Warming past 1.5°C: Quantifying our Faustian bargain with fossil fuels

Print Friendly, PDF & Email

Climate Code Red

The climate system will heat well past 1.5 degrees Celsius (°C) and perhaps up to 2°C without any further fossil fuel emissions. That’s the conclusion to be drawn from new research which should also help demystify the rhetoric from the 2015 Paris climate talks of keeping warming to below 1.5°C .

Our Faustian bargain: the byproduct of burning dirty fossil fuels are short-lived atmospheric aerosols which provide temporary cooling.

It’s not that 1.5°C isn’t dangerous: in fact, at just 1–1.1°C of warming to date, climate change is already dangerous.

A safe climate would be well below the present level of warming, unless you think it is OK to destroy the Arctic ecosystem, tip West West Antarctic glaciers into a self-accelerating melt, and lose the world’s coral reefs, just for starters.

The new research quantifies the effect of losing the very temporary planetary cooling provided by atmospheric aerosols.

Aerosols (including black-carbon soot, organic carbon, sulphates and nitrates and dust) are very short-lived particles in the atmosphere that have a cooling impact that lasts around a week.

Most of these aerosols are anthropogenic, that is produced by human activity, and most of the anthropogenic aerosols are a byproduct of the extraction and burning of fossil fuels.

Perhaps best known are the polluting sulphates and nitrates from coal-fired power stations, that combine with water molecules in the atmosphere to produce what is popularly known as “acid rain”.

The problem is our “Faustian bargain”: these aerosols are keeping the planet cooler than it would otherwise be, but are coming from burning fossil fuels that pour carbon dioxide (CO2) into the atmosphere, heating the planet for centuries to come.

The absolutely essential moves to eliminate fossil fuel emissions will also cut the cooling aerosol impact; the net effect will push the planet towards very dangerous warming conditions.

The big question is how much would that warming be?

A number of scientists have estimated the figure at around 0.5°C. Writing in the Huffington Post in late 2015, Prof. Michael E Mann noted:

While greenhouse warming would abate, the cessation of coal burning… would mean a disappearance of the reflective sulphate pollutants (aerosols) produced from the dirty burning of coal.

These pollutants have a regional cooling effect that has offset a substantial fraction of greenhouse warming, particularly in the Northern Hemisphere.

That cooling would soon disappear, adding about 0.5°C to the net warming…

So evidently, we don’t have one-third of our total carbon budget left to expend, as implied by the IPCC analysis. We’ve already expended the vast majority of the budget for remaining under 2°C. And what about 1.5°C stabilization? We’re already overdrawn.

Now, new research published last week, “Climate Impacts From a Removal of Anthropogenic Aerosol Emissions”, has looked at the aerosols issue in more detail in.

The work uses the latest generation of climate models, in which the aerosol-cloud interaction is more sophisticated, and also examines each aerosol component discreetly, rather than lumping them together as some simpler climate models do.

One limitation is that this research utilises four climate models, whereas  big inter-comparison projects are based on around 30, so more work needs to be done on these results.

Bjørn Samset of the University of Oslo and his colleagues used four climate models, which cover a range of climate sensitivities, to see what would happen to the global average temperature if the short-lived greenhouse gases (methane, nitrous oxide etc) were kept at their current level, but CO2 emissions ceased once they have reached a level of 420 parts per million (ppm). (This is 15 ppm above the current level of 405 ppm, or just another five years of emissions at the current rate.)

The result was average warming of 1.35°C over the four models, above a late 19th century baseline. (It has been demonstrated that global average temperatures increase while CO2 is increasing, and then remain approximately constant until the end of the millennium despite zero further emissions.)

They then asked what would happen if all anthropogenic aerosols emissions were to cease.

The answer was that “removing aerosols induces a global mean surface heating of 0.5–1.1°C”, with a multi-model mean of 0.7°C. Samset says the vast majority of this net temperature change would be due to sulphate emissions from fossil fuel sources.

This is because, in general terms, the other two forms of anthropogenic aerosols — black carbon and organic carbon, which have major contributions from biofuel and other biomass burning — cancel each other out, at roughly 0.1°C each, one cooling and one warming.

In other words, going to zero emissions with CO2 at ~420ppm would result in a warming of around 2°C at equilibrium, if the level of short-lived gases was constant.

