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Study Concludes That to Limit Global Warming to 2 °C, Less Than 25% of Proven Fossil Fuel Reserves Can be Burnt Between Now and 2050

The theme of the current issue of Nature is that the climate situation may be even worse than you think.

Less than a quarter of the proven fossil fuel reserves can be burnt and emitted between now and 2050, if global warming is to be limited to two degrees Celsius (2 °C), according to a new study published in the journal Nature today. This issue of Naturethemed “The Coming Climate Crunch”—features a number of related papers and commentary on greenhouse gas emissions and the difficulty of cutting back, as well as an editorial calling on commitment from “the highest levels” to make the needed changes.

The study, led by Malte Meinshausen at the Potsdam Institute for Climate Impact Research (PIK), calculated how much greenhouse gas emissions can be pumped into the atmosphere between now and 2050 to have a reasonable chance of keeping warming lower than 2 °C (above pre-industrial levels)—a goal supported by more than 100 countries to prevent dangerous climate change.

Two possible futures: One in which no climate policies are implemented (red), and one with strong action to mitigate emissions (blue). Shown are fossil CO2 emissions (top panel) and corresponding global warming (bottom panel). The shown mitigation pathway limits fossil and land-use related CO2 emissions to 1000 billion tonnes CO2 over the first half of the 21st century with near-zero net emissions thereafter. Greenhouse gas emissions of this pathway in year 2050 are ~70% below 1990 levels. Without climate policies, global warming will cross 2 °C by the middle of the century. Strong mitigation actions according to the blue route would limit the risk of exceeding 2°C to 25%. Credit: M. Meinshausen et al. (2009) Click to enlarge.

The researchers, involving scientists from Germany, the United Kingdom and Switzerland, concluded that the limit is 1,000 billion tonnes of carbon dioxide between the years 2000 and 2050. The world has already emitted one third of that in just nine years.

The three-year study concluded that greenhouse gas emissions must be cut by more than 50% by 2050 relative to 1990 levels, if the risk of exceeding 2 °C is to be limited to 25%.

If we continue burning fossil fuels as we do, we will have exhausted the carbon budget in merely 20 years, and global warming will go well beyond two degrees. Only a fast switch away from fossil fuels will give us a reasonable chance to avoid considerable warming. We shouldn’t forget that a 2°C global mean warming would take us far beyond the natural temperature variations that life on Earth has experienced since we humans have been around.

—Malte Meinshausen

The study also compared the volume of CO2 emissions that could result from the burning of known economically recoverable fossil fuel reserves—oil, gas and coal—and found that these reserves are four times larger than the emission budget between now and 2050.

To keep warming below 2 °C, we cannot burn and emit the CO2 from more than a quarter of the economically recoverable fossil fuels up to 2050, and in the end only a small fraction of all known fossil fuel reserves.

—Bill Hare, co-author of the study

The study used a single, efficient computer model which incorporated the effects of all greenhouse gases, aerosols and air pollutants, and the range of possible responses of the carbon cycle and earth’s climate system. This was combined with about a thousand emission pathways.

The study explicitly takes into account the uncertainties related to modeling climate change. Throughout the study, probability statements were used to summarize the current level of knowledge based on observational data. It also used a huge number of different simulation results from the latest assessment report of the Intergovernmental Panel on Climate Change. In taking this comprehensive approach the researchers went a step further than previous work.

The new results have direct relevance to the international negotiations now underway.

With every year of delay, we consume a larger part of our emissions budget, losing room to manoeuvre and increasing the probabilities of dangerous consequences.

—Reto Knutti, co-author from the ETH Zurich

A companion study, also published in Nature today by Myles Allen and colleagues, shows the necessity to limit the total amount of carbon that humankind ever emits.

In principle, it is the sum of all CO2 emissions that matters. In practice, substantial reductions in global emissions have to begin soon, before 2020. If we wait any longer, the required phase-out of carbon emissions will involve tremendous economic costs and technological challenges—miles beyond what can be considered politically feasible today. The longer we wait, the more likely our path will lead us into dangerous territory.

—Malte Meinshausen

The authors of both papers collaborated on a Commentary article focusing on their long-term policy implications, published today in Nature Reports Climate Change.


