The strongest storms to strike the east and southeast Asian regions, particularly in countries such as China, Japan, Korea and the Philippines, have become more intense over the last 40 years, a new study says.

Results of the study showed that the increase in sea-surface temperatures in coastal areas has provided more energy to typhoons, causing the wind speeds to rapidly increase.

In the study published in the journal Nature Geoscience, researchers analyzed data gathered from centers in Japan and Hawaii. The scientists found that typhoons in the northwest Pacific had intensified by about 12 to 15 percent on average since 1977. The northwest Pacific has since been plagued by most tropical cyclone activity due to the deep well of ocean heat that could cause typhoons.

Also, according to the researchers, the proportion of landfalling Category 4 or 5 storms, which are the most destructive of storms like Super Typhoon Haiyan that killed 6,300 people in the Philippines in 2013, has doubled in number. The increase in intensity was said to be bigger in China, Taiwan and northern regions.

"It is a very, very substantial increase," Wei Mei, a researcher from the Department of Marine Sciences at the University of South Carolina and co-author of the study, said in a report by The Guardian.

"We believe the results are very important for east Asian countries because of the huge populations in these areas. People should be aware of the increase in typhoon intensity because when they make landfall these can cause much more damage."

However, the researchers are uncertain about whether the higher water temperatures are due to changing natural climate patterns or man-made climate change.

"With such a short record it is impossible to distinguish between natural decadal variability and [any] anthropogenic signal," Suzana Camargo, a hurricane-climate researcher at Columbia University said in a report by Climate Cental.

Mei and his team said that climate models suggest that warming will continue in these ocean regions, which also follows that more landfalling typhoons would fall under the strongest categories and would intensify more rapidly.

"We want to give the message that typhoon intensity has increased and will increase in the future because of the warming climate," Mei said in a statement. "Understanding intensity change is very important for disaster preparation."

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