Uncovering how grasslands changed our climate

Grasslands are managed worldwide to support livestock production, while remaining natural or semi-natural ones provide critical services that contribute to the well being of both people and the planet. Human activities are however causing grasslands to become a source of greenhouse gas emissions rather than a sink.

A new study uncovered how grasslands have changed our climate over the last centuries. The ability of grasslands to absorb more carbon dioxide and pack it in the soil - was estimated to have intensified over the last century, but mainly over sparsely grazed and natural grasslands. Conversely, over the last decade, grasslands intensively managed by humans have become a net source of greenhouse gas emissions - in fact, it has greenhouse gas emission levels similar to those of global croplands, which represent a large source of greenhouse gases.

The cooling services provided by sparsely grazed or wild grasslands, makes it clear that countries should assess not only the greenhouse gas budgets of their managed pastures (such as specified in the current national greenhouse gas reporting rules of the UN's Framework Convention on Climate Change), but also the sinks and sources of sparsely grazed rangelands, steppes, tundra, and wild grasslands. Full greenhouse gas reporting for each country could facilitate the assessment of progress towards the goals of the Paris Agreement and better link national greenhouse gas budgets to the observed growth rates of emissions in the atmosphere.

(text edited from official press release of main author)

Reference: Chang J, [...] Goll, et al. (2021). Climate warming from managed grasslands cancels the cooling effect of carbon sinks in sparsely grazed and natural grasslands. Nature Communications DOI: 10.1038/s41467-020-20406-7