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Why We Can’t Reverse Climate Change With ‘Negative Emissions’ Technologies
By Howard J. Herzog
Featured prominently in the report is a discussion of a range of techniques for removing carbon dioxide from the air, called Carbon Dioxide Removal (CDR) technologies or negative emissions technologies (NETs). The IPCC said the world would need to rely significantly on these techniques to avoid increasing Earth's temperatures above 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, compared to pre-industrial levels.
Given that the level of greenhouse gases continues to rise and the world's efforts at lowering emissions are falling way short of targets climate scientists recommend, what contribution we can expect from NETs is becoming a critical question. Can they actually work at a big enough scale?
What Are Negative Emissions Technologies?
There is a wide range of opinion on how big an impact these techniques can have in addressing climate change. I became involved in the debate because two of the most prominent negative emissions technologies involve CO2 capture and storage (CCS), a technology that I have been researching for almost 30 years.
Many NETs remove the CO2 from the atmosphere biologically through photosynthesis—the simplest example being afforestation, or planting more trees. Depending on the specific technique, the carbon removed from the atmosphere may end up in soils, vegetation, the ocean, deep geological formations, or even in rocks.
NETs vary on their cost, scale (how many tons they can potentially remove from the atmosphere), technological readiness, environmental impacts and effectiveness. Afforestation/reforestation is the only NET to have been deployed commercially though others have been tested at smaller scales. For example, there are a number of efforts to produce biochar, a charcoal made with plant matter that has a net negative carbon balance.
A recent academic paper discusses the "costs, potentials, and side-effects" of the various NETs. Afforestation/reforestation is one of the least expensive options, with a cost on the order of tens of dollars per ton of CO2, but the scope for carbon removal is small compared to other NETs.
On the other extreme is direct air capture, which covers a range of engineered systems meant to remove CO2 from the air. The costs of direct air capture, which has been tested at small scales, are on the order of hundreds of dollars or more per ton of CO2, but is on the high end in terms of the potential amount of CO2 that can be removed.
A handful of commercial companies are testing direct air capture technology,, which takes carbon dioxide out of the air. This project in Italy will use the CO2 to ultimately produce natural gas to power vehicles. Climeworks
In a 2014 IPCC report, a technology called bio-energy with carbon capture and storage (BECCS) received the most attention. This entails burning plant matter, or biomass, for energy and then collecting the CO2 emissions and pumping the gases underground. Its cost is high, but not excessive, in the range of $100-200 per ton of CO2 removed.
The biggest constraint on the size of its deployment relates to the availability of "low-carbon" biomass. There are carbon emissions associated with the growing, harvesting and transporting of biomass, as well as potential carbon emissions due to land-use changes—for example, if forests are cut down in favor of other forms of biomass. These emissions must all be kept to a minimum for biomass to be "low-carbon" and for the overall scheme to result in negative emissions. Potential "low-carbon" biomass includes switchgrass or loblolly pine, as opposed to say corn, which is currently turned into liquid fuels and acknowledged to have a high carbon footprint.
Some of the proposed NETs are highly speculative. For example, ocean fertilization is generally not considered a realistic option because its environmental impact on the ocean is probably unacceptable. Also, there are questions about how effective it would be in removing CO2.
A 2017 study at the University of Michigan did a literature review of NETs. One the one hand, they showed that the literature was very bullish on NETs. It concluded these techniques could capture the equivalent of 37 gigatons (billion tons) of CO2 per year at a cost of below $70 per metric ton. For comparison, the world currently emits about 38 gigatons of CO2 a year.
However, I think this result should be taken with a large grain of salt, as they rated only one NET as established (afforestation/reforestation), three others as demonstrated (BECCS, biochar and modified agricultural practices), and the rest as speculative. In other words, these technologies have potential, but they have yet to be proven effective.
Other studies have a much harsher view of NETs. A study in Nature Climate Change from 2015 states, "There is no NET (or combination of NETs) currently available that could be implemented to meet the <2°C target without significant impact on either land, energy, water, nutrient, albedo or cost, and so 'plan A' must be to immediately and aggressively reduce GHG emissions." In another study from 2016, researchers Kevin Anderson and Glen Peters concluded, "Negative-emission technologies are not an insurance policy, but rather an unjust and high-stakes gamble. There is a real risk they will be unable to deliver on the scale of their promise."
The bottom line is that NETs must be shown to work on a gigaton scale, at an affordable cost, and without serious environmental impacts. That has not happened yet. As seen from above, there is a wide range of opinion on whether this will ever happen.
A critical question is what role NETs can play, both from a policy and economic point of view, as we struggle to stabilize the mean global temperature at an acceptable level.
One potential role for NETs is as an offset. This means that the amount of CO2 removed from the atmosphere generates credits that offset emissions elsewhere. Using negative emissions this way can be a powerful policy or economic lever.
For example, with airline travel the best approach to net zero emissions may be to let that industry to continue to emit CO2, but offset those emissions using credits from NETs. Essentially those negative emissions are a way to compensate for the emissions from flying, which is expected to rely on fossil fuels for many years.
About 25 percent of our current carbon emissions can be classified as hard to mitigate. This offset model makes economic sense when the cost of negative emissions is less than the cost to cut emissions from the source itself. So if we can produce negative emissions from say BECCS at about $150 per ton of CO2, they can economically be used to offset emissions from aircraft that would cost several hundred dollars per ton CO2 to mitigate by changing how planes are fueled.
The economics of using NETs to correct an "overshoot" are very different.
