In relation to this article responding to Climate Council CEO Amanda McKenzie’s claim that heatwaves are “worsening” and “hot days” have doubled in Australia in the last 50 years, a spokesperson for the Climate Council gave the following responses. Questions from The Conversation are in bold.
Could you please provide a source, or sources, to support Ms McKenzie’s statement that heatwaves are “worsening” and hot days have doubled in the last 50 years?
Specifically, there has been an increase of 0.2 days/year since 1957 which means, on average, that there are almost 12 more days per year over 35°C.
What did Ms McKenzie mean by the terms “heatwaves” and “hot days”?
Hot days – the number of hot days, defined as days with maximum temperatures greater than 35°C.
Heatwaves – three days or more of high maximum and minimum temperatures that is unusual for that location.
Furthermore, heatwaves have several significant characteristics. These include (i) frequency characteristics, such as the number of heatwave days and the annual number of summer heatwave events; (ii) duration characteristics, such as the length of the longest heatwave in a season; (iii) intensity characteristics, such as the average excess temperature expected during a heatwave and the hottest day of a heatwave; and (iv) timing characteristics, including the occurrence of the first heatwave event in a season.
Is there any other comment you would like us to include in the article?
Climate change – driven largely by rising atmospheric carbon dioxide concentrations from the burning of coal, oil and gas – is increasing temperatures and cranking up the intensity of extreme weather events globally and in Australia.
Temperature records tumbled yet again during Australia’s ‘Angry Summer’ of 2016/17. In just 90 days, more than 205 records were broken around Australia.
Heatwaves and hot days scorched the major population centres of Adelaide, Brisbane, Canberra, Melbourne and Sydney, as well as the rural and regional heartlands of eastern Australia. The most severe heatwave of this Angry Summer began around January 31 and continued until February 12, with the highest temperatures recorded from February 9-12.
This heatwave was made twice as likely to occur because of climate change, while the extreme heat in New South Wales over the entire summer season was at least 50 times as likely to occur because of climate change.
The severe heatwave of February 2017 that spread across much of Australia’s south, east and interior caused issues for the South Australian and New South Wales energy systems. In New South Wales around 3,000MW of coal and gas capacity was not available when needed in the heatwave (roughly the equivalent of two Hazelwood Power Stations).
In South Australia, 40,000 people were left without power for about half an hour in the early evening while temperatures were over 40°C. This heatwave highlights the vulnerability of our energy systems to extreme weather.
In Australia, the most commonly used definition (and the one used by the Climate Council) is from the Bureau of Meteorology (BOM). It provided the first national definition of a heatwave in January 2014, describing it as:
A period of at least three days where the combined effect of excess heat and heat stress is unusual with respect to the local climate. Both maximum and minimum temperatures are used in this assessment.
The BOM uses a metric called the “excess heat factor” to decide what heat is “unusual”. It combines the average temperature over three days with the average temperature for a given location and time of year; and how the three day average temperature compares to temperatures over the last 30 days.
Researchers, including Australian climate scientist Dr Sarah Perkins-Kirkpatrick, are trying to standardise the definitions of “heatwaves” and “hot days” and create a framework that allows for more in-depth studies of these events.
Are heatwaves ‘worsening’?
There’s not a large body of research against which to test this claim. But the research we do have suggests there has been an observable increase in the frequency and intensity of heatwaves in Australia. Research published in 2013 found a trend towards more heat waves in Australia between 1951 and 2008.
A review paper published in 2016 assessed evidence from multiple studies and found that heatwaves are becoming more intense and more frequent for the majority of Australia.
The following chart shows heatwave days per decade from 1950 to 2013, highlighting a trend toward more heatwave days in Australia over time:
Have hot days ‘doubled’ in the last 50 years?
While the number of “hot days” (as defined by the BOM) has not doubled over the last 50 years, as McKenzie said, the number of “record hot days” certainly has. “Record hot days” are days when the maximum temperature sets a new record high.
Given that McKenzie made her statement on a fast paced live TV show, it’s reasonable to assume she was referring to the latter. Let’s look at both figures.
