What it means to stabilize climate


in Canada, Science, The environment

Mica Prazak with a beer

This speech, given to the Canadian Council of Chief Executives, contains a basic error about the nature of climate stabilization. In part, it reads:

Never losing sight of the ultimate long-term objective of the exercise – stabilizing the level of man-made greenhouse gas emissions in the atmosphere at non-dangerous levels not in 2020, or even 2030, but 4 decades hence in 2050. Recognizing that we are running a marathon, not a sprint; and acting accordingly. (emphasis in original)

As stated, this is a very ambitious goal. Stabilizing the global concentration of greenhouse gasses by 2050 would mean reaching the point of zero net human emissions in that year. That would require either the total elimination of fossil fuel use and deforestation, or the deployment of technologies that capture greenhouse gasses from the atmosphere and sequester them.

Right now, greenhouse gas concentrations are about 385 parts per million (ppm), and rising at 2 ppm per year. Even if they kept up that rate between now and 2050, concentrations would ‘only’ rise to 469 ppm – a figure not enormously higher than the commonly cited target of 450 ppm. Of course, it is unlikely that emissions per year would stay completely flat until 2050, then drop instantly to zero.

Given the other contents of the speech (such as affirming that 80% of North American electricity will come from oil and gas in 2020), I don’t think the literal meaning of the passage quoted is the one intended. I fear, instead, that rather than talking about stabilizing concentrations of greenhouse gasses, the speaker may have been talking about stabilizing emissions. If so, this is a disastrous suggestion. If we are to avoid dangerous anthropogenic climate change, global emissions almost certainly need to peak between 2015 and 2020, declining sharply after that.

A simple analogy to personal debt easily explains the difference between concentration and emission stabilization. If you are going into debt because you are spending more each year than you earn, stabilizing your level of spending is not going to get you out of debt. It will just leave you in the position where your level of debt increases by the same amount every year. Stabilizing your debt requires that your expenditures match your income every year. While your level of wealth is lower than it was when you started, it is still stable. So too it will be when humanity reaches the point of zero net greenhouse gas emissions: what we already put in the atmosphere will stay there for hundreds of thousands of years, but at least we will no longer be adding to it.

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{ 25 comments… read them below or add one }

R.K. January 22, 2009 at 2:07 pm

“As we all know, energy insecurity is the large and growing gorilla in the room. Smart grids and conservation, renewable fuels and renewable power are all extremely important but in an 80/20 world they will represent only the 20 percent at least until 2020. It’s the other 80 percent that we need to worry about. In Europe, the 80 percent of energy insecurity means oil and natural gas and here in North America with our substantial natural gas reserves that is important. ”

This definitely isn’t the way someone intent on stabilizing concentrations by 2050 would talk.

If you want to keep using fossil fuels in stationary facilities, you need carbon capture for 80-90% of the emissions, then air capture for the rest.

If you want to use them in mobile applications, you need enough air capture to offset it all.

Milan January 22, 2009 at 2:39 pm

I am certainly starting to hope that air capture is more viable than I thought it was when I read Wallace Broecker’s book.

Emily January 22, 2009 at 2:52 pm

This photo has an interesting tone to it. It hangs in limbo somewhere between joyous, colourful wackiness, and drunk-guy-in-a-dirty-basement-holding-a- beer-next-to-an-old-bucket-ness.

Somehow, you harmonize the two with fashion magazine gloss and lighting.

It’s a triumph.

Magictofu January 22, 2009 at 3:18 pm

Milan, should natural CO2 absorption mechanisms be addressed in assessing GHG level stabilization? I read a few things here and there about this but never found anything clear and conclusive… or that I can trust.

Milan January 22, 2009 at 3:22 pm


You may find this previous post useful.

In short, there are some sinks that absorb CO2 from the air relatively quickly, but have a limited capacity. Much larger (geological) sinks also exist, but CO2 only enters them extremely gradually.

Milan January 22, 2009 at 3:30 pm

These RealClimate posts are also relevant:

Target CO2
7 April 2008

Can 2°C warming be avoided?
31 January 2006

. January 22, 2009 at 3:46 pm

Contribution of Working Group III to the
Fourth Assessment Report of the
Intergovernmental Panel on Climate Change

Technical Summary (PDF)

“Essentially, any specific concentration or radiative-forcing target requires emissions to fall to very low levels as the removal processes of the ocean and terrestrial systems saturate. Higher stabilization targets do push back the timing of this ultimate result beyond 2100. However, to reach a given stabilization target, emissions must ultimately be reduced well below current levels. For achievement of the stabilization categories I and II, negative net emissions are required towards the end of the century in many scenarios considered (Figure TS. 8) (high agreement, much evidence) [3.3.5].

