The way Mom explained it, before she died, homo sapiens was doing alright.

But that was centuries ago.
The Stenward Technique, an inexpensive desalination method, made water plentiful. The molecules of holograms could be converted into those of their material counterparts. War was obsolete with the Pangaea Collective, or PanCol (the oligarchic government that ruled most of the world); the oligarchs were reluctant to allow resources that could sold for a profit be wasted on battles that would  only result in reducing people available to work for them. Arguments were few, and rebellions virtually nonexistent.
Life was good.
Until the world crashed down. 
Two events caused the universe's collapse. One: the population inexplicably boomed. Numbers swelled from seven to ten billion, seemingly overnight. It became rare to find an unoccupied square foot of land; food and water were easily acquired, but nobody had considered space.
Ships were sent into space to find amenable planets- all that did was empty the PanCol’s bank account. Laws regulated the number of children produced. Billions were jailed for exceeding the quota, then released when the law was revoked. All we could do was put unneeded children to “sleep,” when Reuben Ivanov introduced a genius solution.
He created a material light enough to float on the ocean’s surface, but strong enough to hold thousands. Great rectangles of it, named L.A.N.D. (Lactic Acid Neutralized Drifts) were spread over the ocean, one end attached to land, the other stretching over the water, expanding the continents. 
Deemed safe for the time being, crowds flocked to the floating lands. The world prospered again. After fifteen years, nobody worried about the L.A.N.D.. Ivanov became a celebrity, traveling the globe, flaunting his latest inventions to foreign bigwigs. The population worshipped him, rightfully so...then came the unthinkable.
In 2169 came the second event: near England, cracks in the L.A.N.D. emerged eighteen years after installation. In summer of 2172, the L.A.N.D. completely melted. Hundreds of houses built on it sank into the ocean, dragging along thousands of people. Scientists believed the heatwave ( a 124°F high) was causing the L.A.N.D. molecules to unglue, dissolving the material. 
Panic spread like the plague. Reports of melting L.A.N.D. flooded in, from Alaska to Japan to South Africa. The government was in tatters, as millions thronged to the mainlands.
That is also the year I turned fourteen.
?
Humans could spend ten minutes outside before contracting heatstroke. I tried to make the most of those minutes; it was the only time I wasn’t cooped up inside. But just sitting on the porch, like I was now, made me sweat. All I could do was think. And thinking always led to the same thing: the word soon. Soon was overused. The government said soon a hovercraft would come bring us to safety. Soon they’d find a way to prevent the L.A.N.D. from melting. Empty promises, but if they weren’t fulfilled, soon my home, with my family and me in it, would sink under the unforgiving ocean. What a wonderful world I lived in…
“Hi, Cay.” My little brother sat by me. I smiled. Dad said one day I’d become a teenager and be constantly annoyed with him; I couldn’t imagine that happening. I didn’t understand: would I just wake up one day and hate Ben? I wanted to protect Bentley, not be annoyed with him.
“Look.”
Using my fingernail, I carved his name into the material of the extension, which was warped and soft.
The L.A.N.D. was originally more metal than cloth, except it was too light to be classified as metal. Before the heatwave, it was impossible for anything to crack the L.A.N.D.. Today a dropped water bottle dented it. Now soot-colored (compared to the glamorous gray it once was), it had the consistency of overripe tomatoes. Worrying, as the heatwave showed no sign of ending. We were living on frozen butter.
“That’s not good.” Ben frowned.
“I know.”
“But they said they’ll send a hovercraft soon to get us.”
Last month, three dozen hovercraft had brought everyone else on our extension to the mainland, but the government miscounted. Eight people had had to be left behind. My noble father volunteered, with the promise of another hovercraft to be sent soon.
But the PanCol was stretched tight, sending hovercrafts to the entire extension. A week became two, which blossomed into three, then multiplied to six.
Neighbors were replaced with memories. The other five left lived miles away, and the PanCol had confiscated our car to decrease weight put on the L.A.N.D. It was a lonely life.
