Underground internet cables criss-crossing coastal regions will be inundated by rising seas within the next 15 years, according to a new study.

Thousands of miles of fibre optic cables are under threat in US cities like New York, Seattle and Miami, and could soon be out of action unless steps are taken to protect them.

The report, presented at a meeting of internet network researchers in Montreal, is among the first to reveal the damage a changing climate will cause for the network of cables and data centres that underpins so much of modern life.

What shocked computer scientist Professor Paul Barford and his colleagues most when they investigated the effect of rising tides on US cities was the speed at which the internet will be compromised.

"Most of the damage that's going to be done in the next 100 years will be done sooner than later," said Professor Barford, a researcher at the University of Wisconsin-Madison.

"That surprised us. The expectation was that we'd have 50 years to plan for it. We don't have 50 years."

Most of this infrastructure was constructed around 25 years ago along trails running parallel with highways and coastlines, with no thought given to how geography would alter as the climate changed

In their study, presented at the Applied Networking Research Workshop, the scientists combined a comprehensive map of the internet’s physical structure with projections of sea level rise produced by the US National Oceanic and Atmospheric Administration (NOAA).

10 photographs to show to anyone who doesn't believe in climate change Show all 10 1 /10 10 photographs to show to anyone who doesn't believe in climate change 10 photographs to show to anyone who doesn't believe in climate change A group of emperor penguins face a crack in the sea ice, near McMurdo Station, Antarctica Kira Morris 10 photographs to show to anyone who doesn't believe in climate change Floods destroyed eight bridges and ruined crops such as wheat, maize and peas in the Karimabad valley in northern Pakistan, a mountainous region with many glaciers. In many parts of the world, glaciers have been in retreat, creating dangerously large lakes that can cause devastating flooding when the banks break. Climate change can also increase rainfall in some areas, while bringing drought to others. Hira Ali 10 photographs to show to anyone who doesn't believe in climate change Smoke – filled with the carbon that is driving climate change – drifts across a field in Colombia. Sandra Rondon 10 photographs to show to anyone who doesn't believe in climate change Amid a flood in Islampur, Jamalpur, Bangladesh, a woman on a raft searches for somewhere dry to take shelter. Bangladesh is one of the most vulnerable places in the world to sea level rise, which is expected to make tens of millions of people homeless by 2050. Probal Rashid 10 photographs to show to anyone who doesn't believe in climate change Sindh province in Pakistan has experienced a grim mix of two consequences of climate change. “Because of climate change either we have floods or not enough water to irrigate our crop and feed our animals,” says the photographer. “Picture clearly indicates that the extreme drought makes wide cracks in clay. Crops are very difficult to grow.” Rizwan Dharejo 10 photographs to show to anyone who doesn't believe in climate change Hanna Petursdottir examines a cave inside the Svinafellsjokull glacier in Iceland, which she said had been growing rapidly. Since 2000, the size of glaciers on Iceland has reduced by 12 per cent. Tom Schifanella 10 photographs to show to anyone who doesn't believe in climate change A river once flowed along the depression in the dry earth of this part of Bangladesh, but it has disappeared amid rising temperatures. Abrar Hossain 10 photographs to show to anyone who doesn't believe in climate change A shepherd moves his herd as he looks for green pasture near the village of Sirohi in Rajasthan, northern India. The region has been badly affected by heatwaves and drought, making local people nervous about further predicted increases in temperature. Riddhima Singh Bhati 10 photographs to show to anyone who doesn't believe in climate change A factory in China is shrouded by a haze of air pollution. The World Health Organisation has warned such pollution, much of which is from the fossil fuels that cause climate change, is a “public health emergency”. Leung Ka Wa 10 photographs to show to anyone who doesn't believe in climate change Water levels in reservoirs, like this one in Gers, France, have been getting perilously low in areas across the world affected by drought, forcing authorities to introduce water restrictions. Mahtuf Ikhsan

The most at-risk stretches of cable were unsurprisingly those already close to sea level, meaning the slight increases predicted for the next few years will be enough to cover them.

The researchers estimated that in total more than 4,000 miles of buried fibre optic cable in the US will be submerged by 2033.

Massive underwater internet cables link North America with the rest of the world, and the landing points where these cables end will be submerged “in a short period of time”, according to Professor Barford.

While the large transoceanic cables are completely waterproof, the buried smaller fibre optic cables are not and if they are submerged there could be far-reaching impacts not only in the coastal US but potentially around the world.

Flooding in coastal cities has been acknowledged as a major threat, and many areas have already begun building hardy sea walls to prepare for the worst. Professor Barford said such preparations will go some way to protecting the internet, but will probably not be enough.

"The first instinct will be to harden the infrastructure," said Professor Barford.

"But keeping the sea at bay is hard. We can probably buy a little time, but in the long run it's just not going to be effective."

Professor Barford said recent hurricanes and storm surges in the eastern US had already given a taste of the kind of flooding that is to come. He said this study should serve as a “wake-up call” that prompts a discussion about how to protect the world’s precious internet from climate change.