We’ve Only Got Five Years Before Our 1.5°C Carbon Budget Is Blown
Originally published on Carbon Brief.
In its most recent synthesis report, published in early 2014, the Intergovernmental Panel on Climate Change (IPCC) laid out estimates of how much CO2 we can emit and still keep global average temperature rise to no more than 1.5C, 2C or 3C above pre-industrial levels.
That same year, Carbon Brief used these estimates to calculate how many years of current emissions were left before blowing these budgets.
Updating this analysis for 2016, our figures suggest that just five years of CO2 emissions at current levels would be enough to use up the carbon budget for a good chance – a 66% probability – of keeping global temperature rise below 1.5C.
Budgets
The IPCC estimates carbon budgets for 1.5C, 2C and 3C. For each temperature limit there are three budgets. The first gives a 66% probability of staying below the given temperature, the second a 50% chance, and the last a 33% chance.
Strictly speaking, these aren’t probabilities, but are the proportion of all the model simulations that keep warming below that temperature limit.
The IPCC’s synthesis report presented the total carbon budget from the beginning of the industrial revolution and said what was remaining, as of the beginning of 2011.
Using data from the Global Carbon Project, Carbon Brief has brought these budgets up to date. In 2015, for example, worldwide CO2 emissions from fossil fuel burning, cement production and land use change were 39.7bn tonnes – slightly lower than the 40.3bn from 2014.
As of the beginning of 2011, the carbon budget for a 66% chance of staying below 1.5C was 400bn tonnes. Emissions between 2011 and 2015 mean this has almost halved to 205bn tonnes. The result is that, as of the beginning of 2016, five years and two months of current CO2 emissions would use up the 1.5C budget.
As it is now May, this means there are now fewer than five years remaining before the budget is blown. So, if the current rate of emissions continues, the 1.5C budget would be used up sometime in 2021.
The equivalent remaining budgets for a 66% chance of staying below 2C and 3C are 20 years and three months, and 55 years and six months (respectively) of current emissions. You can see all the budgets in our updated graphic at the top of the article, and the full spreadsheet with data sources here.
You can explore how the 1.5C, 2C and 3C carbon budgets have changed over time in the interactive chart below. Use the slider to move from 1959 to 2016.
And we’ve also created an animation of how the different carbon budgets have shrunk – starting at the Earth Summit in Rio in 1992 and finishing when 1.5C budget is expected to be used up in 2021.
Note that we calculate the remaining carbon budget in any one year by assuming that annual emissions from that point continue at the same level. This means that on some occasions the budget actually increases from one year to the next. This happens when a dip in annual global emissions means the reduction in cumulative emissions in future years is larger than the amount of CO2 removed from the budget for that year.
Multiple methods
It’s worth noting that there’s more than one way to construct a carbon budget. A paper published in Nature Climate Change earlier this year looked at the different approaches and their relative merits.
The simplest budget is one that only considers CO2.
CO2 has a near-linear relationship with temperature. This means every tonne of CO2 emitted to the atmosphere makes roughly the same contribution to global temperatures. It allows scientists to make a relatively simple estimate of the cumulative CO2 emissions that would produce a particular amount of warming – say, 1.5C or 2C.
However, we don’t only emit CO2 into the atmosphere. We also emit methane, nitrous oxide, ozone, hydrofluorocarbons, and a host of other greenhouse gases. These all have different warming impacts on the planet and different lifetimes in the atmosphere.
Scientists have two main approaches for calculating carbon budgets that take other greenhouse gases into account. The IPCC synthesis report includes budgets for both, which are summarised in this table:
The first is the snappily-titled “threshold exceedance budget”, or “TEB” for short. These are the type used for the “Complex models, RCP only scenarios” rows in the IPCC table.
To calculate a TEB, scientists simulate global temperatures in Earth system models according to a pathway of future emissions that considers all greenhouse gases. Scientists run the model until global temperature rise crosses a given threshold – say 1.5C. They then work out the cumulative CO2 in the atmosphere at that point – and this is the carbon budget.
The other gases are, therefore, taken into account when calculating how the Earth’s climate reached 1.5C of warming, but the resulting budget is still only expressed in CO2.
