With such a powerful tool at our disposal, the choice before us is alarmingly simple: we can choose to save our children or not.
Excellencies, Ministers, Ladies and Gentlemen,
The United Nations and the world it serves are going through an unprecedented period of change.
As the pace of that change quickens, it would be all too easy simply focus on protecting ourselves from the problems - to mitigating the disasters.
However, with the 2030 Agenda for Sustainable Development and the Paris Agreement on Climate Change, we have started to recognize that while each nation will always have its own priorities and challenges, by focusing on what we have in common rather than what makes us different, we can create an incredible force for positive, meaningful change.
The Vienna Convention and its Montreal Protocol probably exemplify that more than any other agreement in history - clearly demonstrating the kind of fast, bold action that can be delivered by using science to identify the priorities, policies to set us on the right course and public-private co-operation to scale up the solutions.
It's why the writer and astronomer Carl Sagan said "The hole in the ozone layer is a kind of skywriting. At first it seemed to spell out our continuing complacency before a witch's brew of deadly perils.
But perhaps it really tells of a newfound talent to work together to protect the global environment."
He certainly has a good case.
Because without the Montreal Protocol, ozone depleting substances would be 2.5 times their current levels and an extra 2 million people would be diagnosed with skin cancer every year - that's equivalent to the entire population of this beautiful city of Vienna.
With them, not only will we restore the ozone layer and spare the climate from 135 billion tonnes of CO2 equivalent emissions, but the benefits for global health are estimated to be worth $1.8 trillion by 2030 and the benefits to agriculture, fisheries and materials are likely to be worth $460 billion by the middle of the century.
So, it is no accident that the Montreal Protocol is quoted again and again as an example of what can be achieved when 197 countries set their minds to it.
Unfortunately, as the saying goes, you are only as good as your last success. And it will not be the history books that determine our success or failure; it is whether there will be anybody left to read them.
Hydrofluorocarbons (HFC's) played a crucial role in delivering the Montreal Protocol and reversing damage to the ozone layer. However, we have already spent five years discussing why they in turn must be phased out.
Ladies and gentlemen, if we continue debating the differences in our approach to resolving this, then by 2030, HFCs could cancel out the climate benefits already achieved by the Protocol.
But if we can focus on our common ground and agree to phase out HFCs, then we will continue to protect the ozone layer, we will avoid 0.4C of global warming by 2050, providing a massive push for the Paris Agreement on Climate Change and we will help deliver the 2030 Agenda for Sustainable Development.
When phasing out chlorofluorocarbons (CFCs), some of the obstacles seemed insurmountable. How could we possibly expect millions of patients to stop using metered-dose inhalers for problems like asthma or chronic obstructive pulmonary disease, particularly when use has doubled in the last 20 years? Yet the co-ordinated effort from the pharmaceutical and healthcare industries created a replacement that is both more effective and less expensive, turning one of the last CFC sticking points into a global step forward for patients and planet alike.
Nobody claims it will be easy to use the evolving, even imperfect knowledge of today to deliver hard, fast, decision action that will pivot humanity to a new pathway within just a few years, but which will affect us for generations to come.
Like so many aspects of climate change, we can see how our decisions and actions have consequences that we will never experience: it's the ultimate paradox and this is our chance to show the world that the Montreal Protocol offers a proven mechanism to crack it.
Don't get me wrong, HFCs were our only viable option based on the science available at that time and without them we would be facing a much bigger challenge today. But having phased them in, we are the only ones who can phase them back out to prevent them growing by 7 per cent a year, taking us towards HFC emissions of up to 8.8 gigatonnes carbon dioxide equivalent per year by 2050. That's nearly 20 times the weight of the entire population of the earth.
That's why it's such good news that we are all committed to phasing out HFCs, working on the positive premise that we can and will find a way to resolve the remaining challenges.
However, if we fail to provide solutions and compromise on the details by the time we leave Vienna, then that bigger agreement is in jeopardy - a responsibility that would be shouldered equally among developed and developing countries.
Ladies and gentlemen, I mentioned the power of science, policy and co-operation. That extent of that power was confirmed last month, with news that the hole in the ozone layer has been reduced by an area the size of India, thanks to the phasing out of CFCs under the Montreal Protocol.
So, with such a powerful tool at our disposal, the choice before us is alarmingly simple: we can choose to save our children or not.
I for one believe that we can choose to go down the Dubai Pathway and take decisive steps to secure Kigali as a turning point. If we do, the ozone will transform ominous skywriting into a story of hope, through the 2030 Agenda and the Paris Agreement on Climate Change.
But whether we do, only you can decide.