Carbon Sequestration for Climate Change Mitigation

IPCC defines mitigation of climate change as a human intervention to reduce the sources or enhance the sinks of greenhouse gases. Carbon dioxide as the most easily controlled of the greenhouse gases to be removed and subsequently stored away from the atmosphere. A global forum IPCC members countries, almost every country around the world come up with an agreement to control global warming 1.5‎°C limit based on the pre-industrial level in 2015. The agreement is recognized as the Paris Agreement which demonstrated the political will to limit global temperature rise and other climate impacts with carbon dioxide removal (negative emission: decrease emission rate and remove past emissions as well) on a massive scale (hundreds of billions of tonnes of CO₂ in the period to 2100) from the atmosphere.
Global Warming or climate change are hot topics these days. All the human civilization's future, welfare depends on action relay on the action taken by each individual nation for Climate change mitigation and carbon sequestration to control the production of greenhouse gases mainly CO₂. First, prioritize should be given to reduce greenhouse gas emissions rapidly and deeply as when there is less emission entering into the atmosphere than less need for carbon dioxide removal. So, removal of CO₂ must not delay and pathways that rapidly cut emission must be prioritized.

Carbon dioxide emission

There are many approaches to control carbon dioxide emission and remove excess carbon dioxide from the atmosphere on a very large scale. But the risk they carry and their social acceptability differ depending on the context. A single approach alone may not have full removal solution. However, the approaches which remove carbon dioxide from the atmosphere and permanently sequestrate it in nature with proven benefits to people, the environment as well as climate. The reliability, cost and benefits, impacts, and risks of many approaches are not well understood so, further research is essential before they ascertain as a part of the climate solution. While implementing carbon dioxide removal approaches it is required to minimize negative consequences to environmental and social values.

Approaches to Sequestrate Carbon for Climate Change Mitigation
A. Low cost approaches
a. Enhancement of forest carbon stocks through

• Restoration of the ecological functioning of degraded forest landscapes or low productive land by promoting multifunctional landscapes, including reforestation and afforestation. This help to store atmospheric carbon dioxide into tree stem and forest ground. 
• Natural regeneration of forests, assisted so that it sustains ecological balance as well.

b. Enhancement of soil carbon through:

Carbon sequestration in agricultural land to enhance soil quality and productivity of the farm.

Soil sequestration using sustainable production of biochar.

B. The balance between costs and benefits but unknown risks are not yet clear.

• Afforestation on non-degraded land which may produce negative social impacts which may not compensate for the opportunity costs of land conversion.
• Bioenergy with carbon capture and storage is land-intensive which limited in spatial suitability but in appropriate circumstances with adequate safeguards, provide carbon dioxide removal.
• Direct air capture and storage is expensive and energy-intensive but has large potential and fewer and less severe land-competition impacts. It is fully an engineered approach with geological storage.
• Permanently storing a sizable amount of carbon dioxide by enhancing weathering of minerals on land in larger volume to reduce negative impacts from mining and transportation.

C. Not suitable at the current time due to ecological and social uncertainties far outweigh the known benefits.

• Large-scale ocean fertilization has a high potential for carbon sequestration but has damaging side effects for ocean ecosystems. It is fully engineered approaches with ocean storage.
• Enhanced weathering of minerals added to the oceans appears to have environmental and other costs that outweigh the potential climate benefits. 

Alternative mitigation ways to reduce carbon dioxide removal may be possible by reducing excessive land use for food production, bioenergy or both by increasing efficiency in agriculture. Changing lifestyle reduces 20 - 25 % pasture and cropland to produce animal feed resulting from a reduction in meat consumption which provides space for the forest which ultimately becomes carbon storage.

This article is a brief summary of Position Paper "Carbon dioxide removal, including Carbons Sequestration in Natural Systems" by WWF, Climate and Energy Department published in September 2018.