“But they said it’d be a week...it’s definitely been more than that.” As Ben's face fell, I added, “Then again, they might be coming tomorrow. Or now! Maybe they’re flying here this moment.”
Dad’s voice echoed out to us. “Come here!”
It’s hot outside anyway. We headed inside the house, feet shuffling.
The moment Dad turned I knew.
“The hovercraft’s coming in two hours. We did it.” He laughed, clutching the phone. His arms wrapped around Ben and me, squeezing joyfully. I couldn’t breathe, torn between laughing and crying. “We did it.”
?
Sunlight streamed around the hovercraft’s outline. Should I shade my eyes or block my ears from the roar of its propeller? Discomfort didn’t matter; this machine was our return to safety, to civilization, to not living in terror.
And Ben.
He’d be safe.
I stood, feet sinking into the ground, between Dad, Ben, and our single suitcase. I wish Mom were here, I thought. She could’ve picked any weekend to visit Grandma in England. but it had to be the weekend the L.A.N.D. first melted. I fought down the sorrow guilt anger. Now was a happy moment. There were few enough of those left that I should enjoy them while possible.
“Take one memento. Only bringing the necessary. Sorry,” a disembodied voice informed us in clipped phrases, sounding anything but sorry. Dad looked at us, shock mixed with indecision. The zipper snagged as we pulled the suitcase open and rummaged through it. Dad stood first, clutching his copy of Pericles, the first play he saw with Mom. Ben clung to his stuffed giraffe. I was empty-handed.
This suitcase held my life, and I had to choose one part? No thanks.
“Anything’s better than nothing,” Dad whispered. I shook my head. I’d rather live on memories than a painful reminder.
“Board single-file,” the voice said. A grey rope tumbled to the ground. Ben pulled himself up first; Dad beckoned me next. I didn’t see him. There was something I wanted.
Dad’s shouts didn’t fade as I sprinted into the house, but the voice was too loud to be ignored. “Board, or we’ll be forced to leave without you.”
I ran into my bedroom, snatched the photo of Mom, and was outside in seconds.
Dad was halfway up the ladder when he saw me. His face lit up, then morphed into fury.  “CHAOS!”
I was the fastest runner in school. The hovercraft was close. I had time. Right?
Wrong.
As my feet pounded the L.A.N.D., the ground moved. I thought I imagined it, but it happened again.
It shook.
The ground was caving under my feet. Where it once was vaguely pliable, it was cracking in half. No, not cracking; it was melting, an odd grey puddle, seeping into the ocean and dying it metallic silver. Holes littered the ground, ocean water swallowing the torrents of liquified L.A.N.D..They expanded, the ground dissolving into nothing. Dad’s frightened shout echoed. 
Run, Chaos.
The ghostly, thundering rush of water against water, and the terror rumbling in my ears, was deafening. I screamed, ripping my throat raw, as the L.A.N.D. under my feet disappeared.
The ocean was cold- surprising, considering the temperature. Maybe it’s just cold compared to the sunlight. But water was water, and I couldn’t breathe underwater. Hold your breath, I thought. I tried, but I couldn’t tell if it was minutes or seconds before I opened my mouth, gulping in saltwater.
Coughingthrashingcan’tbreathewhattodocan’tthinkgonnadie
Which way was up? Didn’t matter anymore. I felt my muscles relax and my brain go foggy. Here's my grave, I thought. I’d always liked the mysterious, undiscovered ocean. Until now.
Something poked my head. Couldn’t they let me die undisturbed? So inconsiderate. I looked up reluctantly, salt stinging my eyes.
Grey rope.
Ladder.
My misfiring brain connected the dots. I grabbed at the rope, but I couldn't tell if I had made contact...eternity passed before my head broke through the water. Retching and gasping, the salt burning my throat still felt like a blessing.
Someone was holding me. Dad.
He stood at the dangling ladder’s base, the hovercraft suspended above. He smiled, one arm iron around my hand, other hand grasping a rung. “You’re safe now, Chaos."