cost electricity
– better health, safety and environmental outrcomes (overall),

then you will get broader support much more easily.

The other items on the Alarmists agenda are not wanted!


Peter Lang:

Why aren’t you alarmed about the consequences of AGW – is it because you are sceptical about the findings of climate scientists?

If one accepts the scientific consensus on this issue, one hardly needs to be left wing to be alarmed about one’s childrens’ or grandchildrens’ futures. In fact, lack of alarm might be taken as indicative of either ignorance or bigotry and I am wondering into which category you fit.


In support of previous post see these articles:

Institute of Public Affairs (run by ex Productivity Commissioner) says:

“Labor’s push to price emissions is out of step with international developments at Cancun.”

“Japan derails climate talks by refusing to renew Kyoto treaty”


Oh, and the IPA is a completely independent right-wing funded think tank.
It may be run by an ex-Productivity Commissioner but it is certainly not supported by the P.C.,which is what you imply. Check out exactly who is represented there.


quokka, thanks for the link
Considering the enerty and economy relationship, I think humans are doomed to commit themselves to the burning of fossil fuels at as fast a pace as possible and therefore the upper curve is probably the most credible. The only thing missing in the report is the effect this will have on the melting of Greenland’s ice. We may very well be burning fossil fuels at a rapid clip even as our coastal cities are beginning to be swallowed by the oceans.


gallopingcamel, the NASA report you site is from the year 2000. Much has changed in Greenland since 2000. The report is a compilation of data just before we started seeing rapid changes that are now occurring in Greenland. Therefore your conclusion is based on out of date information.


Peter Lang’s logic here amounts to something like this:

“Hitler was anti-smoking. Therefore, all people who are against smoking are Nazis.”

Anyone who is worried by the conclusions of a vast body of scientific literature on climate change is clearly an anti-capitalist, communist peddling, economic illiterate.


Gene Preston,
As you point out, the GISP data was published 10 years ago. Furthermore, the data set ends in 1905.

However, it is still the best quality data we have for Greenland. There are ways to fill in the gap from 1905 to the present day and an update should be available quite soon.


GP global emissions declined in 2009 and it could turn out they declined in 2010. Therefore we have to question an emissions graph that shows continuous increases to 2050 and beyond.

The view that the peaking of all fossil fuels is imminent (with or without financial side issues) has been put by several authors including Aleklett, Heinberg, Rutledge and Patzek. Google any of these names and look at their analyses.


On the matter of ‘ Temperature is the “cause” and CO2 is the “effect” ‘, I’d think that particular effect is of serious concern; that CO2 is the leading cause of current Temperature rise is irrelevant to historical fact that temperature rise leads to rise of CO2 (and methane). Wouldn’t this be CO2 (and methane) in addition to emissions from fossil fuel burning and deforestation? This looks very likely to lead to even greater warming; any interpretation that temperature rise leads to rising CO2 as means there’s no cause for concern looks very misguided.

I haven’t had an opportunity to read more than the summary of the linked report on emissions and concentrations; does it provide and include estimates of CO2 and methane release attributable to temperature rise?


Peter Lang – if climate change is being used to push other barrows it’s because of the party political division that’s arisen around the issue. When the Green-Left are the loudest and most consistent voices calling for action their other concerns will inevitably colour their position and their proposals. The problem is the Right in Australia has completely failed even to demonstrate that they accept that climate change is an issue of importance to the security and prosperity of our nation. When they start showing they are serious about developing effective policy to limit the costs and consequences of unmitigated climate change rather than focus on policy to limit the costs of – and preventing others – doing anything about it we might see better, more focused climate policy all around.

Which is not to say there aren’t other issues of importance – and many of them inextricably intertwined with climate change, like it or not; population, resource depletion, loss of biodiversity and habitat destruction, food security, sustainable poverty alleviation…. issues no ‘side’ of politics looks able to deal with effectively, especially when most attempts are attacked and undermined in the mangle of party politics. The Left give lip service to some of these issues, the Right can’t seem to manage even that much, having invested too much in entrenched opposition to environmentalism.


You’re a troll, hypointellect, incapable of spelling out an apparent error, and incapable of standing correction. You have cut and run before we have even had a chance to read your smear. I charge that you are too cowardly to defend it.

It is indeed a guest post, with its key reference. What are you doing about global warming?


(1) I’ve asked Professor Wigley himself. I am awaiting a reply.
(2) Silly to repeat myself. See
(3) As far as what I’m doing to prevent climate disruption, with my wife Claire, see
(4) You might want to check out the rest of my blog there, and the sidebar.

‘Twas an honest question. “(2)” above will spell out the details grounding my doubts.


Thanks for standing your ground.

The contradictions you claim can’t be seen through the paywall, but seem to be no more than the use of different scenarios being fed into different models. However, that is what climate researchers do – up to the limits of their computing power, testing uncertainties in the models. Tell us more…

(I’m impressed with your heat pumps, described in your link!)


Actually, there is no paywall, at least if you know where to look. It is odd, however, that something would be put as a “Key reference” if it weren’t publicly available.

Well, that’s remedied, now, by going to:

No, in both instances, it’s the “Level 1” scenario. Setting that completely aside, there is NO correct climate scenario that brings CO2 levels below where they are now, or were as of the date of the paper. And that’s what the blog post says, and that’s what I thought was very, very odd.

Thanks on the heat pumps! It feels good to be Carbon free on our home.


Thanks for the link to the reference. It includes a description of the model MAGICC and its components. It is based on upwelling diffusion to mix the ocean layers and the heat and CO2 carried by them. Since the 1990 date of the model, diffusion has fallen out of favour, with the Southern Pump (in the roaring forties) now believed to be the main mechanism to turn over most of the ocean strata – but crucially, not the warmed surface layer.

About ice melt, it says, “this method was only meant to be used out to 2100”, and one can gather that other components are similarly vulnerable to extrapolation.

I too, am unhappy with the bald decline of CO2 in the run of the model shown in Fig 2. Although it demonstrates how a model can be used, the run shown is contradicted by many authoritative voices saying that the CO2 is up there for centuries to millennia. Now that the Paris agreement says we must urgently achieve “net zero reductions”, this graph suggests instead to would-be emitters that the ocean surface can offset a major fraction of all emissions for hundreds of years into the future.

It has become common practice to show a hairy plot with many runs of the model overlaid, showing the uncertainties increasing as the model reaches into the future. Fig 2 would have benefited.


The Paris agreement of 2015 was for “net zero emissions”. (Not net zero reductions – as we should fear.)


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