So how will you spend your 37 tons of carbon?

Inspired by a letter to New Scientist by Londoner Guy Robinson, herewith a not-so-abstract thought experiment based on the trillionth-ton climate change concept.

According to a pair of papers recently published in Nature, the Earth stands a good chance of warming more than 2 °C above pre-industrial levels if our cumulative atmospheric emissions of carbon since those days reaches a trillion tons. So far, we've emitted about 520 billion tons. leaving us with just 480 billion tons before we enter into dangerous global warming territory.

But some of our total emissions are tied to agricultural (methane from rice farms) and forestry (chopping down the tropics) practices, leaving us with a substantially lower allowance associated with burning fossil fuels. Just what the number is depends on a wide variety of factors, including the efficiency of carbon sinks and how your climate models are calibrated. Meinshausen et al. say if we want to keep the chance of exceeding 2 °C to around 25%, then we can only afford to emit 190 GtC. If we're happy with a higher risk factor of 50%, our allotment rises to around 300 GtC. Allen et al. estimate that cranking out 480 GtC produces a 50% chance of putting us over the edge.

Let's split the differences. If we're OK with a 25% chance of catastrophic climate change, then we can maybe emit 250 GtC. Now comes the really interesting part, the one Robinson's letter introduces:

Divide that 250 billion tons by the population of the planet, currently 6.7 billion, and you get 37 tons. That's 37 tons per person. Not per year, but forever. What does that mean? Well, the average American is responsible for about 20 tons of carbon dioxide each year, which is about 5.4 tons of carbon. So that means Americans will use up their quota in less than seven years.

The average Kenyan, by comparison will take 462 years at current consumption levels. And the Japanese are good for 15 years.

Of course, we could assign those 250 GtC to every human equally. This is not entirely a thought experiment. Something along these lines is almost certainly going to be raised in December at Copenhagen. If we did distribute current total fossil-fuel emissions of around 8.5 Gt per year equitably, that would give us all almost 30 years to find alternatives to burning coal, oil and gas. (For the sake of keeping the math simple, I've neglected population growth. The numbers shrink as populations increase. I suppose one could argue that any child born from now on will have to share his or her parents' emissions quota, or parents could buy unused portions from the estates of those who have died...)

Again, this is all based on a 25% probability of exceeding 2 °C. Is that acceptable? It's a political question, not a scientific one. Another political question is this: why should developing countries be happy with apportioning only future emissions rights?

Most climate change plans call for rich nations to cut their emissions by between 80 and 100 percent over the next few decades, while some of the poorest countries are allowed to grow a bit, at least until the mid-century or so. Which makes sense. But if we follow this trillionth-ton line of thinking to its logical conclusion, we have to accept that the vast majority of the carbon that we've put into the air was emitted by rich countries.

In effect we in the Western world have already blown our share of the trillion tons.

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I am a great proponent of reducing one's footprint, whether for carbon, water, area... But to have a real impact, governments and (most especially) churches need to think seriously about population.
If the Catholic church started handing out condoms and birth control pills, it would do more to mitigate the coming disasters than almost any other action.

Divide that 250 billion tons by the population of the planet, currently 6.7 billion, and you get 37 tons. That's 37 tons per person. Not per year, but forever.

Hang on a minute - what about all the people who haven't been born yet? How much do they get?

well, if my 37 tons are allocated in the future the way they're spent today, I'll only actually get 3 or 4 tons.

A good 10 tons will be taken up by government for its own business, fighting wars, etc.

Another 10 tons will be taken by various corporate entities in the form of subsidized business class travel, b2b transactions, stock market manipulations, and the rest.

10 more tons will be lost in transmission.

And 3 or 4 tons will have to be set aside to pay for heating because i live in a cold climate and am not allowed (by visa an immigration regulations) to move to a warmer one.

well, if my 37 tons are allocated in the future the way they're spent today, I'll only actually get 3 or 4 tons.

A good 10 tons will be taken up by government for its own business, fighting wars, etc.

Another 10 tons will be taken by various corporate entities in the form of subsidized business class travel, b2b transactions, stock market manipulations, and the rest.

10 more tons will be lost in transmission.

