The 2016 Great Barrier Reef heatwave caused widespread changes to fish populations



File 20180725 194140 1cri4pn.jpg?ixlib=rb 1.1
Some fish fared better than others amid the extreme temperatures of the 2016 heatwave.
Rick Stuart-Smith/Reef Life Survey

Rick Stuart-Smith, University of Tasmania; Christopher Brown, Griffith University; Daniela Ceccarelli, James Cook University, and Graham Edgar, University of Tasmania

The 2016 marine heatwave that killed vast amounts of coral on the Great Barrier Reef also caused significant changes to fishes and other animals that live on these reefs.

Coral habitats in the Great Barrier Reef (GBR) and in the Coral Sea support more than 1,000 fish species and a multitude of other animals. Our research, published in Nature today, documents the broader impact across the ecosystem of the widespread coral losses during the 2016 mass coral bleaching event.

While a number of fish species were clearly impacted by the loss of corals, we also found that many fish species responded to the increased temperatures, even on reefs where coral cover remained intact. The fish communities in the GBR’s southern regions became more like those in warmer waters to the north, while some species, including parrotfishes, were negatively affected by the extreme sea temperatures at the northern reefs.




Read more:
How the 2016 bleaching altered the shape of the northern Great Barrier Reef


The loss of coral robs many fish species of their preferred food and shelter. But the warming that kills coral can also independently cause fish to move elsewhere, so as to stay within their preferred temperature range. Rising temperatures can also have different effects on the success, and therefore abundance, of different fish populations.

One way to tease apart these various effects is to look at changes in neighbouring reefs, and across entire regions that have been affected by bleaching, including reefs that have largely escaped coral loss.

We were able to do just this, with the help of highly trained volunteer divers participating in the Reef Life Survey citizen science program. We systematically surveyed 186 reefs across the entire GBR and western Coral Sea, both before and after the 2016 bleaching event. We counted numbers of corals, fishes, and mobile invertebrates such as sea urchins, lobsters and giant clams.

Sea temperatures and coral losses varied greatly between sites, which allowed us to separate the effects of warming from coral loss. In general, coral losses were much more substantial in areas that were most affected by the prolonged warmer waters in the 2016 heatwave. But these effects were highly patchy, with the amount of live hard coral lost differing significantly from reef to reef.

For instance, occasional large losses occurred in the southern GBR, where the marine heatwave was less extreme than at northern reefs. Similarly, some reefs in the north apparently escaped unscathed, despite the fact that many reefs in this region lost most of their live corals.

Sea temperatures the culprit

Our survey results show that coral loss is just one way in which ocean warming can affect fishes and other animals that depend on coral reefs. Within the first year after the bleaching, the coral loss mostly affected fish species that feed directly on corals, such as the butterflyfishes. But we also documented many other changes that we could not clearly link to local coral loss.

Much more widespread than the impacts of the loss of hard corals was a generalised response by the fish to warm sea temperatures. The 2016 heatwave caused a mass reshuffling of fish communities across the GBR and Coral Sea, in ways that reflect the preferences of different species for particular temperatures.

In particular, most reef-dwelling animals on southern (cooler) reefs responded positively to the heatwave. The number of individuals and species on transect counts generally increased across this region.

By contrast, some reefs in the north exceeded 32℃ during the 2016 heatwave – the typical sea temperature on the Equator, the hottest region inhabited by any of the GBR or Coral Sea species.

Some species responded negatively to these excessive temperatures, and the number of observations across surveys in their northernmost populations declined as a consequence.

Parrotfishes were more affected than other groups on northern reefs, regardless of whether their local reefs suffered significant coral loss. This was presumably because the heatwave pushed sea temperatures beyond the level at which their populations perform best.

Nothing to smile about: some parrotfishes don’t do well in extreme heat.
Rick Stuart-Smith/Reef Life Survey

Local populations of parrotfishes will probably bounce back after the return of cooler temperatures. But if similar heatwaves become more frequent in the future, they could cause substantial and lasting declines among members of this ecologically important group in the warmest seas.

Parrotfishes are particularly important to the health of coral reef ecosystems, because their grazing helps to control algae that compete with corals for habitat space.




Read more:
How the 2016 bleaching altered the shape of the northern Great Barrier Reef


A key message from our study is not to overlook the overarching influence of temperature on coral reef ecosystems – and not to focus solely on the corals themselves.

