A Safe Climate

This post presents the current predicament of world emissions and explains the prominent studies that seek to make our climate safe.

Humanity’s CO2 emissions by country for year 2016 are shown in chart 1 –

Chart 1. Fossil fuel CO2 emissions by source in 2016. Hansen and Sato, 2016, Reprinted from Figure 5(a) of Regional climate change and national responsibilities.1

But chart 22 shows China and India have contributed a much smaller portion of total CO2 emitted since preindustrial times.

Chart 2. Cumulative fossil fuel CO2 emissions by source 1751-2016. Hansen and Sato, 2016, Reprinted from Figure 5(b) of Regional climate change and national responsibilities.1

Furthermore, as shown in chart 3(a), China’s per capita carbon emissions in 2016 were near global mean (or “average”), and India’s less. Chart 3(b) displays cumulative carbon emissions per capita from 1751 to 2016. This the the total quantity of carbon emissions emitted by each country since preindustrial times divided by the population of each country in 2016. China’s contribution is less than global mean and India’s contribution is tiny.

Chart 3. Per capita fossil fuel CO2 emissions in 2016 and cumulative. Hansen and Sato, 2016, Reprinted from Figure 6 of Regional climate change and national responsibilities.1

Those countries most to blame for climate change, and therefore should be leading wth radical CO2 reductions, are those that instead have the highest cumulative-per-capita emissions: the U.S., U.K., Germany, Canada, Russia, Australia and Japan. Instead, these countries shamefully continue to be laggards as shown in Chart 4. (The decline of U.K. emissions is due to combination of reduced coal and gas consumption, reduced manufacturing and increased bioenergy supply.3 Bioenergy relies on deceitful carbon accounting as discussed in the post titled Biofuels.)

Chart 4. Territorial CO2 emissions of highest cumulative-per-capita emissions. The chart is repeated on the RHS with the U.S. excluded for clarity. Data obtained from Global Carbon Atlas.4

The most immediate priority of all nations is to make our climate safe and only science can prescribe the necessary changes. Arbitrary actions, although well intentioned, will be inadequate because there is no time remaining for half-measures –

“winning slowly is the same as losing”.


Two prominent endeavours have pursued the stabilisation of greenhouse gases to limit warming: the United Nations Framework Convention on Climate Change (UNFCCC), and that of Dr James Hansen and colleagues (hereafter referred to as ‘Hansen & Co’). The most important finding of both is that it’s too late for emission reductions alone to be adequate, and now ‘negative emission technology’ (NET), otherwise known as ‘carbon dioxide removal’ (CDR), is required. Negative emissions are the burden being handed to young people.6



The United Nations Framework Convention on Climate Change (UNFCCC) is a treaty with the objective of: “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.”7 This is informed by the Intergovernmental Panel on Climate Change (IPCC), within which “experts review and synthesize available scientific and technical knowledge.”8 The IPCC does not carry out its own scientific research, instead it informs the UN of existing relevant science. It’s interesting to learn the history of the UNFCCC’s formation to understand just how slow and ineffective the process has sadly been –

The first joint meeting of scientific bodies to assess CO2 in the atmosphere was held in 1980, between the United Nations Environment Programme (UNEP), International Council for Science (ICSU) and the World Meteorological Organisation (WMO) –

 Figure 1. Extract from WMO, 1986, Report of the International conference of the Assessment of the role of carbon dioxide and of other greenhouse gases in climate variations and associated impacts.9

At a 1985 meeting of theWMO, it was established that assessments be periodically undertaken of the state of scientific understanding of greenhouse gases and implications, and that a global convention to limit greenhouse gases be considered –

 Figure 2. Extract from WMO, 1986, Report of the International conference of the Assessment of the role of carbon dioxide and of other greenhouse gases in climate variations and associated impacts.9

In 1988, the 43rd meeting of the UN General Assembly endorsed the formation of the Intergovernmental Panel on Climate Change (IPCC) –

Figure 3. Extract from the Record of the resolutions adopted by the United Nations General Assembly at its 43rd session in 1988.10

