Open Access

Katja Frieler, Anders Levermann, Joshua Elliot, Jens Heinke, Almut Arneth, Marc F. P. Bierkens, Philippe Ciais, Douglas B. Clark, Delphine Deryng, Petra Döll, Pete Falloon, Balázs M. Fekete, Christian Folberth, Andrew D. Friend, Catrin Gellhorn, Simon N. Gosling, Ingjerd Haddeland, Nikolay Khabarov, Marc R. Lomas, Yusuke Masaki, Kazuya Nishina, Kathleen Neumann, Taikan Oki, Ryan Pavlick, Alex C. Ruane, Erwin Schmid, Christoph Schmitz, Tobias Stacke, Elke Stehfest, Qiuhong Tang, Dominik Wisser, Veronika Huber, Franziska Piontek, Lila Warszawski, Jacob Schewe, Hermann Lotze-Campen, Hans Joachim Schellnhuber

• In order to achieve climate change mitigation, long-term decisions are required that must be reconciled with other societal goals that draw on the same resources. For example, ensuring food security for a growing population may require an expansion of crop land, thereby reducing natural carbon sinks or the area available for bio-energy production. Here, we show that current impact-model uncertainties pose an important challenge to long-term mitigation planning and propose a new risk-assessment and decision framework that accounts for competing interests. Based on cross-sectorally consistent simulations generated within the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) we discuss potential gains and limitations of additional irrigation and trade-offs of the expansion of agricultural land as two possible response measures to climate change and growing food demand. We describe an illustrative example in which the combination of both measures may close the supply demand gap while leading to a loss of approximately half of all natural carbon sinks. We highlight current limitations of available simulations and additional steps required for a comprehensive risk assessment.