News & Comment

The tendency of modern science to reduce complex phenomena into their component parts has many advantages for advancing knowledge. However, such reductionism in climate science is also a problem because it narrows the evidence base, limiting visions of possible futures and the ways they might be achieved.

Extensive evidence reveals that Earth’s snow cover is declining, but our ability to monitor trends in mountain regions is limited. New satellite missions with robust snow water equivalent retrievals are needed to fill this gap.

The current focus on the long-term global warming potential in climate policy-making runs the risk of mitigation options for short-lived climate pollutants being ignored, and tipping points being crossed. We outline how a more balanced perspective on long- and short-lived climate pollutants could become politically feasible.

Indigenous reindeer herding in the circumpolar North is threatened by multiple drivers of environmental and social changes that affect the sustainability of traditional family-based nomadic use of pastures. These impacts are exacerbated by indigenous peoples’ lack of voice in governance strategies, management and adaptation responses.

Bitcoin is a power-hungry cryptocurrency that is increasingly used as an investment and payment system. Here we show that projected Bitcoin usage, should it follow the rate of adoption of other broadly adopted technologies, could alone produce enough CO₂ emissions to push warming above 2 °C within less than three decades.

Scenarios have supported assessments of the IPCC for decades. A new scenario ensemble and a suite of visualization and analysis tools is now made available alongside the IPCC 1.5 °C Special Report to improve transparency and re-use of scenario data across research communities.

Climate change mitigation scenarios are finding a wider set of users, including companies and financial institutions. Increased collaboration between scenario producers and these new communities will be mutually beneficial, educating companies and investors on climate risks while grounding climate science in real-world needs.

Biological communities beneath Antarctic ice shelves remain a mystery, hampering assessment of ecosystem development after ice-shelf collapse. Here we highlight major gaps in understanding of the patterns and processes in these areas, and suggest effective ways to study the ecological impacts of ice-shelf loss under climate change.

Climate change will almost certainly cause millions of deaths. Climate engineering might prevent this, but benefits — and risks — remain mostly unevaluated. Now is the time to bring planetary health research into climate engineering conversations.

The SDGs and CitiesIPCC offer an unprecedented opportunity for urban transformation, but bold, integrated action to address the constraints imposed by economic, cultural and political dynamics is needed. We move beyond a narrow, technocentric view and identify five key knowledge pathways to catalyse urban transformation.

Transformation is required for cities to fulfil their leadership potential on climate change. Five action pathways can guide them: integrate mitigation and adaptation; coordinate risk reduction and climate adaptation; cogenerate risk information; focus on disadvantaged populations; and improve governance and knowledge networks.

To realize ambitious climate targets, research should focus more on effective ways to encourage rapid and wide-scale changes in climate mitigation actions, and less on understanding climate change beliefs.

With country-specific development objectives and constraints, multiple market failures and limited international transfers, carbon prices do not need to be uniform across countries, but must be part of broader policy packages.

A well-defined relationship between global mean sea-level rise and cumulative carbon emissions can be used to inform policy about emission limits to prevent dangerous and essentially permanent anthropogenic interference with the climate system.

The atmospheric concentration of CO₂ at the time of passing 1.5 °C or 2 °C is unknown due to uncertainties in climate sensitivity and the concentrations of other GHGs. Impacts studies must account for a wide range of concentrations to avoid either over- or underestimating changes in crop yields and land and marine biodiversity.

Climate change-driven alterations in storminess pose a significant threat to global capture fisheries. Understanding how storms interact with fishery social-ecological systems can inform adaptive action and help to reduce the vulnerability of those dependent on fisheries for life and livelihood.

The benefits of limiting global warming to the lower Paris Agreement target of 1.5 °C are substantial with respect to population exposure to heat, and should impel countries to strive towards greater emissions reductions.

In key European cities, stabilizing climate warming at 1.5 °C would decrease extreme heat-related mortality by 15–22% per summer compared with stabilization at 2 °C.

Low-probability, high-consequence climate change events are likely to trigger management responses that are based on the demand for immediate action from those affected. However, these responses may be inefficient and even maladaptive in the long term.

New international governance arrangements that manage environmental risk and potential conflicts of interests are needed to facilitate negative emissions research that is essential to achieving the large-scale CO₂ removal implied by the Paris Agreement targets.