Reviews & Analysis

As temperatures rise, plants unfold their leaves earlier in spring, but whether plant roots respond similarly is seldom quantified. Now, a meta-analysis suggests that leaf and root phenology do not respond to warming in the same way, even within the same plant types.

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.

The climate system may respond in different ways to reductions in atmospheric CO₂ concentrations. Work now shows a delayed recovery (hysteresis) of the tropical rainbelt, with widespread implications for water resources.

Flooding-adaptation studies often ignore unique social, cultural and institutional drivers. Now, research illuminates the drivers that are unique versus shared across socio-cultural contexts and adaptations, which vary in ease of implementation.

Most emissions scenarios in line with the Paris Agreement have shown a large amount of net-negative CO₂ emissions during the second half of this century. A new set of scenarios expands this picture.

Eastward flow in the Southern Ocean is the primary conduit between ocean basins. A comprehensive study of multi-decadal observational records and model experiments reveals that warming in the upper ocean is causing this flow to accelerate.

We find that if all countries adopt the necessary uniform global carbon tax and then return the revenues to their citizens on an equal per capita basis, it will be possible to meet a 2 °C target while also increasing wellbeing, reducing inequality and alleviating poverty. These results indicate that it is possible for a society to implement strong climate action without compromising goals for equity and development.

Finding effective ways to support rural communities in adapting to climate change is critical for building climate-resilient societies. Now research shows the potential of risk-transfer policies for improving adaptation and securing the livelihoods of smallholder farmers.

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.

Climate change is threatening agricultural productivity and the welfare of farmers. Increasing employment in non-farm sectors could mitigate such negative impacts, especially in developing countries.

Assessing the global implementation of climate adaptation is critical. Now, research quantifies where adaptation is happening and where gaps remain.

Trade liberalization in the early 21st century increased the adaptation capacity of global food systems to climate change; further liberalization and trade facilitation could help to avoid dozens of millions being undernourished at mid-century. The global trade agenda should explicitly include climate change adaptation to achieve SDG 2 Zero Hunger.

Southern salmon populations face increased risk from a warming climate. New analysis of salmon ear bones shows outsized reliance on rarely used cold-water habitat for population survival through drought years — habitat that is expected to shrink under climate change.

Subscriptions to a free, weekly deforestation alert system available on the simple interface Global Forest Watch reduced deforestation in the protected areas and logging concessions of tropical African forests. This suggests that freely available near-real-time forest monitoring systems can help reduce emissions from deforestation if they are integrated with forest policies.

We find that the public prefers the costs of climate action to be constant over time, irrespective of whether average costs are low or high. Policymakers interested in combating global warming should therefore introduce policies that initially rely on stable cost schedules instead of the widely discussed alternative of ramping up costs over time.

Using a multi-sector model of human and natural systems, we find that the nationwide cost from state-varying climate policy in the United States is only one-tenth higher than that of nationally uniform policy. The benefits of state-led action — leadership, experimentation and the practical reality that states implement policy more reliably than the federal government — do not necessarily come with a high economic cost.

Improvements in public transport are often regarded as essential to combat climate change. A study investigating the Chinese high-speed rail system suggests that these benefits could operate through channels other than those that one might expect.

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.