Not going to zero emissions would be worse in the short term: other recent work shows warming would be 2.2-2.4°C by 2050 if we continue on the current high-emissions path.

And it would be disastrously worse not to go to zero emission very fast, due to the longer-term impacts: continuing on the current high-emissions trajectory would bring warming of 4.1–5°C by 2100.

A new UK Met Office forecast released yesterday on climate conditions for 2018-2022 say that “over the whole five-year period… global average temperature is expected to be between 1.10°C and 1.40°C relative to pre-industrial conditions”, which would likely be warmer than the record-breaking El Nino year in 2016 of 1.14°C. And the Met says there is a 10% chance one of those years will bust through 1.5°C.

So whereas the Paris agreement delays strong action for decades, and serious carbon drawdown till the second half of this century, the brutal fact is that present greenhouse gas levels are such that we will steam past 1.5°C, and are heading to 2°C as a result of what we have already done.

And that is why all “1.5°C scenarios” actually “overshoot” to around 2°C before cooling the system by a theoretical, massive-scale carbon drawdown.

It is possible and necessary to reduce the warming impacts of the short-lived gases impacts, which is calculated to be around 0.9°C, of which methane is the largest component.

Half the methane emissions are natural, primarily from wetlands. And half are from human activities, the most important sources being extracting and processing fossil fuels (26-32%), livestock (26-28%), and landfills/waste (20-27%). Stopping the use of fossil fuels would reduce total methane emissions by 15%.

Eliminating methane from animal husbandry and rice production would cut methane emissions by 20%. Together this impact would be around 0.3-4°C.

On the other hand, it is expected non-anthropogenic methane emissions from wetlands and the Arctic will increase.

If the planet warms enough, large polar permafrost and/or methane clathrate carbon stores will be mobilised, releasing large amounts of both methane and CO2, and introducing large positive feedbacks to long-term climate change.

In February 2013, scientists using radiometric dating techniques on Russian cave formations to measure melting rates warned that a 1.5ºC global rise in temperature was enough to start a general permafrost melt.

The resilience of natural carbon sinks is deteriorating, and there is also evidencethat carbon stores in tropical rainforests are now flipping to become sources of carbon, both CO2 and methane.

So the work by Samset  and his colleagues has added new understanding as to where the climate system is heading, even as we reduce fossil fuel use.

If  large-scale methane emissions reduction are difficult due to human system inertia and/or non-anthropogenic increases, or if carbon cycle feedbacks kick in as they now appear to be starting to do in both in the tropics and at the poles, then we are heading past 2°C by mid-century, regardless of whether we continue on a high-emissions path, or on a zero-emissions path that also unravels the aerosol cooling.

It is also possible to deploy carbon drawdown, but this is not yet available at sufficient scale to meet the Paris schema, and research funding has so far been grossly inadequate.

(Removing around 150 billion tonnes of CO2 from the atmosphere would reduce warming by ~0.1°C.)

The storage of atmospheric carbon envisaged in the Paris agreement –– which delays emissions reductions now in favour of high levels of carbon drawdown much later in the century –– is enormous. Some of the world’s leading scientists recently noted that:

The scale of the decarbonisation challenge to meet the Paris Agreement is underplayed in the public arena. It will require precipitous emissions reductions within 40 years and a new carbon sink on the scale of the ocean sink. Even then, the world is extremely likely to overshoot.

A catastrophic failure of policy, for example, waiting another decade for transformative policy and full commitments to fossil-free economies, will have irreversible and deleterious repercussions for humanity’s remaining time on Earth.

Thus, without solar radiation management (replacing anthropogenic aerosols from fossil fuel use with anthropogenic aerosols spread from planes or fired into the atmosphere) it will be difficult to avoid 2°C no matter what CO2 emissions path we take, and all but impossible not to overshoot 1.5°C by at least a third.

It is not yet clear that there is demonstrable clear net environmental benefit from solar radiation management, and we should only do it if that is the case.

But in not doing it, we need to be honest about what will be lost and what further tipping points may be crossed.

And all the above figures are based on a late-19th-century baseline, not true pre-industrial which could add ~0.2°C to the figures.

The numbers from Samset et al. are close to those of Xu and Ramanathan, who found that by 2015, the combined effect of CO2 and short-lived climate pollutants impact was 1.9°C, less total aerosol forcing of 0.9°C, resulting in the observed warming of 1°C.

