According to a new study from Cornell University, about one-fifth of the global population, of 2 billion people worldwide, will be forced to resettle or go deeper inland by 2100 due to the continuous rise in sea level.

The study, published in the journal Land Use Policy, showed that the growing global population could make the matter worse. The researchers expected that there are about 1.4 billon “climate change refugees(难民)” in the world by 2060 and by 2100 the number of the displaced people due to the rising sea level could reach up to two billion.

“We’re going to have more people on less land and sooner than we think,” said lead author Charles Geisler, professor at Cornell. “The future rise in global average sea level probably won’t be gradual. Yet few policy makers are observing the significant barriers that coastal climate refugees, like other refugees, will run into when they move to higher ground.”

For the study, the researchers reviewed(回顾) potential problems that climate change refugees may face if they go deeper inland. The researchers identified these land difficulties with relocation using three organizing groups. Including depletion(损耗) zones, win-lose zones and no-trespass(不得擅自进入) zones. By doing so, the researchers were able to provide primary estimates of their toll(损失) on inland resettlement space. The researchers found that some inland regions were unlikely to support new waves of climate change refugees due to the remains of war, road developments and rare natural resources.

Apart from the rising sea level, increasing storm weather and the booming global population are also having a huge influence on the number of climate change refugees. Storm can push seawater further inland. The increasing global population requires more land even as the ocean swallows up rich costal zones and river deltas(三角洲). These force people to search for new places to move to higher ground.

The way Jason Momoa describes Hawaii’s beloved inactive volcano, Mauna Kea, makes you understand why it’s considered sacred(神圣的).

"It’s kind of the umbilical cord(脐带) to earth," the actor tells CNN. "You know, if you think about the Hawaiian islands, that’s the biggest mountain in the world, right? All the way up. So Mauna Kea is the most sacred. We call it the belly button, too. That’s like our birthplace. That’s how our islands were formed. So how can that not be sacred?"

He would know. Jason, a native of Hawaii, has had a near-constant presence there when he’s not working, fighting with local protestors to stop the construction of the Thirty Meter Telescope, or TMT, which would drill directly into the mountain and invade its precious water supply. So far, protestors have successfully blocked the only road crews seeking to go up the mountain in order to build the billion-dollar observatory.

"It started in 2015. What’s happening over there was just not right," Jason says. "And I went over there to meet with everyone to bring the point to the world." Jason joins the protests when he can. He cared so deeply about the preservation of the land that when he had spare time to lend his support, he was there. "You also have to remember, that’s our water source. So having an 18-story building built on top of the tallest mountain from the sea level on our water level is terrible."

The Game of Thrones star says he feels the movement is working and describing his part in it as a calling to do what he feels right in his soul. "There’s massive progress that’s bringing our people together," he says, adding, "I think there are a lot of problems in Hawaii. There are a lot of things that have happened in our history, a lot of injustice, and so we’re shining a light on it. People like myself or Dwayne Johnson, Bruno Mars are trying to spread the concern all around the world. For my soul I need to be there."

Wild animals are equipped with a variety of techniques to avoid becoming lunch for a bigger animal, also known as a predator (捕食者) in nature. The most well-known methods include the classic fight and flight as well as freeze.

A team of researchers wondered whether closeness to people might impact those survival strategies. “We often see that animals are more tolerant around us in urban areas, but we don’t really know why.” says evolutionary biologist Dan Blumstein. “Is it individual plasticity, meaning individuals change their fear of us and that leads to tolerance? Or can there be an evolutionary factor involved?”

To find out, Blumstein and his colleagues combined information from 173 studies of over 100 species, including mammals, birds, fish and even mollusks. It turns out that regardless of evolutionary ancestry, the animals react in a similar way to life among humans: they lose their anti-predator characteristics. That pattern is especially pronounced for plant-eating animals and for social species. This behavioral change is perhaps unsurprising when it’s intentional, the result of domestication or controlled breeding. But it turns out that urbanization alone results in a similar change, though around three times more slowly.

The main point is: we’re essentially domesticating animals by urbanization. We’re selecting for the same sorts of characteristics that we would if we were actually trying to domesticate them. If the urbanization process helps animals better co-exist with people, it could be to their benefit. But if it makes them more defenseless to their nonhuman predators, it could be a real problem. Either way, these results mean that city living has enough of an influence on wild animals that evolutionary processes kick in. Those reductions in anti-predator characteristics become encoded in their genes. We’re changing the population genetics one way or another.

What the researchers now wonder is whether the mere presence of tourists in less urbanized areas can cause similar changes in wild animals. If so, serious questions exist for the idea of ethical, welfare-oriented eco-tourism. If we wish to help animals keep their anti-predator defenses, the researchers say, we might have to intentionally expose animals to predators. It’s just yet one other way that we’re changing the world around us.