In mid-1992, 12 years after the first joint scientific meeting about CO2, the UN adopted for signature the Framework Convention on Climate Change. This was open for signature for two years before it “came into force” in mid-1994.11

Under this convention, the first annual meeting by signatory governments, named Conference Of Parties (COP), was held in 1995, in Berlin. Twenty one COPs were held before an agreement was finally reached to limit warming at COP21 in Paris –

During a summit in Paris in December 2015, organized under the United Nations Framework Convention on Climate Change (UNFCCC), 195 countries adopted the Paris Agreement which includes a long-term temperature goal:

“Holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognizing that this would significantly reduce the risks and impacts of climate change;” (Article 2.1.a).


“In order to achieve the long-term temperature goal set out in Article 2, Parties aim to reach global peaking of greenhouse gas emissions as soon as possible, recognizing that peaking will take longer for developing country Parties, and to undertake rapid reductions thereafter in accordance with best available science, so as to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty.” (Article 4.1).

WMO, 2018, Understanding the IPCC Special Report on 1.5°C.12

It took until COP19 (nineteen annual meetings), just for an agreement to be reached to peak emissions.13

Now in early 2019, 3 years after the Paris Agreement, 25 years since the UNFCCC came into force, 31 years since the formation of the IPCC, and 39 years since the first joint scientific meeting about atmospheric CO2, NOTHING has been achieved except to INCREASE CO2 emissions. CO2 emissions have increased by 91% since the first joint scientific meeting in 1980, and increased 61% since 1995 when COP1 took place.14 To make matters worse: (i) the sections below explain that limiting warming to 1.5℃ (the goal of the Paris Agreement) is not safe, (ii) the scale of emission reductions prescribed are beyond any historic precedent,15 (iii) prescribed emission reductions depend on concurrent massive CO2 removal, (see chart 10 on this page) (iv) the annual increase of CO2 emissions is near record rate,16 and (v) 1.5℃ is imminent.17

Figure 4. Heads of delegations at the 2015 United Nations Climate Change Conference (COP21), which led to the signing of the Paris Agreement.18


To hold global average temperature steady, emissions need to reach ‘net zero’. Net zero emissions are achieved when emissions of greenhouse gases to the atmosphere are balanced by anthropogenic removals.

An increase in global average temperature of e.g. 1.5°C corresponds to a limited net amount of CO2 being emitted. This amount of CO2 is usually referred to as the carbon budget for 1.5°C.

The rate at which CO2 will be emitted determines how many years remain until emissions must reach ‘net-zero’.

Limiting warming to 1.5°C or 2°C without overspending the corresponding carbon budget would require very fast changes in electricity production, transport, construction, agriculture and industry.

IPCC. 2018. Understanding the IPCC Special Report on 1.5°C.12

Net zero emissions requires both rapid emission reductions (i.e. decarbonisation) AND anthropogenic removals, also known as “negative emission technologies” (NETs) or “carbon dioxide removal” (CDR). This is because: (i) There is a limit to the rate of CO2 emission reductions that civilisation can manage, and because civilisation has left this task recklessly late and continues to treat it with indifference, the scale and urgency of CDR is incredible, (ii), There is a limit to the minimum level of CO2 emissions that civilisation can manage (also known as a “carbon-floor”), and this must be perpetually offset. A typical future optimistic CO2 emission scenario is shown below –

Figure 5. Net zero emissions concept. IPCC. 2018. Understanding the IPCC Special Report on 1.5°C.12

Also note that –

Additional warming by non-CO2 greenhouse gases tends to be off-set by aerosol cooling; thus within the range of uncertainty CO2 provides a good approximation of the net human-made forcing.

p. 13, Climate Change in a Nutshell: The Gathering Storm, 18 Dec 2018.19

The IPCC’s Special Report on 1.5°C presents the six future emission categories (or pathway groups) shown below (note the worryingly small probabilities of success associated with each) –

Table 1. Reprinted from p. 100, Table 2.1, IPCC Special Report on 1.5°C.20

For each of the pathways above, there are corresponding prescribed future rates of decarbonisation and associated increasing CDR. Placing CDR aside for the moment, it’s useful to consider historic examples of decarbonisation. There have been three notable examples: France and Sweden in the 1980s due to an increased supply of nuclear energy, and Russia in the 1990s after the collapse of the Soviet Union.

