Will Paris climate accord change the world?

But certainly, we should not downplay this achievement, or its significance.

First, and most importantly, we must remember why 195 countries came to Paris, including more than 150 heads of state, in the largest such gathering in UN history.

The reason they came is that the climate is changing, in all four corners of the globe.

Some changes are only creeping, at first, barely noticeable. Who would notice, or perhaps care, that the vitality of beech trees had declined in northeast France?

But everyone in Europe is familiar with an important cause: an exceptional drought and heat wave in 2003, which caused 15,000 heat-related deaths in France alone.

Climate change is here, and increasing the risk of such extreme events, whose impacts can unravel suddenly and unpredictably around the globe.

We are all affected.

Scholars have drawn links between climate change and a record heat wave in Russia in 2010, and higher global food prices that year. Similarly, climate change is implicated in a warming trend in the eastern Mediterranean, record drought in Syria, and resulting unrest and civil war.

Yes, these pictures are fuzzy and unsure, but we ignore them at our peril.

To control these risks, and put them behind us, countries meeting for the last two weeks in Paris had to meet three objectives.

First, a new climate agreement had to lay a clear path to a future, zero-carbon society. They could achieve this by committing to a target to eliminate greenhouse gas emissions this century.

In Paris, they have agreed just that. In addition, they have agreed to offer more ambitious climate action over time. This continuing cycle of commitments, every five years, will stiffen their ambition, and make the longer term goal more credible.

How will this commitment change the real world?

Importantly, it has reduced the risks of unmanageable climate change. This affects us all. In developing countries, it dramatically increases the prospects for broader, deeper prosperity, which is impossible in an unstable climate.

This long-term goal also means that progressive, forward-thinking businesses and investors can now more clearly sense the way the wind is blowing.

They can invent new, cheaper ways to cut carbon emissions and save energy, knowing that there will be demand for these products. They will drive the world away from fossil fuels, towards a future powered by cleaner renewables, and cut the cost of this low-carbon transition.

Similarly, the Paris Agreement will guide spending decisions in cities around the world, towards lower carbon, more efficient technologies and systems, which create greener, healthier and safer spaces.

Second, to ensure that this agreement was more than a piece of paper, we needed transparency. Countries have, indeed, agree to monitor their emissions, report the climate action that they are taking, and review their progress towards those targets.

And third, we needed fairness.

Even the most ambitious outcome from Paris cannot avoid climate change altogether: far from it. Temperatures will continue to rise for several decades; regrettably, they are locked into our planet’s climate system.

But we can diminish the effects of these future heat waves and storms, by helping the poorest and most vulnerable countries prepare.

That is why these countries have quite rightly called for help, at this climate conference, and others, for a decade or more. The Paris Agreement has listened.

This Agreement has achieved strong and robust climate finance, which richer countries will continue to supply developing nations. Where large, more prosperous emerging economies can afford it, and want to, they can also step up and help.

With these achievements, this Paris Agreement is catching up with the real-world, where we have seen significant shifts in public opinion, investment choices, and business decisions in recent years - away from dirty energy and towards clean solutions.

This job is not done.

More action is needed to secure a stable climate that underpins prosperity.

If we leave climate action too late, then we will have to cut emissions too much, too fast, at too high a cost. That is why it is important that countries return, in four years’ time, to consider raising their existing ambition, which so far falls far short of the long-term goal they have set, to avoid dangerous climate change.

For further action, we are depending on the world’s innovators, entrepreneurs and engineers to deliver the new, cheaper, low-carbon technologies, where solar power and LED lighting have blazed such a trail in the past five years.

And we can be confident that business will respond, because they came in unprecedented numbers to Paris, to work alongside nations. The greatest ambition, arguably, came not from nations but from the cities, entrepreneurs and investors on the side lines of the conference.

Paris demonstrated, in this way, an unprecedented coalition between governments, cities, companies, and campaigners, to address a pressing global issue. It showed that multilateralism is working.

This collective, political moment when leaders came together in Paris can empower an economic revolution. They have reached an agreement which can sustain and accelerate an economic transformation.

Jennifer Morgan is global director of the World Resources Institute, a think tank in Washington