Tag Archives: climate emergency

A deep look at carbon capture and storage (CCS) and its role in the climate crisis

Carbon Capture and Storage (CCS) is the process of capturing carbon dioxide (CO2), a greenhouse gas, and depositing it somewhere it will not reach the atmosphere again — typically in a suitable geological formation. The goal is to reduce the amount of greenhouse gases in the atmosphere and limit (or even reverse) man-made climate heating.

Does it work?

It’s not science fiction. The technology already exists and several projects are already underway. The carbon dioxide is typically extracted from a single point source (like a cement factory or a fossil fuel facility), and injected into a porous structure where the CO2 can be absorbed without leaking back into the atmosphere. Carbon dioxide can also be absorbed from the air, although the efficacy of this process is much lower.

Carbon capture and storage can reduce the emissions of a plant by up to 90% and when coupled with other technologies, CCS can even lead to negative emissions.

The technology is regarded by many researchers as a key tool in our fight against global warming and greenhouse gas emissions as it is not only a way to reduce our emissions, but maybe even to grab some of the greenhouse gases already present in the atmosphere and store them. However, CCS comes in many different forms and, at this moment, there are only a handful of operating CCS projects in the world.

Simply put, it works — the physics of the process is valid. But whether or not CCS will really be used on a wide scale and help us keep climate change in check is a very different question.

Why CCS

The planet is heating up. Over the past century, the planet’s average surface temperature has risen by about 2 degrees Fahrenheit (a bit over 1 degree Celsius) — a change driven largely by increased carbon dioxide and other man-made emissions into the atmosphere.

We won’t get into the details of how we know climate change is happening and that it’s caused by mankind. All the available figures and scientific evidence point in this direction. Greenhouse gas emissions have increased steadily since 1890, and as a result, temperatures are rising. The problem is very real and burying our head in the sand won’t help one bit.

If we want to truly manage this crisis, we need to reduce our emissions, achieve net zero emissions, and, ultimately, find ways to revert previous emissions. The good news is that CCS can help with both.

Right now, society most focused on producing renewable energy to replace polluting and carbon-intensive fossil fuels. In truth, it’s not just just the environmental aspect of it, renewable energy is already cheaper in many parts of the world (but that’s a different story). Important as this may be, it’s not enough on its own.

A substantial part of our emissions comes from other industrial activities (like cement factories, for instance) which are extremely hard to decarbonize, and it’s not like all fossil fuel power plants will disappear overnight — we need to reduce emissions from them in the meantime. This is where CCS can come in and make a difference.

However, we can’t just capture carbon dioxide, put it in a box and wash our hands, it just doesn’t work that way. You can’t build a carbon storage factory. Luckily enough though, nature has done that herself.

Geology to the rescue

Some subsurface geological features are excellently suited as carbon storage sites. Some brine-filled pores in sandstone formations, or other similar structures sealed by a natural and impermeable caprock such as a shale or clay. Essentially, you need a porous rock to inject the carbon in, and impermeable rocks to act as a seal around it.

In some contexts, carbon storage has been used for several decades (most notably for enhanced oil recovery), but as a tool to tackle global heating, it’s a relatively new concept. For many current CCS projects, the technology used to lock CO₂ deep underground is the same technology used to enhance oil reservoirs. In one oil field (called Sleipnir), some 23 million tons of CO₂ have been injected underground. In the case of Sleipnir, the positive effect of injecting CO₂ is counterbalanced by the extraction (and subsequent burning) of oil. But what if we could just have the positive effect and not do the oil part? That’s pretty much how the idea of carbon storage emerged.

It’s been actively researched in the US since 1997, but the technology first took off in Norway in the 1980s. Although the basic principle is still the same, CCS as a field of science has grown and developed massively since. CCS publications and studies have increased exponentially in the past 20 years, with international collaboration spurring multiple projects. Still, as of 2019, there are only 17 operating CCS projects in the world, capturing 31.5Mt of CO₂ per year, of which just 3.7 is stored geologically. Compare that to the 5.1 billion metric tons of energy-related carbon dioxide the US emitted in 2019 alone — it takes the US just a couple of days to emit more CO₂than is stored year-round in the entire world.

But this doesn’t mean that CCS can’t grow. The latest IPCC Assessment Report on Mitigation mentioned CCS 35 times in the summary for policymakers. The International Energy Agency has repeatedly said CCS is a key technology for mitigating climate change. More and more, researchers are looking at CCS as one of the key ways to address some parts of our greenhouse gas emissions.

