Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide (CO2) to reduce its concentration in the atmosphere and mitigate the greenhouse effect. Some common methodologies for carbon sequestration include:

1. Afforestation and reforestation: Planting trees and other vegetation can absorb CO2 from the atmosphere as they grow. The carbon is stored in the trees and other plant material, as well as in the soil. This method is relatively inexpensive and can be implemented on a large scale. However, it can take decades for trees to mature and begin sequestering significant amounts of carbon.
2. Soil carbon sequestration: Carbon can be sequestered in soil through practices such as no-till farming, cover cropping, and manure management. These practices can increase the amount of organic matter in the soil, which can sequester carbon. Soil carbon sequestration can be relatively inexpensive and can be implemented on a large scale, but the amount of carbon that can be sequestered is limited.
3. Carbon capture and storage (CCS): CCS involves capturing CO2 emissions from power plants and other industrial sources, and then storing the CO2 in underground geological formations or oceans. CCS is an expensive and technically challenging method, but it has the potential to sequester large amounts of carbon.
4. Biochar: Biochar is a form of charcoal that is produced by heating organic matter in the absence of oxygen. Biochar can be used as a soil amendment, and it has the potential to sequester carbon for hundreds or even thousands of years. Biochar is a relatively new technology, and more research is needed to fully understand its potential for carbon sequestration.
5. Ocean fertilization: Some researchers are exploring the use of ocean fertilization as a method of sequestering carbon. This involves adding nutrients to the ocean, which can stimulate the growth of phytoplankton, which absorb CO2 from the atmosphere as they grow. Ocean fertilization is a relatively new and controversial method, and more research is needed to fully understand its potential for carbon sequestration.

There are pros and cons to each of these methodologies for carbon sequestration, and no single method is likely to be a complete solution to the problem of climate change. Instead, it is likely that a combination of different methodologies will be needed to effectively sequester carbon and mitigate the greenhouse effect.