Plants are flowering faster than scientists predicted（预测）in reaction to climate change, which could have long damaging effects on food chains and ecosystems.
Global warming is having a great effect on hundreds of plant and animal species around the world, changing some living patterns, scientists say.
Increased carbon dioxide (CO2) in the air from burning coal and oil can have an effect on how plants produce oxygen, while higher temperatures and changeable rainfall patterns can change their patterns of growth.
“Predicting species’ reaction to climate change is a major challenge in ecology,” said the researchers of several U.S. universities. They said plants had been the key object of study because their reaction to climate change could have an effect on food chains and ecosystem services.
The study, published on the Nature website, uses the findings from plant life cycle studies and experiments across four continents and 1,634 species. It found that some experiments had underestimated（低估）the speed of flowering by 8.5 times and leafing by 4 times.
“Across all species, the experiments under-predicted the speed of advance — for both leafing and flowering — that results from temperature increases,” the study said.
The design of future experiments may need to be improved to better predict how plants will react to climate change, it said.
Plants are necessary for life on the Earth. They are the base of the food chain, using photosynthesis（光合作用）to produce sugar from carbon dioxide and water. They let out oxygen which is needed by nearly every organism on the planet.
Scientists believe the world’s average temperature has risen by about 0.8℃ since 1900, and nearly 0.2℃ every ten years since 1979.
So far, efforts to cut emissions（排放）of plant-warming greenhouse gases are not seen as enough to prevent the Earth heating up beyond 2℃ this century — a point scientists say will bring the danger of a changeable climate in which weather extremes are common, leading to droughts, floods, crop failures and rising sea levels.
72. What is the key information the author wants to give in Paragraph 1?
A. Plants’ reaction to weather could have damaging effects on ecosystems.
B. The increasing speed of flowering is beyond scientists’ expectation.
C. Climate change leads to the change of food production patterns.
D. Food chains have been seriously damaged because of weather.
73. We can learn from the study published on the Nature website that __________.
A. plants’ flowering is 8.5 times faster than leafing
B. there are 1,634 plant species on the four continents
C. scientists should improve the design of the experiments
D. the experiments failed to predict how plants react to climate change
74. Scientists pay special attention to the study of plants because __________.
A. they can prove the climate change clearly
B. they are very important in the food chains
C. they play a leading role in reducing global warming
D. they are growing and flowering much faster than before
75. What can be inferred from the last two paragraphs about the world’s temperature?
A. It has risen nearly 0.2℃ since 1979.
B. Its change will lead to weather extremes.
C. It is 0.8℃ higher in 1979 than that of 1900.
D. It needs to be controlled within 2℃ in this century.