We All Feel the Increasing Impacts of Global Warming

Summary: All over the world unprecedented weather extremes are occurring, with profound effects on human activities and health.  This post reports some recent climate events.  These instances are consistent with the forecasts that climate scientists have been making for several decades.  The IPCC issued a new, more urgent report in October 2018 specifying that we have to keep the world temperature increase below 1.5°C above pre-industrial levels, primarily by eliminating all emissions worldwide in about two decades.

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Tidal flooding, Eastern U. S.  Many cities along the Eastern seacoast of the U. S. already suffer fair-weather tidal flooding due to rising sea levels.  According to the U. S. National Oceanic and Atmospheric Administration (NOAA) as reported by National Public Radio (NPR), tidal flooding is worsening in more than 40 U. S. coastal cities.  Most of these flood days are not related to storm activity, but rather to rising sea level.  Tides are worst, i.e., highest, when the moon is full or new.  This image

Source: NPR All Things Considered https://www.npr.org/programs/all-things-considered/2019/07/10/740176584

 

shows downtown Annapolis, MD, founded three centuries ago on the shores of Chesapeake Bay, flooded during a high tide in 2017.  As NPR reports, NOAA finds that tidal flooding events in Annapolis have increased by 925% over the last 50 years.  The city is planning a Flood Mitigation Project in conjunction with many agencies including the U. S. Naval Academy, which is located in Annapolis.

Charleston, SC is also suffering from worsening ocean flooding (NPR).  The city is built on a low-lying peninsula, exposed to the sea.  In addition, in recent years flooding has been aggravated by extreme rainfall.  Both of these factors result from worsening global warming.  The city issues flood warnings as frequently as weekly during the summer.  Its officials now understand they must plan for 2-3 feet (0.6-0.9 m) of flooding over the next 50 years.

Temperatures for January-May 2019 for most regions around the globe are warmer than average or set warmest records, whereas only a very few regions were cooler than average (see the following image).

Source: NOAA National Centers for Environmental Information, State of the Climate: Global Climate Report for May 2019, published online June 2019, retrieved on July 10, 2019; https://www.ncdc.noaa.gov/sotc/global/201905 .

The average is for the 30-year reference period from 1981-2010.  It is seen that for the vast majority of global surface pixels the 5-month averages were mildly or much warmer than the 30-year reference period.  In an accompanying graphic NOAA shows land and ocean temperature departures from the 30 year reference period for the January-May interval annually from 1880 to the present (not shown).  Starting about 1976 the departures are all only positive, trending up to 0.8-1.1°C (1.4-2.1°F) above the average between 2015 and 2019.  The full 139-year record shows clearly that, although there are year-to-year variations, the long-term trend in the 5-month global average temperature has been gradually increasing by about 1.3°C (2.3°F) starting at about 1910.

Global warming has been determined to have caused two current climate extremes.  First, a severe heat wave blanketed much of western Europe during the end of June 2019.  It broke heat records across much of the area.  A group of experts in the field of climate attribution examined the temperature data in two ways, as described in a commentary in the journal Nature. 

Attribution science has made great strides in recent years.  In this case, the scientists examined the heat wave in two ways.  First, they compared the actual temperature record with results from climate models for the European region, running cases that included or excluded a man-made greenhouse effect.  They found that the record heat was five times more likely with extra greenhouse gases than without.  Second, they assessed whether historical records going back 100 years are consistent with the actual heat wave data when climate models are used to “hindcast” the data.  They found that global warming and air pollution made the current heat wave 100 times more likely than without those factors. 

More generally, the commentary summarizes that about two-thirds of the 200 attribution inquiries reported to date have positively identified global warming as making the particular event being studied more likely or more severe than without warming.

Second, a report from India describes “Zero Day, the day when a city’s taps dry out and people have to stand in line to collect a daily quota of water.”  This is currently happening in many Indian states because aquifers are being over-drawn and this year’s monsoon rains were 30% less abundant than usual.  The image below exemplifies the disaster:

Women in Rajasthan, India walk long distances to collect drinking water.

Source: Nature India, https://www.natureasia.com/en/nindia/article/10.1038/nindia.2019.84?WT.ec_id=NINDIA-20190710&sap-outbound-id=124373C6B945724353776A88CBC27CF245889A7F&mkt-key=005056B0331B1ED888DF526EE5C22187.

Zero Day has already occurred in the city of Chennai, and is predicted to happen next year in many cities, including the capital, Delhi.  In all 600 million people may be impacted.  Groundwater is the source for most of India’s rural inhabitants and for its agriculture.  The Ministry of Drinking Water and Sanitation states that global warming is one factor contributing to this crisis.

