Bleaching has struck the southernmost coral reef in the world

Tess Moriarty, University of Newcastle; Bill Leggat, University of Newcastle; C. Mark Eakin, National Oceanic and Atmospheric Administration; Rosie Steinberg, UNSW; Scott Heron, James Cook University, and Tracy Ainsworth, UNSW

This month corals in Lord Howe Island Marine Park began showing signs of bleaching. The 145,000 hectare marine park contains the most southerly coral reef in the world, in one of the most isolated ecosystems on the planet.

Following early reports of bleaching in the area, researchers from three Australian universities and two government agencies have worked together throughout March to investigate and document the bleaching.

Sustained heat stress has seen 90% of some reefs bleached, although other parts of the marine park have escaped largely unscathed.

Bleaching is uneven

Lord Howe Island was named a UNESCO World Heritage site in 1982. It is the coral reef closest to a pole, and contains many species found nowhere else in the world.

Coral bleaching observed at Lord Howe in March 2019.
Author provided

Two of us (Tess Moriarty and Rosie Steinberg) have surveyed reefs across Lord Howe Island Marine Park to determine the extent of bleaching in the populations of hard coral, soft coral, and anemones. This research found severe bleaching on the inshore lagoon reefs, where up to 95% of corals are showing signs of extensive bleaching.

However, bleaching is highly variable across Lord Howe Island. Some areas within the Lord Howe Island lagoon coral reef are not showing signs of bleaching and have remained healthy and vibrant throughout the summer. There are also corals on the outer reef and at deeper reef sites that have remained healthy, with minimal or no bleaching.

One surveyed reef location in Lord Howe Island Marine Park is severely impacted, with more than 90% of corals bleached; at the next most affected reef site roughly 50% of corals are bleached, and the remaining sites are less than 30% bleached. At least three sites have less than 5% bleached corals.

Healthy coral photographed at Lord Howe marine park in March 2019.
Author provided

Over the past week heat stress has continued in this area, and return visits to these sites revealed that the coral condition has worsened. There is evidence that some corals are now dying on the most severely affected reefs.

Forecasts for the coming week indicate that water temperatures are likely to cool below the bleaching threshold, which will hopefully provide timely relief for corals in this valuable reef ecosystem. In the coming days, weeks and months we will continue to monitor the affected reefs and determine the impact of this event to the reef system, and investigate coral recovery.

What’s causing the bleaching?

The bleaching was caused by high seawater temperature from a persistent summer marine heatwave off southeastern Australia. Temperature in January was a full degree Celsius warmer than usual, and from the end of January to mid-February temperatures remained above the local bleaching threshold.

Sustained heat stressed the Lord Howe Island reefs, and put them at risk. They had a temporary reprieve with cooler temperatures in late February, but by March another increase put the ocean temperature well above safe levels. This is now the third recorded bleaching event to have occurred on this remote reef system.

Satellite monitoring of sea-surface temperature (SST) revealed three periods in excess of the Bleaching Threshold during which heat stress accumulated (measured as Degree Heating Weeks, DHW). Since January 2019, SST (purple) exceeded expected monthly average values (blue +) by as much as 2°C. The grey line and envelope indicate the predicted range of SST in the near future.
Source: NOAA Coral Reef Watch

However, this heatwave has not equally affected the whole reef system. In parts of the lagoon areas the water can be cooler, due to factors like ocean currents and fresh groundwater intrusion, protecting some areas from bleaching. Some coral varieties are also more heat-resistant, and a particular reef that has been exposed to high temperatures in the past may better cope with the current conditions. For a complex variety of reasons, the bleaching is unevenly affecting the whole marine park.

Coral bleaching is the greatest threat to the sustainability of coral reefs worldwide and is now clearly one of the greatest challenges we face in responding to the impact of global climate change. UNESCO World Heritage regions, such as the Lord Howe Island Group, require urgent action to address the cause and impact of a changing climate, coupled with continued management to ensure these systems remain intact for future generations.

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The authors thank ProDive Lord Howe Island and Lord Howe Island Environmental Tours for assistance during fieldwork.

