As I write this article, I am on the Eurostar from London St Pancras to Brussels. You might think this a strange diversion in the final week of my campaign to become leader of the Liberal Democrats. But today's trip is at the very heart of why I want to lead our party.
Because whether we are a party of eight MPs or 208, we cannot hope to address so many of the challenges we face as a society on our own. The great threats of the coming decade - global climate change, mass migration, international economic upheaval, and a deteriorating security situation - are international challenges, requiring international solutions.
At a time when the liberal voice not just in Britain, but across Europe, has been dangerously weakened, we must stand together with our European allies and make sure our voice is heard. I will be starting a conversation today with some key liberal figures in Europe, including the International Secretary of D66, leading members of the ALDE group in the European Parliament, and the liberal think tank European Policy Centre.
I will be talking to key figures first about the threat of Grexit. There's an overwhelming imperative for Greece finally to embrace reform - such as ensuring that wealthy Greeks all pay their taxes, making their economy more open and transparent, and putting the public sector in a more sustainable footing. But just as Greece commits to reform, EU leaders must recognise the importance of debt relief. And once we are past this immediate crisis, we should look at liberal ways to bolster the fragile European economy - including potentially a reduction in trade tariffs with North America.
There is a crucial role for the EU to play in leading the drive to reduce emissions and tackle climate change. We must make sure that across Europe the right economic incentives exist to promote investment in green infrastructure - both from national governments and from businesses.
We will only manage the impact of global mass migration if European countries work together to share the burden fairly and humanely. So far Britain has failed to step up to the plate. And in particular, a stronger joint response is needed to the humanitarian disaster that is taking place on the shores of the Mediterranean - and the EU must lead the way in this. Across Europe, liberalism and humanity must prevail over those who peddle a message of division and fear.
And Europe must show a united front against Russian aggression, challenging Putin's assault on Ukrainian sovereignty and showing solidarity with other countries on Russia's borders. Peace and security is in the interests not just of Europe, but of Russia too - we must reinforce that point with tougher sanctions if Russia does not moderate its behaviour. And we must continue to argue for deepening Ukrainian democracy, to make sure its citizens have a real say over decisions about the nation's future.
But - for all its massive potential as a force for good - Europe is far from perfect. As Liberal Democrats we must not abandon our critical faculties when it comes to the EU. If we support greater devolution here in Britain, that principle must apply to the EU too. We must always ask ourselves - would it be better for this decision to be taken closer to the people it will ultimately affect? We must be clear in challenging poor financial discipline and openness. And we must keep arguing for those proposed EU reforms which the Tories and Labour have persistently ignored - tackling the influence of lobbyists, and increasing transparency about Council decisions.
If I am elected leader, I will be on a mission to get Liberal Democrats elected at every level. But I will also be on a mission to keep Britain in a reformed Europe. We can achieve so much more together to improve lives and safeguard the future of our planet by working together with our fellow liberals across Europe. And my work starts today.