 

Analysis

 

The Paris Agreement of December 2015 pledged 193 members of the United Nations voluntarily to reduce greenhouse gas emission rates sufficiently to keep the planet below a 2°C rise above pre-industrial levels by 2100.  But the Agreement is failing; the rate of emissions is still increasing, raising the total accumulated greenhouse gas burden of the atmosphere.  As a result, the IPCC issued a new, more drastic report in October 2018 specifying that we have to keep that temperature increase below 1.5°C, and to reach a worldwide reduction of emission rates to zero by about 2040, or 21 years from now. 

Failing to achieve this goal will lead to more intense warming, and will contribute to more rapid sea level rise, impacting coastal cities around the world, as discussed above.  It will also contribute to the more intense extremes of heat, such as Europe has experienced, as well as more extreme heat and aridity such as India is experiencing.

The economic harm alone is problematic, since in general our political structures don’t budget for funds to revive the losses, and insurance may be inadequate or nonexistent.  All people of the world have to mobilize individually and politically to eliminate fossil fuel use and develop a renewable energy economy to achieve the goal of zero emissions.

© 2019 Henry Auer

Removing Carbon Dioxide from the Atmosphere

In October 2018 the Intergovernmental Panel on Climate Change (IPCC) issued a Special Report updating the occurrence of weather and climate extremes since 2014.  It compared the effects of an increase in the long-term global average temperature of 2°C (3.6°F) with that of a 1.5°C (2.7°F) increase, referenced to the pre-industrial climate, on humanity and the natural world.  Its conclusions emphasized the necessity of limiting warming to the more stringent goal of 1.5°C to avoid severe harms to our planet by later in this century.

In its models the Report used four climate scenarios.  All the scenarios admit that global emission rates, to greater or lesser extents, will not be reduced adequately, or fast enough, to limit the temperature increase without deployment of technologies to remove carbon dioxide (CO₂), a principal greenhouse gas, from the atmosphere.  CO₂ results from humanity’s burning of fossil fuels.  CO₂ removal, also called “negative emissions”, would compensate for any failure to reduce direct emission rates of greenhouse gases from their original sources.  An example of one of the scenarios is shown here:

Net emission rates per year throughout the remainder of the 21^st century (Blue line), representing the result of the following contributions.  Grey shading , annual CO₂ emission rates from burning fossil fuels; Brown shading , annual CO₂ emission rates or reductions from agriculture and forestry;  Gold shading , annual CO₂ reduction rates from bioenergy with carbon capture and storage.

Source: IPCC Special Report, Summary for Policymakers https://www.ipcc.ch/site/assets/uploads/sites/2/2018/07/SR15_SPM_High_Res.pdf

 

Large scale CO₂ removal is considered in an article by Lu and coworkers, entitled “Gasification of coal and biomass as a net carbon-negative power source for environment-friendly electricity generation in China”, released April 9, 2019 in Proceedings of theNational Academy of Sciences.

 

As an aside, the importance of scrutiny of scientific reports by anonymous peer reviewers is brought out in this article, for the authors thank “…the reviewers for valuable and constructive suggestions. We are particularly grateful to one of the reviewers for her/his painstaking efforts to critique several versions of the manuscript and for questions raised that contributed to an important improvement in the final presentation.”  Peer review remains the gold standard for assessing the worthiness of scientific reports.

 

The authors recognize the wide availability of plant waste in China.  In Combination with the widespread use of coal already in place in the country, the authors model using various mixtures of agricultural Biomass with coal in an efficient technology for generating Electricity, coupled with use of process heat to drive CO₂ Capture and Storage (CBECCS).  The model extends over the long-term lifetime of such equipment. 

 

The authors find:

• Crop waste proportions greater than 35% mixed with coal would yield net-zero emission of CO₂ evaluated over the service lifetime, moving toward significant levels of negative emissions as the crop waste proportion increases;
• The cost of generating electricity over the lifetime, including the equipment costs, is US$ 0.092/kwh (kilowatt-hour);
• As China moves toward a national policy of imposing a price on carbon in the near future, a cost of US$52/ton would render CBECCS competitive with China’s current pulverized coal power plants; and
• Conventional pollutants widely acknowledged to arise from coal-fired electricity generation and vehicle exhaust (oxides of sulfur, oxides of nitrogen, black soot and PM_2.5 aerosols (2.5-micrometer or smaller particles detrimental to human health)) are significantly reduced by CBECCS. Severe urban smog in China has been a major driver to curb use of fossil fuels because they produce high levels of these pollutants.  CBECCS would contribute significantly to improving public health in the country.

