What, Again? Greenhouse Gases Accumulate in the Atmosphere

Summary: This post tabulates important findings from the six Assessment Reports (ARs) that the United Nations Intergovernmental Panel on Climate Change (IPCC) has released since 1990.  As shown here, climate scientists have recognized, as of the date of each AR, that a) man-made GHGs continue to be emitted and accumulate further in the atmosphere, b) predicted emissions risk accumulating climatically dangerous levels of GHGs, and c) principles are proposed to minimize further emissions so as to keep accumulated GHG levels to as low a level as possible.

 Here attention is restricted to three topics, a historical review of accumulated atmospheric GHGs, projections of future emission rates and accumulated totals, and ways to stabilize accumulated atmospheric GHGs. Coming posts will consider other aspects of climate, presented over the three decades that ARs have been issued, resulting from the projected accumulated GHG levels.

Some may feel this and the coming posts sound like broken records; they may suffer from “climate fatigue”.  Humanity, however, has not responded to the worsening climate documented in the AR series. The critical, dire climate projections summarized here should provide powerful incentives to take meaningful action at this time.

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The United Nations Intergovernmental Panel on Climate Change (IPCC) released the first of three volumes of its Sixth Assessment Report (AR6) in August 2021.  ARs have been issued at intervals of 6-7 years since 1990. They document the history of the annual rate of global GHG emissions, due to human activity, of the principal greenhouse gases (GHGs) and of the total amount of GHGs accumulated in the atmosphere since the industrial revolution (Ind. Rev.) began.  Using climate models and a range of scenarios of GHG emission rates they present projections for each scenario of future climate characteristics to the end of this century.  They also discuss general principles (but not specific policies) for limiting future emission rates.

The general results and projections presented in ARs 1-6 are broadly consistent with each other across the AR series.  They record the profound increase, due to human activity, in accumulated atmospheric GHGs across the years, emphasizing the results for the most significant GHG, carbon dioxide (CO₂).  Accumulated CO₂ is shown in the graphic below, adapted here by adding vertical lines for the years in which the various ARs were released, as well as the additional red line corresponding to the date of the Paris Climate

Direct measurements of atmospheric carbon dioxide (smoothed over the 12 months of a year) taken atop the Mauna Loa volcano in Hawaii beginning in 1958.  The base level prior to the Ind. Rev. is 280 ppm.  Ppm, parts of carbon dioxide in 1 million parts of air. The vertical lines represent the dates of issue of the respective Assessment Report (AR), and the date of the Paris Agreement.

 

Agreement of 2015.  The principal goal of the Paris Agreement is to reduce emissions sufficiently to keep the increase in the global average temperature to below 2.0°C (3.8°F), and preferably 1.5°C (2.7°F) by 2100.  It is seen in the graphic that there is a consistent increase in CO₂ emission rate beginning with the first measurements in 1958 and continuing throughout the three decades following AR1. 

The topics selected for this post are tabulated below in the Details section.  The authors of AR1 recognized already in 1990 that atmospheric accumulation of man-made GHGs was increasing.  As the graphic above and the entries for the successive ARs in the table show, the growth in accumulated levels continued unabated up to the present (AR6).  Furthermore, projected future trends for various emission scenarios were generally comparable throughout the series.  Finally, the need to reduce annual emissions was recognized from the beginning and reiterated, with increasing urgency, throughout the series.

 Whereas the need to reduce emissions begins in AR1 and extends up to the present in AR6, the strength of climate science underpinning those conclusions has increased dramatically.  For example this first of the three volumes of AR6 was compiled by 234 climate scientists chosen from among all the nations of the IPCC.  They reviewed over 14,000 research articles published since AR5.  The capabilities of gathering data and using more powerful computers to analyze them, and to develop more refined, detailed climate models, have all increased dramatically. 

 Drafts of the chapters in AR6 were reviewed by other scientists as well as by national governments.  We can feel assured that the final text represents scientific and political consensus views.

