What Carbon Budget?

Orbital changes are responsible for the Milankovitch cycles that make Earth move in and out of periods of glaciation, or Ice Ages. In line with these cycles, July insolation has slowly decreased over the last 12,000 years. While insolation was at a peak some 12,000 years ago, temperatures rose only slowly at first, as the ice receded that was formed during the most recent Ice Age.

Some previous temperature reconstructions did suggest that a peak on temperature was reached around 6,000 to 7,000 years ago, followed by a decrease in temperature that continued until the industrial age. However, Samantha Bova and colleagues found that most of the records used in such reconstructions represented seasonal temperatures rather than annual ones.

They developed a method of evaluating individual records for seasonal bias and after adjusting for this, they found that the mean annual sea surface temperature has been rising steadily for the past 12,000 years, due to retreating ice sheets during the period from 12,000 to 6,500 years ago and, more recently, due to the increase in greenhouse gas emissions.

Paris Agreement

The Paris Agreement calls for a global average temperature well below 2°C above pre-industrial levels, with efforts taken to ensure that the temperature doesn't exceed 1.5°C above pre-industrial levels.

So, what are pre-industrial levels? The 'pre-' in pre-industrial means before, suggesting that pre-industrial levels refers to levels as they were in times before the Industrial Revolution started.

While emission of greenhouse gases did rise strongly since the start of the Industrial Revolution, the rise in emission of greenhouse gases by people had already started some 7,000 years ago with the rise in modern agriculture and associated deforestation. As this new study shows, the temperature has risen steadily since.

A recent post confirms earlier warnings that the temperature may already have risen by more than 2°C, and it looks even more that way when moving the baseline back 7,000 years. Moreover, this recent post again warns that the temperature rise is accelerating as tipping points are getting crossed, feedbacks are growing stronger and further heating elements are kicking, all interacting in non-linear ways to speed up the temperature rise.

So, where are those efforts that politicians pledged they would be taking?

What Carbon Budget?

Instead of making a genuine effort, most politicians and mainstream media keep telling people that there was a carbon budget to be divided among polluters, as if people should happily continue to consume the polluting products that are pushed by advertisers, for decades to come.

In reality, however, there is no carbon budget, there is no pollution budget. Instead, there is just a huge pollution debt to be paid and every minute of delay causes exponential growth of this debt and of the prospect of rapid human extinction and ultimately extinction of all life on Earth.

Carbon dioxide levels

[ click on images to enlarge ]

The IPCC image on the right shows CO₂ concentrations (up to 2000 ppm) and, underneath, the temperature rise (relative to 1986-2005) for the various RCPs.

What is RCP2.6? As the IPCC described in AR5, the temperature does not rise above 1.5°C (relative to 1850-1900) under the RCP2.6 scenario, and CO₂ concentrations do not rise above 421 ppm.

It looks like CO₂ concentrations will soon cross this 421 ppm threshold, given that the average daily CO₂ level recorded at Mauna Loa, Hawaii, was 419.12 ppm on February 4, 2021, a record high. The next day, February 5, 2021, the daily level was even higher, 419.45 ppm. The annual peak is typically reached in May, so levels can be expected to rise further over the next few months and cross the 421 ppm threshold soon.

 

Crossing the 421 ppm threshold implies that the RCP2.6 scenario is no longer applicable and that politicians won't be able to honour the pledges made at the Paris Agreement without geoengineering.

How much could temperatures rise? The IPCC image shows that the IPCC at the time when AR5 was written expected the temperature to rise by 3.7°C (with a range of 2.6°C to 4.8°C) under RCP8.5 by 2081–2100 relative to 1986–2005, and to keep rising beyond 2100 and reach 7.4°C and possibly 9.4°C relative to 1986–2005 over time.

The IPCC adds that, by 2100, CO₂ concentrations would reach 936 ppm under RCP 8.5., but when also (next to CO₂ concentrations) including the prescribed concentrations of CH₄ and N₂O, the combined CO₂-equivalent concentrations for RCP8.5 is expected to rise to 1313 ppm by the year 2100.

Meanwhile, a study discussed in an earlier post found that when the 1200 ppm CO₂-e gets crossed, the clouds feedback starts to kick in that can push the temperature up by an additional 8°C.

In line with IPCC AR5 figures, methane's Global Warming Potential (GWP) over a few years is 150.

Since AR5 was published, a study found methane's 100 year GWP to be 14% higher than the IPCC value. When applying an extra 14% to methane's short-term GWP of 150, it rises to 171.

Let's take the above (February 5, 2021) CO₂ level of 419.45 ppm and add the WMO 2019 level of methane of 1877 ppb, which with a short-term GWP of 171 translates into heating equivalent of 320.967 ppm CO₂.

