Despite warnings from scientists worldwide, policymakers and corporations continue to rely on natural carbon sinks such as lands and oceans to compensate for their fossil fuel emissions. This assumption comes from an understanding of the active participation of land in the flows of elemental life components such as carbon, nitrogen, water, and oxygen. Greenhouse Gases (GHGs) like carbon dioxide are perpetually released and removed from the atmosphere through a natural cycle involving these ‘sinks’.
Land, particularly plants and healthy ecosystems, possesses an extraordinary capability to absorb carbon through photosynthesis and store it in living biomass. Statistics reveal that about 56% of human-emitted carbon dioxide is absorbed by oceans and land, with land accounting for approximately 30% of this figure.
Acknowledgment of Land’s Role in Curbing CO2 Emissions
The United Nations Framework Convention on Climate Change (UNFCCC) recognised the role of land (forests and agricultural land) as a mitigation pathway to reduce CO2 emissions in 1992. The 1997 Kyoto Protocol further solidified this recognition. It advocated that governments should implement policies to augment the carbon sink capacities of their territories and offset these enhancements against requirements for reductions in emissions resulting from fossil fuel consumption.
Recent data from The Intergovernmental Panel on Climate Change (IPCC) in 2019 revealed that land use generated 13% of anthropogenic CO2 emissions during 2007-2016. However, it also served as a net sink of around 11.2 gigatonnes of carbon dioxide per year, corresponding to 29% of the total CO2 emissions in the same period. Essentially, over the last three decades, around 29-30% of human-induced CO2 emissions have been absorbed by global land sinks.
Increasing Concerns Over the Effectiveness of Land Sinks
Despite their significant role, there are increasing concerns about the effectiveness of land sinks in combating global warming. Rising heat levels contribute to moisture stress in forests and lead to widespread burning. Combined with deforestation for economic activities, this results in a reduction of forests’ role as CO2 sinks.
In addition to human-induced factors like deforestation, natural variation in sunshine, temperature, and rainfall can also affect the strength of the land carbon sink while rising CO2 concentration remains a concern. According to the IPCC’s Climate Change 2021 Report, CO2 emissions are at their highest in at least two million years, with humans emitting 2,400 billion tonnes of CO2 since the late 1800s.
Possible Solutions to Enhance Natural Carbon Sinks’ Efficiency
To maintain global temperatures within 1.5°C above pre-industrial levels, as per the Paris Agreement, we need to decrease GHG emissions significantly. Part of the solution includes enhancing methods to remove emissions from the atmosphere, such as growing more trees. However, an equally important step involves transitioning from fossil fuels to renewable energy sources – ultimately eliminating the use of fossil fuels.
Artificial carbon sequestration technologies present another possibility. These technologies aim at efficiently capturing large amounts of carbon, converting it, and storing it for thousands of years. This technology encompasses passing air through a stack of electrically charged electrochemical plates and could provide a viable environmental and economic case for using coal in the future.
Global Initiatives Complementing Natural Carbon Sink Enhancement
Various global initiatives aim to complement the efforts to enhance carbon sinks. The Bonn Challenge is one such initiative which seeks to restore 150 million hectares of the world’s deforested and degraded land by 2020, and 350 million hectares by 2030. The United Nation General Assembly declared 2021-2030 as the UN Decade on Ecosystem Restoration to “prevent, halt and reverse the degradation of ecosystems worldwide”. The LEAF Coalition, led by the US, the UK, and Norway, aims to mobilise at least USD 1 billion in financing countries dedicated to protecting their tropical forests.