World leaders are meeting this week at the World Economic Forum in Davos. When they’ve finished counting their money, perhaps they could spare a moment to discuss the children of Syria. These innocents have been bombed, gassed and starved for four years in Ghouta and elsewhere, and it is time for even the sternest of leaders to search their souls for some humanity. The children bear no blame for this dreadful civil war, and they are our only hope for a better Syria.

As directors of Doctors Under Fire and advisers to the Union of Syrian Medical Charities (UOSSM), we and others persuaded the Russian government and the Syrian regime to allow nine children with curable cancer and 20 others out of Ghouta over Christmas; they will now live, but there are many others who might not. We also managed to do the same for 500 children in Aleppo on 16 December. We understand that the Russians, and in particular the foreign secretary, Sergei Lavrov, intervened directly with President Assad to make the evacuations of children happen. A few people have described our requests as appeasement of the Assad regime, but we have witnessed enough terror in the war zones of the world over the last 30 years to see things differently. This is pragmatic humanity. We want to give hope to a generation so completely let down by their own and global leaders.

The slaughter of the children of Ghouta is a disgrace to all, on all sides of this conflict.

Since 1 January, we have been in discussions with the Russians about the release of another 125 children from Ghouta who need life-saving medical treatment. We gave a list of these children, with their ailments, to the Russian embassy in London last week for onward transmission to Moscow, which promised to take up the cause with Damascus. Interviewed by the BBC last Friday, the Russian ambassador to the EU said that these children would be allowed out of Ghouta for medical care, but nothing as yet has happened. Meanwhile, there has been continuous bombardment, at least three strikes with chlorine gas and and hundreds killed in Ghouta alone since the beginning of the year. We are told that up to 75% of the children in Ghouta are likely to have PTSD and a whole generation is missing its education. These children are the future of Syria, but time is running out to give them a future worth contemplating.

The world, the UN and the five permanent members of the UN security council in particular seem to be standing by and watching in silence, unable or unwilling to get involved. Last Thursday the Foreign Office minister Alistair Burt told us that there is little the UK can do until a ceasefire is achieved, but the British government has at least already promised £1bn in aid to Syria. Other wealthy nations need to follow suit. Feeding and rebuilding Syria will be a gargantuan task.

We appeal to President Putin, who undoubtedly is able to influence Assad, to show some humanity, provide a tiny ray of hope and let these very ill children out of Ghouta. The Geneva peace talks need to resume as soon as possible, but it almost feels as if the UN mechanism is running out of steam over Syria. If the security council’s permanent five, especially Russia, get behind the peace process, there is just a chance it could work. If a ceasefire can be put in place, there is enough money swilling around Davos to feed and rebuild Syria, and enough people like us two to make it happen.

The slaughter of the children of Ghouta – and Syria’s 500,000 dead, 11 million displaced and 4 million refugees – is a disgrace to all, on all sides of this conflict, and to the world leaders who sit on their hands.

President Putin, you have a chance to right this wrong. President Trump, President Macron, Prime Minister May and others, you have a chance to give the children of Syria a future. For the sake of humanity, use your influence, power and wealth at Davos to make it happen.

• David Nott and Hamish de Bretton-Gordon are directors of Doctors Under Fire and advisers to the Union of Syrian Medical Charities.