If CO₂ were coloured, the sky would have changed hue in our lifetime. That’s striking enough, but perhaps more striking is the inevitable next question: would we have noticed?  After all, any number of other major environmental changes have occurred in the last fifty years. The transformation has been remarkable, on the global scale the list includes global urbanisation, habitat destruction, the acidification of the oceans and the spread of micro-plastic fragments all at an unprecedented rate, and more locally includes hedgerow destruction, the precipitous decline in bird and butterfly numbers, ancient woodland loss and declining air quality. Despite all this, most of us, most of the time have something approaching an optimism bias: we believe the natural world to be a constant, whereas it is in constant flux, and most recently as a result of human activity. After all, we make extensive use of our smartphones, without giving too much thought much of the time to the environmental destruction involved in mining the rare metals which go into them.

All this bodes ill for the major climate conference, COP26, which begins this week in Glasgow. The scientific evidence is now overwhelming, and the news pictures of collapsing glaciers, dried up lakes and, this summer, out-of-control wildfires as far apart at Greece and California have rammed it home: we really are beyond living on borrowed time. Urgent action to transition to net zero carbon emissions in the next thirty years is essential if the planet on which we live and depend is not to pass tipping points, beyond which the way of life we have taken for granted will become unsustainable. There are some views that we have already passed some points of no return. And yet success is far from guaranteed. The UN’s estimate of the pre-Glasgow climate-action pledges is that they fall far short of the changes which are needed to constrain global temperature rise within tolerable bounds. One sympathises with the motive behind the Prime Minister’s announcement that in the battle against climate change, ‘humanity is 5-1 down at half-time’, but anyone who knows anything about soccer knows what typically happens in the second half of games like that.

It’s easy – and not incorrect – to pin the blame for this lack of inter-governmental action on the shadowy lobbying of powerful groups or large multinationals, or the power plays of governments angling for geo-political advantage. But there’s something else at work too: the optimism bias that pervades our view of the natural world, and the assumption that (because we’d all, really, like to live in fairy stories rather than horror movies) either it will all turn out right in the end, or that ‘something will turn up’.  We are like recalcitrant teenagers: this is homework we’ve known we had to do for thirty years, and here we are rushing to finish it off long after it was due to be handed in.

The University has been re-examining its own climate action pledges. There are some challenging questions for us as for other organisations. There are elements of our impact on the environment which we can control, and elements on which we are dependent on the actions of others – for example, the emissions embedded in our supply chain or our energy supply. We’ve made good progress on the latter. More challenging are the carbon emissions embedded in what we do. We have some excellent, high-quality and highly efficient buildings, but we also have a legacy of poorly performing buildings erected in earlier generations. Should we be working at their efficiency, however limited that might be, or replacing them? We’ve made the decision that it makes better long-term environmental sense to replace the poorest performing buildings with better ones – and this explains the enormous building site on Howard Street which will transform not just the look and feel of city campus but its environmental performance too. We have hugely reduced institutional travel, and my sense is that a good number of the journeys we undertook before the pandemic will never return – I know I am travelling much less and have few plans to return to what was often a frenetic and in itself exhausting pre-pandemic schedule.

We are, of course, a city centre university. This presents us with some advantages and some disadvantages in terms of our active travel planning: unlike green field campus universities, encouraging cycling and public transport use for travel to work is practical, but it also makes issues around car parking particularly challenging. As a result of the strategy reset we completed during the early stages of the pandemic, we undertook to review and overhaul our commitment to climate action as well as our net zero targets, and detailed work on that is now underway. This approach needs to be much wider than just thinking about our estate – as an anchor institution in our region, we need to reflect on how we are embedding climate action in our campus, our courses, and our community engagement.

The challenge of climate change is the challenge of our time and will be the challenge of our children’s and grandchildren’s time. The changes we need to make are enormous. They do depend on actions by governments. They do depend on actions by institutions, universities included. But, and I think we all know this in our bones, they fundamentally depend on what each of us does: the sky has, in a sense, changed colour, and it’s not changing back.