Bottlenose dolphins swimming in the ocean © Tahlia Cohen / Unsplash

Bottlenose dolphins swimming in the ocean © Tahlia Cohen / Unsplash

What effect is global warming having on our oceans?

18 Jul 2022

Keywords
  • climate change
  • coral
  • coral bleaching
  • coral sea
  • fight for the reef
  • great barrier reef
  • greenhouse gas emission
  • marine protected areas
  • marine species
  • renewable energy

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Our oceans are fundamental to life on Earth. They cover 70% of our planet, hold about 97% of the water on which we depend, and produce at least half the oxygen we breathe.

They also help determine our weather patterns, acting much like Earth’s lungs. Oceans absorb the sun’s heat and spread it evenly around the globe. By capturing carbon dioxide from the atmosphere, and then storing it for hundreds of years at great depths, they help to slow the rate of global warming. Without healthy oceans, Earth would likely be much hotter and unable to support life.

But healthy oceans are, of course, not only critical to humans. They support diverse ecosystems and intricate food chains for countless fish, mammals, plants and birds.

 

A variety of fish swimming, Osprey Reef, Coral Sea © Darren Jew

 

A system in crisis

Our continuing reliance on fossil fuels and the destruction of forests is having a profound impact on land and at sea.

Between 1850 and 2019, it’s estimated that some 2,390 billion tonnes of carbon dioxide were emitted into the atmosphere. It has accumulated to such an extent that not even our generous ocean carbon “sinks” are capable of capturing it all. Trapped in the Earth’s atmosphere, this carbon dioxide continues to exacerbate the greenhouse effect.

As a result, global temperatures - on the mainland and in our oceans - have soared. Between 2016 and 2020 was the warmest period in history.

Feeling the heat 

Rising temperatures are being felt around the world. It’s melting the polar ice caps, which causes fresh water to spill into our oceans and sea levels to rise. In the 20th century, Earth’s oceans rose, on average, by nearly 20 centimetres.

Now, this may not seem like a lot, but it’s sufficient to seriously threaten people and their livelihoods, marine habitats and the animals they support. From a human perspective, it’s putting low-lying coastal communities at increasing risk. Massive storm surges are eroding beaches, to the extent that about 70% of beaches internationally have been reduced during the past century. On our very own island continent, the potential implications for Australia’s tourism industry, not to mention our coveted way of life, are unfathomable. 

 

Bleached coral on Lizard Island, Queensland © WWF-Aus / Alexander Vail

 

But some of the greatest impacts of global warming are not so obvious. Deep in our oceans, another of the deadly side effects of global warming - underwater heatwaves - threaten to destroy coral ecosystems like the Great Barrier Reef.

Since 1910, sea surface temperatures surrounding Australia have increased by 1°C, causing underwater heatwaves that have bleached corals all along our beloved Reef. With each subsequent bleaching event - in 2016, 2017, 2020, and again in 2022 - more corals have died. The Reef’s very future now hangs in the balance.

But that’s not all. Warmer ocean temperatures are not only increasing the severity of damaging weather events, such as storms and floods; they also cause ocean acidification. Global warming threatens our oceans on multiple fronts and has dire consequences for us all.

Australia needs to do more
Recent reports indicate that without urgent action our planet is on a path[MR2]  to reaching air temperature rises of 3°C. This would literally cook our oceans.

Current commitments to net-zero targets are vitally important, but they must be backed by strong short-term policies to get us there, to deal with the amount of greenhouse gases already in the atmosphere. Then, the next vital steps are to substantially reduce our emissions and speed up the transition to renewable energy sources and a low-carbon future.
 
Green sea turtle (Chelonia mydas) silhouetted against the sun. Sipadan Island © Jürgen Freund / WWF

 

Recent scientific analysis has shown that Australia’s approach to reducing emissions is woefully inadequate. Under our previous federal government’s targets, in the time it would take us to reach net-zero, we would have emitted more than double Australia’s share of greenhouse gas emissions for holding global temperatures to 1.5°C. Australia has recently improved its emissions reduction target to 43% below 2005 by 2030 levels. While this is a welcome step up in ambition, it is still well below Australia’s potential and opportunity and is not aligned with doing our share to hold warming to 1.5°C. If every other country had an emissions target as low as Australia, the world would warm by at least 2°C and the Great Barrier Reef will be completely destroyed.

Australia can increase its currently inadequate emissions reduction target and put Australia on the path to having a 1.5°C aligned climate policy by taking global leadership and making Australia a Renewable Energy Superpower. We know just what to do - and it will create well-paying jobs and opportunities for innovation.

There are big advantages for all of us if we now work together to protect our planet, our oceans and our Great Barrier Reef against further temperature rises. The alternative is unthinkable.

 

Learn more about how we're working to protect the Great Barrier Reef.

 

FIND OUT MORE

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