COP 28 PRIMERS: The Two Dangerous Myths COP28 Is Built Around, and the Two Climate “Solutions” That Make Things Worse

Joseph Romm

Joseph Romm ( is the former acting assistant secretary of energy efficiency and renewable energy with a Ph.D. in physics from MIT.

Dr. Romm has put together four COP28 primers, 1- or 2-pages long, because tragically, the 28th Conference of the Parties to the UN-led global effort to avoid catastrophic climate change (Nov 30 to Dec 12) is built around two dangerous myths. These two myths are the notions of “net zero” and cheap carbon offsets—the subjects of two primers. Net zero itself is built around two supposedly major climate solutions that would, in fact, make things worse if we actually tried to scale them up in the next two to three decades. So, a third primer is on bioenergy plants with carbon capture and storage (BECCS), where growing biomass removes CO2 from the air, and a BECCS system buries it. The fourth is on direct air carbon capture and storage (DACCS), which pulls CO2 directly out of the air and buries it.

Humans generate 50 billion tons (Gt) of CO2-equivalent gases each year, and scientists tell us we must zero out those emissions by mid-century to avoid the worst climate impacts. Net zero is the hope that we could cut emissions by perhaps only 40 Gt/yr or less—and remove from the air 10 Gt/yr or more by 2050 with the three most prominent strategies by far: BECCS, DACCS, and tree planting. But science shows these 3 strategies don’t scale and 2 make things worse. New modeling finds scaling up bioenergy and BECCS increases CO2 emissions and warming for decades, with net cooling not occurring until 2100 or beyond. Scaling up BECCS is not carbon removal, but more like deforestation.

DACCS is a costly and inefficient way to use vast amounts of renewable energy to achieve CO2 reductions. That carbon-free power could have directly replaced the CO2 emissions from fossil fuel plants, cars, and gas heating far more cheaply. Scaling up DACCS will be a costly misallocation of renewables for decades—until fossil fuel emissions are cut perhaps 90%. We should be investing mainly in RD&D of promising carbon removal strategies to see if any might be usefully scalable by 2050. As for trees, even planting one trillion would at best remove just 6% of the CO2 needed by 2050. And that would require a wildly unrealistic area the size of the lower 48 states.

CO2 offsets—where companies/countries meet CO2 pledges by paying a developing country to cut emissions in their place—were artificially cheap (<$5 a ton) since the large majority were not real. So, it seemed like there was a bonanza of cheap offsets richer countries could buy from poorer ones to avoid the cost and effort of cutting their own emissions. But there wasn’t. Genuine offsets that were not double counted (claimed by both buyer and seller) were always going to be much pricier.

This 2-page primer explains the poorly understood but vast implications of the world’s decision at Glasgow (COP26) in 2021 to create “authorized” offsets that solve the double counting problem with a “corresponding adjustment” (CA) that ensures the seller can’t also claim the offsets it sells. First, if the voluntary carbon market doesn’t embrace the CA, “there is a risk [it] undermines the objectives of the Paris Agreement.” Second, the CA makes it much harder for the seller to achieve its Paris pledge—so it’s a bad deal for them. Third, that’s why, in 2023, a World Bank analysis found authorized offsets may cost over $100 a ton. Fourth, offsets make little sense when everybody has to go to zero. Selling off your easiest reductions cheaply to another country is self-defeating.

Below are the downloadable PDFs of the primers.

COP28 PRIMER: CO2 Removal and the Dangerous Myth of ‘Net Zero’

COP28 PRIMER: How the Voluntary CO2 Offset Market Threatens the Paris Agreement

COP28 PRIMER: The Dangers of Scaling up Bioenergy and Bioenergy with CCS

COP28 PRIMER: Direct Air Capture (DAC) and its Fatal Flaw