As shown below, the decarbonisation in France occurred between 1979 and 1988, and at a rate equivalent to a linear decline of -3.25%/yr of the initial level of emissions in 1979. Sweden managed -5.6%/yr21 and Russia endured -5.9%.

Chart 5. CO2 emitted by France with cursor placed at the end of decarbonisation period in 1988.4
Chart 6. Rate of decarbonisation in France between 1979 and 1988.

Prescribed decarbonisation rates for the next decade can be calculated using the table below and compared to the historic reductions above.

Table 2. Reprinted from p. 119, Table 2.4, IPCC Special Report on 1.5°C.20

The level of CO2 from fossil fuels and industry (net) in 2018 is forecast to be 37.1GtCO2.22 Under the assumption that the prescribed decarbonisation for the future pathway 1.5°C-with-low-overshoot begins in 2021, and that there’s no growth of emissions in 2019 or 2020, then CO2 emissions from fossil fuels and industry would need to decline from 37.1GtCO2 to 20.6GtCO2 in a decade (refer to the table above). This is equivalent to an annual linear decline of -4.5% of the original amount each year, as calculated below –

Chart 7. Decarbonisation of the IPCC pathway 1.5°C-with-low-overshoot: (a) Calculation of annual emissions for years 2020–2030 using the figure from Table 2 above, (b) Chart of annual emissions, and (c) Chart (b) placed into historical context by appending World CO2 emissions from fossil fuel and industry, published by the Global Carbon Project23

While this rate of decarbonisation is similar to that which occurred in France, Sweden and Russia, the scale of these examples should be considered: During their respective decarbonisation, France was responsible for 2.1% of global CO2 emissions,24 Sweden 0.4%25 and Russia 9%.26 The decarbonisation that occurred in Russia is the only that was significant at rate and scale, but this caused hardship, riots, massacres and even a decline in the life expectancy of males from 65 down to 58 years.27 A global linear decarbonisation at a rate of -4.5%/yr for a decade is without historic precedent. Alternatively, the pathway 1.5°C-with-high-overshoot, that has a median warming level of 1.7C and a 20% chance of exceeding 2°C28 demands a global decarbonisation rate to 2030 of -2.7%/yr. This rate would need to be enacted in 2021, despite civilisation having carbonised at about this rate since year 2000, as shown below, effectively somehow being an emissions-backflip.28

Chart 8. Recent change of emissions: (a) Calculation of rate of change of emissions for years 2000–2018, (b) Chart of annual emissions23

Even the pathway Higher-2°C, that has 40% chance of exceeding 2°C, and a 13% chance of exceeding 2.5°C as early as 207528 requires immediate decarbonisation at a rate of -1.6%/yr –

Chart 9. Decarbonisation of the IPCC pathway Higher-2°C: (a) Calculation of annual emissions for years 2020–2030 using the figure from Table 2 above, (b) Chart of annual emissions, and (c) Chart (b) placed into historical context by appending World CO2 emissions from fossil fuel and industry, published by the Global Carbon Project23

Therefore even the rapid and drastic decarbonisation shown in Chart 9 above, along with the prescribed concurrent CDR detailed further below, leaves us with a 40% chance of warming the planet to a temperature that hasn’t occurred for around 3–5 million years: as was stated in Part 2

In the mid-Pliocene, 3–5 million years ago, the last time that the Earth’s atmosphere contained 400ppm of CO2, global mean surface temperature was 2–3℃ warmer than today, the Greenland and West Antarctic ice sheets melted and even some of the East Antarctic ice was lost, leading to sea levels that were 10–20m higher than they are today.

WMO, 2017, State of the Global Climate in 2017.29

Decarbonisation is only “half the story”. Goals to limit warming become more challenging once the prescribed scale and rate of concurrent carbon dioxide removal (CDR) is considered.

