The Great Barrier Reef is one of the best protected coral reef ecosystems in the world. However, climate change remains a serious long-term threat. One of the most harmful effects of climate change is the increased risk of damage caused by coral bleaching. Major coral bleaching events are caused by unusually warm water temperatures and have been recorded in the Great Barrier Reef Marine Park in 1998, 2002 and 2006.

The Great Barrier Reef Marine Park Authority (GBRMPA) works in partnership with the Queensland Parks and Wildlife Service (QPWS) and a network of leading scientists, Reef users and other management agencies to monitor:

• climate forecasts
• weather conditions
• sea temperatures
• coral health status

The GBRMPA uses this information to assess the coral bleaching risk and impacts throughout summer. If a coral bleaching event occurs, a response is immediately implemented based upon the GBRMPA's Coral Bleaching Response Plan.

Coral bleaching status on the Great Barrier Reef - 30 March 2011

Reports from the voluntary monitoring network and the QPWS show that the levels of coral bleaching across the entire Great Barrier Reef have remained low to moderate throughout late 2010 and the first two months of 2011.
 
A total of 1206 reef health reports have been received from all sections of the Marine Park since July 2010. The majority of these reports (75 per cent) recorded no bleaching. The majority of the bleaching reports record low levels of seasonal paling and minor bleaching. Overall, six per cent of reports indicated moderate bleaching and less than one per cent indicated high levels of bleaching. Most of the bleaching reports have been received from the central section of the Marine Park following Tropical Cyclone Yasi.

For more information on reef health monitoring on the Great Barrier Reef, please contact reefhealth@gbrmpa.gov.au.

Environmental and climatic conditions on the Great Barrier Reef - 30 March 2011

Coral bleaching risk is largely determined by sea temperatures, which are themselves influenced by a range of environmental and climatic conditions. Globally, 2010 was one of the hottest years on record (World Meteorological Organisation).  Sea surface temperatures around Australia were the highest ever recorded (Bureau of Meteorology). The Bureau of Meteorology's Annual Australian Climate Statement for 2010 provides an overview of Australian climate conditions for 2010 and the past decade.

Summer conditions on the Great Barrier Reef during 2010/2011 were heavily influenced by a series of extreme weather events, including monsoonal cloud cover, rainfall and cyclone activity.   Due to the movement from El Niño to La Niña conditions, particularly heavy rainfall and associated flooding occurred in the Queensland coastal region during December 2010 and January 2011. On 2 February 2011, Tropical Cyclone Yasi (Category 5) crossed the Queensland coast near Mission Beach. All of these factors minimised the build up of heat stress across the Great Barrier Reef over summer.   

Sea temperature forecasts of up to six months in advance are provided for the Great Barrier Reef region by:

• The National Oceanic and Atmospheric Administration (NOAA) in the United States of America.
• The Bureau of Meteorology's operational and experimental products from the Predictive Ocean Atmosphere Model for Australia (POAMA)

In addition, ReefTemp provides daily maps of sea surface temperature conditions around Australia. 

Related information

• Report signs of coral bleaching
• Causes of coral bleaching