保护海洋倡议书英语作文

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热心网友 时间：2024-08-25 07:20

Oceans Becoming More Acidic
The world's oceans are gradually becoming more acidic, according to scientists. Researchers from California indicate that this change is occurring in response to increased levels of carbon dioxide in the atmosphere. While the current decrease in the waters' pH value is not significant, it could pose a severe threat to marine life if it persists, they caution.
Ken Caldeira and Michael Wickett, from the Lawrence Livermore National Laboratory, express their concerns in the journal Nature. The burning of fossil fuels has led to more carbon dioxide being released into the air, and most of it is eventually absorbed by seawater. Upon entering the water, it reacts to form carbonic acid.
Scientists believe that the oceans have already become slightly more acidic over the past century. However, these researchers have attempted to forecast future scenarios by combining knowledge of the oceans' history with climate change computer models.
"This level of acidity will become far more extreme in the future if we continue to emit CO2 into the atmosphere," Dr. Caldeira said. "We have predicted amounts of future acidity that surpass anything seen over the last several hundred million years, except perhaps after rare catastrophic events like asteroid impacts."
The authors warn that ocean pH could be reduced by as much as 0.77 units if carbon dioxide emissions remain unchecked. The implications for marine life are not entirely clear, however. Most organisms reside near the surface, where the greatest pH changes are anticipated, but deep-sea lifeforms might be more susceptible to pH fluctuations.
Coral reefs and other organisms with calcium carbonate in their skeletons or shells could be particularly affected, the team speculates. They may find it significantly harder to construct these structures in water with a lower pH.
In recent years, some have proposed intentionally storing carbon dioxide from power stations in the deep ocean as a means to mitigate global warming. Dr. Caldeira suggests that such a strategy should now be reconsidered.
"Previously, most experts had viewed ocean absorption of carbon dioxide as a positive because it reduces the amount of greenhouse warming when CO2 is released into the atmosphere," he explained. "However, in light of our predictions, this strategy deserves a second thought."