Even if we can save some corals from climate change, such as with more stress-tolerant breeds of coral, we may not be able to stop the impacts of warming seas on fish.

Future ecological outcomes will depend on a complex mix of factors, including fish species’ temperature preferences, their changing habitats, and their predators and competitors. These impacts will not always necessarily be negative for particular species and locations.

The ConversationOne reason for hope is that positive responses of many fish species in cooler tropical regions may continue to support healthy coral reef ecosystems, albeit in a different form to those we know today.

Rick Stuart-Smith, Research Fellow, University of Tasmania; Christopher Brown, Research Fellow, Australian Rivers Institute, Griffith University; Daniela Ceccarelli, Adjunct Senior Research, ARC Centre of Excellence for Coral Reef Studies, James Cook University, and Graham Edgar, Senior Marine Ecologist, Institute for Marine and Antarctic Studies, University of Tasmania

This article was originally published on The Conversation. Read the original article.

Advertisements

How the 2016 bleaching altered the shape of the northern Great Barrier Reef



File 20180418 163978 1aql97h.jpg?ixlib=rb 1.1
Staghorn and tabular corals suffered mass die-offs, robbing many individual reefs of their characteristic shapes.
ARC Centre of Excellence for Coral Reef Studies/ Mia Hoogenboom

Selina Ward, The University of Queensland

In 2016 the Great Barrier Reef suffered unprecedented mass coral bleaching – part of a global bleaching event that dwarfed its predecessors in 1998 and 2002. This was followed by another mass bleaching the following year.

This was the first case of back-to-back mass bleaching events on the reef. The result was a 30% loss of corals in 2016, a further 20% loss in 2017, and big changes in community structure. New research published in Nature today now reveals the damage that these losses caused to the wider ecosystem functioning of the Great Barrier Reef.

Fast-growing staghorn and tabular corals suffered a rapid, catastrophic die-off, changing the three-dimensional character of many individual reefs. In areas subject to the most sustained high temperatures, some corals died without even bleaching – the first time that such rapid coral death has been documented on such a wide scale.




Read more:
It’s official: 2016’s Great Barrier Reef bleaching was unlike anything that went before


The research team, led by Terry Hughes of James Cook University, carried out extensive surveys during the two bleaching events, at a range of scales.

First, aerial surveys from planes generated thousands of videos of the reef. The data from these videos were then verified by teams of divers in the water using traditional survey methods.

Finally, teams of divers took samples of corals and investigated their physiology in the laboratory. This included counting the density of the microalgae that live within the coral cells and provide most of the energy for the corals.

The latest paper follows on from earlier research which documented the 81% of reefs that bleached in the northern sector of the Great Barrier Reef, 33% in the central section, and 1% in the southern sector, and compared this event with previous bleaching events. Another previous paper documented the reduction in time between bleaching events since the 1980s, down to the current interval of one every six years.

Different colour morphs of Acropora millepora, each exhibiting a bleaching response during mass coral bleaching event.
ARC Centre of Excellence for Coral Reef StudiesStudies/ Gergely Torda

Although reef scientists have been predicting the increased frequency and severity of bleaching events for two decades, this paper has some surprising and alarming results. Bleaching events occur when the temperature rises above the average summer maximum for a sufficient period. We measure this accumulated heat stress in “degree heating weeks” (DHW) – the number of degrees above the average summer maximum, multiplied by the number of weeks. Generally, the higher the DHW, the higher the expected coral death.

The US National Oceanic and Atmospheric Administration has suggested that bleaching generally starts at 4 DHW, and death at around 8 DHW. Modelling of the expected results of future bleaching events has been based on these estimates, often with the expectation the thresholds will become higher over time as corals adapt to changing conditions.

In the 2016 event, however, bleaching began at 2 DHW and corals began dying at 3 DHW. Then, as the sustained high temperatures continued, coral death accelerated rapidly, reaching more than 50% mortality at only 4-5 DHW.

Many corals also died very rapidly, without appearing to bleach beforehand. This suggests that these corals essentially shut down due to the heat. This is the first record of such rapid death occurring at this scale.

This study shows clearly that the structure of coral communities in the northern sector of the reef has changed dramatically, with a predominant loss of branching corals. The post-bleaching reef has a higher proportion of massive growth forms which, with no gaps between branches, provide fewer places for fish and invertebrates to hide. This loss of hiding places is one of the reasons for the reduction of fish populations following severe bleaching events.