 Conclusion

In the table given below in the Details section the column “Actions to Stabilize Atmospheric GHGs” summarizes the increasing urgency of acting to reduce annual emission rates essentially to zero as the AR series progresses.  For AR1 and AR2 ambitious reduction goals were already stated, but planetary manifestations of the effects of global warming were not yet readily distinguishable.  By the time of AR6, 2021, extreme weather and climate events have become the subjects of frequent headlines, distributed across heat waves and droughts, famine, uncontrolled wildfires across the globe, intense precipitation events and flooding, and melting of glaciers and ice sheets leading to sea level rise.  Also, by AR6 the science of attribution of extreme climate events has progressed dramatically, and permits ascribing the severity, if not the actual occurrence or not, of events to the effects of global warming.

As noted in the Actions column of the table, early action could have been taken at moderate levels of effort and expense, to avert future, if not yet apparent, hazards.  Such opportunities were not seized.  By 2021 hazardous events are now current, requiring immediate action.  Necessarily these current actions must be far more aggressive, pervasive and expensive.  They also require fundamental and comprehensive changes in social and cultural approaches to the problem.

We must encourage our political, corporate and civic leaders to accept these challenges and overcome them without further delay.

 Details

This writer collated the entries in the following table from either the Summary for Policymakers, a “Headline” document or a press release, all issued by the IPCC in conjunction with each AR.  The entries are necessarily selective rather than comprehensive, and have been edited for brevity.

 

© 2021 Henry Auer

Global Greenhouse Gas Emissions Continue Increasing

Carbon dioxide (CO₂) emissions from sources all around the globe are estimated to be increasing at a renewed, distressingly rapid, rate for 2018 to date, 2.7% for the year, after having been determined to be lower, about 1.6% for the full year of 2017. This evaluation is part of a detailed accounting of all sources of CO₂ emissions and of planetary processes that remove CO₂ from the atmosphere.  The study is undertaken now an annual basis and reported in the “Global Carbon Budget 2018” (C. Le Quere and 70 coauthors, Earth Syst. Sci. Data, 10, 2141-2194, 2018).  The main sources of CO₂ emissions are use of fossil fuels (coal, oil and gas) and the manufacture of cement.  The two largest factors that remove CO₂ are absorption into the waters of the ocean, and plant and soil incorporation of CO₂.  The net balance between all emitting and absorbing factors leads to the increase in man-made atmospheric CO₂ that is the main concern when considering global warming.  The authors present the increasing trend of atmospheric CO₂ in the following graphic:

 

 

Direct measurement of atmospheric CO2 concentration from 1958 to 2018. This graphic represents the difference between man-made sources of CO2 in the atmosphere and its removal by natural earth processes. The authors’ analysis shows that humanity’s use of fossil fuels is a main contributor to increased CO2, and is a main contributor to global warming.
Source: C. Le Quere and coauthors, Earth Syst. Sci. Data, 10, 2141-2194 (2018)

 

 

Why is CO₂ emission such a problem?  This gas persists in the atmosphere for centuries, if not longer.  So the coal that was burned when the industrial revolution began produced CO₂ that is still part of the atmosphere today, and the aggregate amount of fossil fuels we consume at present produces CO₂ that will last for centuries.  The excess accumulation of CO₂ shown above cannot be removed economically on the massive scale needed with currently existing technology: the annual growth of atmospheric in 2017 was 4.6±0.2 billion metric tons measured as carbon/yr (or 16.8 billion metric tons measured as CO₂/yr).

The increased heat-trapping ability of the additional atmospheric CO₂ has alarmed scientists in the past couple of months.  They have issued two dramatic calls to action by the nations of the world (here and here) urging humanity to limit the overall rise in the long-term global average temperature to less than 1.5°C (2.7°F) by 2040 or 2050.  Voluntary national commitments were made by the members of the United Nations to reduce annual emission rates when the Paris Agreement was reached in 2015.  Even at that time, analysis of the commitments recognized that they were seriously insufficient to accomplish the limitation needed.  And in the succeeding three years, even those commitments have not been met.  This is made worse by President Trump’s intention for the U. S. to leave the Paris Agreement; the U. S. remains one of the three top annual emitters of CO₂ in the world and its emissions would increase under the president’s policy.

