Next week the fate of the world is going to be decided. That is a statement that we have rarely, if ever, been able to say with any certainty. But the consequences of another year, five years or decade without a global climate change agreement in the form of a legally binding treaty on all major global polluters could see the progress of degradation accelerate to a point where any further action would be mostly damage control. That is the solemn mandate of the Paris Cop21 Climate Conference, co-operate or face consequences, consequences that will be more tangible than ever before.

As global temperature rise being successfully held at 2 degrees Celsius looks more and more improbable, and unprecedented ice-cap melt (like that of Greenland in 2012) continues to stun Arctic communities and swell the global oceans, the level of climate disruption is now undeniably enormous. Even the kind of serious concerted action we all hope for in Paris will not be enough for those who are already set to face the horrors of the degree of environmental disruption we have now made inevitable. The most striking case of all? The chain of Pacific islands that form the state of Kiribati. Climate scientists have suggested that by 2100, or even earlier, rising sea levels will result in the full submersion of the islands.

This will be a decisive moment in human history. At this point our human capacity for destruction will have been fully realised, we will have effectively destroyed an entire nation. Global leaders in Paris who think that at their feet is placed an impossible and sobering task should be reminded of just how sobering a task lies at the feet of Anote Tong, Kiribati’s President, who every year must plan for the future awaiting a people who will lose the very land they call home to the sea, on account of our actions.

For Liberal Democrats, there’s a serious concern that goes beyond the outcome of Paris. In six short months since May, we have seen the reversal of some of Ed Davey’s most significant strides forward in environment policy in UK history. The scrapping of the wind energy subsidy, as well as of ground-breaking carbon capture infrastructure, is seemingly just the early indication of intent of a Conservative government with all the green credentials of a global oil conglomerate. Simply responding on a case by case basis to these travesties will not be enough, we have to spark an internal debate and rediscover the environmental radicalism that led the party in 1997 to propose “…to shift taxation from jobs, wealth and goods to pollution and the depletion of natural resources”.

Why? Because as Paris is about to prove, environmental policy is no longer a secondary issue. It is about to be thrown into the frontline of public opinion, and the Lib Dems have to provide the unique leadership on the environment they have in the past if we are serious about getting back into government. The situation will evolve year by year and hazardous climate events will become more frequent. Across our island nation, people are waking up to the fact that the floods, droughts and storms at home and abroad that blight our lives and economy are as pressing a problem as inequality, debt and global terrorism. No issue highlights better the desperate need for the fightback to bring the party back to power soon than the ticking time bomb that is our environment.

* Guy Russo was the Parliamentary Candidate in Enfield North at the General Election and is an Ex-President of the Queen Mary University of London Liberal Democrats.