Mallacoota Marlin and Ocean Warming

Black Marlin Caught off Mallacoota (EGN)

The local news this week (May 30) has been about the massive black marlin caught off Mallacoota. I have written about the marlin in Gippsland on a number of occasions (see here and here) on their southward migration as our oceans warm with climate change. Despite this neither the East Gippsland News (image above) or the ABC managed to connect this event with climate change. Whilst it may be taboo for newsrooms to mention climate change in connection with a catastrophic event such as bushfires surely an occasion like this handled correctly could persuade ‘Blind Freddy’ of the obvious. To drive the point home the Guardian ran an article on Queensland gropers being found in New Zealand waters –  across the ‘ditch’ and 3,000 Ks from home. Nor is the Black Marlin the only newcomer to our waters.

In an earlier blog (see link above) I wrote “Little over one month ago in a letter to the Addie (Bairnsdale Advertiser 11.2.16) on the tropical species of leatherjacket discovered and photographed by Don Love off Cape Conran I noted that this was just ‘another example of species moving into our waters as they warm – a direct result of global warming where our lakes and ocean are warming far more rapidly than the land…’ and speculated that to ‘the leatherjacket can be added a number of new, and as yet unidentified, jellyfish in the lakes and possibly the Black Marlin in our nearby oceans.’”

‘2017 sea surface temperature compered to historical records’ (BOM)

Obviously our oceans are warming. As more than 90% of the extra energy the planet receives with the enhanced greenhouse effect is absorbed by the oceans we would expect to eventually see evidence of this. The map of the Bureau of Meteorology for sea surface temperatures around Australia clearly illustrates this. Equally so do the bleaching events that are killing sections of coral on the Great Barrier Reef. These events are a direct result of the water being too warm and no amount of Federal funding can help this unless the problem is addressed.

Also the warming we, and our oceans, are experiencing now is a result of the greenhouse emissions of 40 years ago. An article in Skeptical Science explained: “The reason the planet takes several decades to respond to increased CO2 is the thermal inertia of the oceans. Consider a saucepan of water placed on a gas stove. Although the flame has a temperature measured in hundreds of degrees C, the water takes a few minutes to reach boiling point. This simple analogy explains climate lag. The mass of the oceans is around 500 times that of the atmosphere. The time that it takes to warm up is measured in decades. Because of the difficulty in quantifying the rate at which the warm upper layers of the ocean mix with the cooler deeper waters, there is significant variation in estimates of climate lag… which I have rounded to 40 years.”

Forty years ago there were 340 ppm of CO2 in the atmosphere. Now there are more than 410 ppm indicating that there is a lot more warming in our pipeline. Barring some miracles we are all in for tough times.