Global warming depends on the total accumulated greenhouse gases (GHGs), not the annual emissions rate.  The heat-trapping effect of GHGs depends on their total accumulated amount in the atmosphere.  A goal of simply reducing the annual emission rate does not replace the need to stabilize the total accumulated amount as soon as possible at as low a level as possible.  As long as the emission rate is above zero, GHGs continue accumulating in the atmosphere, thereby raising the long-term global average temperature.  Only achieving zero GHG emission rates as fast as possible stabilizes the total GHG burden at the low level needed.  

This is shown in the model image below.  It assumes that we start at a value of 100 for the atmospheric GHG level.  From year 0 to year 10 the annual emission rate, shown in blue, is 4% of the amount of the previous year (in the image the rate is multiplied by 25 to scale it to 100).  Over this period the cumulative GHG amount, shown in orange, rises by the 4% amount based on the previous year’s level, resulting in a line curving upward: 

 

 

Magically, after year 10 all net atmospheric emission rates fall to zero (blue) – including those originating from electricity generation, transportation, heating and cooling, and cement manufacture. No new GHGs are added to the atmosphere.  As a result, the total accumulated GHG burden (orange) flattens out, stabilized at the year 10 level.  It’s important to note that reducing the annual emission rate to zero cannot lead to a reduction in the total atmospheric GHG level.  This idealized model illustrates the important fact that the sooner annual emission rates approach zero, the lower the stabilized GHG level will be, with the result that the long-term global average temperature likewise will stabilize at a lower value.

 

The relationship between the accumulated GHG level and the  global average temperature.  The Fifth Assessment Report of the Intergovernmental Panel on Climate Change, issued in 2013-2014, modeled the relationship between total accumulated CO₂ in the atmosphere and modeled temperature increases (referred to the value during the early industrial revolution (1861-1880)).  The modeling included four “scenarios”, ranging from the most stringent (zero annual emission rate after 2030-2040; shown in navy blue in the image below), to a “business as usual” scenario (no meaningful policy to reduce emission rates; shown in red below).

 

Historical (black; 1870-2010) and modeled (2010-2100) temperatures (°C) projected for four “scenarios” of differing trends for man-made CO₂ concentrations with greatest to essentially no limitations on annual emission rates.  Data point dots are given every 10 years.  The most stringent (navy blue) falls to a near zero emission rate by 2030-2040; the light blue and orange lines are progressively less stringent, and the red line models the absence of meaningful constraints on emission rates.

 

 

Three important conclusions emerge from the modeling shown.  First, the amount of CO₂ in the atmosphere at any point along the horizontal axis does not depend on the scenario, that is, it is independent of the annual emission rate.  Second, all four scenarios follow more or less the same path along the CO₂-temperature relationship.  This dependence is nearly a linear one: the higher the CO₂ level in the atmosphere, the higher the projected temperature.  Indeed, the most stringent scenario (navy blue) shows no significant increase in CO₂ level between 2050 and 2100 (those points are all bunched together in the image) and consequently no further increase in projected temperature in those decades.  This projection mirrors the results in the model image shown further above.  Conversely, the unconstrained scenario (red) continues to emit CO₂ to 2100, leading to a drastic temperature increase of more than 4.5°C (8.1°F) by the end of the century, a truly frightening possibility.
 
Third, bringing annual emission rates to near zero does not reduce the accumulated CO₂ level after reaching a plateau, nor does this lower the projected global average temperature.  It only keeps the CO₂ level and the temperature stabilized.  

Many countries in the world are not fulfilling the pledges they made under the Paris Agreement.  The New York Times reports,  based on the most recent evaluation by the International Energy Agency, that major emitting countries around the world, including China and India, are continuing to build new coal-fired electricity plants instead of migrating to renewable energy on the scale needed. In fact, China and Japan are exporting them, building new coal plants in many developing countries.  The United States is reneging on its emissions-reducing policies put in place under former President Obama, and is opening federal lands to new fossil fuel extracting leases.  France is showing how difficult  the political scene is for pursuing policies to address global warming; rioting citizens are opposing a small, scheduled increase in taxes on vehicle fuels.