And 3 or 4 tons will have to be set aside to pay for heating because i live in a cold climate and am not allowed (by visa an immigration regulations) to move to a warmer one.

Don't these comments show just how much gobbledy gook the whole Greenpeace paper was. (Hare, Greenpeace Climate Campaign Director since 1992, Meinshausen, Greenpeace consultant since 2000).Independent scientists, both....

By harbinger (not verified) on 10 Jun 2009 #permalink

the capitalist theory of infinite accumulation in the hands of the rich is running up against the limits of nature. as has been the case since the beginning of capitalism, the tale will be told in how this plays out between nation states. global peak oil has occured already or will occur soon. energy from coal will almost certainly be the primary, cheap and feasible substitute for most of the world exacerbating climate change. surely the "third wolrd" has leaders equal in ruthlessness to cheney or obama, but they lack $600b a year in "defense" (har! har! har!) spending. the triple whammy of climate change, oil depletion, and technological/economic dependence on "third world" areas will be truly catastrophic. even now i can hear liberals and conservative crying crocodile tears for suffering in the "third" world. that third worlders bare virtually none of the blame for their fate is a cruel joke of a cruel god named moloch.

What possible use is there in dividing carbon equally? Do you really think it will play out that way?

And the 'the west has blown its share' argument doesn't fly, because the roll-on effects of the cultural success of the west to the rest of the world can't be quantified. Whether they're benefits or detriments. Fair doesn't come into this. Per capita doesn't even come into this. What does enter into this is the normal rough and tumble wrangling between nations over who gets what. The problem is that that isn't happening seriously enough; they're talking but they don't yet really believe what they're saying.

By Nils Ross (not verified) on 10 Jun 2009 #permalink

"third worlders bare virtually none of the blame for their fate is a cruel joke of a cruel god named moloch."

I think that rightly summarizes the situation.

Two points:

1) as per Dunc, no. 3 above, what about future generations?

2) as per Amory Lovins, what if we are really serious about a many-fold increase in the efficiency with which we use energy and other resources, not to speak of a clean energy revolution? If productivity could be increased 100-fold with the technology of the 1750s, can we not do at least as well today? Not that this will happen without concerted political action and pressure on vested interests, of course.

Intersting. But all this talk of a "trillion tons" (I've read the theory) and now 37 tons per American fail to address or rather, bring to the forefront the real reasons we're NOT going to change in time.

Pretending we have this "credit" which can be "expended" before we are in the danger zone is a very, very dangerous theme going 'round and 'round these days.

We are already in the danger zone, right now. Whatever carbon "credits" we've each consumed and expended, it is very clear that we have already entered into a very dangerous era. The lag on reporting current global temperature increases and experiences in regions around the world are already showing very dangerous temperature increases. And now that the solar minimum is coming to an end, we have this to factor in also.

11 tons -- Princeton Environment Institute (or something like that) per
http://www.reuters.com/article/GCA-GreenBusiness/idUSTRE56562Y20090707?…

EXCERPT follows:

The study suggests setting a uniform international cap on how much carbon dioxide each person could emit in order to limit global emissions; since rich people emit more, they are the ones likely to reach or exceed this cap, whether they live in a rich country or a poor one.

For example, if world leaders agree to keep carbon emissions in 2030 at the same level they are now, no one person's emissions could exceed 11 tons of carbon each year. That means there would be about a billion "high emitters" in 2030 out of a projected world population of 8.1 billion.

EACH PERSON'S EMISSIONS

By counting the emissions of all the individuals likely to exceed this level, world leaders could provide target emissions cuts for each country. Currently, the world average for individual annual carbon emissions is about 5 tons; each European produces 10 tons and each American produces 20 tons.

With international climate talks set to start this week in Italy among the countries that pollute the most, the authors hope policymakers will look at the strong link between how rich people are and how much carbon dioxide they emit.

"You're distributing the task of doing something about emissions reduction based on the proportion of the population in the country that's actually doing the most damage," said Shoibal Chakravarty of the Princeton Environment Institute, one of the study's authors.

By Hank Roberts (not verified) on 07 Jul 2009 #permalink