At the very least, the geological potential is there. The US National Energy Technology Laboratory (NETL) reported that North America has enough storage capacity for more than 900 years worth of carbon dioxide at current production rates. Even though there is some uncertainty regarding potential long-term leaking, there’s still more than enough room for the world to dump its carbon underground.

Location, location, location (and technology)

Carbon capture and storage is most effective when it’s applied at point sources such as a single factory or a single storage site — it’s far less effective when dealing with multiple, smaller sources. This is what makes it an excellent technology for heavy-emission industries.

Exasmple of how CCS can work at a biomass plant. Image credits: Wiki Commons.

There are three main types of carbon capture and storage for industrial facilities:

  • post-combustion capture is the most widely used form of carbon capture and storage. It essentially refers to capturing CO₂ from a flue gas generated after combusting a carbon-based fuel, such as coal or natural gas. A number of different techniques are used ,and post-combustion capture is especially interesting for researchers because existing fossil fuel power plants can be retrofitted to include CCS technology in this configuration.
  • pre-combustion capture is widely applied in fertilizers, gaseous fuel (H2, CH4), and power production. The advantage is you also obtain hydrogen which can be used as a fuel. However, retrofitting plants to accommodate pre-combustion capture is challenging and this is mostly an option for new plants.
  • oxy-fuel combustion, where the fuel is burned in oxygen instead of air. This results in a flue gas that is mainly CO₂ and water.

There are multiple technologies for separating CO2, becoming more and more efficient every year. But after it’s separated, the CO2 must be transported. This is most easily done via pipes (and has been done before). For instance, there were approximately 5,800 km of CO2 pipelines in the United States in 2008, and a 160 km pipeline in Norway used for enhanced oil recovery.

After it’s separated and transported, it is injected into a suitable geological reservoir.

Negative emissions — taking carbon from the atmosphere

So far, we’ve mostly focused on using CCS for factories, as a way to reduce emissions. But CCS can also be used as a way to revert emissions — or, as researchers put it, to produce negative emissions.

Cement amounts for about 8% of the world’s greenhouse gas emissions. Image credits: Kåre Helge Karstensen, SINTEF.

The underlying principle is straightforward: you extract carbon from sources in the Earth’s biological cycle and inject them on the ground. This way, you’re not just reducing the carbon you’re outputting, you’re essentially eliminating some of the already existing carbon. So you would take something like wood chips or biological waste such as manure and inject the carbon from it to a geological storage site.

But it can get even more interesting than that. In a recent study, researchers discovered a way to pull carbon dioxide from the atmosphere and turn it back into coal. This approach is actively being researched by fossil fuel companies, who are looking for a way to maximize returns. However, in order for this to truly have a net positive effect, the subsequent burning of the resulting coal would also have to be captured.

Perhaps the most exciting development comes from Iceland, where researchers found a way to extract CO2 and mineralize it into rocks. They’ve essentially created ‘negative emissions plant’ — a plant that turns ambient CO2 into stone switches.

Iceland’s large basaltic fields could be a boon for CCS. Image via Unsplash.

The key to rapid mineralization of carbon is basalt – a volcanic rock which Iceland has an abundance of. Iceland is actually mostly made up of basalt (90%), and within basalt, CO2 can quickly mineralize (morph into carbonate rocks). “The potential of scaling-up our technology in combination with CO2 storage, is enormous,” said Christoph Gebald, the founder and CEO of Climeworks, the company behind the technology.

But for all these exciting developments, there’s one part we’ve purposely left out until now: money.

Without a carbon tax, CCS just won’t work

What about the money? As we’ve seen in the case of renewable energy, green technologies can only truly succeed when they have at least some economic advantage. Separating CO₂ from other chemicals is costly and also requires energy. But unlike renewable energy, in the case of CCS, there’s no real economic advantage — all you have is a method of reducing CO₂ emissions, that’s it.

At the moment, even as CCS is making great strides in terms of technology and research, the funding for said technologies is starting to shrink. This is a problem not just for carbon storage, but for our ability to meet current climate commitments and avoid catastrophic environmental and economic damage.

Nowadays, CCS projects rely on government incentives and standards — even though economists generally agree that these programs are less effective and more costly than a carbon price. Carbon pricing is notoriously unpopular and hotly debated, but increasingly, leading economists are calling for some sort of a climate tax. Without such a tax (or some pricing mechanism), CCS remains a niche technology and is unlikely to scale massively into the future.

