What are nature-based solutions?
Nature-based solutions are means of removing carbon dioxide (CO2) from the atmosphere by conserving, restoring, or managing physical environments.
These are separate from engineered or technology-based solutions for removing CO2, in that they use natural forest, soil, and coastal ecosystems. A landscape that can absorb CO2 from the atmosphere and trap it there is known as a carbon sink.
How can nature-based solutions help tackle climate change?
Reducing CO2 levels in the atmosphere is key to tackling climate change. The Paris Agreement sets out targets for organisations and nations to reduce their CO2 emissions to keep global warming within 1.5 degrees Celsius of pre-industrial levels and avoid “catastrophic” consequences.
However, even as industries strive to decarbonise, some crucial sectors of the economy, such as aviation and agriculture, may prove hugely difficult or even impossible to entirely reduce emissions to zero. Therefore, as well as reducing CO2 emissions, it will be essential to actively remove CO2 that may remain in the economy. This makes nature-based solution’s ability to absorb CO2 from the atmosphere crucially important.
Nature and carbon sinks have kept Earth’s natural carbon cycle balanced since long before humans even stood upright. And they have a crucial role to play in removing CO2 that remains in the atmosphere even as industries strive to reduce their emissions.
How can forests work as nature-based ways of capturing carbon?
Forests remove carbon from the atmosphere using photosynthesis to capture CO2, using the carbon as a source of energy while releasing oxygen. A 2014 study found that the world’s forests had absorbed as much as 30% of annual global human-generated CO2 emissions over the previous few decades. Forests are some of the earth’s most important carbon sinks, but face threats such as creeping urbanisation. Protecting and managing forests is an important part of ensuring they continue to remove CO2 from the atmosphere.
Afforestation is the establishing of a new forest while reforestation is the restoration of a forest where trees have been lost. Afforestation and reforestation require significant planting and maintenance of trees, but offer additional benefits of reducing the chances of desertification and flooding.
Improved forest management also increases the productivity of forests with activities like thinning diseased or suppressed trees. This is because young trees absorb more CO2 to fuel their growth than more mature forests that do not grow at the same rate.
What other ways can the land capture CO2?
Forests are not the only way land can be used to remove CO2 from the atmosphere. Soil all over the Earth’s surface is a massive carbon sink. Simple changes in farming methods can better protect soil and enable it to continue serving as a sources of carbon removal and storage. Such methods include rotating crops and reviving grasslands, which create larger volumes of plant biomass that decay and store more carbon in the soil.
The effectiveness of soil as a carbon sink can be enhanced further by using a substance called biochar. Biochar is a high-carbon form of charcoal, made by burning biomass like wood or agricultural waste in a zero-oxygen environment. When this charcoal is added to soil, more of the carbon absorbed will remain locked in it.
And soil isn’t the only earth-based natural substance that absorbs CO2 – rocks can, too. As they are rained on, weather and erode, rocks naturally absorb carbon. The bicarbonate that is produced is washed into the sea and is eventually stored on the seabed. This process can be enhanced by grinding rock into powder and spreading it over a large area.
How can restoring environments remove carbon?
Mangroves on coasts and riverbanks, as well as salt marshes and sea grasses offer another major source of carbon removal and storage. When protected or restored these coastal ecosystems, which cover 490,000 km2 of the earth, can absorb and store huge amounts of what is referred to as ‘blue carbon’ – in fact, they have the ability to sequester carbon at a faster rate than other types of vegetation.
The regeneration of peatlands, a type of wetland including bogs and swamp forests, is also an important way of creating carbon sinks. Peatlands cover more than 3 million km2 around 3% of the world’s surface, and sequester 0.37 billion gigatonnes of CO2 per year.
What other types of solutions are there?
It’s difficult to predict CO2 levels that will remain in the UK economy. The National Grid’s 2020 Future Energy Scenarios (FES) Report, lays out a Steady Progress scenario in which decarbonisation is slow and limited to power and transport sectors. In this forecast there is still 258 million tonnes of CO2 being emitted in 2050.
Nature-based solutions’ ability to remove CO2 at such a scale can be limited by factors such as the land use needed, which can encroach on food crops for example. Nature based solutions are do not always offer permanent removal of CO2. Forest fires for example would release carbon stored in forests, damaging their ability to remove emissions.
Achieving the levels of carbon capture needed to reach net zero will require a variety of nature-based techniques and technologies are needed, all working in tandem to achieve a net zero future.
Man-made technologies include carbon capture methods such as bioenergy with carbon capture and storage (BECCS) and direct air carbon capture and storage (DACCS). But it can also include methods such as using wood or low-carbon concrete in construction There are more ambitious innovations at play too, such as stratospheric aerosols, cloud seeding, space mirrors, and painting surfaces with a reflective coating.
- Afforestation and reforestation have the potential to capture between 5 and 3.6 billion tonnes of CO2every year at a cost of between £3.90 and £39 per tonne.
- UK Woodland, set up by the UK Government, has 13,000 hectares validated and more than 5,000 projects forestry registered, which will lead to 8 million tonnes of carbon being sequestered annually.
- Apple has invested in mangrove forests as a means of carbon offsetting its operations.
- Natural rock weathering currently absorbs around 0.3% of global fossil fuel emissions annually, and can also helping to counteract ocean acidification once minerals are sweep to costal regions.
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