The timing of emission reductions depends on the stringency of the stabilization target. Stringent targets require an earlier peak in CO2 emissions (see Figure TS.8). In the majority of the scenarios in the most stringent stabilization category (I), emissions are required to decline before 2015 and be further reduced to less than 50% of today’s emissions by 2050. For category III, global emissions in the scenarios generally peak around 2010–2030, followed by a return to 2000 levels on average around 2040. For category IV, the median emissions peak around 2040 (Figure TS.9) (high agreement, much evidence).”

Magictofu January 22, 2009 at 4:06 pm

Thanks for the links, RealClimate is already on my usual reading list and I have read a bit on issues around forest sinks and ocean acidification. I still wonder however about the possibility of a safe level of GHG emission… one which would be below the level of natural absorption. I guess one possible reason no one talk about it (apart from certain CO2-is-plant-food deniers) is that these levels are so low that they are negligible.

Milan January 22, 2009 at 4:13 pm

Biomass and ocean sinks are a stock, not a flow.

They are a bit like reserve tanks on an airplane: they can be full or empty, but they cannot provide any amount of fuel to the engines indefinitely. At the maximum, you would have a fully reforested world, undamaged marine ecosystems, and an ocean sink that has reached equilibrium with the atmosphere. Remember, also, that there is season-to-season and year-to-year variation. Plants are net emitters of CO2 at night, and often in the winter, also. Equilibrium is based on a mean, around which actually annual emissions vary.

That being said, actually reaching the point of zero net emissions could be delayed for some time, if emissions were dramatically lower. If emissions were 1/100th of current levels, for example, you could emit at that level for 100 years and only contribute as much to long-term trends as one year of our current emissions does.

The one way you could get a ‘flow’ of non-climate-altering emissions is if you either built machines that would take carbon out of the air and put it underground, ground up rocks that sequester carbon, or somehow collected and stored biomass somewhere it would never rot.

Milan January 22, 2009 at 4:14 pm

My index has more posts on sinks and climatic equilibria.

Tristan January 22, 2009 at 4:27 pm

There is another way to stabilize your level of debt – vote in an administration that is willing to debase the currency to pursue other economic goals. If the rate of inflation is high enough, and wages go up with inflation, your amount of debt will be reduced to the point, eventually, it amounts no more than a single cup of coffee. (Of course, this only works if the state holds interest rates down all the while – or, if you are lucky to hold any solid assets along with the debt, which since they go up in value faster than the debt, can be used to pay it off during the delay between the rate of change of inflation and the rate of change of interest rates).

I’m not just being a ninny – there is an analogy to this in climate change. Rather than increasing efficiency, we could just destroy the economy. And, in fact, it’s even better than that, because if we need to eliminate the large majority of emissions it’s as simple as making the middle class and poor too poor to afford to do anything carbon intensive. Owning a car, vacations, even books and food, are all luxuries that are very carbon intensive – reducing the ability of the vast majority of the population to have access to meaningful and enjoyable lives would enable the rich to continue to live in luxury without putting the climate at risk for their children.

Magictofu January 22, 2009 at 4:29 pm

I thought the piling up of organic material in forest soil and on ocean floor was a true sink… not everything decompose and get recylced in the carbon cycle. At least this is the way I thought these were sinks (as opposed to ocean acidification for instance).

Milan January 22, 2009 at 4:34 pm

There is another way to stabilize your level of debt – vote in an administration that is willing to debase the currency to pursue other economic goals.

This would be akin to reducing the planet’s climate sensitivity. It could be possible through geoengineering, but it would be a very risky thing to undertake. While it is theoretically possible that the worst impacts of climate change could be nullified, it is also possible that no geoengineering technique will work, or that the unwanted side-effects will be unacceptable.

[R]educing the ability of the vast majority of the population to have access to meaningful and enjoyable lives would enable the rich to continue to live in luxury without putting the climate at risk for their children.

I think it is likely that children born today are already at risk. So does James Hansen and all the 350.org type people.

Poverty is not a solution, as long as it is still sustained by fossil fuels and/or deforestation. The only solution is to stop deforestation, enhance natural sinks, and move to zero-carbon forms of energy.

Pragmatically, that cannot be accomplished through bludgeoning the bulk of the population into reduced emissions. It requires carbon pricing, as well as the aggressive deployment of existing low and zero-carbon technologies.

