Global Biodiversity Crisis

(1) Biodiversity is the sum of all the different species of animals, plants, fungi, and microbial organisms living on Earth and the variety of habitats in which they live. Scientists estimate that upwards of 10 million – and some suggest more than 100 million – different species inhabit the Earth. Each species is adapted to its unique niche in the environment, from the peaks of mountains to the depths of deep-sea hydrothermal vents, and from polar ice caps to tropical rain forests.

(2) Most biologists accept the estimate of American evolutionary biologist Edward O. Wilson that the Earth is losing approximately 27,000 species per year. This estimate is based primarily on the rate of disappearance of ecosystems, especially tropical forests and grasslands, and our knowledge of the species that live in such systems. We can measure the rate of loss of tropical rain forests, for example, by analyzing satellite photographs of continents from different periods that show rates and amounts of habitat destruction – and from these measurements calculate the approximate number of species being lost each year.

(3) This extraordinary rate of extinction has occurred only five times before in the history of complex life on Earth. Mass extinctions of the geological past were caused by catastrophic physical disasters, such as climate changes or meteorite impacts, which destroyed and disrupted ecosystems around the globe. In the fifth mass extinction, which occurred more than 65 million years ago, the Earth was shrouded in a cloud of atmospheric dust - the result of meteorite impact or widespread volcanic activity. The resulting environmental disruption caused the demise of 76 percent of all species alive at the time, including the dinosaurs.

(4) Today’s sixth extinction is likewise primarily caused by ecosystem disturbance – but this time the destroying force is not the physical environment, but rather humankind. The human transformation of the Earth’s surface threatens to be every bit as destructive as any of the past cataclysmic physical disasters.

(Microsoft Encarta, 2008)

1. Определите, является ли утверждение:

All biologists agree with American scientist Edward O. Wilson who claims that about 27,000 species are lost each year.

a) в тексте нет информации

b) истинным

c) ложным

2. Определите, является ли утверждение:

The result of the fifth mass extinction was disappearance of 76 percent of species, including the dinosaurs.

a) истинным

b) в тексте нет информации

c) ложным

3. Определите, является ли утверждение:

The fifth mass extinction of species happened about 56 million years ago.

a) ложным

b) истинным

c) в тексте нет информации

4. Определите, является ли утверждение:

Most biologists agree that life on Earth is now faced with the most severe extinction of species.

a) ложным

b) в тексте нет информации

c) истинным

5. Укажите, какой части текста (1, 2, 3, 4) соответствует следующая информация:

Estimates of species inhabiting the Earth amount to more than 100 million.

a) 3

b) 1

c) 4

d) 2

6. Укажите, какой части текста (1, 2, 3, 4) соответствует следующая информация:

The sixth extinction of species is caused by the human transformation of the Earth.

a) 2

b) 4

c) 1

d) 3

7. Ответьте на вопрос:

How can the rate of loss of tropical rain forests be measured?

a) by analyzing some satellite photographs of continents

b) by analyzing satellite photographs of continents from various periods

c) by calculating the approximate number of species lost each year

d) by analyzing several photographs of continents

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