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.

      *         *         *         *     *

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

 

 

President Obama’s Clean Power Plan to Reduce Emissions

The Administration’s Clean Power Plan will significantly reduce greenhouse gas emissions from the electric power industry over the next fifteen years.

 

Global warming affects all humankind.  Changing weather patterns, consisting of greater and more frequent weather extremes have become more and more common in recent years and decades.  Around the world, extreme rains and floods, droughts and unprecedented sea level rise have occurred in ways that we are now accepting as being “new normals” of weather which humanity did not experience in earlier years.  While we cannot point to individual events as being caused by global warming, the frequency of occurrence and patterns around the world are all consistent with the predictions that global warming will worsen extremes of weather and climate going forward.  The warming arises because of humanity’s burning of fossil fuels for energy as well as from other human activities, not from any natural cycling of climate patterns.

Relative effectiveness of fossil fuels.  Carbon dioxide (CO₂) is the principal greenhouse gas contributing to global warming.  The fossil fuels used to produce energy yield different amounts of heat per weight of CO₂ resulting from combustion.  This is a consequence of the intrinsic chemical properties of each fuel, and cannot be changed by engineering or ingenuity.  These differences are shown in this table: 

           Relative Emission Efficiency of Fuels  

Fuel	Relative amount of CO2 released per unit of heat obtained, compared to natural gas
Natural gas	1.00
Petroleum (fuel oil,  gasoline)	1.55-1.61
Coal	2.00-2.03

                     Source: https://en.wikipedia.org/wiki/Heat_of_combustion

The table shows that burning coal produces twice as much CO₂ as does natural gas when burned for energy.  (Other references give slightly different numbers without affecting this overall conclusion.)  In other words, use of coal as a fuel, say, for generating electricity, releases twice as much CO₂ into the atmosphere as does burning natural gas to obtain the same amount of heat, i.e., to generate the same amount of electricity.  If humankind is concerned about minimizing the worsening of global warming, we would benefit greatly by reducing the use of all fossil fuels, and especially coal.
 

Coal demands of electric generation.  A typical coal-fired electricity generating plant has a power capacity in the megawatt (MW) range.  To have this capacity, it burns large amounts of coal.  The largest coal-fired plant in the U. S. is the Robert W. Scherer Power Plant in Juliette, Georgia .  When operating to capacity, the facility burns almost 1,300 tons of coal every hour, or 11 million tons a year.  The coal used at Scherer comes from the Powder River Basin in Wyoming.  It is transported by train to the plant, a trip of 1,800 miles.  The coal arrives in trains 124 cars long; such a train can reach as long as two miles in length.  A picture of a coal train is shown here.

     http://tcktcktck.org/2014/02/coal-train-photo/

The Scherer facility consumes 3-5 such trainloads of coal every day.  When burned, this coal yields 27 million tons of carbon dioxide annually.  The facility has four separate generating units, each with a capacity of 880 MW.   So smaller facilities might use perhaps one-quarter, or one-half, for example, of the amount of coal that the Scherer plant uses. Overall, the U. S. has about 1,000 fossil fuel-fired generating plants, and, since many plants have more than one generator, a total of about 3,100 generating units that fall under the CPP.
 

The U. S. Clean Power Plan.  President Obama heralded the release of the Final Rule for the Administration’s Clean Power Plan (CPP) on August 3, 2015.  The proposed rule was released over one year earlier and is described here.  The CPP addresses greenhouse gas emissions, primarily CO₂, produced by electricity generation in the U. S.  Emissions from this sector of the energy economy are a main component of overall greenhouse gas emissions in the U. S.
 

Over 4.3 million comments from stakeholders and the public on the proposed rule were received by the Environmental Protection Agency (EPA), many of whose considerations were incorporated in the Final Rule. 
 

The CPP’s goal is to reduce emissions from electricity generation by 32% below the levels of 2005 by the year 2030.  Importantly, the plan does not dictate how these goals are to be met.  Rather, it recognizes that the features of each state’s generation infrastructure differ from one another.  As a result, the specific reduction goal for each state has been assigned differently to account for these distinctions.  In addition, each state is given the responsibility of devising its own specific plan for attaining its particular reduction goal.  Among the general paths to reducing emissions, the CPP names retrofitting existing power plants, eliminating noncompliant power plants, and installing renewable energy facilities.   Additionally, states can trade emission allowances among themselves to help attain their objectives.
 

