Ten new insights in climate science 2024

Abstract

The years 2023 and 2024 were characterized by unprecedented warming across the globe, underscoring the urgency of climate action. Robust science advice for decision makers on subjects as complex as climate change requires deep cross- and interdisciplinary understanding. However, navigating the ever-expanding and diverse peer-reviewed literature on climate change is enormously challenging for individual researchers. We elicited expert input through an online questionnaire (188 respondents from 45 countries) and prioritized 10 key advances in climate-change research with high policy relevance. The insights span a wide range of areas, from changes in methane and aerosol emissions to the factors shaping citizens' acceptance of climate policies. This synthesis and communications effort forms the basis for a science-policy report distributed to party delegations ahead of the 29th session of the Conference of the Parties (COP29) to inform their positions and arguments on critical issues, including heat-adaptation planning, comprehensive mitigation strategies, and strengthened governance in energy-transition minerals value chains.

Keywords: adaptation; climate policy; climate science; governance; just transition; mitigation; resilience; science policy.

Figure 1

Annual methane emissions by source (average for the period 2010–2019) Estimate based on top-down integrative methods (top left) and bottom-up integrative methods (top right). Uncertainty ranges are indicated in square brackets. Data adapted from Saunois et al. Bottom: trends 1983–2024 in global atmospheric methane. Shaded area indicates decade over which emissions sources are attributed.

Figure 2

Recent changes in aerosols, related sources, and examples of remote effects Recent changes in aerosol amounts (difference between 2014–2023 and 2004–2013 period averages), quantified as aerosol optical depth (AOD) observations from MODIS Terra and Aqua. Main sources of aerosol emissions, responsible for the observed AOD changes (icons on map), and examples of remote impacts (local not show here for simplicity) of changes in aerosol loadings over Europe, East Asia, and South Asia are depicted in the top and bottom windows (including Walker circulation, at the bottom). Modified from Persad et al..

Figure 3

Increasing exposure to prolonged heat at different levels of global warming Implications of global warming for the proportion of the population exposed to heat. Map of present heat-humidity risks to humans with inset projections of the heat-humidity changes for West Africa as well as a plotted projection of the percentage of humanity exposed to unprecedented temperatures, both under different warming scenarios. Annual hot-hours global map (under 1.5°C warming) and West Africa and South Asia projections (under 1.5°C, 2°C, 3°C, and 4°C warming). Bottom left plot: projection of fraction of humanity exposed to unprecedented temperatures. Population (%) exposed to unprecedented heat (mean annual temperature  ≥29°C) for the different population distributions: 6.9 billion (green), 9.5 billion (blue), and 11.1 billion (gray).

Figure 4

Direct and indirect pathways of climate-change impacts on MRH Impacts are further amplified by socio-economic factors in a given setting. To strengthen preparedness and protect MRH in a changing climate, solutions must address existing challenges in climate adaptation plans, data, education, and gender and socio-economic norms and be driven by gender equity and reproductive justice.

Figure 5

Unprecedented SST, El Niño costs, and potential weakening of AMOC (A) The mean daily SST across the globe, collected from January 1979 to August 24, 2024 from ERA5. (B) Economic damages calculated as GDP change for the 3–5 years after noteworthy El Niño events with the center line indicating the mean of the projection and shading showing the 95% confidence intervals across regression bootstrap samples.^, Global GDP change is only calculated for countries with statistically significant marginal effects. (C) The historical AMOC strength based on a combination of annually averaged SST observations and reconstructions (red) shown with 11-year running means (black solid) indicating potential AMOC tipping scenario from 2021 to 2200 (gray dashed) with shading of interannual variability and uncertainty.

Figure 6

Amazon’s biological and cultural diversity enhance its resilience to climate change A high biodiversity landscape, both biological and biocultural, has higher resilience to climate-change impacts, compared to less diverse landscapes. Climate change and forest degradation are self-reinforcing feedbacks reducing the diversity of the Amazon system. Reforestation, a transformation toward a new socio-bioeconomy, embracing the knowledge of Indigenous people and local communities as well as protecting and establishing sustainable-use protected areas can increase diversity, effectively disrupting the self-reinforcing feedback loop.

Figure 7

SETS approach to urban heat Illustrated solutions to urban heat using a SETS approach compared to conventional approaches, to guide planning and integrate policies with co-benefits.

Figure 8

Addressing challenges of ETM value chain to achieve a just and equitable energy transition The ETM value chain and the challenges different stages present across environmental, social, economic, and technological domains.

Figure 9

Interaction factors leading to climate policy resistance or acceptance The interaction between political-economic contexts and policy designs can either lead to exclusion, injustice, and vulnerability—resulting in popular resistance—or to inclusion, fairness, and development—resulting in popular acceptance.