A sudden six or seven percent drop in carbon emissions is needed to avoid breaking the Paris climate treaty’s goal of capping global warming at “well below” two degrees Celsius compared to pre-industrial levels.
A sudden six or seven percent drop in carbon emissions is needed to avoid breaking the Paris climate treaty’s goal of capping global warming at “well below” two degrees Celsius compared to pre-industrial levels.
To save the world from the worst ravages of climate change, reducing carbon pollution is no longer enough – CO2 will also need to be taken out of the atmosphere and buried, a landmark UN report is expected to say on Monday.
If humanity had started curbing greenhouse gas emissions 20 years ago, an annual reduction of two percent by 2030 would have put us on the right track. Challenging, but doable. Instead, emissions rose 20 percent to more than 40 billion tons of CO2 in 2021.
That means a sudden drop of six or seven percent a year in carbon emissions is needed to meet the Paris climate treaty’s goal of limiting global warming to “well below” two degrees Celsius above pre-industrial levels. break can be avoided. Staying under the safe aspirational limit of 1.5C would mean an even greater drop.
To put this in perspective, 2020’s painful shutdown of the global economy due to COVID saw a reduction in CO2 emissions by “only” 5.6 percent. Therefore the need for carbon dioxide removal (CDR), or “negative emissions”, is likely to feature prominently in the report of the United Nations Intergovernmental Panel on Climate Change (IPCC).
Even under the most aggressive carbon-cutting scenarios, several billion tons of CO2 would need to be removed from the atmosphere each year by 2050, and hundreds of billions of tons would accumulate in total by 2100. To date, CO2 removal is nowhere near these levels. The largest direct air capture facility in the world removes what humanity emits in three or four seconds a year. There are at least a dozen CDR techniques on the table, with varying efficiencies and costs.
using bioenergy
Most of the hundreds of models that lay out a game plan for a habitable future play a key role in the creation of a negative emissions solution called bioenergy with BECCS, or carbon capture and storage. In a nutshell, this is the recipe: Grow trees, burn them for energy, and bury CO2 underground in an abandoned mine, for example. But what works on paper (or in the so-called integrated valuation model), has not happened in reality.
The UK, one of the few commercial-level BECCS facilities in the world, was removed from the S&P Clean Energy Index last year because it failed to meet sustainability criteria. “I don’t see a BECCS boom,” said Oliver Geiden, a senior fellow at the German Institute for International and Security Affairs and an expert on CDR.
planting trees
Restoring forests and planting trees that absorb and stock CO2 also majorly achieve near-zero emissions in development scenarios, whether in 2050 or later. Many businesses, including fossil fuel companies, rely heavily on carbon offset schemes based on afforestation to compensate for continued carbon pollution.
But the amount of land needed to make a serious dent in CO2 levels through plantations – up to twice the size of India – may conflict with other priorities, such as growing food and biofuel crops. Biodiversity may also suffer, particularly in savannas converted to monoculture tree farms. Newly planted forests may also be prone to more frequent and intense wildfires due to rising temperatures, resulting in the release of all their stored CO2.
Direct Air Carbon Capture and Sequestration (DACCS)
One of the youngest CDR technologies is also one of the hottest: Direct Air Carbon Capture and Storage. With variations, DACCS is a chemical process that removes carbon dioxide directly from the atmosphere, converts it into a solid form or gives it off underground.
Because the CO2 in the air is so sparse – a few hundred parts per million – it is a very energy-intensive and expensive process. DACCS has benefited from the wave of corporate support.
Last year, Tesla CEO Elon Musk launched a $100 million X-Prize for an innovative CO2 removal technology, and Breakthrough Energy founder Bill Gates unveiled a corporate partnership to turbocharge its development. How quickly and at what cost it can rise remains an open question.
advanced weathering
Advanced weathering involves mining and crushing rocks rich in minerals that naturally absorb CO2, and then dispersing them over land or sea. Its purpose is to accelerate a process that normally appears over geological timescales of tens of thousands of years.
Silicate rocks with minerals rich in calcium and magnesium but lacking metal ions such as nickel and chromium are the best raw materials for the job. But, again, it is not clear whether the enhanced weathering can be sufficiently enhanced, and at what cost.
ocean based methods
The oceans already account for more than 30 percent of humanity’s carbon emissions, and scientists are experimenting with ways to increase that potential.
One approach is to increase marine alkalinity, either by adding natural or synthetic alkaline minerals directly or by electrochemical processing of seawater.
Another approach, known as ocean fertilization, increases the density of tiny phytoplankton that produce and sequester organic carbon through photosynthesis, such as plants on land. The addition of nitrogen or iron leads to the growth of phytoplankton.
The main concerns here include unintended consequences on the ecosystem.