Volume 12 Issue 9, September 2022

Time is short to secure a liveable and sustainable future; yet, inaction from governments, industry and civil society is setting the course for 3.2 °C of warming, with all the cascading and catastrophic consequences that this implies. In this context, when does civil disobedience by scientists become justified?

Current greenhouse gas emissions will continue to affect the climate even after we reach net-zero emissions. We must understand how and prepare for a cooling planet.

Credibility is the cornerstone of international climate pledges; meanwhile, ambition is essential to reach the temperature targets. Research shows the flexibility of Paris agreements encourages countries to be ambitious yet maintain credible.

The impact of climate change on tropical Atlantic variability has been elusive, partly due to regional biases in climate models. Now, research shows that current models predict a robust weakening of sea surface temperature variance in the eastern tropical Atlantic, with repercussions for precipitation and climate in the area and beyond.

The Arctic is home to the largest surface water fraction of any terrestrial biome, containing thousands of low-lying lakes. Now, it appears that some Arctic lakes are drying due to rising air temperatures and autumn rains, causing permafrost to thaw and water bodies to drain.

Tree swallows are becoming smaller in response to climate change, but this isn’t driven by reduced growth as chicks. The overall picture is much more complicated, with climate effects impacting adults, juveniles, males and females differently.

Terrestrial water storage over the Tibetan Plateau is projected to sustain large net declines by 2060. Excess water losses in the Amu Darya and Indus basins present the most critical threats of water supply shortage in this region. These results could inform adaptation strategies under future climate change.

Even if greenhouse gas concentrations in the atmosphere are reduced to pre-industrial levels, the climate system might not return to its previous state. Quantification of the spatial patterns of climate hysteresis and reversibility reveals globally widespread irreversible changes in surface temperature and precipitation in response to anthropogenic CO₂ emissions.

Natural climate solutions (NCS) could counterbalance 6% of industrial CO₂ emissions in China throughout 2020–2030, by trapping carbon within ecosystems and reducing greenhouse gas emissions. Implementing 62% of these NCS would cost ≤US$50 per megagram of CO₂ equivalent. NCS can contribute substantially to climate mitigation if appropriate planning strategies are employed.

A comprehensive and systematic literature review reveals that over 58% of human pathogenic diseases are aggravated by climatic hazards that are sensitive to greenhouse gas emissions.

The success of international climate cooperation relies on whether national commitments are believable under the Paris Agreement. Based on the survey with experienced climate policy professionals, the authors explore the determinants of credibility of national commitments.

The Tibetan Plateau is an important source region of freshwater for large parts of Asia’s population. Here the authors quantify past and future terrestrial water-storage changes and find a large net loss in this region, with the Amu Darya and Indus basins as the most vulnerable hotspots.

Greenland ice sheet melt is currently the largest single contributor to sea-level rise. This work combines observations and theory to show that Greenland ice sheet imbalance with recent climate (2000–2019) has already committed at least 3.3% ice volume loss, equivalent to 274 mm of global sea-level rise.

The Atlantic Niño/Niña is an important mode of tropical climate variability, but how it changes with global warming is not clear. Here the authors use a comprehensive model ensemble to show that the Atlantic Niño/Niña system will probably weaken under greenhouse warming.

The Atlantic Niño is an important mode of tropical climate variability, but how it reacts to climate change is not well known due to model biases. Here the authors show a robust weakening of the Atlantic Niño of up to 24–48% under high emissions until the end of the century.

The Atlantic intertropical convergence zone can experience extreme northward shifts, with resultant precipitation changes. Model projections show the frequency of these extreme shifts will increase under climate change, driven by faster sea surface warming north of the Equator.

For some parts of the climate system, the response to declining CO₂ concentrations does not mirror that during the preceding increase. Here the authors quantify this effect for temperature and precipitation, and show that large areas of the world show an asymmetric response to CO₂ forcing.

The Arctic lowlands are characterized by a large number of lakes that cover a substantial part of the surface in some regions. Here, the authors apply a machine learning approach to satellite data to show that permafrost thaw since 2000 has caused a decline in surface water in these regions.

Managing natural systems to mitigation climate change is a key strategy for limiting warming. In China, such natural climate solutions could offset 6% of CO₂ emissions during 2020–2030, contributing to mitigation goals but highlighting the importance of emissions reductions.

The authors develop a climate risk index for marine species under two emission scenarios and find that exploited species in low-income countries have the greatest risk under the high emissions scenario. Mitigating emissions reduces risks, enhances ecosystem stability and benefits low-income countries that depend on fisheries.

The authors reveal the complex interplay of factors influencing climate-related body-size changes in tree swallows. Nest warming increased chick size and success yet adult structural size decreased, and mass of males decreased but females did not, the latter linked to reproduction trade-offs.

A systematic review shows that >58% of infectious diseases confronted by humanity, via 1,006 unique pathways, have at some point been affected by climatic hazards sensitive to GHGs. These results highlight the mounting challenge for adaption and the urgent need to reduce GHG emissions.