  • Meinshausen, M., Meinshausen, N., Hare, W., Raper, S. C. B., Frieler, K., Knutti, R., Frame, D. J. & Allen, M. (2009) Greenhouse gas emission targets for limiting global warming to 2 °C. Nature 458, 1158-1162 doi: 10.1038/nature08017

  • Allen, M. R., Frame, D. J., Huntingford, C., Jones, C. D., Lowe, J. A., Meinshausen, M. & Meinshausen, N. (2009) Warming caused by cumulative carbon emissions towards the trillionth tonne. Nature, doi: 10.1038/nature08019

  • Allen, M. R., Frame, D. J., Frieler, K., Hare, W., Huntingford, C., Jones, C., Knutti, R., Lowe, J., Meinshausen, M., Meinshausen, N. & Raper, S. (2009) The exit strategy: Emission targets must be placed in the context of a cumulative carbon budget if we are to avoid dangerous climate change. Nature Reports Climate Change, doi: 10.1038/climate.2009.38

  • Schmidt, G. & Archer, D. (2009) Too much of a bad thing. Nature doi: 10.1038/4581117a

  • Stephen Schneider (2009) The worst-case scenario. Nature 458, 1104-1105 doi: 10.1038/4581104a

  • Nature editorial: Time to Act



Reducing the use of fossil fuels is the right thing to do. They are finite and harder to come by, so this makes sense on its own. We can pretend that we can just go to war for more oil, or blow up more mountain tops for coal, but we need to find better ways and we all know this to be true. Now, if we can find the leadership to make this happen, we may be on our way to a better tomorrow.


This is exactly what I feared most. The only way for us to turn around climate change is a DRASTIC shift in our lifestyles. How can motivate the world to do this? If you're passionate about slowing climate change, I just watched some videos that are definitely worth checking out. There was a contest at Tomorrows World's site and the students who won have their work on show:

These kids wrote scripts or sent in videos on water efficiency and climate change flooding. Hopefully in the process they'll make a lot people think about their own water efficiency and carbon footprints.
Never hurts to put your ideas out there, so let's encourage them to keep at it. Give them a view and spread the word!


brace yourselves for toppatom and the rest of the holocaust deniers.

on the bright side, anyone reading this will not substantially be effected by climate change... we are too old. If you don't care about future generations then by all means, keep fighting public policy (taking away your right to pollute!)

Great article in Mother Jones this month about plastics. We could eliminate 99% of plastics in 3 years and our happiness level would not change. Small cogeneration and combined cycle systems can double efficiecy of small thermal power machines. sells marvelous systems TODAY! All homes should have one. In fact, all homes should have some power generation capabilities BY LAW... probably wind.


This is the right way to do a climate study - probability calculations. Although we 'Greens' often rant about how CO2 is causing Global Warming in the strictest sense its not true. From one day/month/year to the next the temperature can go up or down. What increased levels of CO2 do is increase the chances it will go up more than it will go down and the greater the levels the greater the odds.

And of course we have 'tipping points' to worry about too. Increased temperatures can also increase the chances of more GHGs getting into the air. As an example; the mountain pine beetle is spreading and killing more and more trees [a needed carbon sink].

These little buggers use to be held in check by deep winter frosts.


.....drastic changes in live style???....

Humans are much more adaptable than most of us think. Using less energy does not always mean less comfort.

We went from a 65 Kwh/day all electric oversized poorly insulated home to a 17 Kwh/day much better built all electric place and our comfort level didn't go down but up.

We went from a 400 HP huge Chrysler 12-15 mpg gas guzzler to a very decent size comfortable Toyota Camry using less than half the fuel and we move around without pain. Our next car, a Prius III (or equivalent) will use even less energy. Within 5 years our PHEV-60+ will probably use even much less.

Switching from ICE gas guzzler to a mostly electrified, quieter, more efficient vehicle will be an easy thing to do.

All stores in our small city have stopped using plastic bags and almost nobody complained. They were not needed. Within a few days, everybody had half a dozen + long lasting fabric bags in their car trunk an used them. We all changed very quickly and without pain.


Meanwhile Australia sets new record low temperature - but of course it's just "weather."

The PDO SST continues to drop, - more FACE studies confirm the fertilization effect of CO2, the Arctic sea ice extent in now in the 1979-2000 mean, Antarctic ice has exceeded first year satellite measure (1979) by .8 million sq km - and all four measuring centers track lower global temps.

The illuminati deny the AGW holocaust and all's well at the prestigious journal "It's Not Nature."

To jimfromthefoothills infinite credit is his remark that cogeneration and combined cycle power units should be in every home. However jim, it's NOT necessary to legislate it. Just make it abundantly obvious that it's efficient, money saving, and good for enviro and (!)national security.

ai's remarks are valid - and should also note that BC had one of it's worst winters in decades. If the cold don't kill em, how 'bout sterile mates for the buggers?

Harvey's downsized energy use is admirable and a good example to those who care to follow suit. I think Harvey's story should go main stream to gauge reaction.

Me, well I'm just here to keep you guy honest. You know that.


