After net zero carbon dioxide emissions are reached, we must continue to remove carbon dioxide

Sunnuntai 24.11.2024 klo 14.46 - Mikko Nikinmaa

It has recently been modelled that even after net zero carbon dioxide emissions are reached, temperatures continue to increase, largely because the seawater continues to warm up deeper and deeper. This will then cause a net increase in atmospheric temperatures. Simultaneously, the increases in ocean temperature will cause large changes in the species distributions of both plants and animals with high certainty of extinction of many cold-water species. The duration and extent of temperature increase depends on when net zero is reached: the later that happens, the longer the duration of temperature increase and greater its extent. (King et al in Earth System Dynamics DOI: 10.5194/esd-15-1353-2024)

Consequently, the modelling adds to the urgency of climate action – essentially stopping the use of fossil fuels. And here is the big problem: although the renewable energy production increases very fast, its increase has not been fast enough with the result that world fossil fuel consumption is still increasing (although its proportion of the total energy production already decreases). Further, and this was the major setback of COP29 in Baku, the oil-producing countries try their best to downplay the role of fossil fuels in causing climate change.

Since carbon dioxide level continues to increase, and since temperature continues to increase even after no change in carbon dioxide level occurs, we must aim not only to net zero, but to a decrease in carbon dioxide to be able to keep temperature changes tolerable. Technical solutions “to plug the pipes” are planned, but at the moment most of the solutions are not feasible at the moment. Also, presently the removal of carbon dioxide by adding forests is not functioning. Rather, wood cutting, intentional forest fires and wildfires are causing the forest sector to be a net source rather than a net sink of carbon dioxide.

A feasible way of removing carbon dioxide would be to utilize seaweed, as suggested by Rowan Hooper in New Scientist (November 6, 2024). Algal growth removes carbon dioxide. If the algae are then harvested, and the harvest sunk to the bottom of the oceans, the carbon will be removed from circulation for hundreds or even thousands of years. The use of algae in carbon dioxide removal could involve either mechanical harvesters or genetically modified sea weed, which would sink to the bottom of the ocean after death.