Read more:
The world’s coral reefs are in trouble, but don’t give up on them yet


The International Union for Conservation of Nature (IUCN), which produces the Red List of threatened species, recently extended this concept to ecosystems that are threatened with collapse. This is difficult to implement, but this new research provides the initial and post-event data, leaves us with no doubt about the driver of the change, and suggests threshold levels of DHWs. These cover the requirements for such a listing.

Predictions of recovery times following these bleaching events are difficult as many corals that survived are weakened, so mortality continues. Replacement of lost corals through recruitment relies on healthy coral larvae arriving and finding suitable settlement substrate. Corals that have experienced these warm events are often slow to recover enough to reproduce normally so larvae may need to travel from distant healthy reefs.

Although this paper brings us devastating news of coral death at relatively low levels of heat stress, it is important to recognise that we still have plenty of good coral cover remaining on the Great Barrier Reef, particularly in the southern and central sectors. We can save this reef, but the time to act is now.

This is not just for the sake of our precious Great Barrier Reef, but for the people who live close to reefs around the world that are at risk from climate change. Millions rely on reefs for protection of their nations from oceanic swells, for food and for other ecosystem services.

The ConversationThis research leaves no doubt that we must reduce global emissions dramatically and swiftly if we are save these vital ecosystems. We also need to invest in looking after reefs at a local level to increase their chances of surviving the challenges of climate change. This means adequately funding improvements to water quality and protecting as many areas as possible.

Selina Ward, Senior Lecturer, School of Biological Sciences, The University of Queensland

This article was originally published on The Conversation. Read the original article.

It’s official: 2016’s Great Barrier Reef bleaching was unlike anything that went before


Sophie Lewis, Australian National University and Jennie Mallela, Australian National University

It is no longer news that the Great Barrier Reef has suffered extreme bleaching.

In early 2016, we heard that the reef had suffered the worst bleaching ever recorded. Surveys published in June that year estimated that 93% of coral on the vast northern section of the reef was bleached, and 22% had already been killed.

Further reports from this year show that bleaching again occurred. The back-to-back bleaching hit more than two-thirds of the Great Barrier Reef and may threaten its UNESCO World Heritage listing.

After recent years of damage, what does the future hold for our priceless reef?

Our new research, published in the Bulletin of the American Meteorological Society’s special report on climate extremes, shows the news isn’t good for the Great Barrier Reef’s future.


Read more: How to work out which coral reefs will bleach, and which might be spared


Coral reefs are complex ecosystems that are affected by many factors. Changes in sea surface temperatures, rainfall, cloudiness, agricultural runoff, or water quality can affect a reef’s health and resilience to stress.

Early analysis of the 2016 bleaching suggested that the Great Barrier Reef was suffering from thermal stress brought on by human-caused climate change.

Our study took a new and comprehensive approach to examine these multiple climatic and environmental influences.

We set out to answer the crucial question: could anything else have bleached the Great Barrier Reef, besides human-induced climate change?

Clear fingerprint

The results were clear. Using a suite of climate models, we found that the significant warming of the Coral Sea region was likely caused by greenhouse gases from human activities. This warming was the primary cause of the extreme 2016 bleaching episode.

But what about those other complex factors? The 2016 event coincided with an El Niño episode that was among the most severe ever observed. The El Niño-Southern Oscillation system, with its positive El Niño and negative La Niña phases, has been linked to bleaching of various coral reefs in the past.

Our study showed that although the 2016 El Niño probably also contributed to the bleaching, this was a secondary contributor to the corals’ thermal stress. The major factor was the increase in temperatures because of climate change.

We next analysed other environmental data. Previous research has found that corals at sites with better water quality (that is, lower concentrations of pollution particles) are more resilient and less prone to bleaching.

Pollution data used in our study show that water quality in 2016 may have been better than in previous bleaching years. This means that the Great Barrier Reef should have been at lower risk of bleaching compared to long-term average conditions, all else being equal. Instead, record bleaching hit the reef as a result of the warming temperature trend.

Previous events

The final part of our investigation involved comparing the conditions behind the record 2016 bleaching with those seen in previous mass bleaching episodes on the Great Barrier Reef, in 1997-98 and 2010-11.

