The Facts About Ocean Warming

Thomas Morris

I have enlisted the help of Dr Brendon Dunphy, a senior lecturer and researcher at the University of Auckland, to shed light on one of the biggest threats to our oceans. His research focusses on understanding the resilience of marine animals to changes in their environment at the population, individual and molecular level. His exploration encompasses a variety of factors, but I am particularly interested in his work in understanding invertebrate responses to ocean warming.

The ocean provides an immense amount of support to our planet. Chief amongst them is helping keep this planet at a liveable temperature. Since greenhouse gases have been flooding our atmosphere, the average temperature of our planet has been steadily increasing. By absorbing 93% of this excess heat since the 1970’s, the oceans are providing this essential service for free. Without this oceanic buffer, global temperatures would have risen much more than they have done to date, some estimates saying up to 36 ˚C.

Photo: Thomas Morris

Photo: Thomas Morris

So why is this important? Well, according to Dr Dunphy “Temperature affects everything.” It is a fundamental variable in ecological studies as seemingly insignificant changes in temperature can have severe effects. Researchers are already witnessing rising sea levels (due to thermal expansion of water and melting ice caps), changes in oceanic currents and changes in climate patterns. It also has dramatic impacts for marine animals; where they live and where they can live … even on their metabolism.


“As temperature increases, so does the metabolism of many animals” says Dr Dunphy. “My research focusses on invertebrates that live in the inter-tidal zone. When these animals are exposed to prolonged increases in temperature, 2-4 ˚C, their metabolic rates lift, forcing them to dig into their reserves that would otherwise be used for reproduction.” He mentions that this does not only affect these animals directly but has knock on effects down the food chain as many of these organisms are prey for predators. As these animals burn through their reserves, predators don’t find enough energy in these food items to support their own metabolic demands. This has major implications across ecosystems.

As we see reports detailing the hottest summer temperatures in history, and how on average, the planet is experiencing hotter than average days more frequently, Dr Dunphy is worried about something else. “All animals depend on the seasons to reset their yearly metabolic clocks; when to stock up on reserves, when to start producing sperm and eggs, when to spawn. They depend on the seasons, on temperature, to tell them when it’s time to do these things. What we are noticing globally, is that we are losing our winters. They are becoming shorter and warmer, impacting the natural rhythms of these animals.”

If the reproduction success of animals is going to be impacted by rising oceanic temperatures, this will have immense impacts on ecosystems, dramatically impacting animal abundance and biodiversity. If we consider that 15% of the planets protein comes from the ocean, even our food security is in jeopardy.


So what can we do?

Dr Dunphy says that we need to stop telling the same story, “We keep saying the same thing, just in different ways. We need to find the key point that resonates with everyone … that inspires people and nudges them out of a carbon-based economy.” He referenced the recent addition of Lime electronic scooters to streets in Auckland. “These e-scooters have captured the imagination of Aucklanders and it’s based on a zero carbon economy. We need ideas and initiatives like this that can change people’s behaviour.”

His dream is to get governments and industry to invest significant money in technology that prioritises the removal of carbon dioxide from our atmosphere and converts it into something useful. “The capitalism machine is pervasive, and there are big opportunities to make it work for the environment”. In October this year, the IPCC released a sobering report outlining the need for a drastic reduction in emissions if we are to remain below the 1.5 ˚C limit, and if we look at how quickly technology is developing at the moment, there might be a realistic shot at achieving this goal. Let’s find that message and help the innovators see the potential.


Rising Tides is a series focussing on the current threats facing our ocean, how these are being tackled and what you can do to help

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