The CDR required for pathways Below-1.5°C and 1.5°C-with-low-overshoot is shown in Chart 10; (a) shows the annual quantity of CDR to be removed each year, and (b) the cumulative or total quantity over time –

Chart 10. Prescribed CDR for pathways Below-1.5°C and 1.5°C-with-low-overshoot. Calculated using prescribed levels of annual CDR addition shown in p. 128, fig 2.13, IPCC Special Report on 1.5°C20

640–950 GtCO2 removal is required for a likely chance of limiting end-of-century warming to 1.5 °C. In the absence of strengthened pre-2030 pledges, long-term CO2 commitments are increased by 160–330 GtCO2, further jeopardizing achievement of the 1.5 °C goal and increasing dependence on CO2 removal.

Residual fossil CO2 emissions in 1.5–2 °C pathways.30

This quantity of CDR is so large that perhaps the only analogy that can be made is of the size and rate of Earth’s natural carbon sinks, as was done in the commentary titled “The world’s biggest gamble”31

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. Only a global zero carbon roadmap will put the world on a course to phase-out greenhouse gas emissions and create the essential carbon sinks for Earth-system stability, without which, world prosperity is not possible.

p. 1, Rockström, J. et al. (2016), The world’s biggest gamble.31

As shown below, the size of global ocean carbon sink averaged about 9GtCO2/yr over the last decade, and the land about 12GtCO2/yr. (Interestingly, also shown is the carbon budget imbalance of 2GtCO2/yr; this is a gap in our understanding as stated in figure 7. This is about 5% of our total emissions).32 Therefore, the quantity of annual CDR by 2050, prescribed for the pathways Below-1.5°C and 1.5°C-with-low-overshoot, is equivalent to an additional carbon sink of the size of a global ocean. By 2100 this is just under 1.7 global oceans, as shown by the right hand axis of Chart 10(a) above.

Figure 6. Fate of anthropogenic CO2 emissions (2008–2017)33
Figure 7. Balance of sources and sinks.33

CDR deployed at scale is unproven, and reliance on such technology is a major risk in the ability to limit warming to 1.5°C.

p. 96, IPCC Special Report on 1.5°C20

One would now expect massive levels of government expenditure being spent on research and development of CDR, but outside the relevant scientific fields there seems to be no concern!

Approaches under consideration include the enhancement of terrestrial and coastal carbon storage in plants and soils such as afforestation and reforestation, soil carbon enhancement, and other conservation, restoration, and management options for natural and managed land and coastal ecosystems. Biochar sequestration provides an additional route for terrestrial carbon storage. Other approaches are concerned with storing atmospheric carbon dioxide in geological formations. They include the combination of biomass use for energy production with carbon capture and storage (BECCS) and direct air capture with storage (DACCS) using chemical solvents and sorbents. Further approaches investigate the mineralization of atmospheric carbon dioxide, including enhanced weathering of rocks. A fourth group of approaches is concerned with the sequestration of carbon dioxide in the oceans, for example by means of ocean alkalinization. The costs, CDR potential and environmental side effects of several of these measures are increasingly investigated and compared in the literature, but large uncertainties remain, in particular concerning the feasibility and impact of large-scale deployment of CDR measures.

p. 121, IPCC Special Report on 1.5°C20

Note that carbon capture and storage (CCS) is not a form of CDR because it does not remove CO2 from the atmosphere; instead its aim, should it ever come to fruition, is to lower the emission of CO2 from fossil fuelled energy generation, allowing it to be produced without an impact on the remaining carbon budget, but –

A variety of pilot projects failed in the past. One was a joint effort by one of the largest U.S. utilities, American Electric Power, and the Energy Department to capture 15 percent of emissions from coal-fired power plants. It closed down after two years. Another carbon capture project attached to a new coal-fired power plant in Mississippi ran into so many technical problems and billions of dollars in cost overruns that after six years its owners abandoned the carbon capture project and converted the plant to burn natural gas for power generation.