“I prefer to have an economy-wide carbon price to create markets for low-carbon technology. Then markets, not advocates, will make decisions about the technology mix. I believe deployment of CCS would be significant under such a policy,” writes Howard J. Herzog Senior Research Engineer, Massachusetts Institute of Technology.

Simply put, new policies are dearly needed to incentivize commercial CCS. No matter how you look at things reaching net-zero emissions (and maybe, someday even negative emissions) seems much harder without CCS — but without financial incentives CCS cannot flourish, even when the technology matures. A University of Warwick report concludes:

“CCS has considerable potential to reduce CO2 emissions not only by a significant amount but also at a social cost that most economists would not consider prohibitive, particularly in comparison to the social costs predicted for a business-as-usual scenario with unregulated carbon emissions.”

More evidence that 2020 was an unusually hot year

The ECMWF’s Copernicus reanalysis had already stated the year of 2020 as the warmest on the record. Now, other five independent analyses surveyed by World Meteorological Organization (WMO) show that it was at least one of the three warmest years. The teams are: United States National Oceanic and Atmospheric Administration (NOAA), NASA’s Goddard Institute for Space Studies (NASA GISS), and the United Kingdom’s Met Office Hadley Centre and the University of East Anglia’s Climatic Research Unit (HadCRUT) and another reanalysis from Japan Meteorological Agency (JMA).

WMO has shown five of its data sets indicating that 2020 was a hot year, with a global average temperature of 14.9°C. This is 1.2°C above the average temperature before industrial activity.

Comparison of global warming trend from six different datasets. Credits: Berkeley Earth.

The centers that analyzed the data consider all sorts of instrumental data, buoys in the sea, stations, aircraft, and satellites. This is usually similar to all approaches, what differs is the way they interpolate the data.

Interpolation means a way of estimating data for a place that did not have a real measurement. Just like superhero movies, when the hero wants to find the source of a villainous activity. Researchers sometimes use the word “triangulate”, which is a form of interpolation. This explains why some researchers report slightly different results. For instance, NASA interpolates data considering the poles, NOAA doesn’t and other centers also vary their methodology, so the average temperature will differ.

NASA agrees with ECMWF in that 2020 is tied with 2016 for ignoble honor of the warmest year on record. NOAA and HadCRUT say it’s the second warmest and JMA says it’s the third warmest. What matters is that it was a very warm year despite the formation La Niña, which tends to reduce the average. The 2016 had the help of El Niño to increase the temperature, which means 2020 was far too warm.

The sixth dataset is from Berkeley Earth, an independent, non-governmental group that gathers data to study climate change. The founder, Richard A. Muller, started the project because he believed some skeptics pointed problems in the way the traditional centers, such as NASA, delivered their results. Spoiler alert: after the first analysis they concluded the data didn’t differ so much from everyone else.

Berkeley Earth concluded that 2020 was the second warmest year since 1850, differing only by 0.022°C. For 45 countries, 2020 was the warmest year ever, especially for European countries. This is because land warms faster than the ocean and the Northern Hemisphere has more land cover. Russia warmed the most, by a staggering 4°C above the pre-industrial era.

2020 temperature difference relative from 1951-1980. Creditis: Berkley Earth.

The year 2021 may not be as hot as 2020 due to the continuation of the La Niña event. Scientists estimate that it could come in fifth place in the heat race. It is important to note that Berkeley Earth’s estimate is just a minor perturbation in the trend. This doesn’t mean an end to global warming.

Unfortunately, Berkeley showed the trending of the temperature curve and it looks terrible. If we continue with the pace we are now, by 2037 the world could be 1.5°C above the 1850-1900 trend. Paris Agreement established the 2°C or less threshold in order to avoid an even worse climate crisis.

France prepares for heatwaves of 25 °C (77 °F) mid-winter

France is experiencing record-high temperatures for this time of year, particularly in its southern regions. It’s exactly the type of event amplified by global warming, meteorologists explain.

It’s almost beach weather in Southern France. In February.

Several cities across France are reporting temperatures of 24°C-25°C (75-77 °F). Biarritz and Saint-Jean-de-Luz, two cities close to the ‎Pyrénées Mountains, as well as Tarbes and Perpignan are reporting record heat for what is supposed to be a winter month.

The heatwave comes in the context of an already mild winter. François Jobard, a meteorologist forecaster at Météo-France said that this is an “abnormal event”, marking the second-hottest start of February since 1900. Simply put, these are temperatures you’d expect to see in June, not February.

