In the summer of 2010-2011 Western Australia experienced an unprecedented marine heat wave that elevated water temperatures 2-4°C above average for more than 2 months. The heat wave resulted in defoliation of the dominant Amphibolis antarctica seagrass species across the iconic Shark Bay World Heritage Site. Researchers alert us of the major carbon dioxide (CO2) emissions resulting from this loss of seagrass meadows at Shark Bay — one of the largest remaining seagrass ecosystems on Earth.