“It was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness.” Charles Dickens had it about right in A Tale of Two Cities. As Nature went to press, negotiators in Paris were edging towards a global deal to try to secure a safe ecological future for all — a few weeks after mass murder on the city’s streets. Nobody was getting too excited about the prospects, or the impact of an eventual deal, but those at the meeting seemed confident that nations would come together to agree, well — something. From a political perspective, a weak treaty that nudges action against climate change forwards is wiser than nothing at all. From a scientific point of view, of course, anything less than full speed ahead is foolishness.

Meanwhile, a week ago and a world away in Washington DC, scientists were meeting to discuss another future for the world. Assuming that the climate talks can secure a habitable planet for humanity, then just what will those humans be like? While environmentalists search for new technologies to safeguard the future, biologists have a whole box of new tools that can reveal and manipulate the genome. As we report on page 173, the atmosphere at the Washington meeting — convened to discuss the implications of human-gene-editing techniques — was cordial and hopeful.

The parallels between the two issues — global warming that can alter the world outside and technology such as CRISPR–Cas9 that can rewrite our world inside — are telling. Most of the major concerns will not affect the people currently worrying about them. They are talking and acting on behalf of generations to come, those unspoken voices that trouble us from the future. Is it fair to leave them an ecosystem very different from the one we enjoy, which they will recognize only as history? Is it ethical to fiddle with the human germ line to introduce changes that will echo through future families and alter the legacy of human diversity?

Politicians and policymakers struggle when they are required to put the needs of the unborn ahead of the demands of voters and funders. So both the climate negotiations and the gene-editing discussions have a zoom function, to illustrate the near-term challenges and opportunities: the local pledges and actions to cut emissions right now, and the basic research needed to make an experimental technique safe for clinical use. Both are necessary steps, but both in their own way dodge the big questions. What does the world do to accelerate these feel-good emissions cuts and gear them up to meaningful collective action? And what does society want to do with a fully operational gene-editing system?

The current discussions on genetics and climate have much to commend them. They have learned the lessons of the past and are trying to break down the conventional political and scientific hierarchy to reflect the rise of nations such as China. The people most directly affected by the decisions reached — indigenous and poor communities in the developing world and individuals and families affected by genetic disorders — are being consulted and listened to (although not enough). The mood is, generally, cordial and constructive.

The worry is that the bar in both discussions is set too low. We should be wary about celebrating times that seem the best only because we have put the worst decisions off for another day.