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Australia’s iconic Great Barrier Reef has suffered through the worst bleaching event in its history, part of the world’s third mass bleaching event.

However, coral reefs from the other side of the continent have also experienced unprecedented bleaching and coral death. This is bad news because the unique coral reefs of Western Australia’s northwest are home to some of the toughest coral in the world.

Western Australia’s unique coral reefs

Although much less well-known, coral reefs in Western Australia are highly diverse. They include, for example, Australia’s largest fringing reef, the World Heritage-listed Ningaloo Reef, as well as Australia’s largest inshore reef, Montgomery Reef which covers 380 square kilometres.

WA’s remote Kimberley region also features “super-corals” – corals that have adapted to a naturally extreme environment where tidal swings can be up 10m. These corals can therefore tolerate exposure to the air during low tide as well as extreme daily temperature swings.

My past research has shown that these naturally extreme conditions increase the heat tolerance of Kimberley corals but that they are nevertheless not immune to bleaching when water temperatures are unusually hot for too long.

Previously I had put these super-corals in tanks and subjected them to a three-week heatwave to see how they would respond, but I always wondered how they would cope in the wild where such events typically unfold over longer timescales. Unfortunately, I did not have to wait long to find out.

The hottest years on record

2015 was the hottest year on record and 2016 will likely be hotter still. This has caused an unprecedented global coral reef crisis. Although global coral bleaching events already occurred in 1998 and 2010, this third global bleaching event is the longest on record and still ongoing.

Sadly, in WA the Kimberley region was hit the hardest. As part of Australia’s National Coral Bleaching Taskforce, colleagues and I conducted extensive monitoring before, during and after the predicted bleaching event along the entire WA coastline. In the southern Kimberley, we also carried out aerial surveys to assess the situation on a regional level.

The severity and scale of bleaching that we observed in April was devastating. Almost all inshore Kimberley reefs that we surveyed had about 50% bleaching, including Montgomery Reef. Researchers from the Australian Institute of Marine Science found that offshore Kimberley reefs such as Scott Reef fared even worse, with 60-90% bleaching in shallow lagoon waters.

Many corals had already died from the severe bleaching in April, but the final death toll has only been revealed during visits to the Kimberley last month. Vast areas of coral reef are now dead and overgrown with algae, both at the inshore and offshore Kimberley reefs.

According to local Indigenous Rangers and Traditional Owners who assisted in the research, this appears to be unprecedented. Such events had never previously been described in their rich local history of the coastal environment.

Bleached staghorn coral on inshore Kimberley reefs in April 2016. Verena Schoepf Dead staghorn coral on the same reefs in October 2016. Verena Schoepf Some good news

There was nevertheless some good news. Corals living in intertidal areas, where they regularly experience exposure to air, stagnant water, and extreme temperature fluctuations, bleached less than corals from below the low-tide mark, where conditions are far more moderate. And importantly, the majority of intertidal corals were able to fully recover within a few months.

Similarly, researchers from the Western Australian Museum and Curtin University confirmed last month that intertidal coral reefs in the central Kimberley (Bonaparte Archipelago) were in great condition.

Overall, these observations confirm the findings from my past research which showed that highly-variable, extreme temperature environments can boost the bleaching resistance of corals.

It is also important to note that the 2016 severe bleaching event in WA was restricted to the Kimberley region. Ningaloo Reef as well as coral reefs in the Pilbara and the Abrolhos Islands all escaped the bleaching. This is great news because some of these locations are still recovering from major bleaching in 2010-11 and 2013.

Healthy coral at Ningaloo Reef in 2016. Morane Le Nohaic The future of WA’s coral reefs

Although it is now clear that WA’s coral reefs are at risk of bleaching during both El Niño (as in 2016) and La Niña years (as in 2010-11), they have some advantages over other reefs that may hopefully allow them to recover from bleaching more quickly and stay healthy in the long term.