It is also close to Baker, Collins et al, who found elimination of aerosols would result in warming of 0.82°C (average across 3 models). And it accords with work published in 2013 by Hansen and others which found that aerosol cooling probably reduced global warming “by about half over the past century”.

The work by Samset et al. also looks at the impact of aerosol removal on rainfall and extreme weather. It finds that precipitation increases 2–4.6%, and extreme weather indices also increase.

There is a higher sensitivity of extreme events to aerosol reductions, per degree of surface warming, in particular over the major aerosol emission regions such as China and India.

The problems posed are wickedly exquisite. The former NASA climate science chief James Hansen has long warned that 2°C is a “recipe for disaster”.

It is clear that we now face an existential threat to human civilisation as the climate teeters on the edge of passing further system tipping points that would make the task of avoiding that threat tremendously difficult.

This requires an emergency response, where we as a society are actually prepared to say openly and often that the scenarios outlined above are real and alarming, and take action accordingly.

In Ireland, a Climate Emergency Measures Bill to be debated this month seeks to ban any new explorations for oil, coal, and gas on Irish territory.

The bill was introduced by People before Profit (PBP) Deputy Brid Smith last November, where it successfully passed the first stage. That would be one early step in an emergency approach.

Source: Climate Code Red. Reproduced with permission.  

  • Joe

    And The COALition’s response to date…emissions climbing each year…just keep digging and exporting ‘King Coal’, just keep Liddell going and going, just get the Adani Carmichael Coalmine and The Galilee Basin up and running, just keep extracting and exporting Gas, just keep going with the SMACK DOWN of any Australian State or Territory that sets RE Targets and gets on with the business of building solar and wind farms, building Big Batteries and building Solar Thermal. There he was today, Two Tongues Turnbull, in Townsville with yet another public spray at the good state of South Australia….”Left Wing Idealogy and Idiocy” as he describes it with what is happening in SA. And Premier Dan also got a ‘little tickleup’ as well for not lifting VIctoria’s ban on gas mining. Turnbull must be insane. Please someone call a Doctor and check on the dudes mental health, he needs the help.

    • Cooma Doug

      I have thought about this a lot. The PM knows of climate change and the extent of the problem. He is knowingly approving of our negligent race to disaster.
      Some of the logic is the statement that coal will be used and we should be exporting it. If we dont wreck the planet someone else will. So its ok to knowingly cause a catastrophy. They are not his words. He twists it around to a positive and keeps a straight face. But that is what he is saying.

      Labor are also at fault, putting bad economics ahead of life. I really think we have to find a way to make denial stink like hell in all its political species.

      • Joe

        Turnbull with exporting coal is like a drug pusher, The drug pushers justify their peddling on the basis that if they don’t do it then another drug pusher will and they make the money. And yes, the Shorten was fence sitting The Adani issue in his speech at The National Press Club last Tuesday. As you say “bad economics ahead of life” and the Shorten uses weasel words that if the economic case and environment approvals stack up….then we go for it!

      • mick

        lots of smart people here have nailed this-he has the ambition for what ever reason but he lacks the political capital to move his own crew in the right direction while not having the moral courage to do anything else

      • Joe

        Whatever happened about the notion of doing what is right and doing the right things. Our current pollies are a bankrupt lot.

    • mick

      yep saw that lousy prick (him not you)

  • Alastair Leith

    In other words, going to zero emissions with CO2 at ~420ppm would result in a warming of around 2°C at equilibrium, if the level of short-lived gases was constant.

    Unfortunately the stock of short lived gases is increasing more quickly than CO2. Methane has contributed to a full third of present day global warming (IPCC AR 5 Ch 8). Conversely simultaneous mitigation of short lived climate pollutants (SLCPs) in parallel with CO2 mitigation would provide a one-shot pause in warming (if achieved at a sufficient scale), in order to buy further time to get CO2 heading down rapidly (which it clearly aint).

    It’s not a trivial issue, and why dual-accounting at 100-year and 20-year timescales would put more realism into the GHG mitigation picture.

    • Jane R

      This is interesting. What are the main steps we would need to take to get a rapid reduction in SLCPs? Ban gas mining and cap existing leaky wells? Change farming practices? Switch away from sooty cooking fires? Ban refridgerants?

