The Great Barrier Reef has been exposed to significant bleaching in recent decades. Bleaching was first observed in 1998. Since then, bleaching has occurred regularly every few years. Research shows that the main reason for bleaching is climate change and its related effects. The air temperature has increased due to the increase in greenhouse gas emissions in the air. The greenhouse effect is strengthened due to greater heat absorption. In parallel with the warming of the air, the surface temperature of the sea water is also warming. Corals live in the Great Barrier Reef area in a range of small temperature differences from 27 to 28 °C. When the water temperature rises, they experience heat stress, so they become transparent, and their white skeleton can be seen through them. With a change in temperature, the chemical properties of water, such as pH and salinity, also change. The temperature of the surface water also depends on the phenomenon of El Niño - Southern Oscillation (hereafter ENSO, which affects the change in the direction of the winds and the temperature of the sea water in the area of the Great Barrier Reef), a large amount of precipitation, tropical cyclones and the rise of the sea level. In order to preserve the Great Barrier Reef in the future, it will be necessary to reduce greenhouse gas emissions on a global and local level. In the future, mass bleaching events will continue to occur, as they predict an increase in air temperature by the year 2100.
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