00:00Ah, you're standing on a beach in Hawaii.
00:08Warm breeze on your face, toes in the sand, a volcano smoldering in the distance.
00:14But this fairy tale won't last long as the whole island is sinking into the ocean,
00:1940 times faster than the scientists previously expected.
00:23Some parts of the island could be underwater by 2050.
00:27Uh-oh.
00:27To understand why it's all happening, we have to go way back in time,
00:32millions of years ago, to see where it all started deep under the Pacific Ocean.
00:38Now, unlike most volcanoes, which usually form along the edges of tectonic plates,
00:42the Hawaiian islands popped into existence smack in the middle of one.
00:47That's because of something geologists call a hotspot.
00:51The Earth's mantle is like a giant pot of thick, bubbling stew.
00:54In a few places, heat builds up so intensely that molten rock,
00:59magma, punches straight through the Earth's crust.
01:02It's like turning up the heat under one part of a stew pot until it boils over.
01:07That upwelling of magma is the hotspot.
01:10As magma reaches the surface, it erupts as lava.
01:14When the lava cools and hardens, it forms land.
01:17When enough of it piles up over the thousands or even millions of years, an island forms.
01:23The hotspot doesn't move and stays rooted deep in the mantle.
01:27But the Pacific plate, the giant chunk of Earth's crust that Hawaii rides on,
01:32is always slowly drifting to the northwest.
01:35So, every few million years, a new volcano forms over the hotspot and the old one gets carried away.
01:42Thanks to all this, a chain of islands form, each one a little older and more worn down than the last.
01:50If you look at a map, you can trace this volcanic breadcrumb trail across the Pacific.
01:55It stretches all the way from the Big Island in the southeast, which is the youngest,
02:00up through Maui, Oahu, and Kauai,
02:03and into the sea as a chain of underwater mountains called the Emperor Seamounts.
02:08The Big Island is still growing today, thanks to active volcanoes like Kilauea and Mauna Loa.
02:14The older islands, like Kauai, are eroding, shrinking, and, sadly, sinking.
02:20Oahu is going in the water at the speed of nearly 1 40th of an inch every year.
02:25That's about as thick as 10 sheets of printer paper.
02:28But certain coastal regions are sinking at 1 inch per year, and that's no joke.
02:34This is happening for a few reasons.
02:36First, as the islands move away from the hot spot, they cool down.
02:41That might sound good in summer, but cooler rock actually shrinks and becomes denser,
02:46making the whole island sit lower in the water.
02:49Erosion gradually makes the island smaller,
02:52and unless there is further volcanic activity or a drop in sea level,
02:56the island submerges below the ocean surface at some point.
03:00Second, there's the weight of the islands themselves.
03:03They're made of solid rock and lava, thousands of cubic miles of it.
03:08Over time, their own mass slowly pushes them downward into the soft underlying mantle.
03:14And third, there's human activity.
03:16The first people who settled here were Polynesian navigators around 1,000 to 1,200 years ago.
03:22These navigators used stars, waves, and bird flight patterns to guide them and reach the Hawaiian islands after weeks at sea.
03:30By the time European explorers arrived in the late 18th century,
03:34Hawaiians had developed a rich society with chiefs, priests, artisans, farmers, and navigators.
03:40The islands were divided into districts, each managed by local leaders, and people lived in harmony with the land.
03:47And then it was time of Kamehameha the Great.
03:51He unified all the Hawaiian islands under a single rule for the first time in 1810.
03:57The islands were developing in the following centuries, and people needed more flat land near the coast.
04:02They started piling in dirt, rocks, and rubble to cover up soggy ground and create new land where there wasn't any before.
04:10It worked for a while, and that's how they built roads, neighborhoods, and even airports at some point.
04:17But that ground is soft and squishy underneath, and now those areas are sinking much faster than the rest of the island.
04:25A new study says that in some parts of Hawaii,
04:27This combination of factors could boost the risk of flooding by over 50% by the year 2050.
04:35It could force communities to prepare for future floods 50 years sooner than they originally thought.
04:40By 2080, flooding is expected to hit Waikiki, downtown Honolulu, and even the local international airport much more often.
04:49That could cause some serious problems for everyday life.
04:53Hawaii's tourism, beachfront buildings, and natural ecosystems could all be in complete chaos.
05:00Over $12.9 billion worth of infrastructure on Oahu alone is in danger from flooding and related damage.
05:08That's roads, hotels, homes, and way more.
05:12The scientists behind the study are hoping their work can actually help.
05:16They want local leaders to use this new data to make smart decisions that reduce future damage and keep people safe.
05:24It could help them figure out how bad flooding might get, how strong the buildings and roads need to be,
05:30and how to design communities that can survive big changes.
05:34Now, Hawaii isn't the only place in the world that's sinking because of its own weight.
05:39The weight of all the buildings in New York City is literally pressing it down into the earth.
05:44That's more than 1.68 trillion pounds of skyscrapers, apartments, towers, and bridges.
05:51That's enough pressure to make the land beneath the city sink by up to 0.08 of an inch per year.
05:57Now, that may not sound like much, but it adds up quickly, and in some spots, the sinking is happening even faster.
06:05Scientists call this slow downward shift subsidence.
06:08To figure all this out, researchers used satellite data to look at just how heavy the city is and how fast the ground is moving.
06:16Turns out, it's not just the building sitting on solid rock.
06:20Some parts of the city were built on squishy stuff like old wetlands, soft sediments, or human-made fill.
06:26The same is in Hawaii.
06:28But even areas built on sturdier ground aren't safe.
06:31The study found that layers rich with clay deep underground can keep compressing slowly over time under the weight of heavy buildings.
06:40This process is called secondary settlement and can keep happening for decades or even centuries.
06:46So even if it looks like everything's fine on the surface, the ground could still be giving way underneath.
06:52The scientists behind the research say this isn't just a New York problem.
06:57Cities around the world are expanding fast, and most of that growth is happening along coastlines.
07:05Jakarta, the capital of Indonesia, is one of the fastest sinking cities in the world.
07:10And it has around 10.5 million people living there, and about 30 million in the greater metro area.
07:17Experts say that by 2030, some parts of the city could be flooded so often or so badly that all these people just won't be able to live there anymore.
07:27Jakarta was built on swampy land.
07:29It's right next to the Java Sea and has 13 rivers running through it.
07:34So flooding has always been a part of life there.
07:36But it's gotten worse lately.
07:39Scientists say that by 2050, about 95% of North Jakarta could be underwater.
07:44And it's already happening.
07:47In the last 10 years, North Jakarta sank by over 8 feet.
07:51And in some places, it's still sinking up to 10 inches every year.
07:56That's more than double what other big coastal cities are experiencing.
08:00On average, Jakarta sinks between one-third of an inch to six inches each year.
08:05And now, nearly half of the city is already sitting below sea level.
08:09So, Indonesia found an original solution to this problem and decided to build a brand-new city in the jungle to replace Jakarta.
08:18They plan to grow Nusantara, the new capital, into a modern, green, and high-tech city in the next 20 years.
08:25City planners are calling Nusantara a sponge city, as it should be able to absorb rainwater into the ground like a sponge, instead of letting it flood the streets.
08:35That way, even with heavy rain, Nusantara won't flood the way Jakarta has.
08:43That's it for today.
08:44So, hey, if you pacified your curiosity, then give the video a like and share it with your friends.
08:49Or, if you want more, just click on these videos and stay on the Bright Side!
08:53Thank you very much.
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