Leading article: Is the glass half full? Why, bless us, so it is

Is that a half-full glass we see, as we look back on another year? As a young newspaper, shortly to celebrate our 17th birthday (28 January 2007, thanks for asking), we are temperamentally bound to be optimistic. Although, at this age, the answer that might be expected by text message is YYSSW - "Yeah, yeah, sure, sure, whatever". Still, we will take that as a yes. Not that we share the common prejudice against 17-year-olds, by which they are portrayed as inarticulate, hooded and antisocial. We are in favour of teenagers, generalising sweepingly, and regard the present generation as the best-educated, most polite and most socially conscious in our nation's history.

Our point is that the bad news of 2006 has been balanced by the good. Most discouraging has been the state of Iraq and the wider Middle East. As the newspaper that led the campaign against Britain's involvement in George Bush's invasion, we derive no satisfaction from the fact that, as the year progressed, it became impossible for even Tony Blair to deny that Iraq is "pretty much a disaster". It is not wise for those who opposed the war to say, as Richard Ingrams did yesterday, that his "hopes" that President Bush's chickens would come home to roost have been confirmed by the worsening situation.

Nor have we had anything other than the utmost respect for the bravery and decency of British soldiers in Iraq, who have worked hard in difficult circumstances to try to make life better for the Iraqi people. The Independent on Sunday is not a pacifist newspaper. We supported the overthrow of the Taliban in Afghanistan and have argued that the military and humanitarian mission to rebuild the country should be pressed more forcefully. Indeed, we agreed with Mr Blair when he promised the Afghan people in 2001 that we would not let them down, and have criticised him only for failing consistently to follow through on that pledge - not least because of the diversion of resources to Iraq. It is as a tribute to the courage of our armed forces that we have devoted this issue to letters home from the front - or fronts, both in Iraq and Afghanistan.

The bad news from Iraq has been compounded over the past year by the further downward spiral of Israeli-Palestinian relations, which has long been such a challenge to optimists. The incursion into Lebanon was a counterproductive attempt to enhance Israel's security in the long term. Both it and the Western intervention in Iraq exacerbate the sense of Muslim grievance - however unjustified - upon which the jihadist death cults feed.

Yet 2006 also saw encouraging progress towards many of the goals for which this newspaper has campaigned. The most important of these is that of restraining climate change. As we have reported all year, global warming is already displacing and impoverishing not just penguins but people around the world. Today, we report the first disappearance beneath the rising sea of an inhabited island, off the coast of India. That is why our Christmas appeal this year is devoted to trying to help those affected by climate change around the world - please give generously. Despite our differences with each of them, we congratulate Tony Blair and David Cameron for pushing Britain to the forefront of global efforts to restrict the output of greenhouse gases. Mr Blair put the issue on the G8 agenda last year; this year Mr Cameron made it possible for Mr Blair and Gordon Brown - should he want to, and he should - go farther. We are not starry-eyed about Mr Cameron. There is, for example, force in the argument made by David Miliband, Secretary of State for the Environment, that effective green action at the global level requires a positive engagement with the European Union. Any attempt to curb the growth of aviation really has to start at the EU level. The Tory leader is a Eurosceptic to his core. But Mr Brown is no passionate pro-European either. Nor is he even a convincing shade of green. At least Mr Cameron, by taking away the threat that the Conservatives might opportunistically oppose green action, has given the Government more scope to take the difficult decisions at home that could give a lead to international talks.

The other global cause that we have espoused, and that Mr Blair also pressed at the G8 last year, is that of poverty, especially in Africa. It saw less follow-up this year. Indeed, the situation in Darfur continued to deteriorate as Russia, China and the Arab League obstructed more forceful action at the United Nations. But much hard, unglamorous and constructive work is being done, and yesterday was recognised by the Queen's award of a knighthood to Paul Hewson, better known as Bono. As the Prime Minister said: "You have tirelessly used your voice to speak up for Africa."

For many years we have also campaigned for better provision for those suffering from mental illness and their families. This year saw welcome progress in public understanding of manic depression - now increasingly known as bipolar disorder - thanks to the honesty of Stephen Fry on the BBC and Alastair Campbell in our pages. Unfortunately, scare stories still associate those suffering from mental health problems with violence. And the Government persists in seeking draconian powers to detain people who have committed no crime in a new Mental Health Bill. Our campaign continues to secure sensible amendments in the House of Lords.

Linked to our mission to promote the psychological health of the nation is our Sunday lunch campaign, to encourage families to eat together. Tomorrow is, of course, an honorary Sunday writ large. But let this not be a one-off annual event. Wishing you a low-carbon, fair-traded, cruelty-free one, so far as is reasonably practicable.

Let this be the season of goodwill to all people - and penguins. Is the glass half full? Well, bless us, so it is. A happy Christmas to all our readers.