Conclusion 

This post demonstrates that continuing to emit GHGs at high annual rates inexorably adds to higher CO₂ levels in the atmosphere, which leads to higher long-term global average temperatures in a straight-line fashion.  Currently there are no technologies ready to be deployed at scale to remove CO₂ from emitting facilities or from the air, and permanently to store it away from the atmosphere.  Only reducing annual emission rates to near zero in the coming two decades, according to the two reports cited at the outset, (some advocate an even shorter schedule) will keep the world from entering a regime of unacceptably high global average temperatures.  All stakeholders need to coalesce around this objective to achieve this goal. 

© 2018 Henry Auer

 

 

Tallying Cumulative Greenhouse Gas Emissions by Fossil Fuel Producers

Summary.  In a recent article Richard Heede has analyzed the accumulated emissions of the greenhouse gases carbon dioxide and natural gas from the beginning of the industrial revolution to the present.  He consulted a wide array of information available to the public to provide a cumulative accounting of total emissions of these gases by the emitting entities (rather than by country or region) using records beginning about 1850.

After establishing a cut-off, 90 entities, accounting for 63% of the world’s accumulated emissions over this period, qualified for tallying.  This post provides tabulated data for the top 20 entities; of these the first five are Chevron, ExxonMobil, Saudi Aramco, BP and Gazprom.

This analysis, based on the emitting entity, represents a departure from commonly used analyses of global greenhouse gas emissions.  Importantly the analysis finds that a significant number of emitting entities are based in developing countries.  This conclusion suggests that the earlier insistence by the developing countries that they be spared from requirements to limit emissions are, at least by 2010 if not before, no longer appropriate for their economic status.  Global warming is clearly a worldwide problem, requiring global approaches to combat its effects.

Introduction. It is a daunting task to track the sources of atmospheric carbon dioxide and methane, two major greenhouse gases, globally from the early days of the industrial revolution to the present.  The additional accumulation of these gases in the atmosphere originates from mankind’s extraction and burning of fossil fuels.  Richard Heede, of the Climate Accountability Institute, has done just that in his recent article “Tracing anthropogenic carbon dioxide and methane [natural gas, CH₄)] emissions to fossil fuel and cement producers, 1854–2010” (Climatic Change (2014) 122:229–241;  doi:10.1007/s10584-013-0986-y; or pdf version).  Climatic Change publishes original research papers after having been rigorously evaluated by independent, anonymous reviewers.

Heede accessed information and records that are publicly available (see Details, Methods, at the end of this post) to find the total amount of fossil fuels (oil, natural gas and coal) extracted from the earth over the period analyzed.  Using the chemistry involved in burning these fuels to carbon dioxide (CO₂) he calculated the resulting emissions.  In addition, carbon dioxide arising from converting limestone to cement is included in his accounting.  Furthermore Heede evaluated the amount of “fugitive” methane, a greenhouse gas about 20-30 more potent than CO₂, originating from other fossil fuel operations.

Results.  Heede has found that the annual rate of global emissions originating from fossil fuels has increased dramatically since the industrial revolution began, as of course has their accumulated totals.  Annual emission rates are shown in the graphic below

Annual rates of emission of CO₂ and methane (as CO₂-equivalents) worldwide, and those originating from the Carbon Majors, in millions of tonnes of CO₂-equivalents (MtCO₂/y).
Source: Heede, (Climatic Change (2014); http://download.springer.com/static/pdf/371/art%253A10.1007%252Fs10584-013-0986-y.pdf?auth66=1389756523_ec1069a48cb76c044189eb5109b5c131&ext=.pdf ).

 

for all industrial sources of CO₂ and for methane worldwide (black curve), and for the 90 entities he tracked in detail, called the “Carbon Majors” (red curve), for the period 1850-2010.  The worldwide annual emission rates grew dramatically, on a relative basis, between about 1860 and 1910, again from about 1945 to about 1975, and is currently undergoing the sharpest rise yet starting at about 2000.  Emission rates for the Carbon Majors mirror the trends seen for total global emissions after about 1930.

