Impacts of rising sea temperatures on the Reef

Rising sea surface temperatures from climate change are already affecting the Great Barrier Reef and have the potential for significant effects across the whole ecosystem.

Temperature plays a critical role in determining the distribution and diversity of marine life. It is critical to reef building and controls the rate of coral reef growth.

Like all marine life, corals have evolved over many thousands of years within limited temperature ranges.

When these limits are exceeded, corals are put under thermal stress, causing them to expel the tiny algae that live within their tissues – it's this algae that gives corals their colour and most of their food and energy.

This results in coral bleaching, and if conditions don't ease within weeks, the corals eventually starve and die.

Coral bleaching is not always fatal, but has been one of the main causes of coral death around the world in the past two decades.

Since 1910–1929 average ocean temperatures around Australia have warmed by 0.68 degrees Celsius.

Records were set in the summer of 2012–13 when the hottest sea surface temperatures for the Australian region were recorded.

Projections 

The Intergovernmental Panel for Climate Change predicts that by 2035 the average sea surface temperature will be warmer than any previously recorded, and by 2100 sea temperatures off north-eastern Australia could be at least 2.5 degrees Celsius warmer than the present average.

Rising sea temperatures are not expected to be uniform across the Great Barrier Reef. Rather, the number, size and duration of warm pools (or hotspots) are all expected to increase.