When we analysed these previous events on the Reef, we found very different factors at play.

In 1997-98 the bleaching coincided with a very strong El Niño event. Although an El Niño event also occurred in 2016, the two were very different in terms of the distribution of unusually warm waters, particularly in the eastern equatorial Pacific. In 1997-98, the primary cause of the bleaching – which was less severe than in 2016 – was El Niño.

In 2010-11, the health of the Great Barrier Reef was impaired by runoff. That summer brought record high rainfall to eastern Australia, causing widespread flooding across Queensland. As a result of the discharge of freshwater onto the reef reducing the salinity, bleaching occurred.


Read more: Feeling helpless about the Great Barrier Reef? Here’s one way you can help


There have been many reports in recent years warning of trouble for the Great Barrier Reef. Sadly, our study is yet another warning about the reef’s future – perhaps the most comprehensive warning yet. It tells us that the 2016 bleaching differed from previous mass bleaching events because it was driven primarily by human-induced climate warming.

This puts the Great Barrier Reef in grave danger of future bleaching from further greenhouse warming. The local environmental factors that have previously helped to protect our reefs, such as good water quality, will become less and less able to safeguard corals as the oceans warm.

The ConversationNow we need to take immediate action to reduce greenhouse gas emissions and limit further warming. Without these steps, there is simply no future for our Great Barrier Reef.

Sophie Lewis, Research fellow, Australian National University and Jennie Mallela, Research Fellow in Coral Reef Monitoring and Reef Health Appraisal, Australian National University

This article was originally published on The Conversation. Read the original article.

World greenhouse gas levels made unprecedented leap in 2016



File 20171031 18689 lpras9.jpg?ixlib=rb 1.1
Human activity, along with a strong El Nino, drove 2016 greenhouse gas levels to new heights.
AAP Image/Dave Hunt

Paul Fraser, CSIRO; Paul Krummel, CSIRO, and Zoe Loh, CSIRO

Global average carbon dioxide concentrations rose by 0.8% during 2016, the largest annual increase ever observed. According to figures released overnight by the World Meteorological Organisation, atmospheric CO₂ concentrations reached 403.3 parts per million. This is the highest level for at least 3 million years, having climbed by 3.3 ppm relative to the 2015 average.

The unprecedented rise is due to carbon dioxide emissions from fossil fuels (coal, oil and gas) and the strong 2015-16 El Niño event, which reduced the capacity of forests, grasslands and oceans to absorb carbon dioxide from the atmosphere.

Greenhouse gas levels are unprecedented in modern times.
WMO

The figures appear in the WMO’s annual Greenhouse Gas Bulletin. This is the authoritative source for tracking trends in greenhouse gases that, together with temperature-induced increases in atmospheric water vapour, are the major drivers of current climate change.


Read more: Southern hemisphere joins north in breaching carbon dioxide milestone


Laboratories around the world, including at CSIRO and the Bureau of Meteorology in Australia, measure atmospheric greenhouse gas concentrations at more than 120 locations. The gases include carbon dioxide, methane and nitrous oxide, as well as synthetic gases such as chlorofluorocarbons (CFCs).

At Cape Grim in Tasmania, we observed a corresponding increase during 2016 of 3.2 ppm, also the highest ever observed.

For 2017 so far, Cape Grim has recorded a smaller increase of 1.9 ppm. This possibly reflects a reduced impact of El Niño on atmospheric carbon dioxide growth rates this year.

Long-term record of background carbon dioxide from Cape Grim, located at the northwest tip of Tasmania.
CSIRO/BoM

For roughly 800,000 years before industrialisation began (in around the year 1750), carbon dioxide levels remained below 280 parts per million, as measured by air trapped in Antarctic ice. Geological records suggest that the last time atmospheric levels of carbon dioxide were similar to current levels was 3-5 million years ago. At that time, the climate was 2-3℃ warmer than today’s average, and sea levels were 10 to 20 metres higher than current levels.

Human-driven change

The extraordinarily rapid accumulation of CO₂ in the atmosphere over the past 150 years is overwhelmingly and unequivocally due to human activity.

Methane is the second-most-important long-lived greenhouse gas in the atmosphere, with 40% coming from natural sources such as wetlands and termites and the remaining 60% from human activities including agriculture, fossil fuel use, landfills and biomass burning.

