Promoting ocean calcifiers to sequester atmospheric carbon

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.

The deep waters in the Baltic are severely deoxygenated. Although the causes of the current state are complex, this is mainly a result of increased eutrophication from sewage and agricultural runoff from surrounding lands, which leads to extreme bioproductivity (Rolff et al. 2022). Some species manage to survive in the upper water layers, but many organisms living on the seafloor are severely impacted by the hypoxia, thereby influencing the health of a wide network of ecosystems and biochemical processes. There are attempts to reduce nutrient runoff into the Baltic (see for example: https://helcom.fi/baltic-sea-action-plan/). However, some argue these will be insufficient and argue for engineering solutions to the issue.

In many Arctic and Northern regions, domesticated or semi-domesticated reindeer (Rangifer tarandus) are the only large herbivores (Uboni et al. 2016). Reindeer play a crucial role in these ecosystems and in the livelihoods and traditions of multiple local and indigenous populations. In light of the major impact of climate change in the Arctic, the capacity of large herbivores to mitigate some of these effects is being explored. Herbivores can have different climate positive effects as they can reduce shrubification and slow ecosystem responses to climate change (Olofsson and Post 2018; Happonen et al. 2021), modify summer and winter surface albedo (te Beest et al. 2016), trample winter snow to thicken permafrost (Beer et al. 2020; Windirsch et al. 2022), and increase biomass and soil carbon sequestration (Ylänne et al. 2018; Ylänne et al. 2021; see also soil management).

Up to 50% of the world’s glaciers are set to disappear this century, with many more at risk if emission reduction targets are not met (Rounce et al. 2023).

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).

Up to 50% of the world’s glaciers are predicted to disappear this century, with many more at risk if emission reduction targets are not met (Rounce et al. 2023). Furthermore, the melting of mountain glaciers impacts the rates and seasonality of meltwater abundance and scarcity.