Perspectives in 2020

The SSP–RCP scenario framework has been an important component of physical, social and integrated climate change research for the past decade. This Perspective reviews the successes of the framework and the challenges it faces, and provides suggestions for improvement moving forward.

The Arctic is warming and undergoing rapid ice loss. This Perspective considers how changes in sea ice will impact the biogeochemistry and associated ecosystems of the region while calling for more observations to improve our understanding of this complex system.

As road transport emissions are set to grow, stronger policy mixes are needed to reach mitigation goals. This Perspective considers the evidence for several policy types—strong regulation, pricing and reduced travel—and the best combination to reduce emissions for passenger and freight vehicles.

In recent decades, the Arctic has warmed at over twice the global rate. This Perspective places these trends into the context of abrupt Dansgaard–Oeschger warming events in the palaeoclimate record, arguing that the contemporary Arctic is undergoing comparably abrupt climate change.

Reference scenarios are used to evaluate different mitigation scenarios, allowing understanding of their relative strengths and weaknesses. This Perspective considers the appropriate use of reference scenarios in mitigation analysis across different policy contexts.

The impacts of extreme weather and climate can be amplified by physical interactions among events and across a complex set of societal factors. This Perspective discusses the concept and challenge of connected extreme events, exploring research approaches and decision-making strategies.

This Perspective maps the history of climate targets and shows how the international goal of avoiding dangerous climate change has been reinterpreted in the light of new modelling methods and technological promises, ultimately enabling policy prevarication and limiting mitigation.

In order to limit warming and the most severe consequences of climate change, net global carbon emissions must reach zero by 2050. Many ecosystems contain carbon that would be irrecoverable on this timescale if lost and must be protected to meet climate goals.

Climate change and other human activities are decreasing ocean oxygen content. This Perspective considers the limited data on effects to coral reefs, including oxygen thresholds for lethal and sub-lethal effects in coral reef taxa, and proposes key research questions to address this critical issue.

Climate change detection is confounded by internal variability, but recent initial-condition large ensembles (LEs) have begun addressing this issue. This Perspective discusses the value of multi-model LEs, the challenges of providing them and their role in future climate change research.

Flash droughts, which develop over the course of weeks, are difficult to forecast given the current state of subseasonal-to-seasonal prediction. This Perspective offers operational and research definitions, places them in the broader context of climate and suggests avenues for future research.

As tundra ecosystems respond to rapid Arctic warming, satellite records suggest a widespread greening. This Perspective highlights the challenges of interpreting complex Arctic greening trends and provides direction for future research by combining ecological and remote sensing approaches.