In which case, what about climate change? And the fact that more than a billion human beings have to live on less than $1 a day? And nuclear proliferation; the threat of a worldwide pandemic; the crisis of globalised capitalism – not to mention the old-fashioned risk of war between states, which always increases as rising powers jostle for position with established ones?
When vendors of the Big Issue accost me at street corners with cries of "Big Issue! Big Issue!", I want to say: "Yes, but which one?" Islamist terrorism is a big issue. It will take a long struggle to reduce the threat to a bearable minimum, and that struggle will need to be conducted more skilfully than it has been over the last 10 years. But the trouble with the decade that starts tomorrow is that there are already half a dozen other king-size threats to the freedoms and way of life enjoyed by most – though not all – who live in developed liberal democracies. And that's before the 2010s have even begun.
There is, however, a pattern that is common to most of these big issues, and may therefore itself stake a claim to be the big issue. We face more and more risks, threats and challenges that affect people in one country – say, Britain – but originate mainly or entirely in other countries, and can only be addressed by many countries working together. That is true of the financial crisis, organised crime, mass migration, global warming, pandemics and international terrorism, to name but a few. The need for international co-operation has never been greater, but the supply has not kept up with the demand. In some areas, we have more international co-operation than we had 10 or 20 years ago. In important ways, however, it has become more difficult to achieve.
One of the main reasons for the difficulty is that power has been diffused both vertically and horizontally. I have written "countries" and "international" co-operation, but the power of national governments is increasingly constrained by multinational companies, banks, markets, media, non-governmental organisations and information flows, by international organisations supposedly above governments and by regions (including nations within states), provinces and cities supposedly beneath them. Beside this vertical diffusion there is the horizontal one: from the west and north to the east and south, with the emergence of new (or new-old) great powers to compete with the United States, Europe and Russia. The rise of China is the most important, and will be a central story of the 2010s, but there are also India, Brazil, South Africa, and others.
None of this is yet properly reflected in the institutional arrangements of the post-1945 international organisations, be it the permanent membership of the UN security council or voting rights in the International Monetary Fund. Historically, major shifts in the power relations between states have usually been accompanied by war. Rereading Samuel Huntington's book The Clash of Civilisations and the Remaking of World Order, first published in 1996, I was reminded that he imagines a Chinese-American war taking place in 2010. Things are not that bad yet, but over the next few decades, the mere avoidance of a major war, whether between China and America or inside Asia, will require conscious effort and statecraft of a high order. Yet this age of transnational problems demands not merely states that don't fight each other – the most basic condition of international order – but states that actively co-operate with each other as they have never done before.
Back in 2000, the United States could still have given a decisive lead, but it wasted a huge opportunity in the eight years of President Bush. The American foreign policy expert Richard Haass, himself a member of the Bush administration in its early years, talks of "a decade of strategic distraction". Now Barack Obama is trying to pick up the pieces, but it may be too late. Historians may yet say: Bush could have, but wouldn't; Obama would have, but couldn't.
At decade's end, the Copenhagen summit on climate change was a perfect vignette of this world of global problems without global governance. In theory, the nearly 200 states of the so-called "international community" would, under UN auspices, seal a legally binding international agreement to address the most obviously global challenge of our time. In practice, at 7pm on the very last day, the US president walked in to what is described as an "unscheduled meeting" with Chinese premier Wen Jiabao and the leaders of India, Brazil and South Africa, and asked "Mr Premier, are you ready to see me?" The five – America, China, India, Brazil, South Africa – then cobbled together a weak political declaration of intent, which the conference subsequently, under protest, endorsed. At the crucial meeting, Europe was nowhere to be seen. Europe's leaders were then photographed huddling disconsolately around a coffee table with Obama, looking like the losing team in a pub quiz.
So at the start of the 2010s we have not so much a multi-polar as a no-polar world. The internet and other forms of instant, worldwide communication offer unprecedented chances for making transnational campaigns on particular issues, but this is no substitute for what, in the jargon, is called global governance. The key to that, even within the international organisations, still lies with the governments of states. For all the proliferation of non-state actors, we still live in a world of states; and, I'll take a bet, still will in 2020. The EU is the exception that proves the rule: it, too, can ultimately only do what the governments of its member states allow it to do.
There are some initiatives we can take directly as citizens. The 10:10 campaign to cut our own personal carbon footprints by 10% by the end of 2010 is a good example. But, rationally, the main target of political activism must continue to be governments. Beyond what our own governments do in our own countries, the ones that matter most will continue to be the most powerful ones. That is simply a fact of life.
According to the best available projections, by 2020, the US, China and the EU will between them produce around half the world's GDP. If, on any of the big issues, you had a shared position of this "G3", together with some or all of the most relevant other major powers, such as Russia, India, Brazil and South Africa, that would not be the end of the matter. You would still want to go, perhaps via the G20, to the broadest possible international coalition, ideally under UN auspices. But it would be a very good beginning. To build such strategic coalitions of the willing and able, coalitions that will vary from issue to issue, is the daunting task of realistic idealism in the 2010s.