Dec 2018, The Washington Post, ‘Carbon removal is now a thing’: Radical fixes get a boost at climate talks.34

In summary, the IPCC’s pathway 1.5°C-with-low-overshoot prescribes the world decarbonise at a rate 1.6 times faster than it has recently carbonised, and carbon dioxide removal (CDR) on the scale of the global ocean operational by 2050, and 1.7 oceans by 2100. The rate of decarbonisation required is a linear -4.5%/yr between 2020 and 2030, despite the world having carbonised at a linear rate of +2.8%/yr between years 2000 and 2018 (i.e 4.5/2.8 = 1.6x). In addition to decarbonisation is the requirement of CDR of about 800 GtCO2 this century, with an ocean-worth (9 GtCO2/yr) operational by 2050 and 1.7 oceans by 2100. This has a 67% chance of causing global surface temperature to exceed 1.5°C and a 10% chance of exceeding 2°C.28

Hansen & Co

Dr. James Hansen, formerly Director of the NASA Goddard Institute for Space Studies, is an Adjunct Professor at Columbia University’s Earth Institute, where he directs a program in Climate Science, Awareness and Solutions. He was trained in physics and astronomy in the space science program of Dr. James Van Allen at the University of Iowa. His early research on the clouds of Venus helped identify their composition as sulfuric acid. Since the late 1970s, he has focused his research on Earth’s climate, especially human-made climate change. Dr. Hansen is best known for his testimony on climate change to congressional committees in the 1980s that helped raise broad awareness of the global warming issue. He was elected to the National Academy of Sciences in 1995 and was designated by Time Magazine in 2006 as one of the 100 most influential people on Earth. He has received numerous awards including the Carl-Gustaf Rossby and Roger Revelle Research Medals, the Sophie Prize and the Blue Planet Prize. Dr. Hansen is recognized for speaking truth to power, for identifying ineffectual policies as greenwash, and for outlining actions that the public must take to protect the future of young people and other life on our planet.

James E. Hansen, Feb 2019, CV35

Dr Hansen has published many studies, in conjunction with other scientists about climate change.36

As explained in Part 2, Hansen & Co make the point that 1.5℃ is not safe because it’s warmer than anytime of the Holocene, and as warm as the Eemian when seas were 6–9m higher. Instead, Hansen prescribes changes needed to reduce atmospheric CO2 to less than 350 ppm, in order to limit global temperature close to the Holocene range –

Dutton et al. (2015) conclude that the best estimate for Eemian temperature is +1℃ relative to preindustrial. Consistent with these estimates and the discussion of Masson-Delmotte et al. (2013), we assume that maximum Eemian temperature was +1℃ relative to preindustrial with an uncertainty of at least 0.5℃.

These considerations raise the question of whether 2℃, or even 1.5℃, is an appropriate target to protect the well-being of young people and future generations. Indeed, Hansen et al. (2008) concluded that “if humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, …CO2 will need to be reduced… to at most 350 ppm, but likely less than that”, and further “if the present overshoot of the target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects”. 

A danger of 1.5 or 2℃ targets is that they are far above the Holocene temperature range. If such temperature levels are allowed to long exist they will spur “slow” amplifying feed-backs (Hansen et al., 2013b; Rohling et al., 2013; Masson-Delmotte et al., 2013), which have potential to run out of humanity’s control. The most threatening slow feedback likely is ice sheet melt and consequent significant sea level rise, as occurred in the Eemian, but there are other risks in pushing the climate system far out of its Holocene range. Methane release from thawing permafrost and methane hydrates is another potential feedback, for example, but the magnitude and timescale of this is unclear (O’Connor et al., 2010; Quiquet et al., 2015).

Here we examine the fossil fuel emission reductions required to restore atmospheric CO2 to 350 ppm or less, so as to keep global temperature close to the Holocene range, in addition to the canonical 1.5 and 2℃ targets.

