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Abstract. All organisms are ultimately dependent on a large diversity of consumptiveand non-consumptive interactions established with other organisms, formingan intricate web of interdependencies. In 1992, when 1700 concernedscientists issued the first “World Scientists' Warning to Humanity”, ourunderstanding of such interaction networks was still in its infancy. Bysimultaneously considering the species (nodes) and the links that glue themtogether into functional communities, the study of modern food webs – ormore generally ecological networks – has brought us closer to a predictivecommunity ecology. Scientists have now observed, manipulated, and modelledthe assembly and the collapse of food webs under various global changestressors and identified common patterns. Most stressors, such as increasingtemperature, biological invasions, biodiversity loss, habitat fragmentation,over-exploitation, have been shown to simplify food webs byconcentrating energy flow along fewer pathways, threatening long-termcommunity persistence. More worryingly, it has been shown that communitiescan abruptly change from highly diverse to simplified stable states withlittle or no warning. Altogether, evidence shows that apart from thechallenge of tackling climate change and hampering the extinction ofthreatened species, we need urgent action to tackle large-scale biologicalchange and specifically to protect food webs, as we are under the risk of pushingentire ecosystems outside their safe zones. At the same time, we need togain a better understanding of the global-scale synergies and trade-offsbetween climate change and biological change. Here we highlight the mostpressing challenges for the conservation of natural food webs and recentadvances that might help us addressing such challenges.