Imagine a London where the entire subterranean region is engulfed with dirty water. Crammed train carriages that once barrelled along 249 miles of track transporting busy office workers, builders, teachers, civil servants, cleaners and students now rest in the murky debris-filled gut of a dying city – flooded iron ghosts. 

Last year’s chilling headlines warning that London is under threat of sinking was not enough to change the minds of well-known climate change doubters or persuade them that the frightening reality of Pacific island homes, schools, businesses, and entire nations disappearing into the ocean, could also soon become a real worry for western metropolises.

Those of us who have seen first-hand the death and destruction climate change is causing often feel like characters in a disaster film warning of impending doom.

For many the penny dropped after watching Hurricane Ophelia batter the UK. It connected to the narrative of Caribbean countries flattened by hurricanes, typhoons and cyclones wreaking havoc in the Pacific islands, and rich arable lands in Africa turned to desert. In some cases, countries lost the equivalent of 200 per cent of their GDP in hours. The loss of life is heart-breaking – as is the trillions of dollars’ worth of damage and the resulting spiralling debt and economic regression.

Europe has experienced an unprecedented heatwave with France registering record-breaking temperatures of 45.9 degrees Celsius. The stark truth is that climate change is not at our door, but in our house and ransacking our treasured belongings.

More needs to be done, not just by governments and industry, but by each and every one of us taking our responsibilities seriously.

Climate change is thankfully high on the agenda at September’s UN General Assembly (UNGA). The gathering is our opportunity to demolish the negative contentions of multilateral sceptics and to mobilise inclusive and responsible action for a sustainable future.

The theme, “A Race We Can Win. A Race We Must Win” is promising, yet we are doomed to failure if we fail to recognise that the tools we need to win against climate change are political will, collaboration, scientific research and innovation. These go hand in hand with financing and global public education campaigns to inspire behavioural change.

The Climate Change Performance Index, which measures climate protection performance, shows a huge swathe of the globe scoring low on climate action, very few countries scoring high and no country achieving top points for climate action.

The evidence for human-induced climate change is irrefutable and includes an average surface temperature rise of 1.62 degrees Fahrenheit since the late 19th century; the warming of the ocean by 0.4 degrees since 1969; a loss of 286 billion tonnes of ice per year from 1993 to 2016 in Greenland; glacial retreat; decreased snow cover, extreme weather events, ocean acidification and about an 8 inch rise in sea level in the last century.  

Only with a truly inclusive and worldwide effort, with every nation, government and community on board can we win the battle. 

This means persuading everyone that climate change exists and is affecting them – their lives and their livelihoods - rather than simply a problem for faraway islands.  We must also demonstrate that we do not have to sacrifice economic advancement to protect our planet. Green vehicles and buildings already exist, and eco-cities are beginning to emerge around the world. The genius of humankind got us into this mess, but can also get us out.

If we sit back with hands folded we send the world to hell in a handcart with ourselves on board, and discussions about trade, security, health and education become futile and meaningless.

My call to policy makers is to consider with the utmost seriousness what they can do to join our Commonwealth efforts to combat climate change. How will they support our work of helping countries to access finance for climate change-related projects, to promote innovative development solutions, to demand strong and enforceable climate legislation, and to launch a robust public education programme which demystifies climate change and places the passion for climate action in the hearts of every man, woman and child? Because if not now, when? And if not us, who?