atmosphere

Carbon Removing Saving from Catastrophe | Burning Issues

 

    • The Intergovernmental Panel on Climate Change (IPCC) asserts that limiting global warming to 1.5˚C could avert the most catastrophic effects of climate change.
    • In its recent report, it laid out four means of achieving this — and all of them rely on removing carbon dioxide from the atmosphere.
    • This is because even if we cut most of our carbon emissions down to zero, emissions from agriculture and air travel would be difficult to eliminate altogether.
    • And since carbon dioxide that’s already in the atmosphere can affect climate for hundreds to thousands of years, the IPCC maintains that carbon dioxide removal (CDR) technologies will be critical to get rid of 100 to 1000 gigatonnes of CO2 this century.
    • CDR approaches that employ trees, plants and soil to absorb carbon have been used at large scale for decades; other strategies that rely more on technology are mostly at the demonstration or pilot stages. Each strategy has pros and cons.

Afforestation and reforestation

  • As plants and trees grow, they take carbon dioxide from the atmosphere and turn it into sugars through photosynthesis.
  • Planting additional trees could remove more carbon from the atmosphere and store it for a long time
  • . Afforestation involves planting trees where there were none previously; reforestation means restoring forests where trees have been damaged or depleted.
  • Afforestation, however, could compete for land used for agriculture just as food production needs to increase 70 percent by 2050 to feed the growing world population. It could also affect biodiversity and ecosystem services.
  • And although forests can sequester carbon for decades, they take many years to grow and can become saturated in decades to centuries. They also require careful management because they are subject to human and natural impacts such as wildfires, drought and pest infestations.

Soil carbon sequestration

  • The carbon that plants absorb from the atmosphere in photosynthesis becomes part of the soil when they die and decompose. It can remain there for millennia or it can be released quickly depending on climatic conditions and how the soil is managed. Minimal tillage, cover crops, crop rotation and leaving crop residues on the field help soils store more carbon.
  • The IPCC, estimates that soil carbon sequestration could remove between 2 and 5 gigatonnes of carbon dioxide a year by 2050. By comparison, the world’s power plants released 32.5 gigatonnes of CO2 in 2017.
  • But while soil stores large amounts of carbon in the beginning, it can become saturated after 10 to 100 years, depending on climate, soil type and how it is managed.

Bioenergy with carbon capture and storage (BECCS)

    • If we burn plants for energy at a power plant and capture and store the resulting emissions, the CO2 the plants previously absorbed is removed from the atmosphere.
    • The CO2 can then be used for enhanced oil recovery or injected into the earth where it is sequestered in geologic formations.
    • The IPCC estimates that BECCS could remove between 0.5 and 5 gigatonnes of carbon a year by 2050. To absorb enough carbon to keep the world at 2˚, however, energy crops would need to be planted over an area of land up to three times the size of India, according to one estimate; and even smaller amounts of BECCS would compete with land needed for food production..
    • BECCS could also end up impacting biodiversity and ecosystem services, and generating greenhouse gas emissions through farming and fertilizer use. What’s needed to advance carbon dioxide removal?
    • Each CDR technology is feasible at some level, but has uncertainties about cost, technology, the speed of possible implementation, or environmental impacts. It’s clear that no single one provides the ultimate solution to climate change.
    • “Carbon dioxide removal alone cannot do it,”
    • . “If there’s one thing the IPCC report really underscores is that we need a portfolio—we need to reduce emissions dramatically, we need to come up with more renewable energy options to replace fossil fuels, we need to electrify a lot of things that are currently run on petroleum and then we need to do an enormous amount of carbon removal.”
    • In fact, a new study just determined that planting trees and improving management of grasslands, agricultural lands and wetlands could sequester 21 percent of the U.S.’s annual greenhouse gas emissions at relatively low cost.
    • Developing the other carbon dioxide removal strategies further is going to take substantial amounts of money.
  • “Establishing a financial incentive to remove carbon such as a carbon tax or penalties for emitting carbon would help as well.

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