We as a society seem unwilling to undertake sufficient efforts to reduce carbon emissions today at costs of tens of dollars per ton CO2 in order to keep enough CO2 out of the atmosphere to meet stabilization targets of 1.5 or 2 degrees Celsius. However, correcting an "overshoot" means we expect future generations to clean up our mess by removing CO2 from the atmosphere at costs of hundreds of dollars or more per ton CO2, which is what the future deployment of NETs may cost.
This makes no sense, economic or otherwise. If we are unwilling to use the relatively cheap mitigation technologies to lower carbon emissions available today, such as improved efficiency, increased renewables, or switching from coal to natural gas, what makes anyone think that future generations will use NETs, which are much, much more expensive?
That's why I see the role of NETs as an offset being very sound, with some deployment already happening today and increased deployment expected in the future. By contrast, treating NETs as a way to compensate for breaking the carbon budget and overshooting stabilization targets is more hope than reality. The technical, economic and environmental barriers of NETs are very real. In formulating climate policy, I believe we cannot count on the future use of NETs to compensate for our failure to do enough mitigation today.
Howard J. Herzog is a senior research engineer at the Massachusetts Institute of Technology.
Disclosure statement: Howard J. Herzog receives funding from Energy Futures Initiative, Exxon-Mobil, QRI, Total.
Reposted with permission from our media associate The Conversation.
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Global Banks, Led by JPMorgan Chase, Invested $1.9 Trillion in Fossil Fuels Since Paris Climate Pact
By Sharon Kelly
A report published Wednesday names the banks that have played the biggest recent role in funding fossil fuel projects, finding that since 2016, immediately following the Paris agreement's adoption, 33 global banks have poured $1.9 trillion into financing climate-changing projects worldwide.
By Patti Lynn
2018 was a groundbreaking year in the public conversation about climate change. Last February, The New York Times reported that a record percentage of Americans now believe that climate change is caused by humans, and there was a 20 percentage point rise in "the number of Americans who say they worry 'a great deal' about climate change."
England faces an "existential threat" if it does not change how it manages its water, the head of the country's Environment Agency warned Tuesday.
By Jessica Corbett
A new analysis revealed Tuesday that over the past two decades heat records across the U.S. have been broken twice as often as cold ones—underscoring experts' warnings about the increasingly dangerous consequences of failing to dramatically curb planet-warming emissions.
By Madison Dapcevich
Ask any resident of San Francisco about the waterfront parrots, and they will surely tell you a story of red-faced conures squawking or dive-bombing between building peaks. Ask a team of researchers from the University of Georgia, however, and they will tell you of a mysterious string of neurological poisonings impacting the naturalized flock for decades.
The initial cause of the fire was not yet known, but it has been driven by the strong wind and jumped the North Santiam River, The Salem Statesman Journal reported. As of Tuesday night, it threatened around 35 homes and 30 buildings, and was 20 percent contained.
The unanimous verdict was announced Tuesday in San Francisco in the first federal case to be brought against Monsanto, now owned by Bayer, alleging that repeated use of the company's glyphosate-containing weedkiller caused the plaintiff's cancer. Seventy-year-old Edwin Hardeman of Santa Rosa, California said he used Roundup for almost 30 years on his properties before developing non-Hodgkin's lymphoma.
"Today's verdict reinforces what another jury found last year, and what scientists with the state of California and the World Health Organization have concluded: Glyphosate causes cancer in people," Environmental Working Group President Ken Cook said in a statement. "As similar lawsuits mount, the evidence will grow that Roundup is not safe, and that the company has tried to cover it up."
Judge Vince Chhabria has split Hardeman's trial into two phases. The first, decided Tuesday, focused exclusively on whether or not Roundup use caused the plaintiff's cancer. The second, to begin Wednesday, will assess if Bayer is liable for damages.
"We are disappointed with the jury's initial decision, but we continue to believe firmly that the science confirms glyphosate-based herbicides do not cause cancer," Bayer spokesman Dan Childs said in a statement reported by The Guardian. "We are confident the evidence in phase two will show that Monsanto's conduct has been appropriate and the company should not be liable for Mr. Hardeman's cancer."
Some legal experts said that Chhabria's decision to split the trial was beneficial to Bayer, Reuters reported. The company had complained that the jury in Johnson's case had been distracted by the lawyers' claims that Monsanto had sought to mislead scientists and the public about Roundup's safety.
However, a remark made by Chhabria during the trial and reported by The Guardian was blatantly critical of the company.
"Although the evidence that Roundup causes cancer is quite equivocal, there is strong evidence from which a jury could conclude that Monsanto does not particularly care whether its product is in fact giving people cancer, focusing instead on manipulating public opinion and undermining anyone who raises genuine and legitimate concerns about the issue," he said.
Many regulatory bodies, including the U.S. Environmental Protection Agency, have ruled that glyphosate is safe for humans, but the World Health Organization's International Agency for Research on Cancer found it was "probably carcinogenic to humans" in 2015. A university study earlier this year found that glyphosate use increased cancer risk by as much as 41 percent.
Hardeman's lawyers Jennifer Moore and Aimee Wagstaff said they would now reveal Monsanto's efforts to mislead the public about the safety of its product.
"Now we can focus on the evidence that Monsanto has not taken a responsible, objective approach to the safety of Roundup," they wrote in a statement reported by The Guardian.
Hardeman's case is considered a "bellwether" trial for the more than 760 glyphosate cases Chhabria is hearing. In total, there are around 11,200 such lawsuits pending in the U.S., according to Reuters.
University of Richmond law professor Carl Tobias told Reuters that Tuesday's decision showed that the verdict in Johnson's case was not "an aberration," and could possibly predict how future juries in the thousands of pending cases would respond.