In 2016, global atmospheric methane also hit record levels, reaching 1,853 parts per billion, an increase of 9 ppb or 0.5% above 2015 levels. At Cape Grim, methane levels climbed by 6 ppb in 2016, or 0.3% above 2015 levels.

Nitrous oxide is the third-most-important greenhouse gas, of which [around 60% comes from natural sources such as oceans and soils], and 40% from fertilisers, industrial processes and biomass burning.

In 2016, global atmospheric nitrous oxide hit a record 328.9 ppb, having climbed by 0.8 ppb (0.2%) above 2015 levels. At Cape Grim, we observed the same annual increase of 0.8 ppb.


Read more: The three-minute story of 800,000 years of climate change with a sting in the tail


If we represent the climate change impact of all greenhouse gases in terms of the equivalent amount of CO₂, then this “CO₂-e” concentration in the atmosphere in 2016 would be 489 ppm. This is fast approaching the symbolic milestone of 500 ppm.

These record greenhouse gas levels are consistent with the observed rise in global average temperatures, which also hit record levels in 2016.

The only way to reduce the impact is to significantly reduce our greenhouse gas emissions. The Kyoto Protocol and the subsequent Paris Agreement are important first steps in a long and challenging process to reduce such emissions. Their immediate success and ultimate strengthening will be crucial in keeping our future climate in check.


The ConversationThe authors thank Dr David Etheridge for his advice on the use of proxy measurements to infer carbon dioxide levels in past atmospheres.

Paul Fraser, Honorary Fellow, CSIRO; Paul Krummel, Research Group Leader, CSIRO, and Zoe Loh, Research Scientist, CSIRO

This article was originally published on The Conversation. Read the original article.

Australia’s 2016 environment scorecard: rains return but in some cases too late



Image 20170222 1344 1u519f3
Green shoots: a mangrove in Cairns enjoys the wet. Not all of Australia was so lucky.
Guillaume Blanchard/Wikimedia Commons, CC BY

Albert Van Dijk, Australian National University and David Summers, Australian National University

After several dry years, vegetation across much of Australia received much-needed rains in 2016. But this broad pattern of improvement belies some major environmental damage in parts of the country – particularly in Tasmania, which was scorched by bushfire, the Gulf Coast and Cape York, which missed out on the rains’ return, and on the Great Barrier Reef, which suffered massive coral bleaching. The Conversation

That is the conclusion of our report on Australia’s Environment in 2016, released today. It’s a summary of the state of the nation’s environmental indicators, which we compiled by analysing huge amounts of satellite imagery, ground data, and water and landscape modelling.

The report and the accompanying Australia’s Environment Explorer website summarise those data into graphs and plots for 13 environmental indicators. With most data extending back to at least the year 2000, this makes it possible to see how the environment is changing.

The overall story is one of rainfall boom after four years of bust. The national average rainfall in 2016 was again well above average, albeit not quite as much as in the bumper years 2010-11.

Our report last year showed soil moisture conditions had reached a six-year low in 2015, as Australia was dragged back towards the conditions experienced during the Millennium Drought.

The rains of 2016 seem to have put at least a temporary end to this. Over the past year the soil moisture in Australia’s landscapes has bounced back to levels not seen since 2012. Vegetation growth, leaf matter and soil protection all followed the same pattern.

https://datawrapper.dwcdn.net/YRw9w/1/

Despite major bushfires in Tasmania in January, there were fewer fires overall than in previous years. As a result, carbon emissions from bushfires were the lowest since 2010, meaning that 2016 was overall a good year for land-based carbon emissions.

Scorecard: winners and losers

We combined the data to produce an overall “environmental scorecard” for each state and territory, as well as for the nation as a whole. Inevitably, this introduces subjective judgements, but because so much of the environment’s health is linked to water availability, the overall pattern would remain similar even if we were to calculate the index differently.

Environmental scores in 2016.
based on data on http://www.ausenv.online

The national environmental score increased to above average (6.7), but the improvements were uneven. Scores fell in Tasmania and the Northern Territory, in the aftermath of dry conditions that had already started in 2015 or before, whereas other states improved by varying amounts.

Large parts of Queensland had been suffering through several years of drought but bounced back with good rains and growth conditions. Despite this, much of the state remains officially drought-declared – although not, ironically, Cape York. Such contrasts are not unusual; it often takes more than a year of good rain for drought declarations to be lifted.