      • Jonathan Milford

        Jane, try ‘Drawdown, the most comprehensive plan ever proposed to reverse global warming’, edited by Paul Hawken. Unfortunately, there are no ways we can stop the main methane emitters, which are permafrost and methane clathrates melting and ruminents belching. In Australia everyone should be eating kangaroo instead of beef, like the aborigines. (I switched 10 years ago: try my kangaroo bolognaise!)

        • MaxG

          The book is a good read, however, it is (unfortunately) neither a plan, nor providing one. But, bundles feasible options together as our current collective knowledge.

          • Jonathan Milford

            The Commonwealth government has a plan called Direct Action. Doubtless many of the feasible options can be found among the successful tenders. The problem, of course, is that the targets, and therefore the tenders, are woefully inadequate. Also, since our emissions are still going up, it is not only too little but too late.

  • Hettie

    Oh shit.

    • Joe

      …it is worse than that. The so called ‘Doomsday Clock’ is about how close we are to global nuclear annihilation. Perhaps we need a second ‘Doomsday Clock’ about how close we are to annihilation due to unrestrained global warmings. The scientists and IPCC have been onto for a while now…the clock is ticking.

      • Alastair Leith

        Good idea, contact Union of Concerned Scientists. Of course it would be, like the nuclear Doomsday Clock, largely guesswork and a gross simplification and reduction of a massive data set, even more so in fact but worth it I think. As new eveidence emerges it should be updated periodically. But scaring the shit out of people only can have an obvious benefit if their are clear paths to action on the individual (easy), community (sort of easy), state, national, corporate and international (so far proved virtually impossible unless you call Paris a major achievement). There may be non-obvious benefits to scaring the shit out of people on climate change, it’s a much debated subject with no clear answers.

  • John Englart

    We’ve known about the aerosol problem for some time, it’s just scientists are getting better at quantifying the impact. Once reducing atmospheric aerosols are accounted for we don’t have any carbon budget left to play with. This is why we have a climate emergency, and why Josh Frydenberg and Malcolm Turnbull’s grossly inadequate climate policies are criminal in nature as it literally condemns people to death both internationally and in Australia. In particular, Turnbull knows the challenge and unequivocably stated so at the Deakin Lecture in 2010. He has betrayed his own words. This gives his lack of action criminal intent.

    • Joe

      The Turnbull….Two Tongues, Hypocrite, Merchant of Death, everyone please feel free to pile in as well.

      • Jonathan Milford

        Methinks my member for Wentworth has been skinned alive by the priest/abbott of his party and become a Turncoat, emitting Turnbullshit.

    • Jane R

      We didn’t have any climate budget to play with anyway. I wish people would stop saying we have a remaining carbon budget. It is abundantly clear that the earth is already too hot, so how can we possibly have any rrmsycarbon budget?

  • Jane R

    Thanks David. Great overview – though frightening. Certainly nothing but emergency action can save us now. Just one question, I thought the global average temperature spiked to +1.6 degrees Celsius in 2016, but was that figure from a different baseline?

    • David Spratt

      AS I remember that was one month in 2016 (March?) not a year, and that was from the NASA dataset with a different baseline (1880-1900) that that used by the MET office.

  • yann kervennic

    There is no way we can trust the social construct we are living in to solve this issue.
    I guess everyone feels it but refuses to say it openly.

    There is probably a way out of this but it is a tough one.

    We have to change track individually, assume that it is not the society that is smart, but us as individual and that we have to build a new of producing made by conscious, individual decisions.

    this industrial complex being that seems miraculous because it functions and gets more and more sophisticated with the same kind of people, just by involving more of them. But it is not sustainable.

    Individual thinking and decision has to take over fascination for the social construct.

    We have to rebuild small communities where all that is produced can be understood and made by any member of this community, except some very rare item that has to be exception not rule like today.

    And for every one of this production, we need to think twice about it; wether it is usefull and ecologically sustainable on the long term.

    This imply going away at least to a great extent, from society now, not later.

    I live in the country side in south of France trying to apply this recipe, i need more around me, we need to be a network to start a new way of producing.

    I would call this natwork; Survive! Try and Join.

