Carbon stocks in vegetation have a key role in the climate system1,2,3,4. However, the magnitude, patterns and uncertainties of carbon stocks and the effect of land use on the stocks remain poorly quantified. Here we show, using state-of-the-art datasets, that vegetation currently stores around 450 petagrams of carbon. In the hypothetical absence of land use, potential vegetation would store around 916 petagrams of carbon, under current climate conditions. This difference highlights the massive effect of land use on biomass stocks. Deforestation and other land-cover changes are responsible for 53–58% of the difference between current and potential biomass stocks. Land management effects (the biomass stock changes induced by land use within the same land cover) contribute 42–47%, but have been underestimated in the literature. Therefore, avoiding deforestation is necessary but not sufficient for mitigation of climate change. Our results imply that trade-offs exist between conserving carbon stocks on managed land and raising the contribution of biomass to raw material and energy supply for the mitigation of climate change. Efforts to raise biomass stocks are currently verifiable only in temperate forests, where their potential is limited. By contrast, large uncertainties hinder verification in the tropical forest, where the largest potential is located, pointing to challenges for the upcoming stocktaking exercises under the Paris agreement.

This is a call for action to scientific journals to introduce reporting requirements for toxicity and
ecotoxicity studies. Such reporting requirements will support the use of peer‐reviewed research
studies in regulatory decision‐making. Moreover, this could improve the reliability and reproducibility
of published studies in general and make better use of the resources spent in research.

Societies worldwide are investing considerable resources into the safe development and use
of nanomaterials. Although each of these protective efforts is crucial for governing the risks
of nanomaterials, they are insufficient in isolation. What is missing is a more integrative governance
approach that goes beyond legislation. Development of this approach must be evidence
based and involve key stakeholders to ensure acceptance by end users. The challenge is
to develop a framework that coordinates the variety of actors involved in nanotechnology and
civil society to facilitate consideration of the complex issues that occur in this rapidly evolving
research and development area. Here, we propose three sets of essential elements required
to generate an effective risk governance framework for nanomaterials. (1) Advanced tools to
facilitate risk-based decision making, including an assessment of the needs of users regarding
risk assessment, mitigation, and transfer. (2) An integrated model of predicted human behavior
and decision making concerning nanomaterial risks. (3) Legal and other (nano-specific
and general) regulatory requirements to ensure compliance and to stimulate proactive approaches
to safety. The implementation of such an approach should facilitate and motivate
good practice for the various stakeholders to allow the safe and sustainable future development
of nanotechnology.