Meanwhile, the Channel Country and many of the Murray-Darling Basin rivers received their best flows since the Big Wet of 2010–12, replenishing floodplains and wetlands along the way.

The bad news

Continued dry conditions in northwestern Tasmania created the conditions for massive bushfires in the first two months of 2016. The fires affected an estimated 95,000ha across the state, including 18,000ha of vulnerable alpine ecosystems in the Tasmanian Wilderness World Heritage Area. Although that is less than 1% of the total World Heritage Area, the ancient vegetation may have changed permanently. Characteristically for Australia, the fires were followed by a deluge, restoring soil moisture levels from May onwards but also causing major flood damage.

In the Top End, areas around the Gulf of Carpentaria missed out on the rains and continued a dry run that has lasted for four years in some places. Cape York was left high and dry, with historically low rainfall records at some locations.

Mangrove trees died in large numbers along 700km of coast on the Gulf of Carpentaria. The record temperatures and ongoing dry conditions were a likely factor. Mangroves provide breeding grounds for many sea organisms and protect the coast from erosion, and their demise may cause knock-on effects into the future.

Evidence of mangrove dieback along a short stretch of Gulf Coast, NT.
Google Timeline

To Australia’s east, high sea temperatures played an important role in large-scale bleaching on the Great Barrier Reef. Reefs and mangroves have been wiped out and recovered before, such as after cyclones. But the sheer scale of last year’s damage was unusual and set against an unmistakable climate warming trend. The big question is whether these ecosystems will be able to recover before suffering the next setback.

So, while all of our national headline environmental indicators suggest signs of general recovery, not everything is easily summarised or understood. The full consequences of the damage done to the Great Barrier Reef, tropical mangrove forests and Tasmania’s wilderness may take several years to become clear.

Worryingly, the factors that drove them into decline are likely to become stronger in future. Add to that the record heatwaves this year, and it becomes clear that climate change will not just quietly disappear.

Albert Van Dijk, Professor of Water Science and Management, Fenner School of Environment & Society, Australian National University and David Summers, Research academic, Fenner School of Environment & Society, Australian National University

This article was originally published on The Conversation. Read the original article.

2016 crowned hottest year on record: Australia needs to get heat smart


Liz Hanna, Australian National University; Kathryn Bowen, Australian National University, and Mark Howden, Australian National University

It’s official, 2016 set another record for being the world’s hottest. Three international agencies have confirmed today that last year was the hottest on record.

NASA reported that 2016 was 0.99℃ hotter than the 20th-century average, while the US National Oceanographic and Atmospheric Administration (NOAA) called it at 0.94℃. NOAA also calculated that global land temperatures were 1.43℃ higher. The UK Met Office, using its own data, also reported that 2016 is one of the two hottest years on record.

The figures vary slightly, depending on the baseline reference period used.

Heat records don’t linger for long any more. 2016 surpassed the 2015 record, which surpassed the 2014 record. Three record hot years in a row sets yet another record in the 137-year history of modern accurate and standardised meteorological observation.

For Australia, the Bureau of Meteorology described 2016 as a “year of extreme events” and the fourth hottest at 0.87℃ above the 1961-1990 average. The warming trend is clear.

Australia is already on average 8℃ hotter than the average global land temperature, so further warming means our heat risk is far greater than for other industrialised countries.

This dangerous warming trend sends a dire warning, as average warming delivers many more extreme heat events, as we’re currently seeing in Queensland and New South Wales. These are the killers.

As Australia lurches from heatwave to heatwave, the message is clear: extreme heat is the new norm – so Australia needs to get “heat smart”.

Rising extremes

In Australia the number of days per year over 35℃ has increased and extreme temperatures have increased on average at 7% per decade.

Very warm monthly maximum temperatures used to occur around 2% of the time during the period 1951–1980. During 2001–2015, these happened more than 11% of the time.

This trajectory of increased temperature extremes raises questions of how much heat can humans tolerate and still go about their daily business of commuting, managing domestic chores, working and keeping fit.

We can’t just get used to the heat

Air-conditioning and acclimatisation are not the answer. Acclimatisation to heat has an upper limit, beyond which humans need to rest or risk overheating and potential death. And air-conditioning, if not powered by renewable electricity, increases greenhouse gas emissions, feeding into further climate changes.

