Description: The crises of climate change and biodiversity loss are interlinked and must be addressed jointly. A proposed solution for reducing reliance on fossil fuels, and thus mitigating climate change, is the transition from conventional combustion-engine to electric vehicles. This transition currently requires additional mineral resources, such as nickel and cobalt used in car batteries, presently obtained from land-based mines. Most options to meet this demand are associated with some biodiversity loss. One proposal is to mine the deep seabed, a vast, relatively pristine and mostly unexplored region of our planet. Few comparisons of environmental impacts of solely expanding land-based mining versus extending mining to the deep seabed for the additional resources exist and for biodiversity only qualitative. Here, we present a framework that facilitates a holistic comparison of relative ecosystem impacts by mining, using empirical data from relevant environmental metrics. This framework (Environmental Impact Wheel) includes a suite of physicochemical and biological components, rather than a few selected metrics, surrogates, or proxies. It is modified from the “recovery wheel” presented in the International Standards for the Practice of Ecological Restoration to address impacts rather than recovery. The wheel includes six attributes (physical condition, community composition, structural diversity, ecosystem function, external exchanges and absence of threats). Each has 3–5 sub attributes, in turn measured with several indicators. The framework includes five steps: (1) identifying geographic scope; (2) identifying relevant spatiotemporal scales; (3) selecting relevant indicators for each sub-attribute; (4) aggregating changes in indicators to scores; and (5) generating Environmental Impact Wheels for targeted comparisons. To move forward comparisons of land-based with deep seabed mining, thresholds of the indicators that reflect the range in severity of environmental impacts are needed. Indicators should be based on clearly articulated environmental goals, with objectives and targets that are specific, measurable, achievable, relevant, and time bound.

Description: The IPCC Sixth Assessment Report has highlighted the multi-century response time of global mean sea level rise associated with anthropogenic climate forcing since pre-industrial times. It is challenging to adequately assess future sea level rise impacts under different emissions scenarios due to large physical process uncertainties that rapidly increase over these timescales. Nevertheless, it is important to explore the multi-century sea level response due to the profound risks that sea level rise poses for low-lying coastal regions around the world. Here, we use two different climate and sea level emulators to investigate multi-century sea level rise commitments for cumulative emission levels at the start of the remaining 21st century decades under the five illustrative SSP-RCP scenarios. Preliminary results indicate that emissions until 2030 “lock in” around 0.61 m (66% model range: 0.33 to 0.91 m) of global mean sea level rise in 2300 relative to 1995-2014 under an intermediate emissions scenario (SSP2-4.5). Corresponding median global sea level commitments for cumulative emissions in 2050 (0.84 m) and 2100 (1.40 m) are around 0.18 m and 0.73 m higher than under a very low emissions scenario (SSP1-1.9). Global results are also downscaled to selected regional sites to illustrate locally-committed sea level rise. The presented work not only informs questions around how much sea level rise is “locked in” and could still be avoided through stringent mitigation but can also be used by practitioners to feed into assessments of minimum adaptation requirements.