Barack Obama observed last year that politics is getting smaller just as the challenges confronting politicians are getting bigger.

That is worryingly true, so I will suggest four major issues that we need to confront, that will shape our lives and where political leadership is essential.

1. Climate change. Global warming is already happening. If the bleakest predictions are accurate that will be catastrophic for future generations and the need to act decisively is urgent.

2. Terrorism. There remains a direct threat to the lives of British citizens. The worst case scenarios are almost too hideous to contemplate, but politicians needs to contemplate them in order to try and prevent them.

3. The shifting World order. We have got used to the most powerful countries being western, liberal and democratic. The rise of China, in particular, has some benefits, but it will fundamentally challenge Britain's relative prosperity and power.

4. The economy. Britain is currently borrowing £480 million every day. Getting the public finances under control without hurting all of us who rely on having decent public services will be extremely difficult. If we get it wrong the consequences will be painful for millions of British people.

Politicians obviously have a desire to see some restoration of public faith in politics, but we all have a deep interest in hoping that our politicians will have the wisdom, vision and support necessary to address these massive challenges facing mankind.