2024年4月24日发(作者：bt种子怎么用百度网盘打开)

Lesson 1 The Sixth Extinction

Extinctions, where entire species are wiped out, are not unusual in our Earth’s

history. In fact, over 90 percent of all species that ever lived are now extinct. In the

last 500 million years, there have been five times when life on Earth has almost

ended. These include the third mass extinction, known as the “Great Dying”,

which killed 90% to 96% of all species. And the fifth event, which

occurred 66 million years ago, caused the death of the dinosaurs. The reasons

for extinctions are varied. According to scientists, they include volcanic eruptions,

asteroids hitting the Earth from space, changes in sea levels, the decrease of the

oxygen content of the sea and global warming. Many scientists say we are now

entering the Earth’s sixth mass extinction. This time, human activity will be to

blame.

Although it is not unusual for species to die out naturally, the rate at which this

is now happening is cause for concern. A 2015 study by scientists who were based

at Brown University and Duke University in the US, looked at how quickly species

die out due to natural causes, that is, the “background extinction rate”. They

found that human activity is causing species to die out 1,000 times faster than

normal. There is a long list of reasons why so many species are dying out: air and

water pollution, forests being destroyed, factory farming and overfishing. It is clear

that human activity has negatively affected all other species on Earth, including

animals and plants.

If a sixth mass extinction occurs, scientists who have studied the issue believe

that up to three quarters of all species on Earth could die out. Of course, as we

humans depend on so many species for our survival, we would also be at risk of

dying out. Our world and our lives depend on the balance in nature between

animals and plants. Without forests, we would have no air to breathe, and without

clean water we would be unable to survive.

Can a sixth extinction be avoided? Experts say that it is not yet too late, if we

take action now. This would mean we have to significantly change the way we live.

For example, we need to take steps to save endangered species, including setting

up special areas where plants and animals can be protected. We need to change

how we work and travel by using cleaner, more natural sources of energy, such as

wind and solar energy. We also need to improve our farming methods to reduce

water, air and land pollution. In short, if we want to survive, we need to stop

destroying the planet that we live on and start to protect it.

The Black Robin

Black robins are the birds that humans saved from extinction. In 1980, there

were only five black robins left in the world. They all lived on a small island off the

coast of New Zealand. Only one of those birds, a female called Old Blue, was able

to lay eggs. Wildlife workers began a programme for raising black robin chicks.

They protected Old Blue’s eggs, helped them to hatch, and took care of the chicks.

Thanks to their efforts, there are now more than 250 black robins, and the

population is spreading. To help them survive, people are restoring their habitats

and removing small animals that hunt them, such as mice and cats from the islands

where they live.