A FTER 29 HOURS of uninterrupted negotiations the latest report from the Intergovernmental Panel on Climate Change ( IPCC ), on how alterations in land use are contributing to such change, was gavelled through in Geneva on the afternoon of August 7th. When, minutes later, your correspondent asked to speak with some of the researchers, she was informed they had “gone to bed”. The report these exhausted delegates produced—all 1,300 pages of it—fires another warning shot about the state of the planet and the way people are transforming virtually every corner of every continent. Human activities affect roughly three-quarters of Earth’s ice-free land, with huge consequences for the climate.

Land masses are natural carbon sinks, absorbing greenhouse gases by a variety of processes, including photosynthesis. They also produce such gases—for instance, when vegetation decomposes or burns. By conserving some ecosystems and destroying others to make way for pastures and fields, or chopping down trees for timber, human activities on the land add an extra layer of complexity to already complex natural cycles.

The report found that between 2007 and 2016 such activities produced emissions equivalent to 9bn-15bn tonnes of carbon dioxide each year, or roughly 23% of all man-made greenhouse-gas emissions. During that time, land surfaces soaked up 8.6bn-13.8bn tonnes of carbon dioxide.

At the moment, then, these sinks and sources are roughly in balance. But climate change, deforestation and agriculture mean the CO 2 -soaking-up ability of the continents is being depleted. The accelerating destruction of the Amazon forest, which researchers fear may be approaching a point of no return, is of particular concern. And across the world, depending on the type of husbandry practised, farming is eroding soil at a rate between ten times and more than 100 times faster than new soil forms.

Climate change, moreover, creates a vicious feedback loop. Higher temperatures promote the degradation of land through drought, desertification and rising seas, and the promotion of wildfires like the ones currently blazing in Alaska, Siberia and Greenland. This, in turn, increases the amount of greenhouse gases being released by landmasses, which further accelerates global warming.

A swelling human population also needs more land to feed itself. Balancing these needs—for space to grow food on the one hand, and natural carbon sinks to keep temperatures low on the other—is a huge challenge. There are, however, solutions. Recently, a report by the World Resources Institute, a multinational think-tank, listed 22 actions that could be taken to feed, sustainably, close to 10bn people by 2050.

Number one on that list is stopping deforestation, along with efforts to regenerate degraded ecosystems. Reducing food waste is also important. More than a quarter of what the world grows to eat is never actually consumed. That creates a huge carbon footprint to no benefit. And diets themselves need to change. In particular, raising livestock contributes disproportionately to the problem. That means eating less meat, an admonition directed mainly at rich countries, whose people, often overweight, might in any case benefit from going on a diet.

This last point presented one bone of contention between the 195 government delegations charged with approving the panel’s report. The role of bioenergy (growing crops for fuel) and BECCS (bioenergy with carbon capture and storage) was another. A previous IPCC report, published in 2018, on the feasibility of limiting global warming to 1.5°C, made it abundantly clear that this would require large amounts of greenhouse gases be removed from the atmosphere and somehow stored away. BECCS , in which power stations capture and store the CO 2 from burning biofuel, has been touted as a way to do that on a large scale, but the area of land required to grow the biofuel needed to absorb billions of tonnes of CO 2 would be enormous—several times the size of India.

Optimistically, the report’s authors conclude that there should be enough room to provide a growing population with sufficient food, without rushing towards a dangerously warm climate. There is, though, a caveat. That outcome would require what one commentator called a “global intelligent response”. But the world, like the delegates, seems to be asleep.■