Perspectives in 2021

Net-zero emissions is more than a concept of physical climate science. It is implemented in social, political and economic contexts. This Perspective proposes seven attributes that are critical for the practical and effective implementation of net zero.

Natural climate solutions, along with reduction in fossil fuel emissions, are critical to mitigating climate change and meeting climate goals. This Perspective outlines a hierarchy for decision-making regarding protecting, managing and then restoring natural systems for climate mitigation.

Assessing the cost of climate change mitigation is essential to policy-making, yet for many the perception remains that meeting climate goals will entail economic loss. This Perspective unpacks key aspects of mitigation cost estimates to clarify interpretation and discussion of costs.

Carbon capture and storage is key to strong climate change mitigation scenarios, but growth is slow. This Perspective argues that confidence in the expansion of carbon capture and storage requires greater attention to reducing uncertainty over injection dynamics and the pace of storage investment decision-making.

Disclosure of climate risk to investments was expected to drive divestment from high-carbon assets. This Perspective considers the limitations of transparency to shift investment and the different markets of low- and high-carbon assets; mobilizing finance requires more than disclosure.

Uncertainty in estimates of the economic impacts of climate change makes it difficult to evaluate the benefits of mitigation. This Perspective reviews methods for determining economic damages from biophysical impacts, highlights critical gaps and suggests priorities moving forward.

There is no common structure for the way national emissions scenarios are created, hindering efforts for comparison and analysis at the larger scale. This Perspective presents a framework to guide individual national scenario creation in a standardized way.

E-fuels—hydrocarbon fuels synthesized from green hydrogen—can replace fossil fuels. This Perspective highlights the opportunities and risks of e-fuels, and concludes that hydrogen and e-fuels should be prioritized for sectors inaccessible to direct electrification.

Contributions to mitigate climate change should be equitable under the Paris Agreement, yet researchers take sharply diverging approaches to assessing national effort. This Perspective evaluates the literature and presents guidelines for policy-relevant—and ethically explicit—research on equity.

Aerosol–climate interactions are important in the Arctic, but they exhibit large spatiotemporal variability. This Perspective argues for community-driven model and observational improvement, emphasizing the need to understand natural aerosol processes and quantify how their baseline is changing.

Assessing future climate-related financial risk requires knowledge of how the climate will change at various spatial and temporal scales. This Perspective examines the demand for climate information from business and finance communities, and the extent to which climate models can meet these demands.