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It’s Not Too Late to Limit Global Temperatures - But Almost

For a couple of years now, climate scientists have agreed that to avoid the most serious consequences of global warming we need to cap the planet’s average temperature at no more than 2 degrees C (or 3.6°F) above where it stood in the 1800s. The temperature has already risen by about 1°C -- the longer we wait to rein in greenhouse-gas emissions, the harder it will be to reach that goal — and the recent international climate talks in Doha made it clear that emissions aren’t likely to be reined in anytime soon.

This raises the question of how much more those emissions could grow before the 2°C target becomes physically impossible to achieve. And a recent paper in Nature Climate Change has a somewhat encouraging answer. Even if annual emissions nearly double by 2020 from today’s 30 billion tons or so, it would still be possible to cap the temperature rise at 2°C, or at worst, rise slightly above that level before coming back down.

Emissions from portable asphalt plant in Wisconsin.
Credit: flickr/Wisconsin Department of Natural Resources

That’s the good news. The bad news is that “possible” doesn’t mean “easy,” by a long shot. Capping temperatures after such a large increase in emissions would be “technically feasible,” co-author Brian O’Neill said in an interview, “but so many things would have to go right that you’d have to be a very optimistic person to bet that it would actually happen.”

O’Neill said the problem is that emissions would have to be cut quickly and drastically after 2020. The technology for doing so already exists, including nuclear power, biofuels and the capture and storage of carbon from power-plant smokestacks before it can enter the atmosphere.

“It would have to be feasible to scale all of them up globally, and they couldn’t be prohibitively expensive,” he said. “You’d have to retire most of the world’s coal-burning plants, and countries would have to work together to make it all happen.”

The good news, say the study’s authors, is that emissions needn’t double by 2020, especially if energy-hungry nations put some effort into improving the efficiency of cars, buildings, factories and other energy hogs.

Coal fired power plant’s smokestack emissions.
Credit:flickr/Emilian Robert Vicol

“If we did nothing other than reduce energy demand through efficiency and lifestyle changes before 2020,” O’Neill said, “we could meet the 2°C target even if we didn’t build more nukes, or if we put limits on the amount of land devoted to biofuels” — two options that would otherwise be impossible.

Still, without some strong new agreements on emissions, meeting the 2°C target is likely to be a tall order given that nations would have to work together.

“Politics is a separate question,” O’Neill said, noting that the 2°C number is an international target that many countries have publicly agreed to in principle. “Whether they’re serious about it or not, we’re not judging.”

But this kind of study can still be useful. “It can inform what’s technically and economically feasible,” O’Neill said. “People need to understand implications of the temperature targets they’re agreeing to. I’m not sure they always do.”

Related Content
Doha Talks: EU Weakened Over New Emissions Targets
Why 2 Degrees?
Analysis of US Delegation's Climate Numbers

Comments

By Dave (Basking Ridge, NJ 07920)
on December 21st, 2012

“…not too late - but almost”.

That’s a vague and rosy interpretation of the situation if ever I saw one. Next to no chance sums it up better than “but almost”.  See for instance:

K. Anderson, A.Bows, Beyond ‘dangerous’ climate change: emission scenarios for a new world ,Phil. Trans. R. Soc. A 2011 369, 20-44. http://rsta.royalsocietypublishing.org/content/369/1934/20.full.pdf+html

Meinshausen et al, Greenhouse-gas emission targets for limiting global
warming to 2 C, Nature, 458, pp1157-63, 2009.
https://www1.ethz.ch/iac/people/knuttir/papers/meinshausen09nat.pdf

Reply to this comment

By Lewis Cleverdon (Central Wales)
on December 21st, 2012

Michael - it is a bit hard to understand the basis of the article, since the proposed worst case scenario of a doubling of CO2 output by 2020 seems more than unlikely - it would require unprecedented annual CO2 increase of 9% or 10% per year reflecting global fossil-fuelled economic growth and/or rising global carbon intensity, and that is not counting any renewables-based economic growth.

The idea that it’s almost too late to mitigate such a scenario seems again unclear, as it implies that emissions control is our sole mitigation option, when that is patently not the case. I’d expect you’re well aware that there are both well-proven Carbon Recovery options (via forestry) and ongoing Albedo Restoration research, both of which will in my view inevitably be required for a commensurate response to resolving warming.

The seriousness of our predicament can be seen to outweigh the unprecedented-growth scenario above once the well documented acceleration of six out of seven major feedbacks is acknowledged, along with the warming due to the inevitable loss of the ‘sulphate parasol’ as our fossil sulphate emissions are ended. (Hansen & Sato report this loss as raising warming by 110% (+/- 30%). Assuming anthro-emissions under an early effective emissions control treaty would give us committed warming of around 2.1C by 2050 (off 0.8C realized, plus 0.7C timelagged, plus 0.6C from the phase-out output) adding 110% would then give around 4.4C of warming realized around 2080 after the timelag. This ‘best case’ emissions control scenario would allow the major feedbacks 68 years of continuous anthro-warming to around five times its present level to boost their interactive outputs - potentially beyond any possibility of control.

