Highlight articles

The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500

This study provides the future greenhouse gas (GHG) concentrations under the new set of so-called SSP scenarios (the successors of the IPCC SRES and previous representative concentration pathway (RCP) scenarios). The projected CO ₂ concentrations range from 350 ppm for low-emission scenarios by 2150 to more than 2000 ppm under the high-emission scenarios. We also provide concentrations, latitudinal gradients, and seasonality for most of the other 42 considered GHGs.

Rainfall intensification increases the contribution of rewetting pulses tosoil heterotrophic respiration

Carbon dioxide is produced by soil microbes through respiration, which is particularly fast when soils are moistened by rain. Will respiration increase with future more intense rains and longer dry spells? With a mathematical model, we show that wetter conditions increase respiration. In contrast, if rainfall totals stay the same, but rain comes all at once after long dry spells, the average respiration will not change, but the contribution of the respiration bursts after rain will increase.

CloudRoots: integration of advanced instrumental techniques and processmodelling of sub-hourly and sub-kilometre land–atmosphere interactions

The CloudRoots field experiment has obtained an open comprehensive observational data set that includes soil, plant, and atmospheric variables to investigate the interactions between a heterogeneous land surface and its overlying atmospheric boundary layer, including the rapid perturbations of clouds in evapotranspiration. Our findings demonstrate that in order to understand and represent diurnal variability, we need to measure and model processes from the leaf to the landscape scales.

The recent state and variability of the carbonate system of the CanadianArctic Archipelago and adjacent basins in the context of ocean acidification

Ocean acidification is the process by which the oceans are changing due to carbon dioxide emissions from human activities. Studying this process in the Arctic Ocean is essential as this ocean and its ecosystems are more vulnerable to the effects of acidification. Water chemistry measurements made in recent years show that waters in and around the Canadian Arctic Archipelago are considerably affected by this process and show dynamic conditions that might have an impact on local marine organisms.

On giant shoulders: how a seamount affects the microbial communitycomposition of seawater and sponges

Seamounts are globally abundant submarine structures that offer great potential to study the impacts and interactions of environmental gradients at a single geographic location. In an exemplary way, we describe potential mechanisms by which a seamount can affect the structure of pelagic and benthic (sponge-)associated microbial communities. We conclude that the geology, physical oceanography, biogeochemistry, and microbiology of seamounts are even more closely linked than currently appreciated.

N2O changes from the Last Glacial Maximum to the preindustrial – Part 2: terrestrial N2O emissions and carbon–nitrogen cycle interactions

Results of the first globally resolved simulations of terrestrial carbon and nitrogen (N) cycling and N ₂ O emissions over the past 21 000 years are compared with reconstructed N ₂ O emissions. Modelled and reconstructed emissions increased strongly during past abrupt warming events. This evidence appears consistent with a dynamic response of biological N fixation to increasing N demand by ecosystems, thereby reducing N limitation of plant productivity and supporting a land sink for atmospheric CO ₂ .

Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections

We assess 21st century projections of marine biogeochemistry in the CMIP6 Earth system models. These models represent the most up-to-date understanding of climate change. The models generally project greater surface ocean warming, acidification, subsurface deoxygenation, and euphotic nitrate reductions but lesser primary production declines than the previous generation of models. This has major implications for the impact of anthropogenic climate change on marine ecosystems.

The contribution of microbial communities in polymetallic nodules to thediversity of the deep-sea microbiome of the Peru Basin (4130–4198 mdepth)

Industrial-scale mining of deep-sea polymetallic nodules will remove nodules in large areas of the sea floor. We describe community composition of microbes associated with nodules of the Peru Basin. Our results show that nodules provide a unique ecological niche, playing an important role in shaping the diversity of the benthic deep-sea microbiome and potentially in element fluxes. We believe that our findings are highly relevant to expanding our knowledge of the impact associated with mining.

Towards an objective assessment of climate multi-model ensembles – a casestudy: the Senegalo-Mauritanian upwelling region

The most robust representation of climate is usually obtained by averaging a large number of simulations, thereby cancelling individual model errors. Here, we work towards an objective way of selecting the least biased models over a certain region, based on physical parameters. This statistical method based on a neural classifier and multi-correspondence analysis is illustrated here for the Senegalo-Mauritanian region, but it could potentially be developed for any other region or process.

Is there warming in the pipeline? A multi-model analysis of the Zero Emissions Commitment from CO2

The Zero Emissions Commitment (ZEC) is the change in global temperature expected to occur following the complete cessation of CO ₂ emissions. Here we use 18 climate models to assess the value of ZEC. For our experiment we find that ZEC 50 years after emissions cease is between −0.36 to +0.29 °C. The most likely value of ZEC is assessed to be close to zero. However, substantial continued warming for decades or centuries following cessation of CO ₂ emission cannot be ruled out.

BG Biogeosciences Highlight articles

Highlight articles

The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500

Rainfall intensification increases the contribution of rewetting pulses tosoil heterotrophic respiration

CloudRoots: integration of advanced instrumental techniques and processmodelling of sub-hourly and sub-kilometre land–atmosphere interactions

The recent state and variability of the carbonate system of the CanadianArctic Archipelago and adjacent basins in the context of ocean acidification

On giant shoulders: how a seamount affects the microbial communitycomposition of seawater and sponges

N2O changes from the Last Glacial Maximum to the preindustrial – Part 2: terrestrial N2O emissions and carbon–nitrogen cycle interactions

Twenty-first century ocean warming, acidification, deoxygenation, and upper-ocean nutrient and primary production decline from CMIP6 model projections

The contribution of microbial communities in polymetallic nodules to thediversity of the deep-sea microbiome of the Peru Basin (4130–4198 mdepth)

Towards an objective assessment of climate multi-model ensembles – a casestudy: the Senegalo-Mauritanian upwelling region

Is there warming in the pipeline? A multi-model analysis of the Zero Emissions Commitment from CO2

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