Together, the existing CO₂ and methane add up to 740.417 ppm CO₂e, which is 459.583 ppm CO₂e away from the 1200 ppm CO₂e cloud tipping point.

In other words, a methane burst alone could drive up the methane level in the atmosphere by 2688 ppb, resulting in the cloud feedback tipping point to get crossed and the temperature to rise by an additional 8°C. Alternatively, the 1200 ppm CO₂e tipping point could get crossed due to a combination of warming elements, as depicted in the chart below, from a recent post, which would result in a total rise of 18°C when the cloud feedback is added on top. 

Methane

A reduction in carbon dioxide levels in the atmosphere isn't the only thing that's needed to avoid the worst of the looming temperature rise. There are many further lines of action that need to be implemented urgently, including efforts to reduce methane levels. 

Ominously, high methane levels were recorded by the N20 satellite on the morning of January 20, 2021. The combination image below shows levels as high as 2636 ppb at 695 mb (panel left) and 2806 ppb at 487 mb (panel right).

High methane levels were also recorded on January 30, 2021 pm. The combination image below shows that the SNPP satellite recorded levels as high as 2704 ppb at 487 mb (panel left), while the MetOp-2 satellite recorded levels as high as 2344 ppb at 469 mb (panel right). 

On February 4, 2021 pm, the MetOp-1 satellite recorded methane levels of 3071 ppb at 469 mb, as illustrated by the image in the right.

High peak methane levels are very worrying; what makes it even more threatening is that so much of the Arctic Ocean on above images is showing to be covered by high methane levels. 

This supports fears expressed earlier, such as in this recent post, about methane's present and future role in accelerating the temperature rise. 

Nitrous oxide

The image on the right shows nitrous oxide levels at Barrow, Alaska, over the past few years. 

Clearly, action to avoid nitrous oxide releases is also needed urgently.  

Conclusion

The situation is dire and calls for immediate, comprehensive and effective action as described in the Climate Plan.


Links

• Seasonal origin of the thermal maxima at the Holocene and the last interglacial - by Samantha Bova et al.
https://www.nature.com/articles/s41586-020-03155-x

• Palaeoclimate puzzle explained by seasonal variation
https://www.nature.com/articles/d41586-021-00115-x

• Important Climate Change Mystery Solved by Scientists
https://www.rutgers.edu/news/important-climate-change-mystery-solved-scientists

• Milankovitch (Orbital) Cycles and Their Role in Earth's Climate - by Alan Buis (NASA news, 2020)
https://climate.nasa.gov/news/2948/milankovitch-orbital-cycles-and-their-role-in-earths-climate

• Milankovitch cycles - Wikipedia
https://en.wikipedia.org/wiki/Milankovitch_cycles

• Insolation changes
https://energyeducation.ca/encyclopedia/Insolation
http://www.geo.umass.edu/faculty/bradley/bradley2003x.pdf

• Paris Agreement
https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement
https://unfccc.int/sites/default/files/english_paris_agreement.pdf

• IPCC AR5 Synthesis Report — Figure 2.8

https://www.ipcc.ch/report/ar5/syr/synthesis-report

• IPCC AR5 Report, Summary For Policymakers

https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_SPM_FINAL.pdf

• Most Important Message Ever

https://arctic-news.blogspot.com/2019/07/most-important-message-ever.html

• Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing - by M. Etminan et al. 

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL071930

• When Will We Die?
https://arctic-news.blogspot.com/2019/06/when-will-we-die.html

• Possible climate transitions from breakup of stratocumulus decks under greenhouse warming - by Tapio Schneider et al.
https://www.nature.com/articles/s41561-019-0310-1

• A World Without Clouds

https://www.quantamagazine.org/cloud-loss-could-add-8-degrees-to-global-warming-20190225

• 2020: Hottest Year On Record
https://arctic-news.blogspot.com/2021/01/2020-hottest-year-on-record.html

• Climate Plan
https://arctic-news.blogspot.com/p/climateplan.html

The real budgetary emergency and the myth of "burnable carbon"

by David Spratt

How fast and how profoundly we act to stop climate change caused by human actions, and work to return to a safe climate, is perhaps the greatest challenge our species has ever faced, but are we facing up to what really needs to be done?

We have to come to terms with two key facts: practically speaking, there is no longer a "carbon budget" for burning fossil fuels while still achieving a two-degree Celsius (2°C) future; and the 2°C cap is now known to be dangerously too high.