Of course, this assumes that emissions stop immediately once the threshold temperature is reached, which is essentially impossible in the real world. It also assumes there is no further warming once emissions have stopped, yet recent research shows this isn’t the case, says Dr Joeri Rogelj, a research scholar at the Energy Program of the International Institute for Applied Systems Analysis (IIASA), who is lead author on the Nature Climate Change study. He explains to Carbon Brief:
The TEB is the approach used to calculate the carbon budget we presented above. In the IPCC’s calculations, they assume emissions continue along the RCP8.5 pathway – where greenhouse gas emissions aren’t curbed – and simulate the impact on global temperatures in 20 different models.
The second approach for carbon budgets that take other gases into account is the “TAB”, or “Threshold Avoidance Budget”. These are the type used for the “Simple model, WGIII scenarios” rows in the IPCC table above.
In calculating TABs, scientists simulate many scenarios in a simple model and only pick scenarios that don’t exceed the temperature in question. From these scenarios, they then estimate a carbon budget for staying below that temperature.
Therefore, rather than using one scenario in lots of models, the TAB approach uses lots of scenarios in one model.
However, as most scientists have been working on how to keep temperatures below 2C or 3C, there aren’t very many scenarios for 1.5C. For example, there is no IPCC budget using this approach that has a 66% chance of keeping below 1.5C.
Many of the scenarios that do keep temperature rise below 1.5C assume application of negative emissions technologies to help offset emissions from human activities. These technologies, such as bioenergy with carbon capture and storage (BECCS), remove CO2 from the atmosphere and store it on land, underground or in the oceans. However, as Carbon Brief recently explored in our negative emissions series, questions still remain over the feasibility of large-scale application of these technologies.
One of the reasons why there are so few IPCC scenarios that keep temperatures consistently below 1.5C is that many allow for a situation in which emissions overshoot the 1.5C budget, and are brought back in line later through the use of negative emissions.
The lack of available scenarios has also been identified as a key challenge for authors of the planned IPCC special report on 1.5C. Future scenario work is expected to remedy this gap, says Rogelj, as more scenarios in line with 1.5C are being published.
So, both the TEB and TAB approach to calculating carbon budgets have their strengths and weaknesses. But which one will scientists favour for future IPCC reports? Rogelj suggests both:
Reprinted with permission.
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See, this just kinda makes me feel like we’re screwed, so I should just ditch the EV and go back to muscle cars.
In *addition* to completely terminating the burning of fossil fuels, we’ll need to suck CO2 out of the air. Methods:
— massive algae blooms in the ocean
— carbon-negative concrete (there’s a magnesium-based type and an iron-based type)
— carbon-negative construction bricks (I know of two types)
— carbon-negative plastics (I know of one type)
— burying biochar instead of allowing material to decompose naturally
— peat bog restoration
— plain old tree planting
— direct CO2 extraction (humidity swing, for example)
Some technologies:
http://www.carbonnegativeregistry.com/
There is tree planting where I live. They get maybe 20-30 thousand per year into the ground. Don’t think survival rate is higher than 75% though.
And then you drive along some scrubby/tree area and see that it has been cleared. The equivalent of maybe 3-4 years planting..
It’s absolute madness.
I don’t know if this is common anymore, but I’ve seen forest cleared to make room for strip malls in the past where all the cut trees were stacked up and just burned. We can’t do this anymore.
There is a company founded by an ex-NASA engineer working on robotic drones that plant trees by themselves. If they are successful we could plant trees by the billions every year. Apparently Parrot (a big drone company) just invested into them to scale up R&D.
http://www.biocarbonengineering.com/
The issue is where? Is there that much available land that has the necessary rainfall to support forests?
And if we have that land then why not just reseed?
The way timber harvesting was traditionally done around where I live was to leave one or two medium age trees standing when all the usable timber was removed. Seed from those trees replanted the area cleared.
We moved away from that because due to erosion problems and went to replanting. But if it’s open land then fly a seed-dropping drone over the area. Then, a few years later, go in and thin so trees are not overcrowded.
Not completely sure what your post is supposed to say.
