Polar chimneys

Surface albedo has a significant impact on global climate (Zhang et al. 2022). Plants play an important role in this. Matthews et al. (2003), for example, estimate that the spread of agriculture has led to a global cooling of around 0.17°C, as agricultural crops tend to have a higher albedo than wild vegetation (Monteith and Unsworth 1990).

Biotic processes play an important role in oceanic carbon uptake, with most attention going  to carbon-consuming photosynthesising organisms. Moore et al. (2023) argue that the potential role of shellfish and other calcifiers in carbon sequestration is significantly overlooked in the CDR literature.

Black Carbon (BC), also known as soot, is produced through the incomplete combustion of fossil fuels and biomaterials. Apart from its negative health impacts, BC also has significant climate effects because it generally has a lower albedo than its surroundings, which increases the amount of radiation absorbed both when BC is present in the atmosphere and when it is deposited on land (Stjern et al. 2017). Due to the large albedo differences, the effects of BC are especially significant in areas that are normally covered in snow or ice (Hadley and Kirchstetter 2012; Sand et al. 2016; Kang et al. 2020).

Roughly one-third of the incoming solar radiation is directly reflected back into space by the Earth’s atmosphere and surface albedo. Clouds play an important role in this, although their role is double as water droplets can also interfere with outgoing longwave radiation, thereby contributing to the greenhouse effect. Over open water clouds can make a particularly big difference as the albedo of the water is below 0.1, thereby absorbing most of the sun’s energy.

There have been several isolated suggestions to mitigate permafrost thaw or influence the thaw processes in the active layer by physically covering the surface with materials (see for example https://groups.google.com/g/geoengineering/c/u2b9Xb5B0C8/m/aXQia-nNDbcJ) in a similar way to how glaciers might be preserved (see Glacier Insulation, and Passive Radiative Cooling). Although different materials have been suggested, these have not been worked out further, and are likely to be a very costly, and impractical solution.

Wetlands and peatlands play important roles in global carbon cycles. Wetlands are areas that are seasonally covered by water. Globally mangroves are often the main topic of focus when it comes to wetlands (IPCC AR6 WG3, 2022, 7.4.2.8). In the Arctic and Northern regions, peatlands are important wetland elements, and will be the focus of what follows. Such peatlands are very carbon rich and store carbon in biomass below and above ground and in soil carbon. Although they only make up 3% of the Earth’s surface, peatlands store up to 21% of terrestrial carbon, and damaged peatlands contribute close to 5% of anthropogenic CO2 emissions (Leifeld et al. 2019). Peatland drainage between 1850 and 2015 has globally already released 80 Gt CO2-eq, and this figure may climb to 250 Gt CO2-eq by 2100 (Leifeld et al. 2019).

Compared to the global state of such areas, Arctic and Northern wetlands and peatlands remain relatively intact (UNEP 2021), and only around 2% of boreal peatlands are currently converted into croplands (Leifeld and Menichetti 2018). However, increasing attention is being paid to the importance of restoring destroyed areas, which make up 78% of total global peatlands, and preserving endangered ones, especially in light of the effects of climate change on such ecosystems. The Resilience and Management of Arctic Wetlands notes (CAFF 2021) therefore highlight the need for increased wetlands resilience to protect against future damage.

Zeolites are porous minerals that can capture methane (Jackson 2019).

Fire is important to the healthy functioning of boreal ecosystems. However, as wildfires increase, they release greater amounts of GHGs into the atmosphere, contributing to climate change. While boreal fires typically contribute 10% of global CO2 emissions, in 2021, an extreme fire year, they accounted for 23% of global emissions (Zheng et al. 2023). Particulate matter in wildfire smoke (soot or black carbon, see also Black carbon mitigation) can also reduce albedo on sea ice and glaciers, enhancing ice melt (e.g., Aubry-Wake et al. 2022). Wildfires are projected to increase in both frequency and intensity over the coming decades (UNEP 2022). By 2050, wildfires in North American boreal forests alone could contribute close to 12 Gt CO2, almost 3% of the remaining global CO2 emissions to keep temperatures to below 1.5oC (Phillips et al. 2022a).