Iceberg management

Arctic sea ice extent has rapidly decreased over the last few decades, with most multi-year ice disappearing altogether. This has already had major effects on local communities and ecosystems. The disappearance of the relatively reflective sea ice also leads to a dramatic decrease of albedo in the Arctic and subsequent high energy uptakes by the darker water during the Arctic summers.

The potential of carbon sequestration by marine based plants such as mangroves, seagrass and algae, often referred to as blue carbon, and the importance of better understanding it, has clearly been recognised (Mcleod et al. 2011). The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (2019) concluded blue carbon can play an important role in both climate regulation and adaptation. The term algae groups together several kinds of marine photosynthetic organisms. These are often subdivided into very small microalgae like phytoplankton, and larger macroalgae like kelp and seaweed. Although there is still large uncertainty about the total amount of carbon sequestered by these marine organisms, a recent estimate by Duarte et al. (2022) indicated that all macroalgae took in as much CO2 as the Amazon rainforest.

The concentration of GHGs in the atmosphere will have to be stabilized or lowered to mitigate or even reverse current global warming. To achieve this, current GHG emissions need to be reduced. Such mitigation strategies will however take time to deploy, and some emission sources will be difficult to mitigate. Moreover, since current atmospheric levels are already having a major warming effect, negative emission or Carbon Dioxide Removal (CDR) measures that reduce the amount of GHGs in the atmosphere are an active topic of research.

Although the rate of deforestation has slowed over the last few decades, the world is still losing forest cover (FAO 2020). Adequate management, protection, and restoration of existing forests, and the planting of unforested areas, play a crucial role in climate mitigation scenarios (IPCC AR6 WG3), and many countries now include forests in their climate mitigation targets (NDCs).The Northern and Arctic regions are essential in this endeavor since they are home to large swaths of boreal forests that make up 27% of total global forest area (FAO 2020).

An increase in GHGs in the atmosphere leads to a greater amount of outgoing infrared radiation from the earth being retained. There are several SRM ideas that seek to compensate for this by reflecting more radiation back to space.

Clouds play an important role in the Earth’s energy system. The effects of clouds are complex and diverse, often having simultaneous cooling and warming effects. Mixed-phase clouds (MPC) are clouds that contain water vapor, ice particles, and supercooled water droplets. MPCs are still poorly understood and 'notoriously difficult to represent in numerical weather prediction and climate models' (Korolev et al. 2017).

The concentration of GHGs in the atmosphere will have to be stabilized or lowered to mitigate or even reverse current global warming. To achieve this, current GHG emissions need to be reduced. Such mitigation strategies will however take time to deploy, and some emission sources will be difficult to mitigate. Moreover, since current atmospheric levels are already having a major warming effect, negative emission or Carbon Dioxide Removal (CDR) measures that reduce the amount of GHGs in the atmosphere are an active topic of research.

Cirrus clouds are high altitude ice clouds. They influence the Earth’s radiation budget as they reflect both incoming and outgoing radiation. However, they ultimately have a warming effect as they are more efficient at trapping outgoing longwave radiation (Kärcher 2017).