It has been known that climate change is causing harm to our planet, but now a team of researchers have found that this phenomenon will be a major cause of flooding in New York City. The study showed that NYC will see floods every 25 years rather than every 500 years.

In the study published on Monday in journal Proceedings of the National Academy of Sciences, researchers found that flood level height rose to about 4 feet between the years 850 and 2005. They said that the major cause behind it was sea-level rise caused by melting ice glaciers and ice sheets and warmer water temperatures.

"Sea level is rising because of climate change. But climate change also appears to be leading to larger and more intense tropical storms", one of the study's scientists, meteorologist Michael Mann, told USA Today.

In a new study scientists said the risk of major hurricane or storm-driven flooding in New York City is already considerably higher than it was 1,000 or even 100 years ago. They said that this has been due to both considerable rise in sea level and changes in the nature of storms.

Researchers wrote: they have seen more intense storm with a greater ability to produce high storm surges at The Battery in NYC during the anthropogenic era than during the pre-anthropogenic era.

A separate research paper this month suggested that Tampa, Fla., also faces a major hurricane flooding risk. The Atlantic Ocean actually has considerably better hurricane records than many other parts of the world, but those still only go back to 1851.

"We see more intense storms with a greater ability to produce high storm surges at The Battery in NYC during the anthropogenic era than during the pre-anthropogenic era," the researchers write.

"I think the punchline is, we made Sandy much more likely already," says Mann. "We're already dealing with greatly elevated risk. We're not just talking about the future. Climate change is already costing us dearly, but it'll be a whole lot worse if we do nothing about it."