Al Gore, politician and environmentalist, US

If there is one "Face of Climate Change" integral to this collection of thinkers and doers, it must be former U.S. Vice President Al Gore. Equally so his presence at a climate conference that carries as much importance as COP21 in Paris. Having gained a reputation as a champion of environmental causes with his multi-award winning documentary "An Inconvenient Truth", his work on climate issues secured him the Nobel Peace Prize.

During the past two weeks of talks at Le Bourget, he has called on the world to do what has to be done, putting to it, three simple, but pertinent questions.

The first, which he delivered to a packed plenary hall half-way through the conference, asked "Must we change?" Referring to weather events such as the floods that had claimed dozens of lives in India in the preceding days, and others which are less sudden but extreme in their persistence, such as the water crisis around Sao Paolo in Brazil, he said the "accumulation of man-made greenhouse gases in the atmosphere is causing a massive disruption of the climate balance, a disruption of the water cycle, a threat to food security."

The answer then, to question one was a clear yes. Is a clear yes. Onto question two: can we change?

Citing findings from researchers, investors and developers Gore spoke of the falling price of renewable energies.

"In my own country in 2015, more than 70 percent of all new electricity generation capacity has come from solar and wind." As such, he concluded, we clearly can change, and the human narrative has shown us to be well capable of adapting to the times and needs thereof.

With reference to outdated modes of living such as slavery, suffrage and Apartheid, he said "there have been many great moral causes that have asked us to choose between what is right and what is wrong." In the case of climate change, he continued, we know what we have to do.

"The right choice is to safeguard the future for the next generation and the generations to come.”

His last question was "will we change?". Perhaps less rhetorical than the first two, but even here, he expressed his belief that the "right choice" would win out. And for those who allow their doubt to get the better of them, he had another concise message. "I ask you to always remember that political will is itself a renewable resource."

At the end of the climate conference, after the Paris Agreement had been unanimously adopted, and the cheering and applause in the plenary hall had died down, he spoke again. This time, against a backdrop of pledged sustainability of that political will.

“Today, the nations of the world concluded a bold and historic agreement, clearly demonstrating that the global community is speaking with one voice to solve the climate crisis. Years from now, our grandchildren will reflect on humanity's moral courage to solve the climate crisis and they will look to December 12, 2015, as the day when the community of nations finally made the decision to act."

He said the components of the agreement, which include a strong review mechanism to build on existing commitments, are essential to unlocking the necessary investments in our future. "No agreement is perfect, and this one must be strengthened over time, but groups across every sector of society will now begin to reduce dangerous carbon pollution through the framework of this agreement."

And as they do, he will be watching. Because the agreement reached at Le Bourget this weekend is not a solution in and of itself. It is, however, a chance to work towards finding one.