We are cutting down rainforests and forests down by huge chunks every year. Those are places that had trees before, they can have trees again. But we can’t replant all those by hand, we’d need millions of people for that. Easy solution: Find some automated way of planting. If we can plant more trees than we cut down right now, then we are on a good path.
I’ll try again.
How much land is available for forestation? The rainforest cut down, for cattle grazing? If so, it is not available.
The forest land we lost to bark beetles? Is there a species that can replace the one(s) lost?
Planting forests sounds good but I’m not sure many people have a good hand on how much land is available.
Replanting is not an issue, as I suggested. Just reseed.
Reseeding delays growth by only a short time, transplanted seedlings are generally one to three year old trees.
Seeding can be done from the air (planes, helicopters, even drones operated from the ground). Seeds can be encapsulated in outer coatings of fertilizer and bitter tasting substances in order to provide a better start and to reduce animals eating the seed.
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We’ve already got machines which can plant up to 10,000 trees per day. The problem is that there is a limited window during which the trees can be replanted and raising seedlings in nurseries requires a lot of effort. Seeding can be done from late summer until spring.
That’s true; If you’re walking on thin ice, you might as well dance…..I never understood that until recently. Or,
You only die once, so you should have a good looking corpse, or something like that.
The 1.5C degree carbon budget is probably already spent, and possibly the 2C degree budget as well. But we should not despair. This simply means that we will need to invest in carbon negative technologies that can be implemented by mid century (reforestation, biochar, atmospheric sequestration into carbon nanofibers). It will be expensive, but every year it looks more and more feasible that we can scrub the skies to early industrial levels.
In the meantime, we should worry about protecting our natural carbon sinks and killing off fossil fuels with clean energy. Every day, I hear another story about coal on life support, electric cars, and so on. There is hope.
Agreed, apart from the carbon nanofibres. The amount of carbon put into the atmosphere every year is around 8.8 gigatonnes (link). No industrial products apart from cement, sand and rock for concrete, and steel are produced in gigatonne volumes. Copper, the standard metal for conductors, is only 18.5 million tonnes a year. Carbon nanotubes – which are very light, being mostly air – will be produced at a few thousand (at a pinch ten thousand) tonnes a year, barely a dent. The large-scale sequestration technologies available seem to be reafforestation, biochar, and olivine weathering. Additions welcome.
Large-scale sequestration?
Concrete. Both Novacem and Ferrock are concretes which are carbon-negative during creation. (Totally different designs; Novacem is magnesium concrete, Ferrock is iron concrete.) Standard “Portland cement” concrete has high carbon emissions.
Switching our concrete technology would therefore be very helpful; it would *both* eliminate a major source of emissions *and* extract CO2 from the air during concrete creation. A lot of concrete is manufactured each year.
In geological terms, major sequestration seems to have historically been performed by massive algae blooms in the ocean, which die and sink to the bottom. This might happen whether we do it deliberately or not so it’s worth paying attention to.
Watching that video of trains being used to store energy by lugging masses 1000m (in elevation) up hill, I noticed that the masses appeared to be concrete (or concrete containers filled with rock). If this technology takes off, that’s a shed-load of concrete, and if it’s Portland, a percentage of the gain is lost before the first Megawatt hour is ever recovered.
If it’s carbon negative concrete on the other hand… such energy storage schemes could be winning the game before they even start.
There will also be many tonnes of (carbon intensive) steel in rail and bogies – and I just don’t know how to solve that one. Suggestions welcome. All I can think of is never let the stuff rust, and recycle every bit of scrap.
https://www.youtube.com/watch?v=Q7J0TcheEMc
Hope these CO2-negative concrete technologies take off. We’d need a carbon tax or some sort of other incentive to really make them take off. Just a quick question, what’s the cost differential between Portland and Ferrock / Novacem? Do these alternatives last as long as well and have similar, better or worse curing / wear properties?
It’s driving me nuts that the alternative concretes aren’t being commercialized. They are more expensive. Part of the higher expense is because they haven’t got economies of scale yet.
They seem to last longer in most environments (Portland-cement concrete actually isn’t that durable) and have better curing and wear properties. Novacem is white as opposed to off-white, which is considered an advantage. Ferrock is stronger than concrete.
