On the suitability of North Brazil Current transport estimates for monitoring basin-scale AMOC changes

The North Brazil Current (NBC) constitutes a bottleneck for the mean northward return flow of the Atlantic Meridional Overturning Circulation (AMOC) in the tropical South Atlantic. Previous studies suggested a link between interannual to multidecadal NBC and AMOC transport variability and proposed to use NBC observations as an index for the AMOC. Here we use a set of hindcast, sensitivity, and perturbation experiments performed within a hierarchy of ocean general circulation models to show that decadal to multidecadal buoyancy-forced changes in the basin-scale AMOC transport indeed manifest themselves in the NBC. The relation is, however, masked by a strong interannual to decadal wind-driven gyre variability of the NBC. While questioning the NBC transport as a direct index for the AMOC, the results support its potential merit for an AMOC monitoring system, provided that the wind-driven circulation variability is properly accounted for

Can plants help us avoid seeding a human‐made climate catastrophe?

Drastic phase down of our carbon dioxide (CO2) emissions from burning fossil fuels within decades will likely be insufficient to avoid seeding catastrophic human‐caused climate change. We have to also start removing CO2 from the atmosphere, safely, affordably and within decades. Technological approaches for large‐scale carbon removal and storage hold great promise but are far from the gigaton‐scale required. Enhanced chemical weathering of crushed silicate rocks and afforestation are proposed CO2 removal approaches mimicking events during the Devonian rise of forests that triggered massive CO2 drawdown and the great late Palaeozoic cooling. Evidence from Earth's history suggests that if undertaken at scale, these strategies may represent key elements of a climate restoration plan but will still be far from sufficient. Climate protests by the world's youth are justified. They recognize the urgency of the situation and the intergenerational injustice of our time: current and future generations footing the immense economic and ecological bill for damaging carbon emissions they had no part in and which world leaders are failing to limit

The Limits of Entrapment: The Negotiations on EU Reduction Targets, 2007-11

In 2007, the EU decided to cut greenhouse gas emissions by 20/30 per cent, something which was considered a proof of the EU's willingness to take on high targets independently of others. In the period 2009-11, the EU was debating but could not reach an agreement on stepping up to a 30 per cent reduction target. This raises the question: why did the EU go from being capable of adopting high targets independently of others to being incapable of agreeing whether it should increase its mitigation effort? It is argued that whereas actors sceptical of a high target could be rhetorically entrapped in 2007, such entrapment was impossible in the 2009-11 period. The lack of entrapment can be explained in terms of changes in the international and socio-economic contexts, which led to changes in the policy processes and the normative environment, which again made effective entrapment impossible

A framework for modelling soil structure dynamics induced by biological activity

Acknowledgments: This work was funded by the Swedish Research Council for Sustainable Development (FORMAS) in the project “Soil structure and soil degradation: improved model tools to meet sustainable development goals under climate and land use change” (grant no. 2018-02319). We would also like to thank Mikael Sasha Dooha for carrying out the measurements for the water retention curves shown in figure 4.Peer reviewedPublisher PD

Diurnal patterns of gas-exchange and metabolic pools in tundra plants during three phases of the arctic growing season

Arctic tundra plant communities are subject to a short growing season that is the primary period in which carbon is sequestered for growth and survival. This period is often characterized by 24-h photoperiods for several months a year. To compensate for the short growing season tundra plants may extend their carbon uptake capacity on a diurnal basis, but whether this is true remains unknown. Here, we examined in situ diurnal patterns of physiological activity and foliar metabolites during the early, mid, and late growing season in seven arctic species under light-saturated conditions. We found clear diurnal patterns in photosynthesis and respiration, with midday peaks and midnight lulls indicative of circadian regulation. Diurnal patterns in foliar metabolite concentrations were less distinct between the species and across seasons, suggesting that metabolic pools are likely governed by proximate external factors. This understanding of diurnal physiology will also enhance the parameterization of process-based models, which will aid in better predicting future carbon dynamics for the tundra. This becomes even more critical considering the rapid changes that are occurring circumpolarly that are altering plant community structure, function, and ultimately regional and global carbon budgets