I wish you’d give your views on why the apparent deficiency of the ‘best case’ of emissions control is not the subject of widespread discussion. Perhaps I’ve overlooked some published refutation of Hansen & Sato’s finding on the ‘sulphate parasol’ loss ? (If so I’d be glad of a link). But even so, the feedbacks’ acceleration and interaction is increasingly well documented by multiple sources, and they are on track to dwarf our current GHG output long before the natural carbon sinks would make any significant dent in whatever peak level of airborne anthro-CO2e ppm we achieve.

My concern with the present widespread acceptance and promotion of the emissions-control-only strategy is that it is made to appear both currently unachievable by White house policy, as well as unfeasible by cogent impracticality critiques from Anderson and others. The presentation of an existential problem without an accompanying credible mitigation strategy is not only generating the defeatism and apathy that disables activists and decimates recruitment, it also discourages general public discussion and attention to the climate issue as people tend to prefer not to think about apparently intractable depressing problems - especially with ubiquitous media outlets pushing escapism.

To make any difference at all to the date of replacement of the bipartisan US policy of postponing international climate action (that Obama evidently adopted in 2009), we need to rouse the public to demand action and to elect those demanding action by providing rational credible solutions alongside the daily descriptions of the problem - and if there are any viable solutions that do not include both modes of geo-engineering, I’ve yet to hear of them despite close attention to the climate issue for many years.

So how about breaking the taboo on the discussion of geo-e on its merits as the necessary and sufficient complement to the essential goal of emissions control ?

Regards,

Lewis

Reply to this comment

By Robert Callaghan
on December 22nd, 2012

Methane sea beds increased in size by one order of magnitude in the last few years with just 0.8°C rise in earth’s temperature. 2°C will be beyond dangerous. We are on track for 3°C by 2050. The upcoming IPCC report will not include climate feedbacks in its calculations rendering them worse than useless. 

The melting tundra is unstoppable and irreversible once started - it has started. Our agricultural system is destroying the food web of life on land and in the oceans. It too is unstoppable and irreversible once started. Ocean acidification may have caused 4 of earth’s 5 last mass extinction events. Meanwhile, China is going to flatten 700 mountains to make way for a new city. 2 million children have been killed in the Congo since 1998 over exotic minerals for smartphones and green energy. We can’t keep eating GMOs and nano-particles waiting for the next iphone to arrive.

http://www.sfu.ca/pamr/media-releases/2012/study-predicts-imminent-irreversible-planetary-collapse.html

http://www.youtube.com/watch?v=PFY31MIubG4

http://www.youtube.com/watch?feature=player_embedded&v=RInrvSjW90U#!

http://thinkprogress.org/climate/2012/11/29/1246891/scientific-american-ice-melting-permafrost-climate-effects-occurring-alarming-pace/

http://thinkprogress.org/climate/2012/12/02/1253931/ipccs-planned-obsolescence-fifth-assessment-report-will-ignore-crucial-permafrost-carbon-feedback/

http://grist.org/food/nanoparticles-in-your-food-youre-already-eating-them/

http://www.npr.org/blogs/krulwich/2012/11/29/166156242/cornstalks-everywhere-but-nothing-else-not-even-a-bee

http://physics.ucsd.edu/do-the-math/2012/08/battery-performance-deficit-disorder/

http://www.skepticalscience.com/arctic-methane-outgassing-e-siberian-shelf-part2.html

http://www.businessinsider.com/big-coal-is-putting-climate-targets-hopelessly-out-of-reach-2012-10

http://www.businessinsider.com/giant-chinese-infrastructure-projects-2011-6?op=1Methane sea beds increased in size by one order of magnitude in the last few years with just 0.8°C rise in earth’s temperature. 2°C will be beyond dangerous. We are on track for 3°C by 2050. The upcoming IPCC report will not include climate feedbacks in its calculations rendering them worse than useless. 

The melting tundra is unstoppable and irreversible once started - it has started. Our agricultural system is destroying the food web of life on land and in the oceans. It too is unstoppable and irreversible once started. Ocean acidification may have caused 4 of earth’s 5 last mass extinction events. Meanwhile, China is going to flatten 700 mountains to make way for a new city. 2 million children have been killed in the Congo since 1998 over exotic minerals for smartphones and green energy. We can’t keep eating GMOs and nano-particles waiting for the next iphone to arrive.

http://www.sfu.ca/pamr/media-releases/2012/study-predicts-imminent-irreversible-planetary-collapse.html

http://www.youtube.com/watch?v=PFY31MIubG4

http://www.youtube.com/watch?feature=player_embedded&v=RInrvSjW90U#!