Hansen et al., 2017, Young people’s burden: requirement of negative CO2 emissions37
Chart 11. Global surface temperature relative to peak Holocene temperature (not preindustrial temperature), published in 2011, based on ocean cores.38 When this was published, peak Holocene temperature was about +0.8℃.39

350 ppm

Chart 12 shows a range of pathways, and three in (b) return global surface temperature to within our range of uncertainty about the Holocene maximum (0.5℃ – 0.75℃) –

Chart 12. Young people’s burden: requirement of negative CO2 emissions.40

Note the units for CO2 extraction (i.e. CDR) above are of units peta-grams of carbon (PgC). This is equivalent to billions of tons of carbon (GtC). To compare these quantities with those from the previous section, and so convert GtC to GtCO2, they must be multiplied by 44/12.

The green pathway shown demands 869GtCO2 and a CO2 reduction rate of -3%/yr (i.e. CO2 emissions in 2030 reduced to two thirds of 2020 level). This is very similar to the IPCC’s pathway 1.5°C-with-low-overshoot that prescribes an annual CO2 reduction rate of -4.5%/yr and CDR of about 800 GtCO2, but Hansen & Co state the global surface temperature in 2100 would lower to less than +1°C.

The blue pathway is more precautionary, by relying more on CO2 reduction (-6%/yr) and less on CDR (153PgC or 561 GtCO2). This quantity of CDR still demands an annual quantity of CDR removal about the size of the global ocean by 2100. This now seems an inescapable requirement.

Our Current Path

Chart 13. 2100 warming projections, Climate Action Tracker41

In the absence of policies global warming is expected, to reach 4.1°C – 4.8°C above pre-industrial by the end of the century. The emissions that drive this warming are often called Baseline scenarios (‘Baselines’ in the above figure) and are taken from the IPCC AR5 Working Group III. Current policies presently in place around the world are projected to reduce baseline emissions and result in about 3.3°C warming above pre-industrial levels. The unconditional pledges and targets that governments have made, including NDCs as of December 2018, would limit warming to about 3.0°C above pre-industrial levels, or in probabilistic terms, likely (66% or greater chance) limit warming below 3.2°C. This result is similar to our estimate last year, reflecting the fact that little has changed in terms of government commitments and targets in the past 12 months.

2100 warming projections, Climate Action Tracker, accessed Feb 2019. 41 Note that NDCs are “Nationally Determined Contributions” and detail the supposed intention of each country to reduce its emissions.42

Clearly, for any chance of avoiding evermore severe and frequent climate impacts, and the collapse of civilisation, not only must rapid decarbonisation begin immediately on worldwide scale, but also massive government investment in research and development of CDR. Current capitalist economic priorities and fossil fuel extraction must cease. But recall the following –

Humanity’s CO2 emissions: (i) are currently trapping two thirds of the energy causing global warming, (ii) are the only rapidly increasing contributor, (iii) solely determine our long term warming commitment, and (iv) continue to grow with no peak in sight. Half of all CO2 ever emitted has been emitted recently and almost all by the world’s energy system.

Part 1

For an understanding of the world’s energy system, refer to the post World Energy Supply and subsequent pages.

