VOA科学技术2014--Scientists: Coral Bleaching Happens Around the World

Scientists say coral reefs around the world, from Australia to Kenya, are experiencing bleaching¹ for the fourth time in the last 30 years. They say the colorful undersea structures are turning white as a result of warming ocean waters.

The U.S. National Oceanic and Atmospheric² Administration (NOAA) and the International Coral Reef Initiative said Monday that at least 53 countries, territories, or local economies have reported bleaching from February 2023 to now.

Coral bleaching happens when the small ocean animals face stress and expel the algae³ that provide them with energy and give them their color. If the bleaching is severe and long-lasting, the coral can die.

Why does it matter?

Coral reefs cover less than one percent of the ocean floor, but they help marine⁴ ecosystems⁵ and economies. Reefs are the rocky structures that corals create over time.

It is estimated that one fourth of marine life depends on reefs for shelter, food and as a place for reproduction. Coral reefs also help coastal⁶ communities by forming a protective barrier against storms and large waves. A 2022 study in the publication Marine Policy found that reefs help to avoid property damage for more than 5 million people worldwide.

The Global Coral Reef Monitoring Network estimates that reefs provide about $2.7 trillion in goods and services every year. That includes billions of dollars from tourism to the value of coastal protection. But rising sea temperatures and human destruction have endangered corals.

People have observed bleaching happening in different parts of the world for some time. In the world's largest coral reef, Australia's Great Barrier Reef, bleaching affected⁷ 90 percent of the coral observed by scientists in 2022. In the Florida Coral Reef, scientists reported notable bleaching last year.

But for scientists to declare a worldwide bleaching event, it has to be documented within each of the major oceans, including the Atlantic, Pacific, and Indian oceans, in both the Northern and Southern Hemispheres.

The fourth worldwide bleaching event

With bleaching happening in the Indian and Pacific oceans, NOAA experts expect that this worldwide bleaching event could be the most extensive yet.

Scientists have reported widespread bleaching in reefs in the Caribbean Sea. Last August coastal sea surface temperatures were between one and three degrees Celsius⁸ above normal. And scientists have documented huge "die-offs" across the area.

Lorenzo Alvarez-Filip is with the National Autonomous⁹ University of Mexico. He said, "What is happening is new for us, and to science." He added, "Everything that you can see while diving was white in some reefs."

What is happening now is being called the fourth worldwide bleaching event. The last one continued for three years and ended in May 2017. It was caused by the warm El Ni?o ocean current event that strongly influences the weather in some parts of the world. Two other bleaching events happened in 2010 and 1998.

Derek Manzello is the coordinator¹⁰ of NOAA Coral Reef Watch. He said in a statement, "More than 54 percent of the reef areas in the global ocean are experiencing bleaching-level heat stress." Manzello added, "As the world's oceans continue to warm, coral bleaching is becoming more frequent and severe."

Selina Stead is a marine biologist and chief executive of the Australian Institute of Marine Science. Stead called climate change "the biggest threat to coral reefs worldwide."

She said scientists are working to learn more about how coral deals with heat and to identify naturally heat-tolerant corals. But she added that it is "critical the world works to reduce carbon emissions¹¹."

David Obura heads Coastal Oceans Research and Development Indian Ocean East Africa which is based in Mombasa, Kenya. He said the coral reefs are "going into a decline that we cannot stop, unless we really stop carbon dioxide emissions."

Words in This Story

stress -n. a condition of physical tension and difficulty

marine -adj. related to the ocean or seas

tourism -n. the industry of providing food, shelter and services for people who travel for pleasure

die-off -n. an event in which a large number of living things dies

decline -n. a worsening of health or the condition of something

1 bleaching   

漂白法，漂白

参考例句：

• Moderately weathered rock showed more intense bleaching and fissuring in the feldspars. 中等风化岩石则是指长石有更为强烈的变白现象和裂纹现象。
• Bleaching effects are very strong and show on air photos. 退色效应非常强烈，并且反映在航空象片上。

2 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

3 algae   

n.水藻，海藻

参考例句：

• Most algae live in water.多数藻类生长在水中。
• Algae grow and spread quickly in the lake.湖中水藻滋蔓。

4 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

5 ecosystems   

n.生态系统( ecosystem的名词复数 )

参考例句：

• There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
• Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样，从雨林到半荒漠等不一而足。 来自辞典例句

6 coastal   

adj.海岸的，沿海的，沿岸的

参考例句：

• The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
• This country will fortify the coastal areas.该国将加强沿海地区的防御。

7 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

8 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

9 autonomous   

adj.自治的；独立的

参考例句：

• They proudly declared themselves part of a new autonomous province.他们自豪地宣布成为新自治省的一部分。
• This is a matter that comes within the jurisdiction of the autonomous region.这件事是属于自治区权限以内的事务。

10 coordinator   

n.协调人

参考例句：

• The UN Office for the Coordination of Humanitarian Affairs, headed by the Emergency Relief Coordinator, coordinates all UN emergency relief. 联合国人道主义事务协调厅在紧急救济协调员领导下，负责协调联合国的所有紧急救济工作。
• How am I supposed to find the client-relations coordinator? 我怎么才能找到客户关系协调员的办公室？

11 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。