This week the free world has a new leader – and such is the global importance of the United States’ leader that those of all political persuasions genuinely wish President Biden well.

America remains the most powerful and most important democracy in the world. Like all leaders, the American President has a responsibility to fight for US interests.

But Joe Biden also has a responsibility of which he is acutely aware: to uphold the democratic values shared by many other countries too.

In doing so he must repair some of the damage done by Donald Trump two weeks ago when he incited his own supporters to march on Congress. I spoke out against his actions, something I did with a heavy heart as a former Foreign Secretary having worked closely and productively with Trump on many issues.

Nonetheless I thought it was necessary to say that even though his actions shamed America, they did not represent America. As we have seen from the many Republicans, including his own Vice President, who refused to go along with his approach, the former President spoke neither for America nor even for the Republican Party.

But Joe Biden’s challenges extend far beyond bringing America together after such divisive antics. According to the Centre for Economics and Business Research, by 2028 China will overtake the USA as the world’s largest economy.

It will be a big moment: for the first time in our lifetimes, the richest country in the world will not be a democracy.

Of course, it will take much longer for China’s GDP per head to catch up with Western levels, something that may not happen in our lifetimes. But the global balance of power is changing – with profound implications for those of us who believe in open societies.

Last week I interviewed Tony Blair about these issues for the think tank Chatham House. You can see some of the questions I asked him on my Facebook page.

He had two key insights: first of all if we are going to defend our own system, we need to make sure it actually works. Populist leaders like Donald Trump and Jair Bolsonaro do not succeed in the end because they fail to make lives better for their own citizens. That is a trap Boris Johnson is wisely determined to avoid with his levelling up agenda, something rightly close to his heart.

Secondly, we need to put back together the Western alliance that was so successful in the Cold War. Here Blair’s point was that for a relationship with another country to work, you have to be prepared to invest in it. That means sticking with it even when the going gets tough.

Individually, no Western country will be as big as China. But collectively we still represent over half of global GDP. I do not, incidentally, suggest a new Cold War with China is the right way forward, far from it. We must find a way to co-exist with China.

That means making much greater efforts to understand each other better, including the sometimes uncomfortable business of recognising China’s new-found strength and influence in the world.

But where we have to, we must also be prepared to work with allies who share our values more effectively to protect our democratic way of life.

I gave the final question in the Chatham House seminar to my 10-year-old son John.

“Will we have fixed the climate crisis before I get to your age?” he bravely asked the former Prime Minister. Blair was surprisingly optimistic that we would. But I suspect it will take much longer to secure the future of open societies.

For John’s sake – and his entire generation – we must not shirk the challenge. Good luck Mr President.