Sounds from human activity flood across the oceans, causing trouble to ocean creatures. And climate (气候) change may make some places even louder.

Researchers have expected the oceans to get noisier because of increasing human activity. “The more goods you buy, the more shipping you have, so the more noise you have.” says Luca Possenti, a scientist studying sound in the ocean at the Royal Netherlands Institute. But Possenti and his co-worker realized that climate change might also influence how sound travels through the water.

Human-caused climate change is changing ocean temperatures, salt levels and acidity (酸度). So Possenti’s team used computers to model how those factors (因素) influence noise levels across the world’s oceans.

When waters become more acidic, they can’t take in sound at some wavelengths as well, so those sounds can travel further, adding to the noise in some areas. This effect is relatively small. Other changes impact the sound level more, the researchers found. Changes to temperature and salt levels can change how well different layers (层) of the ocean mix, which, in turn, impacts how sound travels.

The team predicted (预测) models of the world in about 70 years if climate change continues. And then they compared them with models of the world now. In the North Atlantic, they saw an increase in sound levels in the upper 125 meters of the ocean. This was caused mostly by ice melting (融化) off of Greenland, forming a cold layer of water near the ocean’s surface. Sound traveling through water tends to go toward the coldest area. As a result, sound waves tended to get stuck in the cold top layer-spreading further out across the water, instead of traveling deeper. That increased the noisiness at this depth in the North Atlantic. The models suggested that a single ship could sound about five times as loud underwater because of this. Considering all the ship traffic between Europe and North America, that may stress animals, many of which communicate, and catch food with sound.

【小题1】How is paragraph 2 developed?

A．By quoting an expert.	B．By using examples.
C．By making comparisons.	D．By presenting research findings.

【小题2】What is paragraph 4 mainly talking about?

A．Effects of temperature changes.	B．Some risk factors for a nosier sea.
C．Impacts of acidity on wavelengths.	D．Ways oceans mix and sound travels.

【小题3】What can we learn from the last paragraph?

A．Sea animals will be protected from noises.

B．Added meltwater does more harm than good.

C．Greenland is hit the hardest by climate change.

D．The result of the research is based on prediction.

【小题4】What leads to the sound change in the North Atlantic according to Possenti’s research?

A．Increase in salt levels.	B．Failure of acidity control.
C．Change in the ocean depths.	D．Formation of a cold water layer.