The warm wave of air is coming from the Azores and the subtropical Atlantic area, Jobard explains. While a cold spell is likely to follow this unusually warm period, it seems that the winter will continue to be relatively warm.

“We will continue to see temperatures that are higher than the normal average. This does not rule out several short, colder periods, but the trend will stay mild. After this peak of warmth, we will see a maximum on Monday (February 3), but on Tuesday (February 4) temperatures will cool down noticeably and be closer to normal.”

It’s always difficult to pinpoint singular events as being caused by global warming. However, this is exactly the type of event you’d expect to become more common as our planet continues to heat up. In Perpignan, the average high temperatures in February are around 12°C (54 °F), and they’re usually recorded towards the end of the month. Temperatures in Perpignan are expected to reach 26°C (74 °F) today.

It’s not just that global heating is driving up temperatures worldwide, but it is also causing imbalances in global wind circulation. Our planet heating up is causing heatwaves (and even cold spells) to become more frequent, so it’s much more likely to see temperature spikes such as the ones in southern France in the future.

“Overall we have warmer air masses than before, so with an equal meteorological situation, we tend to beat more records of smoothness than in the past “, Jobard concludes.

Scientists are concerned that the unusually warm weather might also trigger avalanches in the Alps.

The Arctic’s oldest and thickest ice is disappearing fast

Credit: Pixabay.

Arctic ice north of Greenland is, historically speaking, the oldest and thickest ice in the north pole. But although this is the last place that might lose its year-round ice cover, ice mass in the area is already declining at twice the rate as the rest of the Arctic.

Not as stable as once thought

Most of the ice that covers the Arctic is only one to four years old. However, there is a 2,000-kilometer-arc of ice, stretching from the western Canadian Arctic Archipelago to Greenland’s northern coast, which is more than five years old and can measure more than four meters thick. This relatively old region of ice is known as the Last Ice Area.

Although, historically speaking, this band of old ice is stable, recent findings suggest that the Last Ice Area cannot be spared forever from the melting that plagues seasonal ice in the Arctic. According to a new study, ocean currents and atmospheric winds have made the old ice more mobile and have transported it to other parts of the Arctic.

“We can’t treat the Last Ice Area as a monolithic area of ice which is going to last a long time,” said Kent Moore, an atmospheric physicist at the University of Toronto in Canada and lead author of the new study. “There’s actually lots of regional variability.”

For their new research, Moore and colleagues employed satellite and atmospheric data to model sea ice cover, thickness, and motion across the Last Ice Area from 1979 to 2018. The results suggest that the Last Ice Area is made of two important subregions — one to the east and one to the west. — where ice thickness varies from 1.2 meters from year to year. Moore and colleagues concluded that ice in both subregions are thinning, losing about 0.4 meters of ice thickness per decade.

Annual mean sea ice thickness (m) over the Arctic Ocean from 1979 – 2018. The black line surrounds the area where the ice thickness exceeds 3 m and can be considered as the region known as the Last Ice Area. The white lines surround the two areas where the ice thickness exceeds 4m. Credit: Kent Moore/University of Toronto.

Since the 1970s, the Last Ice Area has lost 1.5 meters of thickness and Arctic summers could soon become totally ice-free as early as 2030. For many species of wildlife, such as polar bears and seals, this could signal a disaster.

“Eventually the Last Ice Area will be the region that will repopulate the Arctic with wildlife,” Moore said. “If we lose all the ice, we lose those species. This area will be a refuge where species can survive and hopefully expand their regions once the ice starts returning.”

Moore claims that the dramatic loss of ice in the Last Ice Area can be pinned to the movement of the ice out of the region, towards the west.

These findings don’t bode well in the context of the climate emergency that we are currently experiencing. The Arctic is warming faster than any other region of the globe. For instance, this last June, average temperatures were warmer than usual by nearly 5.5 degrees Celsius (10 degrees Fahrenheit). And since climate models haven’t taken into account the possibility of ice loss in the Last Ice Area, it is possible that the Arctic could reach an ice-free state much earlier than previously predicted. In the face of such calamity, the only solution is the rapid decarbonization of society.

“Historically, we thought of this place as an area that just receives ice,” said David Barber, an Arctic climatologist from the University of Manitoba in Canada who was not involved in the new study. “But these results are teaching us that this is a dynamic area.”

The findings appeared in the journal Geophysical Research Letters.