For example, most of WA’s coral reefs are located far away from major population centres and are thus less affected by environmental threats such as poor water quality (though other threats such as oil and gas exploration do exist). We also know that their isolation, particularly in the case of offshore reefs, helped them recover from previous mass bleaching events.

Finally, it is critical that we identify coral populations worldwide that are already naturally adapted to higher temperatures and have a greater bleaching resistance, such as the Kimberley corals.

These super-corals, while not immune to climate change, should be a priority for research into the limits of coral tolerance, as well as conservation efforts.

Verena Schoepf is affiliated with the University of Western Australia, the ARC Centre of Excellence for Coral Reef Studies and the Western Australian Marine Science Institution (WAMSI). The research presented here was funded by WAMSI, the ARC Centre of Excellence for Coral Reef Studies, the PADI Foundation and an ARC Laureate Fellowship to Prof Malcolm McCulloch.

Riseley, Bedfordshire Nissen huts stored ammunition here, hidden by tall elms whose offspring are just bushes, cursed with perpetual youth

American servicemen came in wartime with concrete and bombs to Coppice Wood. They paved the paths with cement and put up a parking lot – a series of wide bays with Nissen huts storing explosive shells. Chipped and cracked, this network of hard standing remains, though the army is long gone. So too the elms remain, the trees that hid the ammunition stores from enemy aircraft under their canopy.

The elms’ descendants are cursed with perpetual youth. Always a bush, never a tree, seems to be the mantra, the leafy sprays doomed to shrivelled adolescence by Dutch elm disease. Only a few have made it to the heights.

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At an extraordinary meeting on 7 October 2016, COAG Energy Ministers agreed to an independent review of the national electricity market to take stock of its current security and reliability and to provide advice to governments on a...

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Plastic pollution in the sea gives off a smell that attracts foraging birds, scientists find.

Streets around the country have been brightened by the trees’ blooms in the lead-up to summer. Here are some of our favourite snaps from Instagram

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There are now more than 500 pairs of golden eagles in Scotland, a survey of the birds finds.

The use of electric car charging points across Scotland has more than doubled in the last year.

Donald Trump's election doesn't augur well for US solar. Worse news, however, is the Republican Party has retained control of the US Senate.

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The Australian Heritage Council is assessing Quinkan Country for potential inclusion in the National Heritage List. Comments close 13 January 2017.

Caper whites descend on state’s south-east – only to be replaced by plague of flies as temperatures climb to 38 degrees

From butterflies to plain old flies, south-east Queensland is experiencing a two-phase swarm of insects amid weather conditions that allow both species to thrive.

Last Friday residents began reporting a sudden surge of butterflies, an influx of tens of millions of caper whites in what experts said was a phenomenon that occurred about once a decade.

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The journal Climatic Change has published a special edition of review papers discussing major natural hazards in Australia. This article part of a series looking at those threats in detail.

Australia is no stranger to heatwaves. Each summer, large areas of the continent fry under intense heat for days on end, causing power outages, public transport delays, and severe impacts to human health. The estimated impact on our workforce alone is US$6.2 billon per year. Heatwaves are also Australia’s deadliest natural hazard, accounting for well over half of all natural disaster-related deaths.

Along with our colleagues, we have taken a close look at what we know and don’t know about heatwaves in Australia, as part of a series of reviews produced by the Australian Energy and Waster Exchange initiative.

Let’s start with the stuff we know. First, we are very clear on the weather systems that drive heatwaves in Australia’s densely populated coastal areas. Typically, a persistent high-pressure system sits next to the region experiencing the heatwave, pushing hot air from the centre of Australia towards that region. The location of the high depends on the region experiencing the heatwave, but there is always one there.

These high-pressure systems are created and sustained by other weather influences farther afield, for instance. We know for instance that heatwaves in Melbourne are coupled with tropical cyclones to the northwest of Australia.

Other, longer-term variables can affect not just individual heatwaves but their patterns, timing and severity too. So heatwaves are likely to be much longer and more frequent during El Niño than La Niña phases over much of northern and eastern Australia. However, this does not influence heatwaves over Australia’s far southeast – here, the most important driver is changes to wind patterns over the Southern Ocean.