It looks like those "Holocaust Deniers" now number about 13 times the scientist that signed on to the IPCC and some of the scientist that were part of the IPCC are now calling the global warming hoax nothing more than junk science that ignores the fact that the earth has been cooling for a decade.

Don't worry, when it becomes impossible to cling to global warming as a theory in a few years, you can always jump on the global cooling bandwagon, it is due to come back in style soon.

Go to the pasted link if you can "handle the truth" Also, the movie "The great global warming swindle" is available online.


Speaking of denying the holhocaust there were no gas chambers in any of the concentration camps in Germany proper, nor did the Nazis manufacture soap from human remains, nor were there any human skin lamp shades made in Germany, the Katyn Massacre was perpetrated by the NKVD ( forrunner of the KGB) instead og the Germans and by the way the Nazis didn't shrink human heads. But then the Nuremberg Trial lawyers told the world otherwise in 1945.

It's time to dust off all those nuclear power plant proposals that the ecofreaks have managed to stop over the last three decades.

Will S

if you can "handle the truth" Also, the movie "The great global warming swindle" is available online.

That has been roundly debunked, i.e,;

It looks like those "Holocaust Deniers" now number about 13 times the scientist that signed on to the IPCC

How many of these 'scientists' are actively involved (publishing) in climatology?

some of the scientist that were part of the IPCC are now calling the global warming hoax nothing more than junk science that ignores the fact that the earth has been cooling for a decade.

I've only heard politicians and pundits say this. Any 'scientist' would be roundly beaten down by statisticians for cherry-picking. Please provide quotes from 'scientists' who say this.


The movie " The great global warming swindle" is a joke a piece of trash, made by deniers, nothing that's worth loosing time on it. Even the guy who did it recognize that he squewed the facts


Reel$$ has been bought and brought to you by Exxon Mobil and Western Fuels Association.


"BC had one of it's worst winters in decades."

Ha! That's a joke, right? What we needed was a really cold winter, all we got was lots of snow. All you need to get lot's of snow is warm temperatures globaly to put more water vapour into air and -0 temps locally take the water vapour out.


Now jimfromthefoothills... You should know better than to offer troll-talk without facts. Even though the AGW cult has based their dreams on factless psuedo-science, at least do us the favor of demonstrating your claim.

ai-vin, thank you for your meteorological explanation of how winter works. But BC has just emerged from the coldest winter in the last 16 years! Funny how the globe is "warming" but real people feel the chill.

And according to predictions - it's only getting colder. Oh dear, now with 700 scientists telling IPCC to find another job - it looks like Hansen, Algor and his band of lilliputians will have to find a new planet to rob.

PS: I would happily represent Exxon Mobil's cellulosic & algal biofuel initiative if they had one. Likewise for Western Fuels electrification of transport program - if they had one. Big change comes by changing big players.

"Exaggeration leads the coalition of disbelief."

Nat Pearre

"And according to predictions - it's only getting colder."

But you don't believe predictions do you? Or were these made by the Farmer's Almanac, which is far more believable than full climate models on super-computers.

Will S

Funny, we've just had 4 straight days of 90F weather, unheard of in April.

Yes, it's just weather; climate trends are over decades and more. Reel, you should know that by now...


"Farmer's Almanac, which is far more believable than full climate models on super-computers."

Um, yeah Ned. Seems the ol' Almanac IS better at predicting weather than full climate models on super-computers.

But isn't that just a bit of back-to-the-land, Gaia kind of knowlege? Century old farming methods certainly outweigh those fancy silicon-based 'puters!


climate change isn't a new thing, but this article gave me a different perspective on how global warming is actually measured and what could be done to stop the rapid warming of our planet.

I agree that changing our lifestyles won't be extremely painful, the hardest part is getting people to care enough to inconvenience themselves a little. The other day I came across this website about an antarctic expedition that is soon to launch in November:
I thought it was interesting that their main goal was to create public awareness of global warming through studying the climate changes to the antarctic. Check it out!



Why do you claim that wind farms and tidal power will not help reduce CO2 and climate change as well as reduce oil imports ?

The Goracle

I REALLY like the way that Green Car Congress refuses to post articles that contradict the Globalwarmist faith. Here's a great story in National Geographic today:

Sun Oddly Quiet -- Hints at Next "Little Ice Age"?

OK now... lets all start calling National Geographic names - "haters" and the like! They have blasphemed Globalwarmists.


The article if actually read deals with the fact that GHG CO2 is now dominating the trend that even with a decrease in solar output as they described it wouldn't do anything, according to the scientist interviewed. Mmm. Maybe you should've read it or is that too much to ask.

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