The worlds oceans are slowly getting more acidic,”say scientists. The researchers from Ca

The world's oceans are slowly getting more acidic,”say scientists. The researchers from California report that the change is taking place in response to higher levels of carbon dioxide in the atmosphere.
The lowering of the waters’pH value is not great at the moment but could cause a serious threat to current ocean life if it continues, they warn. Ken Caldeira and Michael Wickett, from the Lawrence Livermore National Laboratory, report their concerns in the journal Nature.
Increasing use of oil fuels means more carbon dioxide is going into the air, and most of it will eventually be absorbed by seawater. Once in the water, it reacts to form carbonic acid. Scientists believe that the oceans have already bee slightly more acidic over the last century.
These researchers have tried to predict what will happen in the future by bining what we know about the history of the oceans with puter models of climate change．This level of acidity will get much more extreme in the future if we continue releasing CO2 into the atmosphere, said Dr Caldeira. And we predict the amount of future acidity will exceed（超过）anything we have seen over the last several hundred million years, let alone perhaps after rare disastrous events such as asteroid（小行星) impacts．”
However, it is not absolutely clear what that means for ocean life．Most organisms live near the surface, where the greatest pH change would be expected to occur, but deep-ocean life forms may be more sensitive to pH changes．Coral reefs and other organisms whose shells contain calcium carbonate（小行星) may be particularly affected if the water's acidity levels keep going up, the team predict. They could find it much more difficult to build these structures in water with a lower pH.
In recent years some people have suggested storing carbon dioxide from power stations in the deep ocean as a way of dealing with global warming．But Dr Caldeira said that such a strategy should now be re-considered. Previously, most experts had looked at ocean absorption of carbon dioxide as a good thing-because in releasing CO2 into the atmosphere we warm the planet, and when CO2, is absorbed by the ocean, it reduces the amount of greenhouse warming.”
【小题1】According to Dr Caldeira,     .A．ocean absorption of carbon dioxide is a good thingB．more oil fuels will be used in the near futureC．scientists may predict climate changes with puter modelsD．the future situation of the amount of acidity is extremely serious【小题2】f the water's acidity level keeps rising,     .A．ocean life whose structures contain calcium carbonate may be affectedB．the waters’pH value will bee higher and higherC．organisms living near the surface are more sensitive to pH changesD．some disastrous events will occur more often than before【小题3】Most experts once believed storing carbon dioxide in the ocean would reduce     .A．the CO2 absorbed by the oceanB．the amount of greenhouse warmingC．the acidity of the oceanD．the gradual release of CO2【小题4】The purpose of this passage is to     .A．show people the findings of a research teamB．inform people of how acid the ocean is nowC．introduce Dr Caldeira and his team's researchD．warn people of the higher level of CO2D