Reflecting on the legacy of German post-war leader Willy Brandt, Gro Harlem Brundtland rejects recent isolationist trends and celebrates collective efforts towards achieving a peaceful, just and sustainable world.

Two years ago, the countries of the world came together at the United Nations to agree the new Sustainable Development Goals.

These 17 goals cover all aspects of human life and development from health and education to peace, justice, security and equality. They are the successors to the Millennium Development Goals, but crucially they apply to all countries and not just the developing world.

Every head of state, every government and every citizen has a responsibility to ensure that these goals are met.

I have just returned from Berlin, where I participated in a conference to honour the work and legacy of the great German post-war leader Willy Brandt.

Brandt was a brave German who fought against the Nazis from exile in Norway and Sweden, and then helped rebuild his country after the war and restore its democratic foundations. But his vision extended far beyond national borders – when he talked about peace and solidarity, he meant it in global terms.

The Brandt Commission of 1977 explored the widening gap between the global North and South, and how this could be bridged. It was a huge inspiration to me in my own work in chairing the World Commission on Environment and Development in the mid-1980s.

Since then, the concept we defined – sustainable development – has finally taken root in governments and international institutions, who understand that only a holistic approach can tackle global problems. After decades of disagreement, 2015 saw the elaboration of the Sustainable Development Goals and the Paris Climate Agreement, both of which now apply to all our countries.

Together with the Paris Climate Agreement, the SDGs represent a genuine multilateral success story at a time when prospects for meaningful international cooperation can sometimes appear bleak.

Since the financial crisis ten years ago, we have seen a growing backlash against globalisation and a resurgence of populist, protectionist and xenophobic politics – Brexit and the election of Donald Trump being just two prominent examples.

But listening to the other speakers in Berlin, particularly young people active in the fields of diplomacy, academia and civil society, I was heartened by their determination to work together, learn from each other and reject the siren songs of isolationism.

Later this year, the German government will host the COP23 climate conference in Bonn. In the wake of President Trump’s decision to withdraw the United States from the Paris agreement, some feared this would be the end of the road that began so promisingly in Paris two years ago.

But instead, there is a growing determination that climate action can and must continue, and that the world cannot be thrown off track by the actions of just one President. Crucially, many Americans are saying the same thing – including mayors, state governors, business leaders and civil society.

My report in 1987 was titled “Our Common Future”. Thirty years on, this concept still resonates. From fighting terrorism to managing migration, from developing new models of environmentally-sustainable economic growth to promoting tolerance in multi-cultural societies, we will only make progress if we act in concert with one another.

As Willy Brandt himself said: “the shaping of our common future is too important to be left to governments and experts alone”.

This is why, as The Elders, we have launched our “Walk Together” campaign to mark our 10th anniversary and uphold the values of solidarity, empathy and collective action.

I hope you will follow and participate in this campaign in the months ahead, and help us build a future that is fair and just for all.