• Energy Research

AbstractForests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2–5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6 and satellite-derived approaches2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151–363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.

Abstract Nature-based Solutions’ (NbS) potential for multiple benefits across ecosystems and societies justify their uptake in policy and implementation. This study contributes to closing the gap in quantifying the multiple outcomes of NbS by evaluating the multifunctionality of 85 NbS actions in the Alps. We assessed biodiversity co-benefits, the economic value of four Ecosystem Services (ES) provided by these NbS, and their respective beneficiaries: heatwave mitigation, flood regulation, climate regulation, and landslide protection. Our results show the diversity of NbS, with forest NbS having high values for all ES, river and wetland NbS showing high values for biodiversity, and urban NbS, presenting lower biodiversity value but being highly cost-effective and benefiting a larger population. We estimated an average ES economic value per hectare of NbS of 424,662 Euros, with a three to one return on investment. We discuss the need for integrating biodiversity and multiple ES for future NbS funding and implementation together with their role to mitigate and adapt to climate change.

Abstract Seven years of continuous eddy covariance measurements at an alpine meadow were used to investigate the impacts of climate drivers and ecosystem responses on the inter-annual variability (IAV) of the net ecosystem exchange (NEE). The annual cumulative value of NEE was positive (source) in 2003, 2005 and 2009 (50, 15 and 112 g m−2 respectively) and negative (sink) in 2004, 2006, 2007 and 2008 (29, 75, 110 and 28 g m−2 respectively). The IAV of carbon dioxide fluxes builds up in two phenological phases: the onset of the growing season (triggered by snow melting) and the canopy re-growth after mowing. Respiratory fluxes during the non-growing season were observed to increase IAV, while growing season uptake dampened it. A novel approach was applied to factor out the two main sources of IAV: climate drivers’ variability and changes in the ecosystem responses to climate. Annual values of carbon dioxide fluxes were calculated assuming (a) variable climate and variable ecosystem response among years, (b) variable climate and constant ecosystem response and (c) constant climate and variable ecosystem response. The analysis of flux variances calculated under these three assumptions indicates the occurrence of an important negative feedback between climate and ecosystem responses. Due to this feedback, the observed IAV of NEE is lower than one would expect for a given climate variability, because of the counteracting changes in ecosystem responses. This alpine meadow therefore demonstrates the ability to acclimatise and to limit the IAV of carbon fluxes induced by climate variability.