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Nature has endowed the Earth with numerous giant “sponges”, or carbon sinks, that can help humans fight climate change. These natural sponges, as well as those made by man, can absorb carbon, effectively removing it from the atmosphere.
But what does this sci-fi act really entail? And how long it will actually take – and how much it costs – to make a difference and slow down climate change?
Sabine Fuss has been looking for these answers for the past two years. Berlin economist, Fuss leads a research group at the Mercator Research Institute on Global Commons and Climate Change and was part of the original Intergovernmental Panel on Climate Change (IPCC), set up by the United Nations to assess science, risks and impacts of global warming. Following the panel’s 2018 report and the new Paris Agreement’s goal of keeping global warming at 2.7 degrees Fahrenheit (1.5 degrees Celsius) or less, Fuss was tasked with finding out which carbon removal strategies were the most promising and feasible.
Related: What is a carbon sink?
Afforestation and reforestation – respectively planting or replanting of forests – are well known natural carbon sinks. Large numbers of trees can sequester greenhouse gas carbon dioxide (CO2) from the atmosphere photosynthesis, a chemical reaction that uses the sun’s energy to transform carbon dioxide and water into sugar and oxygen. According to a 2019 study in the journal Science, plantation 1 trillion trees it could store about 225 billion tons (205 billion metric tons) of carbon, or about two-thirds of the carbon released by humans into the atmosphere since the start of the industrial revolution.
According to Jane Zelikova, a terrestrial ecologist and chief scientist at Carbon180, a nonprofit organization that supports carbon removal strategies in the United States, agricultural land management is another natural carbon removal approach that presents a relatively low risk and that is already in the trial phase, according to Jane Zelikova, reduced tillage and crop rotation increase carbon uptake through photosynthesis, and that carbon is eventually stored in root tissues which decompose in the soil. The National Academy of Sciences found that carbon storage in soil was enough to offset up to 10% of the U.S. annual net emissions – or about 632 million tons (574 million tons) of CO2 – low price.
But nature-based carbon removal, such as planting and replanting forests, can conflict with other policy goals, such as food production, Fuss said. Increased, these strategies require a lot of land, often land already in use.
This is why more technological approaches to carbon removal are crucial, they say. With direct air capture and carbon storage, for example, a chemical process extracts carbon dioxide from the air and binds it to filters. When the filter is heated, CO2 can be captured and then injected underground. There are currently 15 direct air capture plants around the world, according to International Energy Agency. There is also bioenergy with carbon capture. With this method, plants and trees are grown, creating a carbon sink, and then the organic material is burned to produce heat or fuel known as bioenergy. During combustion, carbon emissions are captured and stored underground. Another trick to carbon capture involves mineralization; in this process, the rocks are ground to increase the surfaces available to chemically react with the CO2 and crystallize it. Subsequently, the mineralized CO2 is stored underground.
However, none of these technologies have been implemented on a large scale. I am extremely expensive, with estimates up to $ 400 per ton of CO2 removed, and each still requires a lot of research and support before being deployed. But the US is a good example of how a mix of carbon removal solutions could work together, Zelikova said: land management could be used in the agricultural Midwest; basalt rocks in the Pacific Northwest are excellent for mineralization; and the oil fields in the Southwest are ready with the right technology and skilled workers for underground carbon storage, he said.
Related: Why does the Earth rotate?
Ultimately, each country will have to put together their own unique portfolio of CO2 removal strategies because no single intervention will be successful alone. “If we increased any of them exclusively, it would be a disaster,” Fuss said. “It would use a lot of land or it would be prohibitive.” His research has shown that reforestation and reforestation will be more productive in tropical regions, while differences in solar radiation in more northerly latitudes with more albedo (reflection of light in space) mean that those countries will likely have better luck investing in interventions. more technological, such as carbon capture and biomass extraction.
The need to implement these solutions is imminent. The global carbon balance, the amount of CO2 that humans can emit before global temperature rises 2.7 F (1.5 C) above pre-industrial levels, is about 300 gigatons of CO2, Fuss said.
“Over the past few years, we’ve emitted 40 gigatons,” he said. In other words, only a few years remain in the budget. A recent study in the journal Scientific reports suggests that waiting even in a few years may be too late if we are to achieve the goal set in the Paris Agreement. Based on their climate model, the authors predict that, even if we stop emitting greenhouse gases completely, “global temperatures will be 3 ° C. [5.4 F] warmer and sea level 3 meters [10 feet] 2,500 more than in 1850. “To reverse the effects of climate change, 33 gigatonnes of existing greenhouse gases must be removed this year and every year moving forward, the researchers said.
The reality, however, is that these approaches are not ready and there is no consensus on how to pay for them. There is a consensus among scientists on the next step: we need to stop further emissions immediately. But “since emissions are embedded in our daily life and infrastructure,” Fuss said, “[carbon] removal is more in the foreground “.
Originally published on LiveScience.
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