No Carbon Budget Left - David Spratt from Breakthrough  -  "We have no carbon budget left
for burning of fossils fuels - emergency action is now the only viable path"  - David Spratt

For the last two decades, climate policy-making has focused on 2°C of global warming impacts as being manageable, and a target achievable by binding international treaties and incremental, non-disruptive, adjustments to economic incentives and regulations (1).

But former UK government advisor Professor Sir Robert Watson says the idea of a 2°C target "is largely out of the window”, International Energy Agency chief economist Fatih Birol calls it "a nice Utopia", and international negotiations chief Christiana Figueres says we need "a miracle". This is because, in their opinions, emissions will not be reduced sufficiently to keep to the necessary "carbon budget" (2).

The carbon budget has come to public prominence in recent years, including in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report in 2013, as being the difference between the total allowable greenhouse gas emissions for 2°C of warming, and the amount already emitted or spent. The budget varies according to the likelihood of overshooting the target: the higher the risk, the bigger the budget. In the IPCC report, no carbon budget is given for less than a one-in-three chance of failure.

At that one-in-three risk of failure, the IPCC says the total budget is 790 GtC (gigatons, or one billion tons, of carbon), less emissions to 2011 of 515 GtC, leaving a budget of 275 GtC in 2011, or ~245 GtC in 2014 (3).

What is less well understood is that if the risk is low, there is no carbon budget left (4).

Breakthrough National  Climate Restoration
Forum 21-22 June,  Melbourne

Climate change with its non-linear events, tipping points and irreversible events – such as mass extinctions, destruction of ecosystems, the loss of large ice sheets and the triggering of large-scale releases of greenhouse gases from carbon stores such as permafrost and methane clathrates – contains many possibilities for catastrophic failure.

Ian Dunlop, a former senior risk manager and oil and coal industry executive, says the management of catastrophic risk has to be very different from current processes. As serious, irreversible outcomes are likely, this demands very low probabilities of failure: management of catastrophic risk "must centre around contingency planning for high-impact and what were regarded as low-probability events, which unfortunately are now becoming more probable… Major, high-risk industrial operations, such as offshore oil exploration, provide a model, with detailed contingency planning and sequential barriers being put in place to prevent worst-case outcomes" (5).

If a risk-averse (pro-safety) approach is applied – say, of less than 10% probability of exceeding the 2°C target – to carbon budgeting, there is simply no budget available, because it has already been used up. A study from The Centre for Australian Weather and Climate Research shows that "the combination of a 2°C warming target with high probability of success is now unreachable" using the current suite of policy measures, because the budget has expired (6).

This is illustrated in Figure 1 where, as we move to the right (greater probability of meeting target) along the blue line which is the 2°C carbon budget, we reach a point around 90% probability (blue circle) where the total budget intersects with what we have already emitted.

As well, on-going greenhouse emissions associated with food production and deforestation are often conveniently pushed to one side in discussing carbon budgets. UK scientists have shown that if some reasonably optimistic assumptions are made about deforestation and food-related emissions for the rest of the century, then most emission reduction scenarios are incompatible with holding warming to +2ºC, even with a high 50% probability of exceeding the target. In other words, food and deforestation has taken up the remaining budget, leaving no space for fossil fuel emissions (7).

In addition, the carbon budget analysis makes optimistic and risky assumptions about the stability of Arctic, and of polar and other carbon stores such as permafrost. As one example, the modelling discussed in the IPCC report projects an area of summer Arctic sea-ice cover in the year 2100 higher that actually exists at the moment, yet there is a great deal more warming and sea-ice loss to come this century! In fact, many Arctic specialists think the Arctic will be sea-ice free in summer within the next decade, with consequences for global warming that the carbon budget calculations have significantly underestimated. (8)

Australian Climate Council member Prof. Will Steffen says the IPCC carbon budget may "be rather generous". The IPCC report says the modelling used does not include explicit representation of permafrost soil carbon decomposition in response to future warming, and does not consider slow feedbacks associated associated with vegetation changes and ice sheets. Recent research suggests these events could happen well below 2°C of warming, so they should be taken into account, but they are not.

Accounting for the possible release of methane from melting permafrost and ocean sediment implies a substantially lower budget (9). This reinforces the need to take a pro-safety, risk-averse approach to the carbon budget, especially since some research suggests that Arctic permafrost may be vulnerable at less than 2°C or warming (10).

For all these reasons – that is, prudent catastrophic risk management, accounting for food production and deforestation emissions, and for Arctic sea ice and carbon store instability – the idea of "burnable carbon" – that is, how much more coal, gas and oil we can burn and still keep under 2°C – is a dangerous illusion, based on unrealistic, high-risk, assumptions.

