Research Briefing in 2022

Anthropogenic nitrogen deposition is known to affect forest soil respiration, but it remains unclear how soil respiration responds to nitrogen deposition over time. Monitoring of CO₂ emissions over 9–13 years of nitrogen-addition treatments in three tropical forests in southern China reveals a three-phase pattern of soil respiration.

Satellite measurements show that dust emission is enhanced following large wildfires, producing considerable dust loadings for days to weeks over normally dust-free regions. These sequential fire and dust extremes will likely become more frequent and severe under global warming, having increased societal and ecological impacts.

Large channels of meltwater snake beneath the ice in the Weddell Sea region of Antarctica. This water affects the speed of ice flow above and the melt rate of the ice when it reaches the ocean, having a direct role in the response of Antarctica to climate change.

Melting of the edges of the Greenland ice sheet by the ocean since 1979 is — counterintuitively — controlled almost as much by air temperature as by ocean temperature.

Seismometers on the NASA InSight lander have identified unusual signals from meteoroid impacts on Mars. Impact locations were confirmed by satellite images of new craters at these sites and directly constrain the martian interior, confirming its crustal structure and ground-truthing the scaling of impact-induced seismicity.

Modelling of the effect of reservoirs on the climate through time (1900 to 2060) revealed that although carbon emissions peaked in 1987, reservoir-induced radiative forcing will continue to rise for the next decades. Over time, reservoir emissions are shifting from carbon dioxide to methane-dominated pathways, on which knowledge is largely lacking.

Water that has been carried deep into the Earth by oceanic plates in subduction zones, can influence earthquakes and volcanic eruptions. Three-dimensional images of electrical resistivity derived from electromagnetic geophysical data provide new constraints on the distribution, transport, and storage of water in the Cascadia subduction zone.

Ozone depletion is not only a serious health threat but can also affect the climate. Atmospheric chemistry models reveal that springtime Arctic ozone depletion can have major consequences for the seasonal climate in the Northern Hemisphere, including warming over Eurasia and drying across central Europe.

Monitoring of the daily global CO₂ emissions in 2020 reveals the spatial–temporal pattern of the drop in emissions due to the impact of the COVID-19 pandemic. The daily CO₂ emission changes also reveal different patterns of human activities and fossil CO₂ emissions across countries, sectors and periods.

Megathrust aftershocks can be highly destructive if they strike close to shore. Here, we show that aftershocks on the rupture surface have an initially high rate but shut down within several years, potentially for centuries. However, aftershocks also surround the rupture, where they persist for up to 60 years.

In a simulation with a state-of-the-art climate model, obstruction of the ocean gateways in the Canadian archipelago due to ice-sheet growth reroutes currents and alters North Atlantic Ocean conditions, permitting glacial inception in Scandinavia. This mechanism could help to explain periods of rapid ice-sheet growth in Earth’s history.

Preferential P retention emerges in almost 90% of global lakes. This retention leads to a strong elevation in the N:P ratios in lakes outflow, exacerbates the imbalance of the nutrient cycles and can potentially result in biodiversity losses and algal blooms in lakes and downstream ecosystems.

This study shows that by stabilizing the soil, biological soil crusts reduce global atmospheric dust emissions by 60%, corresponding to ~700 Tg of dust per year. According to models of biocrust cover loss, this effect will be reduced in the future, leading to increases in not only dust emissions but also global radiative cooling.

Tree restoration is a popular approach to mitigating climate change, but its hydrological impacts are often overlooked. Tree restoration increases evaporation, as well as increasing downwind precipitation due to enhanced moisture recycling. Our study shows that these combined effects can affect regions’ wetness or dryness, streamflow and water availability.