Heede cites data from the U.S. Department of Energy’s Oak Ridge National Laboratory Carbon Dioxide Information Analysis Center (CDIAC) for providing an estimate for cumulative industrial CO₂ emissions since 1751 of 1,336 GtCO₂ (1,336,000 MtCO₂ (Gt, gigatonnes; Mt, megatonnes); Heede, Online Supplementary Material (Climatic Change (2014)).  Over much of that interval, up to 1930, the cumulative emissions total remained only 10.4% of the total to 2010.  In other words, almost 90% of total worldwide emissions to 2010 have occurred in the 80 years following 1930.

The cumulative, i.e., total historic, global emissions of CO₂ and methane from the 90 Carbon Majors is 63% of the total from 1750-2010; the remainder includes emissions from other, smaller entities not tracked and entities that no longer exist (Heede, Online Supplementary Material (Climatic Change (2014)).

Data for the 20 highest-emitting entities are tabulated below in Details, Cumulative emissions of carbon dioxide and methane.  The five entities with the highest cumulative emissions, as a percent of the total accumulated since 1750 are:

Chevron (USA):                          3.52%

ExxonMobil (USA):                      3.22%

Saudi Aramco (Saudi Arabia)       3.17%

BP (United Kingdom)                  2.47%

Gazprom (Russian Federation)    2.22%

These five alone represent 14.6% of the total historic emissions.  It is noteworthy that even in this upper echelon of historical emitters, entities from four nations are represented, including two that are from the developing world rather than from among industrialized nations.

Discussion

Heede has performed a valuable service in this work by assessing historical emissions of major greenhouse gases according to the emitting entity instead of by region or extent of economic development.  He points out that this finding is not consistent with the early emphasis in deliberations of the United Nations leading to the Kyoto Protocol that the developing countries of the world should be absolved from constraints on emission rates.

Climate scientists agree almost unanimously that man-made emissions of greenhouse gases have led to more, and more severe, extreme weather and climate events in recent decades.  Since CO₂, an important greenhouse gas, remains indefinitely in the atmosphere and cannot be removed, the present pace of occurrence of climate extremes cannot be reversed.  As emissions continue to grow, global warming will only worsen, increasing climate extremes even more.  Projections of future warming and the harms expected as a result are given in the recent Fifth Assessment Report of the Intergovernmental Panel on Climate Change issued September 2013.  For example, projections for 2046-2065 and for 2080-2100 are tabulated below, for global average temperature and sea level rise, for four emissions scenarios of increasing severity (going from RCP 2.6 to RCP 8.5). 

 

Changes in global mean surface temperature in ºC (top) and global mean sea level rise in m (bottom) for the two time periods shown, referenced to the period 1986-2005.  The “likely range” gives confidence limits for a 5%-95% interval.

For temperature, corresponding values for ºF are exemplified as 1ºC =1.8ºF, 2.0ºC = 3.6ºF, and 3.7ºC = 6.7ºF.

For sea level, corresponding values for feet are exemplified as 0.24 m = 0.79 ft, 0.30 m = 1.0 ft, 0.40 m = 1.3 ft, and 0.63 m = 2.1 ft.

Source: IPCC 5AR Summary for Policymakers; http://www.climatechange2013.org/images/uploads/WGIAR5-SPM_Approved27Sep2013.pdf.

 

RCP 2.6 corresponds to a scenario in which emissions fall to zero in a few decades, while RCP 8.5 corresponds to continued expansion of the energy economy with no meaningful constraints on emissions.  Currently there is no worldwide agreement to constrain emissions.  Certain regions or jurisdictions in the world, representing a small fraction of the global emission rate, have constraining policies in place and are in the early stages of implementing them.  Considered planet-wide, therefore, the current status of the energy economy is one whose emissions are largely unconstrained.

Heede’s identification of the 90 highest-emitting entities around the globe provides useful information as we consider ways to address abatement of emissions.  His approach departs from the historical focus on nations and regional associations of nations.  Global warming is truly a global problem, requiring global approaches to mitigating emissions and developing adaptive measures to allay its effects.