A second consideration is that 2°C of warming is not a safe target. Instead, it's the boundary between dangerous and very dangerous (11), and 1°C higher than experienced during the whole period of human civilisation (12), illustrated in Figure 2. The last time greenhouse gas levels were as high as they are today, modern humans did not exist (13), so we are conducting an experiment for which we have no direct observable evidence from our own history, and for which we do not know the full result.

However, we do understand that many major ecosystems will be lost, a 2°C sea-level rise will eventually be measured in the tens of metres (14), and much of human civilisation and large, productive river delta systems will be swamped. There is now evidence to suggest that the current conditions affecting the West Antarctic ice sheet are sufficient to drive between 1.2 and 4 metres of sea rise (15), and evidence that Greenland will contribute more quickly (16), and they are just two contributors to rising sea levels.

It is now clear that the incremental-adjustment 2°C strategy has run out of time, if for no other reason than the "budget" for burning more fossil fuels is now zero, yet the global economy is still deeply committed to their continuing widespread use.

We all wish the incremental-adjustment 2°C strategy had worked, but it hasn't. It has now expired as a practical plan.

We now have a choice to make: accept much higher levels of warming of 3–5°C that will destroy most species, most people and most of the world's ecosystems; a set of impacts some more forthright scientists say are incompatible with the maintenance of human civilisation.

Or we can conceive of a safe-climate emergency-action approach which would aim to reduce global warming back to the range of conditions experienced during the last 10,000 years, the period of human civilisation and fixed settlement. This would involve fast and large emissions reduction through radical energy demand reductions, whilst a vast scaling-up of clean energy production was organised, together with the remaking of many of our essential systems such as transport and food production, with the target being zero net emissions. In addition, there would need to be a major commitment to atmospheric carbon dioxide drawdown measures. This would need to be done at a speed and scale more akin to the "war economy", where social and economic priority is given to what is perceived to be an overwhelming existential threat.

After 30 years of climate policy and action failure, we are in deep trouble and now have to throw everything we can muster at the climate challenge. This will be demanding and disruptive, because there are no longer any non-radical, incremental paths available.

Prof. Kevin Anderson and Dr Alice Bows, writing in the journal Nature, say that "any contextual interpretation of the science demonstrates that the threshold of 2°C is no longer viable, at least within orthodox political and economic constraints" and that "catastrophic and ongoing failure of market economics and the laissez-faire rhetoric accompanying it (unfettered choice, deregulation and so on) could provide an opportunity to think differently about climate change" (17).

Anderson says there is no longer a non-radical option, and for developed economies to play an equitable role in holding warming to 2°C (with 66% probability), emissions compared to 1990 levels would require at least a 40% reduction by 2018, 70% reduction by 2024, and 90% by 2030. This would require "in effect a Marshall plan for energy supply". As well low-carbon supply technologies cannot deliver the necessary rate of emission reductions and they need to be complemented with rapid, deep and early reductions in energy consumption, what he calls a radical emission reduction strategy (18). All this suggests that even holding warming to a too-high 2°C limit now requires an emergency approach.

Emergency action has proven fair and necessary for great social and economic challenges we have faced before. Call it the great disruption, the war economy, emergency mode, or what you like; the story is still the same, and it is now the only remaining viable path.

keynote speaker, David Spratt, explains why there is no carbon budget left to burn.

Sources:
This article was originally published at ClimateCodeRed.org
Above video, NO CARBON BUDGET LEFT TO BURN, was uploaded by Breakthrough.