Tess Moriarty, Phd candidate, University of Newcastle; Bill Leggat, Associate professor, University of Newcastle; C. Mark Eakin, Coordinator, Coral Reef Watch, National Oceanic and Atmospheric Administration; Rosie Steinberg, PhD Student, UNSW; Scott Heron, Senior Lecturer, James Cook University, and Tracy Ainsworth, Associate professor, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Don’t trust the environmental hype about electric vehicles? The economic benefits might convince you

There are plenty of economic reasons to change our gas-guzzling habits.
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Gail Broadbent, UNSW and Graciela Metternicht, UNSW

With electric cars back in the headlines, it’s time to remember why we should bother making the transition away from oil.

In our recent research looking at attitudes towards electric vehicle uptake, we pointed to some of the factors making the case for change. We need to remind ourselves that burning oil, a finite resource, to energise motor vehicles will not only cost the environment, but also the economy.

A critical factor is carbon emissions. The transport sector is the fastest growing contributor of greenhouse gases.

The transport sector contributes some 18% of Australia’s total greenhouse gas pollution and Australia is ranked second worst in an international scorecard for transport energy efficiency.

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Read more:
Costly, toxic and slow to charge? Busting electric car myths

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But even if you don’t believe this is an urgent issue, there are plenty of economic reasons to change our gas-guzzling habits.

A matter of money

In just one year (2017-18), Australia’s imports of refined petroleum cost A$21.7 billion.

Crude petroleum cost us a further A$11.7 billion – that’s more than A$33 billion going to overseas companies who may pay limited tax to Australia.

The argument that electric vehicle motorists, who do pay GST on their electricity, may not pay any fuel tax is really a distraction asking taxpayers to look somewhere else instead of the big companies.

What’s more, the A$18 billion fuel tax goes to general revenue and isn’t pledged to road building.

Unsteady fuel reserves

Policies minimising Australia’s reliance on oil imports could bring significant benefits to businesses and families, and even to public sector agencies with fleet operations.

Around 90% of the oil Australia consumes is imported and road transport is almost entirely dependent on it. The bulk of our automotive gasoline comes from Singapore and South Korea, and in the event of geopolitical imbalance, the supply of our fuel could potentially be jeopardised.

And our fuel stockpiles are very low. Australia has only about 21 days’ supply in stock, rather than the recommended 90 days.

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Read more:
Australia’s fuel stockpile is perilously low, and it may be too late for a refill

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Health risks

Potential geopolitical imbalances affecting the national supply are important, but the health costs associated with fossil fuels are in the scale of billions of dollars in Australia.

This includes premature death, hospital and medical costs, and loss of productivity that arise from toxic air pollution from internal combustion engine vehicles.

It has also been found pollution from burning fossil fuels can cause respiratory illnesses like asthma and neurodevelopmental disorders in children It’s a high price to pay to continue burning fossil fuels.

And noise pollution from traffic can cause health problems, for instance, by elevating blood pressure, or creating cognitive development problems for children, who have noise-related sleep disturbance.

Conventional cars are inefficient

Electric vehicles convert about 60% of their energy to propulsion. Conventional cars, on the other hand, are very inefficient.

For every litre of fuel burned, only about 17 to 21% of the energy is converted to forward motion, the rest is lost as heat and noise. The waste heat collectively warms up urban areas, causing more use of air conditioning in buildings in summer.

And buildings located near heavily trafficked roads may be exposed to high air and noise pollution, so windows may not generally be used for ventilation. This also places demand on air conditioning and electricity.

Renewable energy is cheaper and faster

An important point in the ongoing debate about electric vehicles is that they’re only as clean as the electricity they use. A widespread adoption of electric vehicles means the electricity supply will need to be increased.

And Australia’s current energy supply is notoriously one of the dirtiest in the world.

But the demand for new electricity to supply future electric vehicle uptake will be met by installing renewables because they’re cheaper and faster than installing new coal fired power stations.

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Read more:
How electric cars can help save the grid

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The bottom line on this ongoing debate is really about changing our mindset about transport – let’s not get stuck in the past, let’s join the modern world and charge ahead.

Gail Broadbent, PhD candidate Faculty of Science UNSW, UNSW and Graciela Metternicht, Professor of Environmental Geography, School of Biological Earth and Environmental Sciences, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.