Rusina Rusin on April 16, 2015, with her grandchildren, including Keslynna Myo Sibok, right, at their home in the part of the Marshall Islands' Majuro Atoll that is most vulnerable to flooding. Renee Lewis / Al Jazeera

The atolls of the Marshall Islands are narrow and practically level with the sea, leaving their 68,000 residents nowhere to move to as a rising sea and increasingly frequent floods threatens to swamp the country. Unlike in many parts of the world where climate change often seems a distant threat, for the Marshallese it is already a daily reality.

Keslynna’s grandmother, Rusina Rusin, said the land has been in her family for too many generations to count, passed down from mother to daughter in the country’s matrilineal social system. She said she has noticed the increasing unpredictability of the weather.

“I’ve been living on the ocean so I can see a difference,” Rusin said. I believe it’s an effect of climate change.”

She said the Marshallese are “sea masters,” famed for navigational skills and intimate knowledge of the ocean that allowed them to find and settle the remote atolls thousands of years ago — but now no one can predict what the ocean will bring. Floods suddenly occur without the usual warning signals of storms, rain or wind, Rusin said.

The last flood happened in March; before that in February. But the worst inundation happened in spring last year, when water rushed through Rusin’s home and dragged household items — including Sibok’s prized doll house — out to sea.

“I had to go out to the reef to get my clothes and collect them along with a towel, buckets, and a chair,” Rusin said. She chuckled at that image, but quickly turned serious.

“I’m just a lowly grandmother and widow, not having anything precious except land and grandchildren, but every time it floods it affects the land and it costs me,” Rusin said. “I depend on the crops — the coconut trees, bananas and herbs for medicine — I could never manage a subsistence life if this continues.”

The elevation of the Marshall Islands averages just six feet, with many areas roughly at sea level. Rising waters have prompted residents to build piecemeal seawalls and earthen barriers that do little to stop flooding. During especially high tides, sandbags can be seen stacked around the Majuro airport runway and along some roads in especially low-lying areas.

“Our main concern, because we’re very low-lying, is inundation,” said Reginald White, a meteorologist at the Majuro Weather Service Office who studies climate-change trends including sea-level rise.

The type of risks the country faces from climate change vary depending on whether it is an El Niño or La Niña year — warm or cold phases in the equatorial Pacific Ocean, White said. During an El Niño, which scientists have predicted will occur throughout 2015, wave heights decrease by several inches, but the risk of typhoons is doubled. Conversely, wave heights increase by up to a foot during a La Niña, when increased rainfall can also trigger floods.

“My house got flooded,” White said, recalling the previous year. “Sea level could continue to rise, but when it is combined with spring tide, La Niña and even a moderate storm surge, there will be a major inundation event.”

Floods exacerbated by rising sea levels can taint the country’s limited water resources with salt, as well as damaging its scarce agricultural land.

Seas are rising in the Marshall Islands at least twice as fast as the global average, according to tide gauges and satellite data provided by the country’s government — echoing reports by researchers in other countries who have found indications of regional differences in sea level rise.

The United Nations Intergovernmental Panel on Climate Change last year warned of an average three-foot sea level rise by the end of this century. But with new insight into melting glaciers in West Antarctica and Greenland, other researchers have said that number should be revised to at least six feet — which would swamp much of the Marshall Islands.