1 . The world is literally a greener place than it was 20 years ago, and data from NASA satellites has revealed a source for much of this new greening phenomenon: China and India. This new insight was made possible by a nearly 20­year­long data record from a NASA instrument orbiting the Earth on two satellites.

Taken all together, the greening of the planet over the last two decades represents an increase in leaf area on plants and trees equal to the area covered by all the Amazon rainforests. There are now more than two million square miles of extra green leaf area per year, compared to the early 2000s—a 5% increase.

“China and India account for one­third of the greening, but contain only 9% of the planet's land area covered in vegetation—a surprising finding, considering the common phenomenon of land degradation in populous countries from overuse, ” said Chi Chen, lead author of the study.

“This long­term data lets us dig deeper, ” said Rama Nemani, a co­author of the new work. “When the greening of the Earth was first observed, we thought it was due to a warmer, wetter climate and fertilisation from the added carbon dioxide(CO₂) in the atmosphere, leading to more leaf growth in northern forests. Now, with the data that lets us understand the phenomenon at really small scales, we see that humans are also contributing.”

China's outsized contribution to the global greening trend comes in large part(42%) from programmes to conserve and expand forests. These were developed in an effort to reduce the effects of soil erosion, air pollution and climate change. Another 32% there—82% of the greening seen in India—comes from intensive growing of food crops. How the greening trend may change in the future depends on numerous factors, both on a global scale and the local human level. For example, increased food production in India is promoted by groundwater irrigation. If the groundwater is running out, this trend may change.

The researchers point out that the gain in greenness seen around the world and led by India and China does not offset the damage from loss of natural vegetation in tropical regions, such as Brazil and Indonesia. The consequences for sustainability and biodiversity in those ecosystems remain.

Nemani is pretty excited about the findings, and not just because the greener, the better. “Once people realise there's a problem, they tend to fix it, ” he said. “In the 70s and 80s in India and China, the situation around vegetation loss wasn't good; in the 90s, people realised it; and today things have improved. Humans are incredibly adaptable.”

1. The Earth is getting greener mainly because of ________.

A．the expanding of leaf area in tropical countries

B．the determined efforts to preserve Amazon rainforests

C．the tree­planting programmes and intensive agriculture

D．a favourable climate and increased CO2 in the atmosphere

2. Which of the following statements may the researchers agree with?

A．The greening trend in India will continue to go upwards.

B．More “greening” means better control of climate change.

C．Land overuse threatens the success in the greening on the Earth.

D．The sustainability in global ecosystems will be greatly improved.

3. What does the underlined word “offset” in the last but one paragraph probably mean?

A．Prevent.

B．Survive.

C．Interrupt.

D．Balance.

4. How does Nemani feel about the findings?

A．They are a positive indicator of overall human nature.

B．Their accuracy and reliability need to be further proved.

C．They undervalue humans' contribution to the environment.

D．Their significance for future research cannot be overemphasised.