Know of any sources which estimate costs at scale?
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I’m thinking we should start building buildings designed to last 300 or more years. I’ve been messing around with papercrete, a mixture of Portland and shredded paper.
The *R*-*value* of papercrete is reported to be within 2.0 and 3.0 per inch (2.54 cm); *papercrete* walls are typically 10 to 12 inches thick (about 25–30 cm). A structural wall with R-20 to R-30 ratings. Add some sand and it becomes pretty much fireproof and resistant to insect/rodent damage.
It can be mixed by machine and poured into forms. Exteriors can be stuccoed. In a very cold climate if extra insulation is needed then apply some rigid foam between wall and stucco.
A building shell like this should be usable for centuries. Just redo the interior as tastes change.
The actual expense calculated in 2016 dollars will probably decline as better methods of dealing with it are developed. Full cost accounting including the externalised costs of inaction justify the expense.
Th good news is that if you look at the 2 degree carbon budget, current emissions could be maintained for 27 years at the lax 50% chance level of Copenhagen. That means 50 years with a straight-line decline to zero at the end in 2065. A 2% straight-line annual decline in emissions looks feasible eyeballing current trends, though I’d like to see professional scenarios. It might even be possible with President Trump: he has no real plan to stop the energy transition, and by now even a bonfire of American regulations would not stop the revolution, or derail the Paris agreement. Who would show up for his renegotiation? Or buy the coal he would like to mine?
The problem is the more demanding, but much safer, 1.5 degree target. Even a drastic 5% annual drop in emissions does not stretch the carbon budget to a decade – followed by an eternity of zero net emissions, remember. We are definitely going to overshoot. So the world must have carbon sequestration at a very large, gigatonne, scale, starting in under a decade. This is the priority for research, not unneeded breakthroughs in green energy production.
Thanks for the positive analysis, James.
I get very anxious about this quite often. I’m glad you see the positives.
I have to say 2-3 years ago, I’d have given us no chance – CO2 emissions still increasing, China building coal and more coal and the whole establishment (or so it seemed) up against RE.
Fast forward and the world has changed dramatically.
I’m not sure I hold out hope for the 1.5C target, but I think emissions should fall dramatically in the next 5-10 years, which I think bodes well given your 27 year at current levels estimate.
I do agree with you regarding sequestration though. I hold out hope, in that afforestation is high on the table and being discussed and biochar andother similar technologies are coming – it’s a case of them now becoming viable. The question is how quick – are they where wind and solar were 10 years ago? or 20 years ago? If the former, there’s a chance, if the latter, it’s going to too long to ramp up.
I firmly believe DAC is now necessary as well.
Wind, solar and electric vehicles were always potentially commercial. Now the former two are in fact. Early deployment subsidies have been enough to attract investors and consumers. In summary, market – based policies have worked. Now how can this be carried over to sequestration? It’s the ultimate big government programme. To get any market interest at all, you would need an inverse carbon tax, a sequestration premium. This will be hugely difficult politically. Realistically, nothing will happen until we hit a real crisis, like the complete destruction of a large coastal city.
Well, if a carbon tax were implemented on the *concrete industry*, I think it would help a lot. Standard concrete creation generates quite a lot of CO2. Both Novacem and Ferrock are carbon-negative and there are probably other designs I don’t know about as well.
It would only take a very small carbon tax to shift the price signal and get companies serious about using the carbon-negative concretes, given that the producers of the carbon-negative concretes would be getting a *credit* while the traditional concrete producers would be getting a tax.
Speaking of which.. to me it seems the upper class is not interested at all to safe the planet. What’s their plan B?
They seem not to care at all about this..
The top 1% will probably survive even at +4C.
Most of the climate-denying 1%ers are very, very old and they clearly plan to die before the planet becomes unlivable for humanity. I guess they don’t give a damn about their kids or grandkids.
Again I think you are too pessimistic. In Denmark the government (Lomborgian) is looking with enthusiasm on a proposal to use clams as a way to clean water and remove excess pollutants as well as feddstock for animals. In the shells a lot of CO2 is absorbed and it is usable for a lot of different uses where it will be kept out of the troposphere for a long time.