We have two key tasks ahead. The first is to stop the warming by drastically reducing emissions – the 2015 Paris Agreement was a step along this path. Several studies have shown that Australia can achieve net zero emissions by 2050 and live within its recommended carbon budget, using technologies that exist today, while maintaining economic prosperity.

Our second task is to adapt to the trajectory of increasing frequency of dangerous heat events.

A heat-smart nation

We can prevent heat-related deaths and illnesses through public health mechanisms. Australia enjoys a strong international track record of world-leading public health prevention strategies, such as our campaign against smoking.

We can equally embrace the heat challenge, by adopting initiatives such as a National Climate, Health and Wellbeing Strategy, which has the support of Australia’s health sector. Its recommendations outline a pathway to becoming a heat-smart nation.

At a recent heat-health summit in Melbourne, experts declared Australia must adopt four key public health actions to reduce heatwave deaths.

These are:

• Prevent

• Prepare

• Respond

• Educate.

These fundamental public health strategies are interlinked and operate at the government, health sector, industry and community levels.

Prevention includes reducing greenhouse gas emissions, as well as reducing exposure. The Bureau of Meteorology provides superb heat warnings that allow us to prepare. Global organisations such as the Intergovernmental Panel on Climate Change (IPCC) provide reports that can underpin greater understanding.

The next challenge is for the populace broadly to act on that knowledge. This requires having options to protect ourselves and avoid hazardous heat exposures while commuting, working and at home.

The health sector must also prepare for demand surges. Tragic outcomes will become increasingly common when, for example, ambulance services cannot meet rising demand from a combination of population growth, urbanisation and forecast heat events.

The health sector will need the capacity to mobilise extra resources, and a workforce trained in identifying and managing heat illness. Such training remains limited.

Individuals and workplaces also need to prepare for heatwaves. In a heat-smart nation, we’ll need to reschedule tasks to avoid or limit exposure, including rest periods, and to ensure adequate hydration with cool fluids.

We’ll need to think about housing. Building houses without eaves or space for trees to provide shade forces residents to rely on air-conditioning. In such houses, power failures expose residents to unnecessary heat risks, and many air-con systems struggle when temperatures exceed 40℃.

Urban planners and architects have solutions. There are many options for safe housing design, and the government should consider supporting such schemes.

We’ll need to think about our own health. Active transport, such as walking and cycling, both reduces emissions and improves fitness. Promoting active transport throughout summer requires the provision of shade, rest zones with seats, and watering stations along commuting routes. High cardio-respiratory fitness also boosts heat resilience: a win-win.

Ultimately, Australia has two options: ignore the risks of increasing heat extremes and suffer the consequences, or step up to the challenge and become a heat-smart nation.


This article was co-authored by Clare de Castella Mackay, ANU.

The Conversation

Liz Hanna, Honorary Senior Fellow, Australian National University; Kathryn Bowen, Senior Research Fellow, Australian National University, and Mark Howden, Director, Climate Change Institute, Australian National University

This article was originally published on The Conversation. Read the original article.

Australia’s climate in 2016 – a year of two halves as El Niño unwound


Blair Trewin, Australian Bureau of Meteorology

For Australia’s climate, 2016 was a year of two halves. The year started with one of the strongest El Niño events on record in place in the Pacific Ocean, and the opening months of 2016 were generally hot and dry, especially in northern and eastern Australia.

From May onwards there was a dramatic change in the pattern, with heavy rain and flooding a regular feature of the middle months of the year.

Overall temperatures were the fourth warmest on record in 2016, capping off Australia’s hottest decade. We track these events and more in the Bureau of Meteorology’s annual climate summary released today.

Dry to start

At the start of 2016, many parts of Australia were significantly affected by drought. Long-term drought had existed since 2012 through much of inland Queensland and adjacent northern areas of New South Wales, while shorter-term drought affected Tasmania, central and western Victoria, and parts of South Australia.

While some rain fell between January and April in these areas, it was generally not enough to have much impact on the rainfall deficiencies. Tasmania was hit especially hard, with low water storages restricting hydroelectric production, and long-lived and extensive bushfires in central and western parts of the state a feature of the summer period.

January to April, normally the wettest time of the year across Australia’s far north, was also much drier than normal with rainfall well below average in the Kimberley, the Northern Territory Top End, and on Cape York Peninsula.