Details

 

Methods. Heede evaluated records from all entities presently emitting 8 million tonnes of carbon (29 million tonnes of CO₂ equivalent) or more per year.  This provided a total of 90 entities, grouped into 50 investor-owned companies, 31 state-owned companies and 9 current or former national agencies.  56 of the entities produce crude oil and natural gas, 37 mine coal, and 7 produce cement (for which only data after 1990 were used).

Information was gathered from corporate annual reports, company websiotes, information filed with government agencies such as the U. S. Securities and Exchange Commission, and company histories.  Carbon content of the extracted fuels was evaluated according to equivalencies established by agencies such as the Intergovernmental Panel on Climate Change, the International Energy Agency, and the U. S. Environmental Protection Agency.  This is especially important for coal, whose carbon content can vary significantly according to its type (anthracite or bituminous) and carbon purity.  Account was made not to include non-energy uses (i.e. industrial uses other than combustion for energy).  Usable information could be obtained as far back as 1854.  This history accounts for changes in corporate identities, including mergers and divestments.  It is believed that double-counting of emissions due to overlapping record sources has been minimized.

The resulting data for all 90 entities is linked for review as “Electronic supplementary material” near the end of the online version of Heede’s article .

Cumulative emissions of carbon dioxide and methane. 

The highest twenty investor- and state-owned entities and their attributed CO₂ and CH₄ emissions.

Rank	Entity, nation	Cumulative emissions 1854–2010, MtCO2e	Percent of global emissions, 1751–2010	2010 emissions, MtCO2e
1	Chevron, USA	51,096	3.52 %	423
2	ExxonMobil, USA	46,672	3.22 %	655
3	Saudi Aramco, Saudi Arabia	46,033	3.17 %	1,550
4	BP, United Kingdom	35,837	2.47 %	554
5	Gazprom, Russian Federation	32,136	2.22 %	1,371
6	Royal Dutch/Shell, Netherlands	30,751	2.12 %	478
7	National Iranian Oil Company	29,084	2.01 %	867
8	Pemex, Mexico	20,025	1.38 %	602
9	ConocoPhil-lips, USA	16,866	1.16 %	359
10	Petroleos de Venezuela	16,157	1.11 %	485
11	Coal India	15,493	1.07 %	830
12	Peabody Energy, USA	12,432	0.86 %	519
13	Total, France	11,911	0.82 %	398
14	PetroChina, China	10,564	0.73 %	614
15	Kuwait Petroleum Corp.	10,503	0.73 %	323
16	Abu Dhabi NOC, UAE	9,672	0.67 %	387
17	Sonatrach, Algeria	9,263	0.64 %	386
18	Consol Energy, Inc., USA	9,096	0.63 %	160
19	BHP-Billiton, Australia	7,606	0.52 %	320
20	Anglo American, United Kingdom	7,242	0.50 %	242
	Sum of Top 20 IOCs & SOEs	428,439	29.54 %	11,523
	Total 90 carbon majors	914,251	63.04 %	27,946
	Total global emissions	1,450,332	100.00 %	36,026

Please note that the data in columns 3 and 4 cover different time periods.  The fourth column compares each entity’s cumulative emissions to the Carbon Dioxide Information Analysis Center’s database of global emissions 1751–2010. This table excludes British Coal, whose production and assets have not been attributed to extant companies, and also excludes five of nine nation-states (the Former Soviet Union, China, Poland, Russian Federation, and Czechoslovakia). MtCO₂e, million tonnes of CO₂-equivalents emitted.

Peabody Energy is the world’s largest private-sector coal company (http://www.peabodyenergy.com/).

Abu Dhabi NOC, Abu Dhabi National Oil Company.

IOC, investor-owned company.

SOE, state-owned entity.

Source: Heede, (Climatic Change (2014);

http://download.springer.com/static/pdf/371/art%253A10.1007%252Fs10584-013-0986-y.pdf?auth66=1389756523_ec1069a48cb76c044189eb5109b5c131&ext=.pdf ).

© 2014 Henry Auer