Coral reefs support an extraordinary diversity

Position 1: Without urgent reductions in greenhouse gas emissions, scientists warn that the majority of the world's coral reefs may be lost by 2050.

Position 2: These structures are built by tiny colonial organisms called polyps, which secrete calcium carbonate skeletons over thousands of years.

Position 3: When temperatures exceed a critical threshold, polyps expel the algae, causing the reef to bleach and become vulnerable to disease.

Position 4: Coral reefs support an extraordinary diversity of marine life despite covering less than one percent of the ocean floor.

Position 5: Because polyps depend on photosynthetic algae known as zooxanthellae for energy, they are highly sensitive to rising water temperatures.