Opposition to CPP.  Legislative and industrial opponents of the CPP began expressing their concerns as soon as the Final Rule was issued.  Here are some arguments being presented.
 

The CPP is illegal or even unconstitutional.  The Supreme Court, in Massachusetts v. Environmental Protection Agency and others (2007) interpreted the Clean Air Act, originally passed in 1970, as including the authority to regulate CO₂ as an atmospheric pollutant if EPA found it to endanger the welfare of American citizens.  Following up on the Supreme Court’s decision, EPA did subsequently find that the gas threatens the health and welfare of Americans, and of our environment, in 2009.  As a result of this finding, EPA has the legal authority to regulate CO₂ emissions.
 

To the knowledge of this writer the question of the constitutionality of this rulemaking power is not being considered by the courts at this time.
 

Opponents have called the CPP a “War on Coal”.  In doing so they seek to place the burden of reorganization of the electricity generating industry on President Obama and his administration.  Use of coal in generating electricity has been declining for more than a decade, as has been the number of working coal miners.  A graphic representing the decreasing use of coal is shown here:

Comparison of the use of coal (blue bars) and natural gas (red bars) from 2002 to 2012. 
Source: http://www.energytrendsinsider.com/wp-content/uploads/2013/03/nat-gas-takes-market-share-coal.jpg?00cfb7

 

The graphic shows that the percent share of use of coal in electricity generation has been declining since well before President Obama took office in January 2009.  Perhaps opponents may wish to call this finding “Bush’s War on Coal” (not appropriate) or “Capitalism’s War on Coal”.  In fact the principal factor underlying the diminishing role of coal, and the increasing percent share of use of natural gas, is the growing availability of gas in the U. S. due to the increased use of hydraulic fracturing to produce it.  This has resulted in higher gas production and a lowering of its cost.  The increased availability of natural gas began during the administration of President George W. Bush. 
 

In spite of the increasing layoffs among Appalachian coal miners, the Congressional delegations from these areas appear not have their interests high on their agendas.  Only Rep. David McKinley, Republican of West Virginia, teaming with Rep. Peter Welch, Democrat of Vermont (not a coal mining state), offered a bill for assistance to miners, in Sept. 2014.  Additional searching does not show that this initiative progressed further in Congress.  President Obama’s administration, however, granted $7.5 million in June 2014 to Eastern Kentucky Concentrated Employment Program Inc. to help retrain out-of-work Kentucky miners.   This action is not consistent with a supposed Administration “War on Coal”.

Clearly market forces expected in a capitalist economy are responsible for the declining share in the use of coal.  The CPP does not institutionalize a “War on Coal”, but in view of the profoundly higher rate of emission of CO₂ resulting from its use (see above), the Plan is likely to lead to further reductions in coal use.
 

The CPP will produce only an insignificant decrease in global emissions.  This writer heard this argument expressed on the National Public Radio program “Here & Now” on August 4, 2015.  Such statements are not supported by the facts.  The U. S. is a major global emitter of greenhouse gases, and the CPP alone has the potential of reducing U. S. emissions by almost 10%.  In addition, representatives from all United Nations members are convening in December 2015 to finalize a global agreement to limit greenhouse gas emissions from all members.  A rigorous stand by the U. S. at the domestic level will enhance its ability to obtain meaningful reductions from other nations.  This is a very important factor going forward.

Conclusions
 

Coal is a major fossil fuel used in electric power generation, but results in twice the greenhouse gas emissions per amount of heat generated than the other major fossil fuel, natural gas.  The Obama administration has issued its CPP which would reduce emissions by 32% below 2005 levels by 2030.  This is a significant emission reduction program.  Coupled with the Administration’s regulation to increase transportation fuel efficiency by almost a factor of two by 2025 it will have a major effect on the energy economy of the U. S.

© 2015 Henry Auer