CBECCS is especially feasible in China at the scale needed because the country is endowed with a very large geological storage capacity for the CO₂ produced in the carbon capture and storage portion of the technology.  The model projects that only 0.036% of known geological formations suitable for storage would be needed each year; this capacity is widely distributed geographically across China.

The article lists barriers to implementing CBECCS technology at scale, including

• Deploying and integrating the many component advanced technologies to ensure smooth operation, and to extend it on a scale needed to make a significant contribution to reducing net emission rates;
• Implementing infrastructure to enable delivery of waste biomass to the CBECCS facilities at the scale and regularity needed; and
• Infrastructure and operating costs evaluated for CBECCS are more than double those for current coal generation. These costs can become competitive as China’s carbon pricing regime becomes operational as planned in 2020.

CO₂ Removal from the atmosphere (ambient air) in a pilot project in Canada.

The New York Times published a report on April 8, 2019 describing new technology for CO₂ removal from ambient air and preparing it for geological storage underground.  The company doing this work, Carbon Engineering, has attracted funding from oil companies Chevron and Occidental Petroleum, and the large Australian mining company BHP, as well as others.  Recently the company raised US$68 million.  The oil companies, sensitive to enterprise risk as renewable energy threatens to displace gasoline for transportation, are interested in carbon removal technologies such as being developed by Carbon Engineering as a way potentially to offset CO₂ emissions due to use of their products.  Fiona Wild, BHP’s vice president for sustainability and climate change states “This is about recognizing that climate change poses significant risk to all economic sectors.  Climate change is … a business risk that requires a business response.”  Similarly, Dieter Helm, professor of energy policy at Oxford University, says “If money is being spent on research and development to develop ways to sequester carbon, that is a good thing.”

A schematic flow diagram of Carbon Engineering’s technology is shown here:

Flow diagram for capturing the dilute CO₂ gas present in ambient air (1, left), and preparing it as pure CO₂ (upper arrow at stage 3, Calciner) for storage underground or for use in chemical processes to synthesize fuels.  The fan units include an alkaline solution that serves to absorb most of the ambient CO₂.  As shown at the right, the alkaline substance needed to absorb the CO₂ is regenerated and ultimately fed back to absorb more CO₂ in the fan units.

Source: New York Times, https://www.nytimes.com/2019/04/07/business/energy-environment/climate-change-carbon-engineering.html.

 

So far, according to the report, the pilot plant has produced the calcium carbonate pellets in stage 2.  Calcium carbonate is the mineral limestone.  If heated to a high temperature in the calciner the limestone would release pure gaseous CO₂ for collection.  

 

Discussion

 

An alarming impression of fossil fuel consumption by humanity since the beginning of the industrial revolution is shown here:

Global annual use of the three fossil fuels (gray, coal; orange, crude oil; teal, natural gas) shown from 1800 (before the industrial revolution) to 2017, in energy units of terawatt-hours.  For 2017 the energy from each fuel translates to approximately 5.4 billion metric tons/yr of coal; 30 billion barrels/yr of oil; and 122 billion cubic feet/yr of natural gas (using conversions provided at https://www.unitjuggler.com/convert-energy-from-kgSKE-to-Wh.html). Source: https://ourworldindata.org/fossil-fuels

 

These fuels, when burned, yield man-made CO₂ in comparably large amounts.  Since planetary warming is determined by the total amount of CO₂ that we have added to our atmosphere, one need only look back to this graphic and in her mind’s eye estimate the total area under the curve shown.

 

This result should impress the reader about the daunting task facing implementation of negative emission technology.  Even achieving fractional depletion of added CO₂, as suggested in the first graphic above, is a huge challenge.  A mitigating factor is that humanity has perhaps 1-2 decades to begin carbon removal at scale; in the first graphic above significant negative emissions (Gold shading) aren’t apparent until about 2040.

 

Carbon capture and storage technology at a less sophisticated level than presented here by Yu and coworkers has been known for more than a decade.  Even so, there are only a handful of such projects, operating as pilots, around the world.

 

Occidental Petroleum, and other petroleum extracting companies, already use CO₂, injecting it into operating oil wells to pressurize the crude oil and enable extracting more.  Thus CO₂ is being injected underground to produce more oil, which when refined and burned produces fresh CO₂!  Occidental believes this cycle could help make its operations carbon-neutral.

