Temperature, currents and hotspots

Water temperature is a driver of the distribution, abundance, life history and phenology (the timing of events such as breeding and migration) of marine organisms.

Ocean temperatures are increasing in many locations around Australia. However, the oceans are not warming evenly and there are some regions that are warming faster than 90% of the oceans. In total 24 hotspots occur globally, two of which are in Australian waters (see map below, and further information here). For example, compared to the average temperatures of the 1960s, ocean temperatures off Tasmania, New South Wales and Victoria’s east coast have increased by 0.8°C. This is well above the global average of 0.1°C.

Changes in ocean temperatures often occur in conjunction with altered ocean currents. The marine heatwave observed off the West Coast of Western Australia in 2011 occurred due to a particularly strong Leeuwin Current, which moves warm water south from the tropics. Ocean temperatures were more than 3°C warmer than average during the autumn of this year. For more information on ocean temperatures and currents see the Redmap website.

There are both negative and positive implications of being near a hotspot. If your community is adjacent to one of the marine hotspots you will likely notice the impacts associated with global warming earlier. On the positive side, if you are near a hotspot you are also likely to develop and implement adaptation options earlier. However, experiencing early impact also means that you are likely to have to ‘test’ these early adaptation options, some of which may be unsuccessful.

Global Marine HotspotEEZ map

(Adapted from Hobday & Pecl, 2013)