More than 11,000 scientists foresee “untold suffering” due to climate emergency

If we continue on the same path, humanity is on track to face an “untold suffering” because of a climate emergency caused mainly by human activities, according to a new study signed by more than 11.00 scientists from around the world.

Credit Wikipedia Commons

In the study, published in the journal BioScience, scientists no longer mince words when it comes to talking about the climate crisis, preferring instead to “tell it like it is.” They declare, “clearly and unequivocally that planet Earth is facing a climate emergency,” which threatens every part of our ecosystem.

“We have joined together to declare a climate emergency because the climate change is more severe and accelerating faster than was expected by scientists,” Bill Ripple, professor of ecology at Oregon State University and co-author of the paper, told CNET. “Many of us feel like the time is running out for us to act.”

It’s not the first time thousands of academics united to urge people to take action on climate change. More than 16,000 scientists from 184 countries published a letter in 2017, warning that “human beings and the natural world are on a collision course.”

In this new report, the scientists, who come from over 150 countries, said the climate crisis is “closely linked to excessive consumption of the wealthy lifestyle.” Echoing the words of teenage climate activist Greta Thunberg, the scientists have criticized policymakers for failing to take proper action.

“Despite 40 years of global climate negotiations, with few exceptions, we have generally conducted business as usual and have largely failed to address this predicament,” they said.

They listed six key issues that need to be addressed if humanity wants to prevent the most catastrophic scenarios.

These include replacing fossil fuels, cutting the emissions of climate pollutants such as methane and soot, eating less meat, restoring and protecting ecosystems, building a carbon-free economy and stabilizing population growth by investing into family-planning services and girls education.

Scientists are particularly concerned about population growth, noting that human fertility rates have “substantially slowed” over the last 20 years. The study calls for strengthening human rights, especially for women and girls, in order to combat the issue.

The paper was published just one day after the Trump administration announced a formal process to withdraw the U.S. from the Paris Agreement — an accord in which nearly 200 countries set their own national targets for reducing or controlling pollution of heat-trapping gases.

Climate activist Greta Thunberg slams world leaders at the UN

Swedish teenage climate activist Greta Thunberg told world leaders at the opening of a United Nations conference in New York City that they had stolen her childhood with “empty words.”

Credit: Wikipedia Commons

“You have stolen my dreams and my childhood with your empty words,” Thunberg said at a U.N. climate change summit, admonishing them for not doing enough to protect the environment.

Thunberg, who traveled from Europe to New York for the summit on a zero-emissions sailboat, said she should be in school in her native Sweden rather than at the UN telling world leaders what to do to address climate change.

Listen to the science, she told them, which has been “crystal clear” for 30 years. She admonished them for leaving her generation with the task of sucking billions of tons of carbon dioxide out of the air “with technologies that barely exist.”

“This is all wrong, I shouldn’t be up here,” said Thunberg, who spoke along with UN Secretary-General Antônio Guterres, India Prime Minister Narendra Modi and others. “The eyes of all future generations are on you,” she said.

Leaders from around the world, including French President Emmanuel Macron and German Chancellor Angela Merkel, have gathered in New York this week to make new pledges to curb global-warming emissions. US President Donald Trump, who wasn’t originally scheduled to attend, made a surprise appearance at the summit on Monday.

President Trump took to Twitter, citing the first half of that statement then saying Thunberg “seems like a very happy young girl looking forward to a bright and wonderful future. So nice to see!”

Guterres is calling on countries to step up commitments to reduce their dependence on fossil fuels. “We face at least three degrees Celsius of global heating by the end of the century,” he said. “I will not be there, but my granddaughters will. And your grandchildren, too. I refuse to be an accomplice in the destruction of their home and only home.”

French President Emmanuel Macron acknowledged in his speech after Thunberg’s at the summit the frustration she and other activists are expressing. “I was very struck by the emotion in the room,” Macron said. “I think they’ve identified an absolute urgency that we have to respond to here.”

Thunberg recently celebrated the one-year anniversary of the start of her climate change movement. Last August, she began striking by herself outside the Swedish parliament, and soon, students around the world began walking out of school, demanding action from their governments. She’s been called “the voice of the planet,” and has even been nominated for the Nobel Peace Prize.

United Nations hosts key climate emergency summit in New York

More than 60 world leaders will convene today for a UN summit on “climate emergency” aimed at reinvigorating the Paris agreement on climate change, at a time when mankind is releasing more greenhouse gases into the atmosphere than at any time in history.

