The war in Syria is costing the country £3.2 billion a month in lost growth; a figure that could spiral to £915 billion in total if the crisis continues for another five years, a new report has found.

The cost of conflict for children: Five yeas of the Syria crisis was co-written by Christian charity World Vision and Frontier Economics, Europe's largest independent economic consultancy. It found that since war broke out in Syria in 2011, it has cost the country more than £190 billion in lost growth – economic value that could otherwise have been created through goods and services. This has had a direct impact on food prices, which have soared, the cost of water, health care, and every other part of normal life. A quarter of Syrian schools have been destroyed or damaged since the war began. According to the UNHCR, at least 8.2 million children both in the country and the surrounding region are experiencing disrupted schooling, food insecurity and limited protection from serious harm and abuse.

"What you see in Syria is bombed towns, bombed cities, bombed roads, bombed bridges. That's what Syria is right now," World Vision's Brenda Yu told Christian Today. She recently visited a number of countries neighbouring Syria including Lebanon and Jordan, where millions of Syrian refugees have fled.

Yu met a refugee father who was forced to flee Aleppo with his family. He told her, "Aleppo is war. Bombing. Shelling. Shooting. There is no electricity, nothing to eat or drink."

"Those were his exact words," Yu said. "That's why these figures matter. It's about helping people to understand why it's so important to start thinking ahead while we have the time."

World Vision is urging the international community to prepare for Syria's eventual recovery. The charity says it is vital to learn from experience in Iraq and Afghanistan, and not to wait until the war is over to begin planning Syria's reconstruction.

"As [the cost of war] continues to go up, Syria continues to lose what it could have been," Yu said. "It will take more time and more detailed planning to make this work; to rebuild the country and to give Syrians the help they are hoping for."

According to the report, "direct and indirect impacts on education services resulted in the equivalent of 24.5 million years of lost schooling by the end of 2015." Economic pressures have also spread to neighbouring countries; Jordan has taken in more than 600,000 Syrian refugees, while Lebanon is hosting at least one million. This has caused an immense strain on education, health and other services.

One six-year-old Syrian refugee met by researchers, Heba, draws pictures using only black and red crayons. She draws bodies, barrel bombs, and helicopter gunships. "When I think of Syria, I only see black," she said.

Tim Pilkington, chief executive of World Vision UK, said the conflict in Syria has "shattered the lives of over eight million children."

"With their homes, schools and hospitals bombed and their friends and families killed, many have been forced into appalling living conditions and abject poverty," he said. "When we meet severely distressed children who've fled sniper fire and bombing, our first concern is to keep them fed, clothed and alive. Faced with their suffering it's hard to think in terms of cold economic costs.

"But financial loss translates into human loss – lost education, lost health, lost jobs and lost opportunities. The costs of the conflict are staggering. Unless we act now, this war won't just affect a generation of children, but their children's children.

"We cannot wait until the war is over to plan for their future... We must prepare the ground for peace now."

Yu met a number of parents in Lebanon and Jordan who have been forced to send their children to work to help provide for their family. One man, Ahmed (name changed), has a 12-year-old son who works nine hours a day for about five Jordanian dinars, the equivalent of £4.60. Ahmed's wife was forced to sell her gold ring after the family fled Raqqa, an ISIS stronghold. "We just want to provide a decent future for our children," he said.

Another woman went into labour when she was eight months' pregnant and still living in Syria. She was rushed to the hospital, but there was an explosion and she was knocked over. Her daughter was born prematurely, and is brain-damaged. She believes it was because of the fall.

Families such as these who have experienced such trauma are the reason the international community must act immediately to secure a better future for Syria, World Vision says.

"The UK has gravitas and a great track record. It is the second largest bilateral donor for the Syrian crisis, and is in good standing to gather world leaders and other relevant actors to collaborate," Yu said. "We need to make sure Syria is ready for families like Ahmed's in the future."