Notes

1. Jaeger, C.C. and J. Jaeger (2011), "Three views of two degrees", Reg. Environ. Change, 11: S15-S26; Anderson, K. and A. Bows (2012) “A new paradigm for climate change”, Nature Climate Change 2: 639-70
2. http://www.bbc.co.uk/news/science-environment-19348194; http://www.guardian.co.uk/environment/2011/may/29/carbon-emissions-nuclearpow; http://www.smh.com.au/environment/weather/climate-pioneers-see-little-chance-of-avoiding-dangerous-global-warming-20131105-2wyon.html
3. IPCC (2013) "Working Group I Contribution to the IPCC Fifth Assessment Report Climate Change 2013; The Physical Science Basis: Summary for Policymakers"
4. "For a 90% probability of not exceeding 2C of warming the carbon budget had reduced to zero by 2012, using a multi-agent (that is, the well-mixed greenhouse gases, including CO2 and CH4)", Raupach (2013, unpublished), based on Raupach, M. R., I.N. Harman and J.G. Canadell (2011) "Global climate goals for temperature, concentrations, emissions and cumulative emissions", Report for the Department of Climate Change and Energy Efficiency. CAWCR Technical Report no. 42. Centre for Australian Weather and Climate Research, Melbourne; Rogelj, J., W. Hare et al. (2011) "Emission pathways consistent with a 2°C global temperature limit", Nature Climate Change 1: 413-418 show at Table 1 no feasible pathways for limiting warming to 2°C during the twenty-first century with a "very likely" (>90%) chance of staying below the target, without carbon drawdown.
5. Dunlop, I. (2011), "Managing catastrophic risk", Centre for Policy Development, 
http://cpd.org.au/2011/07/ian-dunlop-managing-catastrophic-risk/
6. Raupach, M. R., I.N. Harman and J.G. Canadell (2011) "Global climate goals for temperature, concentrations, emissions and cumulative emissions", Report for the Department of Climate Change and Energy Efficiency. CAWCR Technical Report no. 42. Centre for Australian Weather and Climate Research, Melbourne. 
7. Anderson, K. and A. Bows (2008) “Reframing the climate change challenge in light of post-2000 emission trends”, Phil. Trans. R. Soc. A 366: 3863-3882; Anderson, K. and A. Bows (2011) “Beyond ‘dangerous’ climate change: emission scenarios for a new world”, Phil. Trans. R. Soc. A 369: 20–44
8. Wadhams, P. (2012) “Arctic ice cover, ice thickness and tipping points”, AMBIO 41: 23–33; Maslowski, W., C.J. Kinney et al. (2012) "The Future of Arctic Sea Ice", The Annual Review of Earth and Planetary Sciences, 40: 625-654
9. IPCC (2013) "Working Group I Contribution to the IPCC Fifth Assessment Report Climate Change 2013; The Physical Science Basis;
10. Vaks, A., O.S. Gutareva et al. (2013) “Speleothems Reveal 500,000-Year History of Siberian Permafrost”, Science 340: 183-186; Schaefer, K., T. Zhang et al. (2011) "Amount and timing of permafrost carbon release in response to climate warming", Tellus 63:165-180
11. Anderson, K. and A. Bows (2011) “Beyond ‘dangerous’ climate change: emission scenarios for a new world”, Phil. Trans. R. Soc. A 369: 20–44
12. Marcott, S.A, J.D. Shakun et al. (2013) "A Reconstruction of Regional and Global Temperature for the Past 11,300 Years", Science 339: 1198-120; Hansen, J., P. Kharecha et al. (2013) "Assessing 'dangerous climate change': Required reduction of carbon emissions to protect young people, future generations and nature", Plos One 8: 1-26
13. Tripadi, A.K., C.D. Roberts et al. (2009), "Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years", Science 326: 1394-1397
14. Rohling, E. J.,K. Grant et al. (2009) “Antarctic temperature and global sea level closely coupled over the past five glacial cycles”, Nature GeoScience, 21 June 2009 `af
15. NASA (2014), "NASA-UCI Study Indicates Loss of West Antarctic Glaciers Appears Unstoppable", Media release, 12 May 2014, http://www.nasa.gov/press/2014/may/nasa-uci-study-indicates-loss-of-west-antarctic-glaciers-appears-unstoppable, accessed 19 May 2014; Rignot, E., J. Mouginot et al. (2014) "Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011", Geophysical Research Letters, doi: 10.1002/2014GL060140; Joughin, I., B.E. Smith et al. (2014), "Marine Ice Sheet Collapse Potentially Under Way for the Thwaites Glacier Basin, West Antarctica", Science 344: 735 -738
16. NASA (2014), "Hidden Greenland Canyons Mean More Sea Level Rise", Media release, 19 May 2014, http://www.nasa.gov/press/2014/may/hidden-greenland-canyons-mean-more-sea-level-rise, accessed 19 May 2014; Morlighem, M., E. Rignot et al. (2014), "Deeply incised submarine glacial valleys beneath the Greenland ice sheet", Nature Geoscience, doi:10.1038/ngeo2167
17. Anderson, K. and A. Bows (2012) “A new paradigm for climate change”, Nature Climate Change 2: 639-70
18. Anderson, K. (2014) "Why carbon prices can’t deliver the 2°C target", 13 August 2013, http://kevinanderson.info/blog/why-carbon-prices-cant-deliver-the-2c-target, accessed 19 May 2014; Anderson, K. (2012) "Climate change going beyond dangerous – Brutal numbers and tenuous hope", Development Dialogue, September 2012; Anderson, K. (2011) "Climate change going beyond dangerous – Brutal numbers and tenuous hope or cognitive dissonance", presentation 5 July 2011, slides available at http://www.slideshare.net/DFID/professor-kevin-anderson-climate-change-going-beyond-dangerous; plus (7) above.