We also know that heatwave trends have increased in the observational record, and, unfortunately, that they will continue to do so. By far the strongest trend is in the number of heatwave days experienced each season. Over much of eastern Australia, this trend is as large as two extra days per season, per decade.

Looking into the future, heatwaves are projected to become more frequent, with increases of between 20 and 40 extra days per season in the north and 5-10 extra days in the south likely by the end of this century, under a “business as usual” scenario. The intensity of heatwaves over southern Australia is also increasing faster than the average temperature. This is not good news for our ageing population, our fragile ecosystems and our outdated infrastructure.

The Australian research community has been successful in leading the development of a comprehensive way to measure marine heatwaves. Just like the atmosphere, areas of the ocean can experience prolonged periods of abnormally warm temperatures. These marine heatwaves can be every bit as damaging as atmospheric ones, decimating marine habitats and killing coral.

What we don’t yet know

Perhaps surprisingly, given the amount of research and public attention that heatwaves attract, they still do not have an official definition. The Bureau of Meteorology uses a concept called excess heat factor, which looks at maximum temperatures and ensuing minimum temperatures over a three-day period, incorporating the key characteristic of heatwaves of heat tending to persist overnight. However, we still do not have a universal definition that fits all situations.

We are also unclear on how the physical mechanisms that drive heatwaves will change under ongoing greenhouse warming. Recent research suggests that background warming will predominantly drive future increases in heatwaves, with some heatwave-inducing systems moving further south. But we don’t really know how future changes to patterns such as El Niño will continue to influence our heatwaves.

We also don’t really understand the extent to which the land surface drives Australian heatwaves. European studies have shown that dry conditions leading up to heatwave season, resulting in more parched soils, are a recipe for more intense and longer events, particularly when coupled with a persistent high-pressure system.

For Australia, we know that dry soil contributed to the deadly heatwave that preceded the Black Saturday bushfires in 2009. But more extensive studies are needed to understand this complex relationship over Australian soil (pun intended).

We also need a more comprehensive understanding of marine heatwaves. So far there has been only a handful of studies describing individual events. We still don’t know how much marine heatwaves have increased over recent decades, or how their causes and severity will change in the future. Given how vulnerable we are to marine heatwaves here in Australia, this topic should be a national research priority.

Finally, we need to develop more practical predictions of how heatwaves are likely to affect people in the future. We know how bad the impacts of heatwaves can be, and we know in general terms how heatwaves will change in the future. Yet the vast majority of our projections come from global climate models. Forecasting the exact impacts calls for finer spatial detail, using regional climate models. But these models are far more computationally expensive to run, and more investment into this area is necessary.

There is no doubt that heatwaves have been, and will continue to be, an integral feature of Australia’s climate, and recent research has taught us a lot about them. But there is more work to be done if we want to safeguard Australians properly from their deadly impacts in the future.

Sarah Perkins-Kirkpatrick receives funding from the Australian Research Council.

Christopher J. White receives funding from various Tasmanian State Government research funding programs, Wine Australia and the Bushfire and Natural Hazard CRC.

Replanting trees is one of the better ways to remove carbon from the atmosphere. CIFOR/Flickr, CC BY-NC-ND

This week international leaders are meeting in Marrakech to thrash out how to achieve the Paris climate agreement, which came into force on Friday. The Marrakech meeting is the 22nd Congress of Parties (or COP22) to the United Nation’s climate convention. One of the key goals of the agreement is to limit global warming to well below 2℃, and aim to limit warming to 1.5℃.

With global greenhouse gas emissions still rising, this is a daunting task. Numerous models, including recent research, suggest we will not be able to achieve this without removing large amounts of greenhouse gases from the atmosphere later this century (known as “negative emissions”).

