根據一份12日發表的2008年全球珊瑚礁現況最新報告，氣候變遷已經成為珊瑚礁最大的威脅，該報告說，全球有19%的珊瑚礁已經消失。
氣候環境威脅包括海水表層溫度、海水酸化、加上其他威脅如過漁、污染、入侵物種等。
這項在澳州湯斯維爾(Townsville)發佈的「全球珊瑚礁監測網路」(GCRMN)報告顯示，如果二氧化碳排放趨勢持續增加，剩下的珊瑚礁群落會在20-40年之內消失。而這項結果則會影響將近5億依賴他們生存的人們。
這項報告顯示將近45%的珊瑚礁群是健康的，另一個希望的指標則是，由於受海水溫度提高的影響，部分珊瑚礁已經從原本的白化現象恢復了，證明他們也已經適應氣候變遷的威脅。
但這項報告同樣指出最近幾年的趨勢沒有獲得改善。而近4年最主要的威脅，例如因印度洋海嘯，造成更多珊瑚礁白化、疾病、人類活動威脅，都使這些曾在1998年受到大規模白化影響的珊瑚礁群沒有自行恢復的機會。
「如果二氧化碳排放量並沒有任何改變，我們將會處在一個含量在50年內倍增的氣候環境中。」 GCRMN組織之一，IUCN全球海洋計畫(GMP)主席魯丁(Carl Gustaf Lundin) 說明。
「當這些碳被吸收，海洋會變得更酸，更會嚴重破壞海岸的海洋生物、浮游藻類群落、進而影響螃蟹甚至是海藻的生存。」 魯丁繼續說道。
當由人為活動所造成的氣候威脅減小，珊瑚礁將有更高的生存機會。妥善經營海洋區域可以促進珊瑚礁的健康；但當遙遠的純淨珊瑚礁被發現的同時，卻更難落實適當執法。
「白化現象發生10年之後(1998)，我們知道只要給予機會，珊瑚礁可自行恢復。但不幸的是，相似程度的環境衝擊會在不久的將來再度發生，甚至已經沒有太多時間可以給予珊瑚礁與人群輕微忍受的機會。」 「氣候變遷與珊瑚礁」（IUCN-CCCR） 工作小組主席及「海岸研究暨印度洋發展計畫」（CORIDIO）之主持人歐博拉(David Obura)博士說明 。
最新一篇關於印度洋珊瑚礁的狀況報告於12月10日開始執行，由CORDIO與GCRMN並肩合作，發現珊瑚礁持續衰退現象，而部份區域的珊瑚礁已有恢復跡象。
「這項報告指出印度洋區域珊瑚礁廣泛衰退現象變得更顯著」 CORDIO以及世界海洋大學林登(Olof Linden)教授指出。「要拯救珊瑚礁，我們需要專注在如何使珊瑚礁適應環境變遷以及引導人們不要繼續進行如過度漁撈等破壞珊瑚礁的活動。」
The world has lost 19 percent of its coral reefs, according to the 2008 global update of the world's reef status issued today. Climate change is considered the biggest threat to coral reefs
The main climate threats, such as increasing sea surface temperatures and ocean acidification, are compounded by other threats - overfishing, pollution and invasive species.
The report, released by the Global Coral Reef Monitoring Network based in Townsville, shows if current trends in carbon dioxide emissions continue, many of the remaining reefs may be lost over the next 20 to 40 years. This will affect some 500 million people who depend on coral reefs for their livelihoods.
The report shows that 45 percent of the world's reefs are currently healthy. Another sign of hope is the ability of some corals to recover after major bleaching events, caused by warming waters, and to adapt to climate change threats.
However, the report shows that, globally, the downward trend of recent years has not been reversed.
Major threats in the last four years, including the Indian Ocean tsunami, more occurances of bleaching, outbreaks of coral diseases and ever-heavier human pressures, have slowed or reversed recovery of some coral reefs after the 1998 mass bleaching event.
"If nothing changes, we are looking at a doubling of atmospheric carbon dioxide in less than 50 years," says Carl Gustaf Lundin, head of the IUCN Global Marine Programme, one of the organizations behind the Global Coral Reef Monitoring Network.
"As this carbon is absorbed, the oceans will become more acidic, which is seriously damaging a wide range of marine life from corals to plankton communities and from lobsters to seagrasses," Lundin said.
Corals have a higher chance of survival in times of climate change if other stress factors related to human activity are minimized. Well-managed marine protected areas can also boost the health of coral reefs, but proper enforcement is difficult, especially in remote areas where the most pristine reefs are found.
"Ten years after the world's biggest coral bleaching event, we know that reefs can recover given the chance. Unfortunately, impacts on the scale of 1998 will reoccur in the near future, and there's no time to lose if we want to give reefs and people a chance to suffer as little as possible," says Dr. David Obura, chair of the IUCN Climate Change and Coral Reefs working group and director of the Coastal Oceans Research and Development in the Indian Ocean Programme, CORDIO, in East Africa.
A new report on the state of Indian Ocean coral reefs, launched today by CORDIO, an organization aligned with the Global Coral Reef Monitoring Network, reveals an overall trend of continued degradation, with signs of recovery in some areas.
"With this report, the far-reaching degradation of Indian Ocean coral reefs has become evident," says Olof Linden of the CORDIO network and professor at the World Maritime University, Malmo, Sweden. "To save coral reefs, we must focus on helping corals to adapt to climate change and on diverting people away from destructive practices such as overfishing."