Other potential ways to lower the CO2 content is to decarbonate the agricultural soil, which has been given a great deal of interest.
Trump, though fairly clueless about science, *should* be staunchly in favor of Tesla Motors as a cutting edge technology company building cars in California. And, the fact that Musk has stated that Tesla needs to build a plant in China just to sell cars there, due to the 30% import tariffs, exactly fits Trump’s “trade deal” narrative.
I think, as crazy as it sounds, that if Elon personally sat down with Trump, and gave him a ride in a Model S/X, that Trump would be hard pressed to deny it as the future of transportation.
In any event, if you believe the projected EV battery/cost curves, the entire new car fleet should electrify sometime in the 2025 to 2030 time frame, regardless of government incentives. That alone will begin removing a sizable portion of CO2 and pollutants.
Yes Tesla is a way in for Trump to tick a few boxes to appeal to climate conscious voters.
I hope Trump remains the unreconstructed denier he appears to be as he’s too far gone to be anything but a disaster for efforts to step the USA up to the plate of its natural leadership position on climate change action (and everything else good for humanity).
Not unless electricity production cleans up.
Unfortunately the inertia of climate changes suggests we can not simply remove CO2 back to a previously safe level.
You can however do something to lower the atmospheric content of other GHG than CO2. Soot that drives the temperature up in the atmosphere and thereby increase the water vapor content can be reduced by various simple and cheap behavior changes.
Sources of methane emissions can relatively economically be used for biofuels or base materials for the petrochemical industries.
I think we still have a fighting chance.
First of all everybody seems to underestimate the progress in wind and solar.
If wind follow the trajectory from the last four decades then wind will deliver as much electric power as the globe produced in 2014 by 2031 and solar will actually do that a few years earlier.
I do not know how BP, Shell, EIA IEA etc. constantly come up with prediction after prediction that wind and solar will stop growth and I am especially curious as to how other old expensive technologies suddenly will bounce back.
Until a proper explanation of the imminent never ever explained showstoppers for wind and solar emerges I will continue to believe wind and solar are the showstoppers for fossil fuels.
BP, Shell, EIA IEA – fossil fuel companies and organizations with long relationships with fossil fuel industries. Boys in a bubble.
Let me suggest that the group of people who write and comment here are less like the old generals and colonels sitting back in the fort telling each other that everything’s quiet outside and more like the scouts out roaming through the far reaches of the territory and starting to see trouble organizing.
We’re watching for examples of new lower costs for renewables, looking at the 4c/kWh PPA and the 3c/kWh Saudi bid for solar, the rumor of a 1.5c/kWh PPA for wind and CFs moving above 50%. We’re straining to see where things are heading and that allows us to form different predictions.
I think there’s a good chance that the fossil fuel industry and the organization that have a long history with the industry may be listening mostly to themselves and creating a reality in which wind and solar are not dropping in price as rapidly as what we see. That would lead them to predict slower growth. I think they may be walking around, slapping each other on the back, and reassuring each other that the only reason wind and solar are being installed is due to government subsidies and that those subsidies will soon be gone.
I think they’re having a Kodak moment. Reality is going to be very hard on them.
The question is whether we could produce biochar at a large enough scale and affordably to have much of an impact.
I’d love to see biochar being made in our forests. We’ve got massive amounts of ‘trash’ that needs to be pulled out of the forests in order to lower fuel loads for wildfires. But how to do it at an affordable price?
Hopefully, the hundreds of thousands of square miles of solar, along with big wind and hydro, and lots of powerlines, and lots and lots of very cheap electrical storage, will be built in order to charge the coming global EV fleet, power continued growth mainly in still developing countries like Asia, South America and Africa (not to mention curbing poverty even in the U.S), power global agriculture, water distribution, sewer systems and the manufacture of all these thousands of square miles of RE and all its (hopefully) solid state battery storage, and finally, our homes and entertainment needs – 24/7 – without ANY fossil fuels. We will, as other commenters have suggested, need to sequester some of the excess CO2. This can be had by literally turning some of the deserts green (requiring vast amounts of water and fertilizer) which in turn requires another substantial percentage of whole global energy requirements! Or we can turn it into limestone (which is more economical and fun?).
