Only if there is a fundamental change in the way we manage land can we reach the targets of climate-change mitigation, avert the dramatic loss of biodiversity and make the global food system sustainable. The WBGU proposes five multiple-benefit strategies illustrating ways of overcoming competition between rival claims to the use of land. These should be promoted by five governance strategies, especially by setting suitable framework conditions, reorienting EU policy and establishing alliances of like-minded states.

Humankind has already fundamentally transformed the terrestrial biosphere. Around the year 1700, most of the world's land was still largely in its natural state; today, however, only about 23% of the global land surface can be designated as wilderness. As convincingly shown by global assessments and progress reports in recent years, humanity is increasingly destroying this natural life-support system, partly as a result of the growing global demand for land and terrestrial ecosystem services. The pressure on terrestrial ecosystems from overuse and competition for use has never been greater than it is today. Around a quarter of the Earth's ice-free land surface is affected by human-caused degradation.

The diverse demands made on land for the purposes of climate-change mitigation, food security and the conservation of biological diversity are already in competition with each other, and land degradation will have a negative impact on all three aspects in the short or long term. The WBGU calls this the 'trilemma of land use' (see illustration), because, at first glance, it appears that any one of these challenges can only be met at the expense of the other two.

Where does international sustainability policy stand at the beginning of the 2020s? The answer is sobering. This report appraises the situation and reveals an urgent need for action by many government ministries (e.g. Environment, Education and Research, Agriculture, Development Cooperation) to develop a new approach to land stewardship: >It looks like the climate-protection goals of the Paris Agreement can only be reached if, in addition to the decarbonization of the global economy, more areas of land are used to extract carbon dioxide (CO2) from the atmosphere. However, this not only offers opportunities, it also involves considerable risks.

>The global food system is in crisis. The food security of a quarter of humanity is under threat, and another quarter suffers from unhealthy overconsumption. At the same time, the environmental damage and other external effects caused by industrial agriculture threaten our natural life-support systems, despite all past efforts – from the ‘Green Revolution’ of the 1960s and 70s to the European Union’s Common Agricultural Policy. >Biodiversity is experiencing a dramatic, human-in-duced mass extinction worldwide, the scale of which has been compared with the great geological extinc-tion events of the past. This also greatly reduces the capacity of ecosystems to contribute to climate regu-lation and food security.

In order to overcome the trilemma of land use, this report offers options for overcoming land-use competi-tion between climate-change mitigation, biodiversity conservation and food security. This requires a funda-mental change in our approach to land stewardship. The aim is to show the way forward with a combination of the exemplary multiple-benefit strategies presented above and their implementation as part of an integrated landscape approach.

Almost 30 years after the Rio de Janeiro Earth Summit, the international community has a framework of institutions at its disposal to address these problems. However, in view of the crisis of multi-lateralism, committed and rapid action by like-minded states is more important than ever. Political will, crea-tivity and courage are required for the urgently needed global transformation of land use towards sustainability. It requires pioneers who explore and pursue new ways; states that set framework conditions, enforce the neces-sary measures and cooperate with each other; and mechanisms for achieving a fair balance between stake-holders. This can be driven forward by a supportive EU policy and a stronger focus on land in international cooperation, as well as new alliances of like-minded states. This report aims to vigorously advocate making the global land-use transformation a political priority

Ecosystems and their diverse services are essential bases for human life and economic activity and deserve to be at the centre of attention, whereby remote effects on land-use changes and land degradation (telecouplings) – e.g. by material cycles or the world trade in agricultural goods – must also be taken into account.

Lead authors: Markus Fischer, Martina Fromhold-Eisebith, Ulrike Grote, Ellen Matthies, Dirk Messner, Karen Pittel, Hans Joachim Schellnhuber, Ina Schieferdecker, Sabine Schlacke, Uwe Schneidewin