 

Carbon Engineering, and Chevron, in contrast, envision using CO2 to synthesize fuels, a process that requires the input of at least as much energy as was released when a fossil fuel was burned and yielded CO₂. Carbon Engineering plans to use renewable energy to generate hydrogen gas needed for making the synthetic fuel.  Thus a competition is implied, wherein a choice must be made between using renewable energy to serve the public directly versus using it in industrial processes to regenerate a carbon-containing fuel. 

 

As with the CBECCS process described by Lu and coworkers, the hurdle to achieve operation of the direct CO₂ removal at scale, as envisioned by Carbon Engineering, is high.  A single Carbon Engineering plant could remove 1 million tons of CO₂ per year.  This is a tiny fraction, about 0.003%, of the CO₂ produced by humanity around the world per year.

 

Both technologies described here are believed by the protagonists to become price competitive as the scale of operations increases and as use of fossil fuels falls due to market pressure if and when a meaningful price on carbon fuels is implemented.  In the meantime governmental resources and the private sector will drive the development of these technologies.

© 2019 Henry Auer

How Do We Answer Our Children?

On Friday March 15, 2019 children all over the world walked away from school and joined organized marches to raise their voices in favor of combatting global warming. 

It’s estimated that around the world about one million marchers joined this protest, according to its organizers.  They gathered in over 1,600 cities in more than 100 countries.

This movement was started in 2018 by Greta Thunberg, a Swedish high school student, now 16 years old.  Her tweeted message from the March 15 protest is shown here:

She told the gathered marchers in Sweden “We are facing the greatest existential crisis humanity has ever faced. And yet it has been ignored. You who have ignored it know who you are.” 

In Africa, Isaac Oindo, from NGO Power Shift Africa, said:  “Some people think climate change is only a future problem but here in Africa we know that it is happening now. We're living through it. However we know that it is going to affect the next generation even more severely which is why it's no surprise to see school children here in Africa and around the world going on strike to demand action.”


In Berlin, Luis Anzolin, age 15, declared “We’re here because it’s important, it’s about our future. Because let’s face it, those sitting in Parliament will probably not be there in the future and it’s going to affect us.”

A 2018 Pew Research Poll conducted in 26 countries found that climate change is viewed as the main international threat in 13 of them.  Young people are more worried about the threats that climate change poses than are those over 50, in the U.S., France, Australia and the Philippines.

These youths, presently in their mid- to late-teen years, realize that within their lifetimes the world’s climate will wreak severe harm on our planet if humanity continues its present profligate energy habits. This was already foreseen in the United Nations’ 5^th Assessment Report (5AR) issued 2013-2014 by the Intergovernmental Panel on Climate Change (IPCC).The report models the future climate expected under four scenarios of greenhouse gas (GHG) emission rates. It finds that for an unconstrained scenario by 2100 the long-term global average surface temperature could reach as high as about 4.6°C (8.3°F) above the average for the two-decade period from 1861-1880, as seen in the image below. 

In this graphic the total accumulated amount of extra carbon dioxide (CO₂) added to the atmosphere since the industrial revolution began, arising from burning fossil fuels, is given on the upper horizontal axis.  The resulting increase in long-term global average temperature, arising from modeling the four emission scenarios, is shown on the vertical axis, referenced to the 1861-1880 average.  The four scenarios range from most stringent (falling to zero emissions at about 2040) shown in dark blue, giving a temperature increase of about 1.8°C (3.2°F) by 2100; passing on through the progressively less stringent scenarios shown in light blue and orange; and ending on the scenario that continues present trends of largely unconstrained emissions (red) mentioned earlier.

The black line in the lower left represent actual historical data, with each decadal year given by a dot, some of which show the year.  It’s seen that this historical “hindcast” reproduces the historical data very well, giving credence that the modeling is correct.  The four successive emissions scenarios follow almost a straight line toward the upper right, toward higher CO₂ levels and higher projected temperatures.

It’s already turning out that our children are right to be alarmed and frightened about their climate future.  In the five years since 5AR was issued, accumulated CO₂ in the atmosphere has continued to increase year by year, as has the long-term global average temperature.  The world has been afflicted with ever more severe bouts of extreme weather and extreme climate, just as the climate scientists writing 5AR foresaw.  These include, in differing regions of the planet, drought and reduced agricultural yield, heat waves and long-term hot temperatures also reducing agricultural yield, more extreme precipitation resulting in fresh water floods, more severe storms, fair weather tidal flooding along shorelines, and ocean warming resulting in displaced fisheries.  The science of attribution has made great progress in recent years; events such as listed here in many cases are deemed to have been made more severe because of global warming.  Our perceived sense of worsening weather and climate events is real, and is due to worsening warming.

