Some 18 million British children, women and men have fled their homes as a result of the civil war that has torn Britain apart over the last two years. About 280,000 people have been killed, and many more wounded. That, proportionately translated, is the scale of the Syrian tragedy. And there is no end in sight.

The Guardian today documents individual human stories from this disaster. They are more moving than any statistic. But the numbers are eloquent too. Some 6,000 refugees pour out of Syria every day, straining international humanitarian aid resources and destabilising the country's neighbours. Syrian refugees already make up 10% of the population of Jordan. That's like the whole of Bulgaria moving to Britain.

António Guterres, the UN high commissioner for refugees, says the displacement of people has not risen "at such a frightening rate" since the Rwandan genocide of 1994. And he told the Guardian yesterday that this might mean asking countries like Britain to take some of Syria's uprooted. The absolute size of the humanitarian catastrophe may not yet match the largest, but Syria is working hard to catch up.

Moreover, its political knock-on effects are potentially far greater than those of any mere tsunami, drought or earthquake. Syria's civil war has set the old Sunni-Shia wound bleeding again in the whole neighbourhood. Iran, Hezbollah and Shia Muslims in Iraq support the forces of president Bashar al-Assad against internal and external Sunni foes. Blood flows more freely than water across the arbitrary, post-colonial frontiers of the region. Beside the external Islamic patron states, including Saudi Arabia and Turkey on the Sunni side, there is Russia arming al-Assad's forces against rebels who are being (very tentatively) supported by the US – almost as if we were back in the cold war.

Syria also fits into a larger picture, with the UNHCR recording an 18-year high of more than 45 million forcibly displaced people worldwide at the end of 2012. The current rate of displacement is about one person every four seconds. Give the wider Middle East another year or two, and the world will have a whole England of the uprooted (around 56 million people). "Something must be done," we cry, as we pack our suitcases for the summer holidays. But what? Make the decisive, massive military intervention that alone would defeat Assad, and you face another Iraq. Don't intervene, and accept another Bosnia. The record of western military intervention in this region is disastrous. Yet the notion that not intervening in any way, militarily or otherwise, is always the most moral option simply does not stand honest scrutiny.

Syria demands that we think again about the relationship between politics and humanitarian action. Earlier this month, the former foreign secretary David Miliband reflected on this in his last major public speech before leaving his first life, as a politician in London, to begin his second life, as the leader of a humanitarian organisation – the International Rescue Committee – in New York.

On the one hand, the morality of what he will do as a humanitarian is far simpler than that of what he did, or might still be doing, as a politician. Deploying tents to shelter people in desperate need is more obviously, unambiguously good than deploying half-truths to win votes. In that sense, David might exclaim "it is a far, far better thing that I do, than I have ever done". On the other hand, it could also be a far less effective thing than what his brother Ed may yet have a chance to do as Britain's prime minister.

For the nature of humanitarian relief in man-made disasters is that you are treating the symptoms and not the causes. Were politicians to address the political causes of Syria's disaster, that would be more valuable than everything all the humanitarian organisations in the world can do. If the US, Europe and Russia really got together and said, "we're going to de-escalate this conflict, through stopping all the arms supplies we have any influence on, followed by a negotiation involving all the relevant internal parties and external powers, including Iran under its new president", they might get somewhere. But it's simply not happening, nor likely to happen any time soon.

David Cameron described the situation inside the country as a "stalemate", with Assad's military position somewhat strengthened, and growing sectarian extremism on the opposition side. Pressed for a no-fly zone by angry Syrian refugees in the Zaatari refugee camp – a tent settlement so densely populated it is said to be Jordan's fourth largest city – US secretary of state John Kerry explained to them that "a lot of different options are under consideration". Translation: Washington sees no good ones.

That's no excuse for abandoning the politics. But given that they are blocked, humanitarian relief becomes even more vital. Until the surgeons finally tackle the causes of the disease, we have to keep changing the bandages, alleviating the pain and feeding the patient. But this too is not happening enough. Governments have only met a third of the UN's funding targets for humanitarian assistance for Syria. That puts even more strain on non-governmental humanitarian organisations, yet Oxfam says people have so far donated just a third of its £30m Syria target. Four months into a six-month campaign for Syria, the UK-based Disasters Emergency Committee, a seasoned coalition of charities, has only raised £17m. By contrast, its six-month campaign for victims of the Asian tsunami raised £392m, and that for the Haiti earthquake, £107m.

It seems that visually shocking natural disasters, where people are seen to be innocent victims of what insurers call "acts of God", get us giving far more generously than political conflicts do. The Disasters Emergency Committee's 2009 campaign for Gaza raised just over £8m, its 2008 one for the Democratic Republic of Congo, £10.5m. This is perhaps understandable, but not rational. Why should what innocent people suffer as a result of "acts of God" be considered worse than what innocent people suffer as a result of their compatriots fighting each other in the name of God?

As a columnist on international affairs, I get tired of telling governments they "must" do something, knowing perfectly well that nine times out of 10 they won't. This time I have a simpler conclusion. Before we go away on holiday, we should all make a donation to humanitarian relief for Syria. That's what I shall do when I've clicked the "send" button for this column.

Twitter: @fromTGA