  • Bronwyn Plarre

    Our leaders are playing GOD with our future.
    And all over a stupid economic system that totally advantages the 1% rich & powerful.
    Why is this article relegated to a niche RE blog (sorry Giles, its a great read). Why isn’t it on the headlines of all paper & digital media, & on the minds & lips of all decision-makers?!
    Do they really think they can play with the laws of physics & chemistry? They can alter the ‘laws’ of economics cos they invented it, and we’ll all be better off living within the laws & limits of nature.
    I’m not religious but I need to shout “for god’s sake, change the trajectory we’re on”. All you reading this probably feel you’re doing all you can. Do more. Bring on the Climate Emergency Response. See you on the streets & the digital equivalent!

    • Jonathan Milford

      Bronwyn, you are close to the crux of the problem, literally. BC the Greeks came to the understanding that ‘Nature is God, God is Nature’. We (necessarily) live by the laws of nature. This is Pantheism, if you want to call it a religion, rather than a philosophy. Have a look at the Pantheist Creed and see if you agree. We are shouting too, but we replace ‘god’ with ‘nature’: “for nature’s sake, change the trajectory we’re on”. As the aborigines say: “look after country”.
      I was brought up as a Christian but, like many, gave up belief in their supernatural God because I could believe neither in the terrible things he perpetrated in the Old Testament nor the miracles of the New. I read Barbara Thiering’s books explaining the miracles as a catalogue of Jesus breaking Jewish laws, in order to reduce Judaism down to Hillel’s Golden Rule and little else, She also explains how he escaped death on the cross (Latin crux). I am on my knees every Sunday, weather permitting, doing bush regeneration: this is for the love and conservation of nature. We are encouraged that Liberal MPs and councillors locally have formed, so there is some chance we may be able to ‘change the trajectory’. Most of our work is with Labor though, as they seem less captured by the fossil fuel lobby.

      What a pity it is too little too late.

  • solarguy

    Very depressing news indeed! My two sons are in their 20’s and haven’t even had kids yet and are very aware of a hotter future with more extreme storms etc, they are concerned not just for themselves, but for their kids too.

    They have also noticed, as I have, how every year is getting hotter. I have been keeping records of my solar production for years now, including recording my own max temperatures on the back porch and this January had more hotter days and higher temps up to 4 degrees, than Jan 2017.

    I get very bloody annoyed at the climate change deniers!

  • Colin Vincent

    How is increasing methane release from the Arctic, particularly due to loss of permafrost, “non-anthropogenic”?

    • Alastair Leith

      Good point! It is anthropogenic but it’s indirect rather than direct, so doesn’t get counted. There are many emissions that are obscured and reallocated in the UNFCCC GHG accounting methodology, please check out Put the Climate on Pause for issues around Short Lived CLimate Pollutants and the difference between 20 and 100 year accounting.

      Then there is the way land clearing for livestock production (and land clearing for cropping for livestock feed) is completely dissaociated with not just livestock production but agriculture entirely by putting it in the Land Use and Land Use Change and Forestry (LULUCF) catagory where it gets hidden in scale by the sequestration of native forests in outback woodlands, plantations, state forests and national parks. The livestock industry do not own the nations forests, and even if they did it makes no sense to hide emissions from land clearing by offseting it with the sequestration from Australia’s forests and woodlands. There’s no entitlement to the countries only sequestration source on the part of the agricultural (livestock) industry, they’ve removed most of these forests and woodlands in the first place, and what’s left belongs to Australia not their industry.

  • Keith Parsons

    It’s NOT 1.5 degrees C. That’s a specific temperature, i.e., 1.5 degrees above 0 degrees C. It’s 1.5 C degrees which a difference in temperature.

    • Alastair Leith

      It’s an abviation. The correct term is not “1.5 ºC difference” either, it’s 1.5 ºC difference in global air temperature anomoly (an average of many air temperature readings and data sets adjusted for vaious factors) to be precise. These are all simplifactions and abriviations used as jargon.

  • Alastair Leith

    A new UK Met Office forecast released yesterday on climate conditions for 2018-2022 say that “over the whole five-year period… global average temperature is expected to be between 1.10°C and 1.40°C relative to pre-industrial conditions”, which would likely be warmer than the record-breaking El Nino year in 2016 of 1.14°C. And the Met says there is a 10% chance one of those years will bust through 1.5°C.

    How about the fact that the general benchmark used of 1850-1900 average temperature used by IPCC when we talk about general warming is ~0.2 warmer than the actual pre-industrial temperatures immediately prior to the invention of the steam engine?