http://thinkprogress.org/climate/2012/11/29/1246891/scientific-american-ice-melting-permafrost-climate-effects-occurring-alarming-pace/

http://thinkprogress.org/climate/2012/12/02/1253931/ipccs-planned-obsolescence-fifth-assessment-report-will-ignore-crucial-permafrost-carbon-feedback/

http://grist.org/food/nanoparticles-in-your-food-youre-already-eating-them/

http://www.npr.org/blogs/krulwich/2012/11/29/166156242/cornstalks-everywhere-but-nothing-else-not-even-a-bee

http://physics.ucsd.edu/do-the-math/2012/08/battery-performance-deficit-disorder/

http://www.skepticalscience.com/arctic-methane-outgassing-e-siberian-shelf-part2.html

http://www.businessinsider.com/big-coal-is-putting-climate-targets-hopelessly-out-of-reach-2012-10

http://www.businessinsider.com/giant-chinese-infrastructure-projects-2011-6?op=1

Reply to this comment

By Grant T B (CS CO 80907)
on December 24th, 2012

K. Anderson speaks on this on the Tyndall Centre site and ecoshock.org. Worthwhile.

Reply to this comment

By Lewis Cleverdon (Wales)
on December 24th, 2012

Robert - Your assertion that the major feedbacks are unstoppable is, fortunately,  misinformed. Various scientists and others have been promoting this perspective based on the false assumption that Emissions Control is our only option for mitigation. Given both ongoing research into Albedo Restoration techniques (including stratospheric, tropospheric, land surface and sea-surface options) and the millennia of human experience of Carbon Recovery via charcoal sequestration in farm soils, it is actually very clear that we have at least the potential ability to cool the planet - and thereby halt the feedbacks’ acceleration - while ending GHG outputs and gradually cleansing the atmosphere.

Quite what entity is so set against discussing these necessary techniques that they would rather propagate massive despair, apathy and defeatism seems unclear - but it is very influential. The ‘logic’ of its case is that we should watch the world burn through the deficiency of even the best case of Emissions Control, rather than applying in addition globally accountable and stringently supervised geo-engineering. That is such nonsense that it points directly to some undeclared agenda - about which your guess is as good as mine.

Regards,

Lewis

Reply to this comment

By Survival Acres (USA)
on January 3rd, 2013

“Even if annual emissions nearly double by 2020 from today’s 30 billion tons or so, it would still be possible to cap the temperature rise at 2°C, or at worst, rise slightly above that level before coming back down.”

One of the most misinformed, misleading statements I’ve ever had the displeasure to read.  This is so incredibly wrong I barely know where to begin.

You are overlooking lag time and the multitude of positive feedback effects. It is well understood now that limiting to 2C is in fact, factually impossible.

“For a couple of years now, climate scientists have agreed that to avoid the most serious consequences of global warming we need to cap the planet’s average temperature at no more than 2 degrees C”

Also dead wrong. This figure was fabricated by an economist—W.D. Nordhaus—not a climate scientist. 2C leads to catastrophic warming, now being widely recognized.

The evidence is overwhelming, and is shown in the following categories, any one which will lead to the same outcome that utterly refutes the claims made in this article:

2c Projection as a Tolerable Limit
2C Projection as Achievable or Even Desirable
Emissions of C02 Are Still Increasing
Climate Projection Are Incorrectly Pegged At The Year 2100
Methane Hydrates and Their Contribution
The Albedo Effect
Global Deforestation
Atmospheric Carbon Loading
The Failure to Include Permafrost Melting
Arctic Ice Melt
Rising Sea Levels Will Displace Hundreds of Millions
Sea Level Rise Due To Ice Melt
Sea Level Rise Due To Thermal Expansion
Ocean Collapse
Coral Collapse
Oxygen Depletion
Wet-Bulb Temperatures Will Wipe Out All Mammal Species
Cumulative Impacts

The 2ºC “target” is a politically (not scientifically) set target from the European Union (EU) that goes back to the mid 1990s.

Since then, although the weight of scientific evidence has increasingly shown that a globally averaged 2ºC temperature increase will be disastrous for humanity and much of life on Earth, the figure has stuck.

A safe limit was established at +1ºC even before 1990 (Villach Conference, 1987). The Avoiding Dangerous Climate Change conference in Exeter (2005) arrived at a limit of 1ºC (although acknowledging that dangerous climate change for developing countries is below 1ºC).

Many papers have been published over the years saying that 2ºC is too dangerous, and the precautionary weight of evidence is 1ºC to 1.5ºC. (These figures are now superseded by actual changes in the Arctic.)

The EU now acknowledges that a 2ºC global warming is not safe.

It’s already significantly too late to limit warming to 2°C.

Together with Corinne Le Quéré of the UK’s Tyndall Centre for Climate Change and colleagues from the Global Carbon Project, Peters calculated just how far apart international goals and reality are when it comes to climate change. Their conclusions, published in the scientific journal Nature Climate Change on Sunday, were the following:

Between 1990 and 2011, global emissions of carbon dioxide have increased by 54 percent, and this is expected to jump to 58 percent based on projections for 2012. Humans will have released some 35.6 gigatons of greenhouse gases into the atmosphere in this year alone, with an average increase of 3.1 percent per year. That number was slightly lower in 2012, measuring 2.6 percent, though that was mainly due to the economic crisis, the paper says.

These emissions are in line with the most extreme scenario, dubbed “RCP 8.5,” from the world climate report that will be presented in 2014. This means that realistically, it would take more than a decade for CO2 emissions to sink. But that would be too late to reach the two-degree target.

How did Climate Central error so greatly and allow such a misleading article to get published?

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