Africa’s climate is one of the least-researched and poorly understood, but a new report provides reliable scientific information about the continent’s changing climate, equipping decision-makers to plan better.

In this paper, Friends of the Earth International outlines the current climate science and the need for equity, fairness and justice in how we take action. It highlight how people are impacted by climate change, by dirty energy and by so- called false solutions which pretend to address the climate crisis.

Analysis of observations and model projections provides large-scale emergent constraints on the extent of CO2 fertilization, with estimated increases in gross primary productivity for both high-latitude and extratropical ecosystems under elevated atmospheric CO2 concentrations.

The wintertime Arctic stratospheric polar vortex has weakened over the past three decades, and consequently cold surface air from high latitudes is now more likely to move into the middle latitudes. However, it is not known if the location of the polar vortex has also experienced a persistent change in response to Arctic climate change and whether any changes in the vortex position have implications for the climate system.

Extreme large-scale North American cold events are associated with strong undulations in the tropospheric jet stream which bring cold polar air southward over the continent. Here we propose that these jet undulations are associated with the North American part of the Circumglobal Teleconnection Pattern—a pair of zonally oriented waves of zonal wave number 5 which are in zonal quadrature with each other. While the Pacific/North American pattern is associated with the first circumglobal wave pattern, North American extreme cold events are associated with the second pattern.

Reconstructions of Earth’s past climate strongly influence our understanding of the dynamics and sensitivity of the climate system. Yet global temperature has been reconstructed for only a few isolated windows of time, and continuous reconstructions across glacial cycles remain elusive. Here I present a spatially weighted proxy reconstruction of global temperature over the past 2 million years estimated from a multi-proxy database of over 20,000 sea surface temperature point reconstructions.

Megadroughts are comparable in severity to the worst droughts of the 20th century but are of much longer duration. A megadrought in the American Southwest would impose unprecedented stress on the limited water resources of the area, making it critical to evaluate future risks not only under different climate change mitigation scenarios but also for different aspects of regional hydroclimate. We find that changes in the mean hydroclimate state, rather than its variability, determine megadrought risk in the American Southwest.

Understanding the causes of recent climatic trends and variability in the high-latitude Southern Hemisphere is hampered by a short instrumental record. Here, we analyse recent atmosphere, surface ocean and sea-ice observations in this region and assess their trends in the context of palaeoclimate records and climate model simulations. Over the 36-year satellite era, significant linear trends in annual mean sea-ice extent, surface temperature and sea-level pressure are superimposed on large interannual to decadal variability.

In January 1998, the collaborative ice-drilling project between Russia, the United States, and France at the Russian Vostok station in East Antarctica yielded the deepest ice core ever recovered, reaching a depth of 3,623 m. Ice cores are unique with their entrapped air inclusions enabling direct records of past changes in atmospheric trace-gas composition. Preliminary data indicate the Vostok ice-core record extends through four climate cycles, with ice slightly older than 400 kyr.

Reconstructing the past variability of Arctic sea ice provides an essential context for recent multi-year sea ice decline, although few quantitative reconstructions cover the Holocene period prior to the earliest historical records 1,200 years ago. Photochemical recycling of bromine is observed over first-year, or seasonal, sea ice in so-called “bromine explosions” and we employ a 1-D chemistry transport model to quantify processes of bromine enrichment over first-year sea ice and depositional transport over multi-year sea ice and land ice.