See the Tabbed Pages for links to video tutorials, and a linked list of post titles grouped by topic.

This blog is expressly directed to readers who do not have strong training or backgrounds in science, with the intent of helping them grasp the underpinnings of this important issue. I'm going to present an ongoing series of posts that will develop various aspects of the science of global warming, its causes and possible methods for minimizing its advance and overcoming at least partially its detrimental effects.

Each post will begin with a capsule summary. It will then proceed with captioned sections to amplify and justify the statements and conclusions of the summary. I'll present images and tables where helpful to develop a point, since "a picture is worth a thousand words".

Tuesday, April 30, 2019

Our Children: The Climate Activists We Need!

On Strike for the Climate.  Greta Thunberg, then aged 15, decided not to go back to school after a summer of record temperatures in Sweden in 2018.  Instead she picketed solo outside the Swedish parliament, with her books and a sign reading “School Strike for Climate”.  She felt powerless as Swedish politicians failed to address climate change in a meaningful way, even as they campaigned for reelection in Sweden. In short order, now 16 years old, she has engendered a global movement of school students protesting inaction on the climate around the world.  She started the #FridaysForFuture climate protests, for example involving over 30,000 pupils in Belgium alone in January 2019.  At the annual United Nations climate talks in Poland in December 2018, she berated the delegates, saying “You are not mature enough to tell it like it is.  Even that burden you leave to us children.”  Elsewhere she has said, perhaps with wisdom exceeding her years, “Change is on the horizon, but to see that change we also have to change ourselves.”

A globe-wide international strike of students marching against climate inaction took place in March 2019, a sequel to Greta Thunberg’s activism.  1,700 strike events occurred on every continent (except Antarctica).  In the U. S. alone there were 100 strikes.  Nadia Nazar, an organizer of a strike in Washington, D.C., said “We’re the first generation that’s being significantly affected by climate change, and the last generation that can do something about it.”

Many of these children, born just after the 21st century began, realize they will be living through most of its remainder.  They see and read about the harms already being inflicted upon humanity by weather and climate extremes.  They also recognize that global warming poses an existential threat to our planet as this century unfolds, and understand that, barring energetic, ambitious action starting now, their lives risk becoming unsustainable as the earth continues warming. (Please see the post “How Do We Answer Our Children?”)  

Climate scientists agree that our children’s climate worries are justified.  Twenty-two prominent climate scientists from 10 countries published a letter to the editor of Science (12 April 2019) in support of the youthful climate strikers.  The writers affirm: “Their concerns are justified and supported by the best available science. The current measures for protecting the climate and biosphere are deeply inadequate.”  Confirming our children’s calls to action they state “It is critical to immediately begin a rapid reduction in CO2 and other greenhouse gas emissions…. The young protesters rightfully demand that … solutions [already known to us] be used to achieve a sustainable society…. Without bold and focused action, their future is in critical danger.” 

The letter forcefully concludes “The enormous grassroots mobilization…of the youth climate movement…shows that young people understand the situation. We approve and support their demand for rapid and forceful action….Only if humanity acts quickly and resolutely can we limit global warming [and its consequent ecological damage, and assure the] well-being of present and future generations. This is what the young people want to achieve. They deserve our respect and full support.”

Climate Science. The science behind our understanding of global warming and its consequences has been understood already for many decades.  Indeed, the first findings that burning fossil fuels by humankind produces carbon dioxide (CO2) that warms the atmosphere were uncovered during the nineteenth century.  These are summarized in the Details section at the end of this post.

IPCC Assessment Reports. The Intergovernmental Panel on Climate Change (IPCC) has been issuing Assessment Reports presenting scientific data and discussing warming mitigation and adaptation methodologies since 1990, at intervals of 5-7 years.  The most recent one, the fifth, appeared in three parts over 2013-4. 
The basic conclusions throughout this series have not wavered significantly from those presented in the first Report; the difference over this 24-year period has been rather that a) the number of climate scientists at work, and our understanding of climate science based on their results, have grown dramatically; and b) technologies that permit more extensive and more accurate gathering and analysis of climate data have likewise grown significantly.  This has permitted the conclusions and recommendations made in the Fifth Assessment Report to be offered with the highest levels of certainty and confidence, compared to those in the previous versions. 

Even so, over this interval our policymakers have not embraced these recommendations as energetically and as early as would have been needed to respond to the climate crisis. Instead, policymakers have reacted inadequately to the growing threat of damages and harms to health and society that global warming poses.  In Ms. Thunberg’s words, our political leaders have not been “mature enough to tell it like it is.  Even that burden [they are leaving to their] children.”

Most recently, an IPCC Report on Global Warming of 1.5°C, which appeared in October 2018, summons the world to take more immediate, extensive, and radical actions than in earlier reports so that the rise in global average temperature remains below about 1.5°C (2.7°F).  Because of earlier inaction this Report now foresees the need to reduce net global annual greenhouse gas emission rates to near zero by 2050.  This will require committed technological development and deployment at the enormous scale needed to match the rate of production of CO2 and other greenhouse gases.  It also depends on the worldwide exercise of political will that reflects scientific necessity and moral responsibility. There is no longer any scientific doubt that global warming leads to extremes of weather and climate that contribute to, or cause, climate disasters at an ever-increasing and ever more devastating pace.  Again as Ms. Thunberg states, “to see that change we also have to change ourselves.”


The early scientific history leading to identification of CO2 as a greenhouse gas and the understanding that it could harm our environment includes the following discoveries and reports:
1790s: Horace-Benedict de Saussure, a Swiss geologist and alpinist, constructed a glass-covered box with a thermometer inside: his “heliothermometer”.  Without understanding why, he discovered that the temperature inside the box was much higher than the air outside.  (We now know that glass is greenhouse-active.)
1820s: Joseph Fourier, a French physicist with an interest in global heat exchange, understood that the atmosphere acts as what we now call a greenhouse, retaining heat from the sun that keeps the earth warm.  But he had no way to verify his theory.
1859: John Tyndall, a British experimental physicist was the first to demonstrate in his laboratory that CO2 (and many other gases) absorb heat radiation.  This established that CO2 in the atmosphere behaves as a greenhouse gas, retaining solar energy as extra heat.
1896: Svante Arrhenius, a Swedish chemist, built on the knowledge of his predecessors.  He knew that burning fossil fuels generates CO2.  He calculated (using pencil and paper, before the advent of calculators and computers) the extra warming that could arise from this added CO2, and warned of the effects that continued fossil fuel use could have. 
1958: Charles Keeling, an American geologist, was the first to measure directly the CO2 content of the atmosphere.  It was higher than before fossil fuel use began, and continues to grow to record levels to this day.

© 2019 Henry Auer

Friday, April 12, 2019

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 21st 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

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 PM2.5 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.

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.  
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 Source:
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