UN headquarters in New York. Credit: Wikipedia Commons

Countries are expected to announce new actions to limit the causes of warming or to speak on initiatives developed by a coalition of nations. UN secretary-general António Guterres had asked countries to commit to net-zero emissions by 2050, reduce subsidies for fossil fuels, and stop building new coal-fired power stations.

“People want solutions, commitments, and action. I expect there will be an announcement and unveiling of a number of meaningful plans on dramatically reducing emissions during the next decade, and on reaching carbon neutrality by 2050,” said Guterres.

Who is attending?

Among the list of those absent will be US President Donald Trump, who pulled his country out of the Paris Agreement upon taking power. Brasilian president Jair Bolsonaro, under whose leadership the Amazon rainforest is continuing to burn at record rates, will also be absent.

On the other hand, China, the world’s biggest carbon emitter by far, but also a leader in the renewables sector, will be present and represented by foreign minister Wang Yi, with Guterres hinting last week that the East Asian giant will be committing to new measures.

“There’s a tension between the countries that want to go ahead to translate their goals into real policies and those that do not,” said Laurence Tubiana, CEO of the European Climate Foundation and one of the architects of the Paris agreement. “We can hope for the best.”

India’s Prime Minister Narendra Modi will speak in the morning session, along with the leaders of New Zealand, the Marshall Islands, and Germany’s Angela Merkel. Like China, India is coal-addicted but has also set itself highly ambitious renewable energy targets, particularly in the solar energy sector.

What are the expectations?

Seventy-five countries are expected to bring enhanced commitments. But officials have also been careful to manage expectations and said today’s summit is also a run-up event to the 2020 UN climate summit that the UK will host in Glasgow. Still, there is some sense of increased urgency.

The goal of “carbon neutrality” — where most emissions are eliminated and those that remain are offset (by measures such as the planting of new trees and, potentially, carbon capture technology in the future) was considered so radical in 2015 that it was left out of the text of the Paris agreement.

Now, though, it has become a rallying cry for countries like the United Kingdom and France as well as major corporations, who are leading the charge in countries like the US where the political leadership has sought to distance themselves or even undermine the cause.

Heatwaves lead to death and decay of corals, research shows

The rise of ocean temperatures is not the single and worst effect of climate change on corals, according to a new study, which warned over the consequences of heatwaves, leading to their death and decay.

Credit: Flickr

Researchers reporting in the journal Current Biology showed that severe marine heatwaves, as happened in Australia’s Great Barrier Reef (GBR) in 2016, are worse for corals than the phenomenon known as bleaching, in which they corals expel the algae living in their tissues and turn white.

“The water temperatures are so warm that the coral doesn’t bleach, it dies,” says Tracy Ainsworth of The University of New South Wales, Sydney, Australia. “We still see the coral become white as the animal dies and its skeleton is exposed to the water, and then we see it very rapidly become overgrown by colonizing algae from both the inside out and the outside in.”

Ainsworth and her team had shown in a previous study that just a 0.5ºC increase in water temperature changes the extent of mortality in corals during bleaching. In the new one, they examined GBR corals following the 2016 mass bleaching event.

At that time, reefs of the northern GBR were exposed to a rapid and severe rise in sea surface temperatures, with more than 30% experiencing temperatures above the established threshold for coral survival. After the heatwave, the corals showed rapid degradation and mortality as microbial biofilms took over.

Ainsworth and colleagues simulated the severe heatwave conditions seen on the GBR in 2016 with two coral species that showed high mortality that year, seeking to better understand the phenomenon.

Their studies show that marine heatwave events on coral reefs are entirely different from the way coral bleaching has been understood.

The simulated heatwave conditions caused immediate heat-induced mortality of the coral colony, as the coral skeleton rapidly dissolves, and its structure is lost. Within days, a complex microbial biofilm encases the exposed coral skeleton, further accelerating the loss of calcium carbonate from the reef to weaken it even further.

Researchers argued that the findings suggest that severe heatwave- induced mortality events should be considered as a distinct biological phenomenon from coral bleaching. They said that such heatwave mortality events and the rapid reef decay that results, likely will become more frequent as the intensity of marine heatwaves increases in the coming years.

“This work provides very clear evidence that the intense heatwave conditions, which are now becoming a feature of bleaching events, are far more severe and are changing how we understand the impact of climate change on coral reefs and the consequences of severe heat-wave events,” said says William Leggat, first author of the study from the University of Newcastle, Australia.