It was the least active Australian tropical cyclone season since comprehensive satellite records began in 1970, with only three cyclones in the region, none of them severe, and only one of which made landfall.

The rains are here

Widespread heavy rains began in May – something well predicted by seasonal forecast models – as the El Niño ended and conditions in the Indian Ocean became very favourable for Australian rainfall, with unusually warm waters between Western Australia and Indonesia. Each month from May to September was wetter than average across most of the continent, with heavy rains extending into areas such as inland Queensland where the winter is normally the driest time of the year.

The wet conditions culminated in September, when nationally averaged rainfall was nearly three times the average. It was the wettest September on record for New South Wales and the Northern Territory, and in the top four wettest for every state except Western Australia and Tasmania.

May to September was the wettest on record over Australia, with some locations in inland New South Wales breaking previous records for the period by nearly 200 millimetres. Rainfall returned to more normal levels in eastern mainland Australia from October onwards, although Tasmania remained wet, and a tropical low brought widespread heavy rains extending from the Kimberley south through central Australia as far south as South Australia and Victoria in the year’s final days.

Despite flood damage in places and some rain-affected harvests, the wet conditions were generally positive for agriculture. They also led to large increases in water storage levels in many areas, especially in the Murray-Darling Basin and in Tasmania.

Flooding and storms were also a feature of this period. In early June, an East Coast Low affected almost the whole east coast from southern Queensland southwards.

Northern Tasmania saw some of its most severe flooding on record, and the Sydney region suffered significant coastal erosion with some property damage. The heavy September rains led to major flooding on several inland rivers, particularly the Lachlan River in central New South Wales, and went on to produce the highest flood since the early 1990s on the Murray River in South Australia as the waters moved downstream.

An intense low-pressure system in South Australia at the end of September caused major wind and flood damage there. In Tasmania, which had further flooding in November, the seven months from May to November were the wettest on record, after the seven months from October 2015 to April 2016 had been the driest on record.

Over Australia as a whole, it was the 17th wettest year on record with rainfall 17% above the long-term average. Tasmania had its second-wettest year on record, despite the dry start, and South Australia its fourth-wettest. Below-average rainfalls in 2016 were largely confined to parts of the northern tropics, coastal areas of southern Queensland and northern New South Wales, and some parts of coastal Western Australia. Heavy rains in the year’s final week were enough to lift Adelaide to its second-wettest year on record, while Uraidla, in the Adelaide Hills, had the largest annual rainfall total at any South Australian site since 1917.

The heat is on

It was the fourth-warmest year on record for Australia, with temperatures 0.87℃ above average nationally, 0.33℃ short of the record set in 2013.

The year got off to a very warm start; it was the warmest autumn on record for Australia, and the first half of the year was also the warmest on record, although there were no individual heatwaves on the scale of those experienced in 2013 or 2014.

The second half of the year was less warm. During the wet months in mid-year, heavy cloud cover led to cool days but warm nights, then a cool October resulted in spring temperatures almost exactly matching the long-term average. A warm start and cooler finish is typical of a post-El Niño year as rainfall typically changes from below to above average.

It was the warmest year on record in many parts of the northern tropics, along much of the east coast, and in parts of Tasmania. Darwin, Brisbane, Sydney and Hobart all had their warmest year on record. The warmth on land in these coastal areas was matched by warmth in the oceans.

Sea surface temperatures in the Australian region were the warmest on record, with the first half of the year especially warm. The record warm waters contributed to extensive coral bleaching on the Great Barrier Reef, and also affected fisheries in Tasmania.

Temperatures were closer to average in other parts of the country, including inland areas of the eastern states, South Australia and most of Western Australia. In a few parts of southern Western Australia, which had its coldest winter since 1990, temperatures in 2016 were slightly below average (one of only a handful of land areas in the world where this was the case), and there was some frost damage to crops in what was otherwise a very productive year for Australia’s grain-growers.

2016 continues a sequence of years with Australian temperatures well above average. While 2016 did not set a record, the last four years all rank in Australia’s six warmest, and the last ten years have been Australia’s warmest on record. 2016 is also almost certain to be the hottest year on record globally.

The Conversation

Blair Trewin, Climate scientist, Australian Bureau of Meteorology

This article was originally published on The Conversation. Read the original article.