Milan January 22, 2009 at 4:39 pm


Biomass is a ‘true’ sink in some sense. Carbon dioxide that is in soil is not causing warming. It is not, however, the kind of sink that gives you an indefinite ‘allowance’ to emit. The only mechanisms that can do that are those that put carbon dioxide into rocks for long periods of time.

These include:

  • Reacting with chalk in ocean sediments
  • Reacting with water in the atmosphere to form a weak acid, then dissolving rocks to form minerals like magnesium carbonate.

These processes are very slow. Calcium carbonate absorption occurs on a scale of about 5,000 years. The reaction of CO2 with igneous rocks takes about 400,000.

One proposal for long-term air capture and sequestration is to grind up those kinds of rocks, increasing the reaction rate.

Milan January 22, 2009 at 4:42 pm

Actually, even geological sequestration isn’t necessarily forever. Carbon that gets formed into rocks that then subduct can still be released by volcanoes.

. January 22, 2009 at 4:53 pm

Study: Global warming decimating old-growth forests at stunning rate

Globe and Mail Update
January 22, 2009 at 4:47 PM EST

CALGARY — The death of old-growth forests in the western United States and Canada is increasing at a stunning rate, a troubling trend linked directly to global warming that could soon transform forests into carbon dioxide emitters rather than much-needed carbon sinks, a new study warns.

Tristan January 22, 2009 at 6:23 pm

“Poverty is not a solution, as long as it is still sustained by fossil fuels and/or deforestation. The only solution is to stop deforestation, enhance natural sinks, and move to zero-carbon forms of energy.”

I agree, so what about carbon pricing in conjunction with the destruction of the middle class? If carbon taxes are high, and people don’t have much money, they’ll consume less carbon – right?

I’m being cynical, I know, but I think it’s important to imagine what these scenarios would look like in case they start to happen.

Milan January 22, 2009 at 6:45 pm

In the end, we cannot claim to have solved the climate change problem until both movie stars and people living in slums in India are living low carbon lives.

Tristan January 23, 2009 at 1:18 am

“until both movie stars and people living in slums in India are living low carbon lives.”

I don’t disagree. I’m merely saying that people living in slums can live lower carbon lives either by being richer or by being poorer (read – more dead).

The best solution for the rich would be to simply eliminate the bottom billion or so, the ones who don’t produce cheap products for strong currency consumption. Then they wouldn’t produce any carbon.

Milan January 23, 2009 at 9:01 am


a) A massive global war of class extermination

b) Renewable energy, efficient vehicles and buildings, good forest management

Which of these is a solution that makes the slightest lick of sense? Your (sensible) position that rational actor models do not fully account for human behaviour squares awkwardly with this assertion that ruthlessly killing a billion people is the “best solution for the rich.”

Magictofu January 23, 2009 at 9:16 am

How can you be rich without the poors anyway?

. January 26, 2009 at 9:58 pm

Some climate damage already irreversible


Associated Press

January 26, 2009 at 5:00 PM EST

WASHINGTON — Many damaging effects of climate change are already basically irreversible, researchers declared Monday, warning that even if carbon emissions can somehow be halted temperatures around the globe will remain high until at least the year 3000.

“People have imagined that if we stopped emitting carbon dioxide the climate would go back to normal in 100 years, 200 years – that’s not true,” climate researcher Susan Solomon said in a teleconference.

Ms. Solomon, of the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory in Boulder, Colo., is lead author of an international team’s paper reporting irreversible damage from climate change, being published in Tuesday’s edition of Proceedings of the National Academy of Sciences.

. January 29, 2009 at 10:53 am

The erroneous belief that stabilizing emissions would quickly stabilize the climate supports wait-and-see policies but violates basic laws of physics.”

— Dr. John Sterman, risk analyst at the Sloan School of Business, M.I.T.

. January 30, 2009 at 7:19 pm

Canada, U.S. in harmony on climate change: Prentice

By Juliet O’Neill, Canwest News Service
January 30, 2009 4:01 PM

OTTAWA — Prime Minister Stephen Harper and U.S. President Barack Obama have almost the same principles and goals on climate change, Energy Minister Jim Prentice said Friday.

In an interview with Canwest News Service, he said Obama’s principles are “virtually identical” to those of the Conservative government and Canada’s targets for reducing greenhouse gas emissions are “somewhat more aggressive.”

Milan October 28, 2009 at 4:32 pm

This is a great quote:

“If you ask a scientist how much more CO2 do you think we should add to the atmosphere, the answer is going to be none.

All the rest is economics.”

-Gavin A. Schmidt

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