Climate scientists have been calling for policies to mitigate global warming and to adapt to its consequences since at least the First Assessment Report almost three decades ago.  Policymakers in many countries, but especially in the U. S., have ignored or even sought to suppress these findings.

We must answer our children now.  Scant time remains for those in power the world over to act meaningfully to mitigate worsening warming and to implement adaptation measures to address effects that are already underway.  Being human, our policymakers themselves have children and grandchildren, or may have them soon.  Their children, like ours, call out for meaningful action.  Doing nothing is no longer an option, since it consigns all those in future generations to lives of misery and hardship.

Our children are waiting for us to act.  Their future calls for nothing less than decarbonizing our energy economy as completely as feasible, using existing and newly invented technologies.

 

 © 2019 Henry Auer

Former Vice President Biden Says Climate Change Is An “Existential” Threat

Former U. S. Vice President Joe Biden spoke before the United States Conference of Mayors on January 24, 2019.  Following the link above takes you to the YouTube video of his address.  Fully half of his 30-minute speech was devoted to the dire need for the U. S. to address climate change rather than retreat from the issue the way the present Trump administration is doing. 

Vice President Biden summarized the important climate and economic benefits generated by the funds in the Obama administration’s Recovery Act of 2009 (intended to stimulate the economy out of the Great Recession) that were directed to mitigating climate change in the U. S.  He then proceeded to offer a heartfelt, sincere and cogent statement on why and how U. S. federal policy should continue to combat climate change by doubling down on policies that reduce greenhouse gas emissions and build a renewable energy economy.  By doing so the U. S. would rejoin all the other nations of the world in our unified campaign to limit further global warming, to which we all subscribed in the Paris Agreement of 2015.

The link above takes one to the video of Biden’s speech.  The portion dealing with climate change begins at about 16 min, 19 sec (16:19) of the video, and continues to about 29 min, near the end.  (For those unfamiliar with YouTube, if you mouse over any part of the video screen the timeline of the video pops up at the bottom of the screen.  Then as the mouse scans along that timeline, you can stop at 16:19 [or any other time you wish].  If you then click on that position the video will begin playing at that point.)

Here are some direct quotes from Biden’s talk, with the time for each statement indicated.

• The Recovery Act included “the single biggest investment in clean energy in the history of the country - $90 billion.  It leveraged $150 billion in the private sector. [It] created hundreds of thousands of clean energy jobs…By the end of the administration there was 30 times as much solar energy and [we were] creating clean energy jobs 12 times faster than any other sector of the economy.” (16:19)
• “There’s no reason that in 2025 all of North America can’t get half of electricity from non-polluting sources.  It’s within our grasp but for special interests!” (20:40)
• Addressing the mayors directly, he said “You also know…it’s a matter of survival.  The threat posed by climate change is existential.” (21:26)
• “You know what the military said [to President Obama and Vice President Biden]?  ‘You know what our greatest security threat is?  Global warming….If sea levels rise…you have tens of millions of people migrating.  That’s how wars start.’” (21:42)
• “Our government’s own most recent report found that heat stress and drought can kill up to a quarter of our corn and soybean harvest.  What’s that going to mean for you mayors from the Midwest…? What does that mean … when John Deere [a major manufacturer of farm equipment] has nothing to plow? (23:40)
• Our scientists have spoken…Since when did we become science deniers?  The United Nations told us…we have 12 years to act before it’s irreversible” (24:07)
• (Referring to the Trump administration intention to pull out of the Paris Agreement)…“you’ve stepped up [addressing the mayors]….400 of you said, no, no, not me….57% of you pledged to take action in 2019”  (25:50)
• “…this is the most urgent priority facing the nation, and we’ll be judged by our children and grandchildren for what we do today.” (27:48)    

  Conclusion

This writer finds it highly significant that Vice President Biden, in his appearance before the United States Conference of Mayors for 2019 devoted so much emphasis to the single issue of climate change.  With all the problems facing our mayors, such as economic and social injustice, and opioid abuse, to name only a few, he chose to stress the importance of the climate change issue as an “existential” threat, stating “this is the most urgent priority facing the nation”.

Skeptics may downplay this speech as being merely a political gesture from someone grappling with the decision of whether to run for president in two years.  Yet there are many other ways he could have addressed our country’s mayors.  Here’s a man who was at the center of national power for eight years.  He came to understand the singular, generational, global significance of man-made emissions of greenhouse gases that have led to intolerable levels of global warming in the short time, geologically speaking, of a figurative blink of an eye.  Mr. Biden is to be praised for this effort.  We all should support his call to action on climate change, regardless of whether he runs for president.

© 2019 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