So, yes, we need MORE energy with NO CO2 emissions. This means that the target goal (within the 2 degree timeframe) is NO CCGT, NO coal, NO oil and gasoline and of course, NO home gas generators, no matter how efficient. This also means NO NG for cooking and hot water. I don’t want to take a cold shower when the sun isn’t shining (but believe we should incorporate passive solar in ALL building design, anyways to help reduce centralized power requirements).
We had better approve of the large amount of solar on all four corners of the planet (so to speak) so that we can export summer’s solar into a winter’s night via HVDC lines (yet to be properly developed over such long distances and is still too expensive) thereby VASTLY reducing overcapacity and over storage requirements inherent in all localized RE systems. There is no other way around this required “go big on RE” build up other than outright energy poverty – or the (here hated) advanced option of splitting heavy metal.
Folks, this is a reality check and we can’t provide for our kids’ future with just RE decentralization because it is mathematically impossible due to the physical limitations of EROEI and ESOI.
I’ve made examples many times before and will continue to do so (“everywhere” on the internet comment sections). If a locale receives little wind and only 5 hours of (good) sunlight on average in its winter, they will have to collect close to 24 hours worth of sunlight – and store most of it. This means that whatever the EROEI is on the panels, at least 4 multiples of the energy input will have to be used in that overbuild manufacture. Along with all the additional energy needed for all the additional batteries.
Granted, IF there are global powerlines, then all this extra capacity will be used to export to the other winertime areas of the world (during that locale’s summer), thereby cutting down on overall eroei requirements.
NIMBYism will have to be outlawed if we are to meet the 2 degree challenge because humanity can’t live on conservation alone.
I’m not done yet. The world is still primarily powered by ancient sunlight to the tune of about 175 quadrillion btu since Jan 1st. Solar and wind, unfortunately, only provided about 3 quads btu since then. 175/ 3 = solar and wind has to be scaled up by a factor of about 58 times (plus storage).
I get this info from a little CO2 widget from whatsthebackupplan.com
My computer is acting up but wanted to say, at least this 50 multiples (or 100 with storage?) is actually quite encouraging because that’s not really at all “impossible”!
I was looking at a CO2 widget that revealed that fossil fuels provided about 175 quads btu since Jan 1st, and that solar and wind provided about 3 quads (actual energy, not just capacity rating). This means that, with storage, we might only have to scale up by a factor of about 100. This IS doable, right?
Always take a close look at how they are measuring energy. Is it primary energy or the amount of energy we actually use (as opposed to waste).
Take cars, for example. A typical gasmobile might be only 20% efficient. Five quads go into gasmobiles but four are ‘discarded’ as waste heat. It flows off the engine block and radiator. It flows out of the tailpipe. But with an EV we might lose 10% charging batteries (they get hot) and 10% in the electric motor and drivetrain. 80% efficient. Only 20% as opposed to 80% is wasted.
Same for gas, coal and nuclear plants. Lots of energy lost as unusable heat.
Take a look that the chart below (the light grey part). We waste more than 50% of the energy we use. As we move to renewables and EVs we avoid most of that waste.
.
Europe already has 200 TWh of hydro power storage and plenty of hot water tanks (storing heat energy is cheap and easy and fossil fueled hot water heaters will need to be replaced anyway).
That’s way more than what is needed, because nights and calm periods never last that long. (Yes, some dams might need additional turbines – so what?).
I appreciate the work that these people do to try to forecast the future and I tend to believe these forecasts. However, those in denial will say that we cannot even forecast the weather more than a few days into the future, therefore, such studies and models like this cannot be accurate. It is mixing “apples and oranges” but in there minds they can choose to disbelieve and go on about their polluting ways.
I think a better approach is to focus more on the history that has happened to get us to this point. By showing the facts from 150 years ago until today is much harder to refute. Thus, we could say that we don’t know exactly when these thresholds will be met, we just know that they will be met and we may see disastrous results for people being born today if we don’t change our ways.