For thousands of years, the world’s coral reefs have experienced relatively stable environments. No longer. Now, and increasingly in coming decades, coral reefs and their associated ecosystems face combined temperatures and ocean chemistries unlike anything experienced for millions of years.

Even lower end climate change projections indicate that most tropical reefs will be pushed into a non-coral-dominated state by as early as 2050. That’s the sobering view of Prof. Ove Hoegh-Guldberg from the University of Queensland.

There is a ‘race between the ability of coral populations to modify genetically and the rate of environmental change,’ Ove says.

He sees the challenge to coral as like the Red Queen’s dilemma in Lewis Carroll’s book, Through the looking glass and what Alice found there. The Red Queen announces, ‘It takes all the running you can do, to keep in the same place’.

Some reefs actually are running – at up to 14 km per year polewards. However, coral reefs at the northern end of the Great Barrier Reef are unlikely to be able to travel the required minimum of 1500 km over the next hundred years to keep pace even with lowest projected temperature rises.

Ove warns, ‘Unless we stabilise global conditions and dramatically modify and increase our conservation efforts, critically important ecosystems such as coral reefs will largely disappear by the middle to late part of this century’.

Highlighting the threat, in early 2016 record high sea temperatures led to severe coral bleaching on reefs north of Cooktown. By late March, 95 per cent of the reefs were seriously bleached.

‘What we're seeing now is unequivocally to do with climate change,’ said Professor Justin Marshall, a reef scientist from the University of Queensland, in an interview with ABC TV.
 

• What ecosystems are under threat in your community? Who is responsible for these ecosystems?
• Is the health of local ecosystems being monitored? What are the first steps needed to protect local ecosystems?

Further reading
Hoegh-Guldberg, O. (2012) The adaptation of coral reefs to climate change: is the Red Queen being outpaced? Scientia Marina, 76, 403–408.