But scientists are becoming increasingly sceptical of the concept, as it may create more problems than it solves, or fail to deliver. Instead, we need to ramp up action before 2020, before even the earliest targets of the Paris Agreement.

Going negative

Some models suggest that up to 1 trillion tonnes of carbon dioxide needs to be removed from the atmosphere to meet the 1.5℃ goal.

This idea is increasingly being called out as a risky and “highly speculative” strategy to limit warming to 1.5℃, as it puts food security and biodiversity at risk, and may not even be possible to deliver. The Convention on Biodiversity has also now weighed in on the issue, declaring that carbon removal techniques are highly uncertain.

A recent report from the Stockholm Environment Institute (SEI), summarised here, argues that the scale of negative emissions assumed by many climate models is improbably high.

The key components of negative emissions are reducing deforestation, planting trees, and an untested technology called “bioenergy with carbon capture and storage” or BECCS. The involves burning plant matter to produce energy, capturing the waste CO₂, and then storing it underground. The result is less CO₂ in the atmosphere.

But there are several problems with these strategies. For one, the scale of land required for the expected level of negative emissions suggests serious social and ecological risks, since land plays a crucial role in food security, livelihoods and biodiversity conversation.

Indeed, the scale of bioenergy supply in many cases is equivalent to the current global harvest of all biomass – for food, feed, and fibre - assuming a doubling of human harvest of biomass by 2050.

The SEI paper argues that the risks and uncertainties associated with negative emissions could lock us into much higher levels of warming than intended, substantially undermining society’s overall mitigation efforts.

Better ways to remove carbon

So does all of this mean the 1.5℃ goal is out of reach? Some may think so.

However, the SEI analysis finds that if emissions were cut sufficiently quickly and ambitiously, we wouldn’t need to rely so much on negative emissions. We could also choose negative emissions methods with lower impacts on biodiversity, resource demands, and livelihoods.

The SEI analysis optimistically suggests that a maximum of 370 billion to 480 billion tonnes of CO₂ could be removed without exceeding biophysical, technological and social constraints. This would be done through protecting forests and allowing degraded forests to regenerate, along with some reforestation.

Even that would be extremely challenging to achieve, but done right, for example through community forestry and agro-ecological farming,, climate mitigation and sustainable development could go together.

In fact, securing land rights of indigenous peoples and local communities who protect and preserve the carbon stocks in forests is one of the most cost-effective forms of climate mitigation we have, with obvious social co-benefits.

Scaling up

The real threat of negative emissions is the potential to delay emissions reduction into the future. Many modelled pathways for 1.5℃ that include substantial negative emissions suggest that emissions do not begin to decline until the late 2020s.

But limiting negative emissions to lower levels would require immediate global mitigation on a scale greatly exceeding that which has so far been pledged by nations under the Paris Agreement.

We cannot wait until 2020 to speed up global action on climate change - less action now will mean more work later.

Key for strengthening pre-2020 action in Marrakech will be a facilitative dialogue on enhancing ambition and support and a high level ministerial meeting on increased ambition of 2020 commitments under the Kyoto Protocol.

Many countries, including Australia, still have completely inadequate targets for 2020, making arguments about whether they are on track to meet them or not moot.

The Moroccan government has dubbed Marrakech the “action COP”. Action here must focus on the urgent need for global emissions to begin declining before 2020, and on the finance needed to deliver it. This includes scaling up the rollout of renewable energy, halting and reversing the loss of the world’s forests, and tackling rich world consumption patterns to ensure equitable mitigation pathways.

Limiting global warming to 1.5℃ is not only possible, it is the only chance of survival for the most vulnerable communities around the world, who are increasingly exposed to rising sea levels, drought and food shortages.

As Erik Solheim, head of the UN Environment Program (UNEP), and Jacqueline McGlade, UNEP’s chief scientist, wrote in a recent report, those most vulnerable “take little comfort from agreements to adopt mitigation measures and finance adaptation in the future. They need action today”.

Kate Dooley receives funding from the Australian government through an Australian Post-graduate Award.