  1. Hansen, J. and Sato, M., 2016. Regional climate change and national responsibilities. Environmental Research Letters11(3), p.034009 showing updated version()()()
  2. Figure 5 of Regional climate change and national responsibilities()
  3. https://www.carbonbrief.org/analysis-uk-carbon-emissions-in-2017-fell-to-levels-last-seen-in-1890()
  4. http://www.globalcarbonatlas.org/en/CO2-emissions()()
  5. https://www.rollingstone.com/politics/politics-news/bill-mckibben-winning-slowly-is-the-same-as-losing-198205/()
  6. https://www.earth-syst-dynam.net/8/577/2017/()
  7. p9 of The United Nations Framework Convention on Climate Change()
  8. Chapter 2. Evaluation of IPCC’s assessment process()
  9. WMO, 1986, Report of the International conference of the Assessment of the role of carbon dioxide and of other greenhouse gases in climate variations and associated impacts hosted at https://library.wmo.int/index.php?lvl=notice_display&id=6321()()
  10. http://www.un.org/en/ga/search/view_doc.asp?symbol=A/RES/43/53 hosted at https://research.un.org/en/docs/ga/quick/regular/43()
  11. https://unfccc.int/process/the-convention/what-is-the-convention/status-of-ratification-of-the-convention()
  12. https://library.wmo.int/doc_num.php?explnum_id=5188()()()
  13. https://en.wikipedia.org/wiki/2013_United_Nations_Climate_Change_Conference()
  14. World’s CO2 emission in 1980 was 19,388MtCO2 and 23,007MtCO2 in 1995 (See Part 1). 37,100/19,388 = an increase of 91%.()
  15. p.16, C.2.1, https://report.ipcc.ch/sr15/pdf/sr15_spm_final.pdf()
  16. chart 3 in Part 1()
  17. https://www.theguardian.com/environment/planet-oz/2017/may/09/planet-could-breach-15c-warming-limit-within-10-years-but-be-aware-of-caveats()
  18. https://en.wikipedia.org/wiki/2015_United_Nations_Climate_Change_Conference#/media/File:COP21_participants_-30_Nov_2015(23430273715).jpg()
  19. http://www.columbia.edu/~jeh1/mailings/2018/20181206_Nutshell.pdf()
  20. IPCC, 2018: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. In Press.()()()()()
  21. Territorial emissions in 1979 = 85MtCO2, 1984 = 57MtCO2(ref: http://www.globalcarbonatlas.org/en/CO2-emissions), (57 – 85)/(1984 – 1979) = -5.6%/yr of original amount.()
  22. http://www.globalcarbonproject.org/carbonbudget/18/presentation.htm()
  23. Boden, T. A., Marland, G., and Andres, R. J.: Global, Regional, and National Fossil-Fuel CO2 Emissions, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A., doi 10.3334/CDIAC/00001_V2017, 2017; available at: http://cdiac.ess-dive.lbl.gov/trends/emis/overview_2014.html()()()
  24. In 1984 France emitted 407MtCO2 and the World 19,217 MtCO2 (refer http://www.globalcarbonatlas.org/en/CO2-emissions), 407/19217 = 2.1%()
  25. In 1981 Sweden emitted 69MtCO2 and the World 18,787MtCO2, 69/18787 = 0.4%()
  26. In 1992 Russia emitted 1,993MtCO2 and the World 22,195MtCO2, 1,993/22,195 = 9%()
  27. https://en.wikipedia.org/wiki/Dissolution_of_the_Soviet_Union()
  28. p. 2A-28, Table 2.SM.12, Huppmann, D., Kriegler, E. and Mundaca, L., 2. SM Mitigation pathways compatible with 1.5 C in the context of sustainable development–Supplementary Material()()()()
  29. WMO Statement on the State of the Global Climate in 2017()
  30. Luderer, G., Vrontisi, Z., Bertram, C., Edelenbosch, O.Y., Pietzcker, R.C., Rogelj, J., De Boer, H.S., Drouet, L., Emmerling, J., Fricko, O. and Fujimori, S., 2018. Residual fossil CO 2 emissions in 1.5–2° C pathways. Nature Climate Change8(7), p.626.()
  31. Rockström, J. et al. (2016), The world’s biggest gamble, Earth’s Future, 4, 465 – 470, doi:10.1002/2016EF000392.()()
  32. On average over 2008 – 2017, emissions from fossil fuels and industry were 34.4GtCO2/yr and from land use change 5.3GtCO2/yr, (1.9 / (34.4 + 5.3) = 4.7%) ()
  33. https://www.globalcarbonproject.org/carbonbudget/18/presentation.htm()()
  34. https://www.washingtonpost.com/national/health-science/carbon-removal-is-now-a-thing-radical-fixes-get-a-boost-at-climate-talks/2018/12/11/d22efd40-fd01-11e8-83c0-b06139e540e5_story.html?utm_term=.1aac8acdcff4()
  35. http://www.columbia.edu/~jeh1/hansencv_201804.pdf()
  36. http://www.columbia.edu/~jeh1/publications.shtml()
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