Trees are the coolest source of CO2 Removal on the planet.
Trees and vegetation are known to help cool ambient air temperatures through evapotranspiration. If left undisturbed, forests can also be a vital source of carbon storage. Estimates from the Global Forest Resources Assessment (FRA 2015) show that the world’s forests and other wooded lands store more than 485 gigatonnes (Gt) of carbon: 260 Gt in the biomass, 37 Gt in dead wood and litter, and 189 Gt in the soil.
In the most recent IPCC Special Report Summary for Policymakers (SPM), the world’s leading climate scientists assess the pathways the global community can pursue over the next few decades to prevent overshoot of warming beyond 1.5°C. The fact that all pathways to limit global warming to 1.5°C require mitigation via some form of Carbon Dioxide Removal (CDR) is not to be overlooked. But these removal amounts vary across pathways, as do the relative contributions of Bioenergy with Carbon Capture and Storage (BECCS) and removals in the Agriculture, Forestry and Other Land Use (AFOLU) sector. BECCS sequestration is projected to range from 0-1, 0-8, and 0-16 GtCO2/yr, in 2030, 2050, and 2100 respectively; the AFOLU-related measures are projected to remove 0-5, 1-11, and 1-5 GtCO2/yr in these years. These contributions appear meager, and they are… but every little bit counts in this climate.
A reasonable argument can be made for increased investment in and use of CCS to achieve emissions reductions. The SPM makes it clear that forests alone won’t be able to make a significant numerical difference in reduction of CO2 from the atmosphere. And as the New York Times aptly points out, “the world is currently much better at cutting down forests than planting new ones.”
On the surface, CCS seems like a logical outgrowth from the nature of GHG emissions production. The IPCC’s Special Report on Climate Capture and Storage (SRCCS) describes CCS as a mitigation activity that separates CO2 from large industrial and energy-related point sources, which has the potential to capture 85-95% of the CO2 processed in a capture plant. Direct Air Capture (DAC) technologies like ClimeWorks remove CO2 from the air. Proponents argue that DAC is a much less land-intensive process than afforestation: Removal of 8 Gt/CO2 would require 6.4 million km² of forested land and 730 km³ of water, while DAC would directly require only 15,800 km² and no water.
However, as our blog has cautioned readers in the past, CCS requires significant financial investments from industry and government and are only regionally accessible. Only places that have sufficient infrastructure and political support can pursue this path of technological sequestration, leaving underdeveloped countries at a major disadvantage. A recent report published in Nature Research further emphasizes that BECCS will have significant negative implications for the Earth’s planetary boundaries, or thresholds that humanity should avoid crossing with respect to Earth and her sensitive biophysical subsystems and processes. Transgressing these boundaries will increase the risk of irreversible climate change, such as the loss of major ice sheets, accelerated sea level rise, and abrupt shifts in forest and agricultural systems. Above all else, CCS ultimately supports the continual burning of fossil fuels. CCS technology may capture carbon, but it also has the potential to push us over the edge.
Mitigation has historically been the focus of the FCCC and other collaborative climate change efforts. Global climate change policy experts are familiar with the binding language associated with activities related to mitigation in the multilateral environmental agreements: Article 4(1)(b) of the Convention calls for commitments to formulate, implement, publish and update national programs containing measures to mitigate climate change; and Article 3 of the Kyoto Protocol (KP) calls for Annex I Parties to account for their emissions reductions in order to promote accountability and activity guided by mindful emissions production. In the waning hours of the KP, the Paris Agreement has become the new collective rallying document, whose ambitious emissions reduction target has inspired the likes of the IPCC to offer us pathways to get there.
If we are not currently on track towards limiting GHG emissions well-below 2°C in the grand scheme of the FCCC, why not insure some success, however small, buy securing CO2 in forests, not CCS? Forests are a well-established CDR technology that do not have the associated risks with CCS. While the most recent UN Forum on Forests report kindly reminds us that forests are also crucial for food, water, wood, health, energy, and biodiversity, the SPM upholds that mitigation contributions from carbon sequestration technology are numerically minuscule in the face of the large-scale change necessary to avoid CO2 overload. A much more engaged energy overhaul is needed.
The ideal SPM pathway states that afforestation can be the only CDR option when social, business, and technological innovations result in lower energy demand and a decarbonized energy system. A more middle-of-the-road scenario achieves necessary emissions reductions mainly by changing the way in which energy and products are produced, and to a lesser degree by reductions in demand. This speaks to the need for a broad focus on sustainable development rather than continuing business as usual. Regardless of the pathway, forests need to be preserved, whether it be for carbon sequestration, their cooling effects, or merely beauty.
Sometimes there is no turning back.