The BOM defines “hot days” as days with a maximum temperature higher than 35°C. The BOM data show there were more hot days in Australia in 2013, 2014, 2015 and 2016 than in any of the 50 years from 1966 to 2016 (the last year for which data are available).
In fact, there were more hot days in the years 2013-2016 than in any other year as far back as 1910. If we compare the decades 1966-76 and 2006-16, we see a 27% increase in the number of hot days.
The Bureau of Meteorology has issued its seasonal forecast for the winter, and it should be a warm one throughout southern Australia and the very tips of the Top End.
After a warm autumn, particularly in the east, this winter is forecast to be warmer and drier than usual – especially over the southern half of the continent.
Not your everyday weather forecast
Seasonal forecasts are very different from your standard weather forecast for the day or week ahead.
Instead of giving exact temperatures or rainfall totals, the bureau provides probabilities of above or below average conditions. So if the bureau says there’s a 70% chance of above-average temperatures, that’s the same as saying there’s a 30% chance it will be below average.
These probabilities are estimated by looking at what’s going on in the Pacific and Indian Oceans, as they strongly influence Australia’s weather, and by running a set, or “ensemble”, of forecasts through the bureau’s seasonal forecast model.
A very different winter from last year
Looking back to last year, while most of Australia experienced quite a warm winter, it was also very wet. Nationally, it was the second-wettest winter on record, with the centre and the east of the continent copping the brunt of the rain. Last winter’s weather was driven by very warm seas in the east Indian Ocean, which meant a lot more moisture was available to deliver rainfall across the country.
This year we are seeing roughly average temperatures in the Indian Ocean, and a slight El Niño in the Pacific. This increases the likelihood of warmer, drier weather for the winter as a whole.
Winter heatwaves on the way
So can we expect to keep the thick coats in the wardrobe and enjoy some winter warmth? Perhaps.
Of course, winter heatwaves aren’t going to bring 40℃ days to Melbourne and Sydney, but we could get warm spells and temperatures into the low twenties in Sydney or the high teens in Melbourne.
It’s also worth noting that the seasonal forecast only looks at whether we’re going to have temperatures above or below average. It’s harder to predict whether we will see bursts of heat, or if the weather will consistently be a little bit warmer than normal through much of the season.
We’ve seen an increase in heatwaves in late autumn and winter in Australia over the past few decades. Notably, in May 2014 Sydney and large areas of southeast Australia had much-warmer-than-average conditions. A study found that this heat event was made at least 20 times more likely by the human influence on the climate.
We’re also seeing trends towards less frequent cold conditions in winter, with frosts becoming much rarer over a substantial part of Australia. Most of Australia is also experiencing fewer cold days. These trends are in line with what we expect from climate change, and are projected to continue.
While winter warmth can be pleasant for most of us, it can also cause plenty of problems. Warmer and drier winters can worsen drought – an effect we saw during the Millennium Drought in southeast Australia – by increasing evaporation and reducing soil moisture.
So while many of us in the south will gladly welcome a warm winter, it’s not good news for everyone. If warm and dry conditions were to persist into spring and summer – which is a distinct possibility with an El Niño watch in place – that would pose even more problems in terms of bushfire prevention, among other hazards.
While it may not lead directly to impassioned critiques of climate governance, nor immediately sort the sceptics from the believers, talk of brewing storms or dried-up reservoirs now carries with it a whiff of trepidation about our collective forecasts.
Bridging the divide
Despite the growing politicisation of weather talk, weather and climate are usually understood as empirically distinct bodies of knowledge. Climate is, to quote British comedy duo Armstrong and Miller, “a long-term trend averaged over many years”, as opposed to weather, “which is what’s going on outside the window right now”.
The problem with this distinction is that climate change’s global reach and extended time scale can make it seem like it is happening somewhere else and to someone else (or, indeed, not at all). So perhaps the distinction is not useful for the cultural processes of adaptation. What might happen if we were to breach official definitions and disciplinary lines and think of the two things together?
Closing the distance between weather as event and climate as pattern can accomplish several things. Most obviously, it reminds us that there is a relationship between the two. Without weather, there would be nothing to amalgamate as climate.
While one heatwave does not equate to “climate change”, many and increasing ones give us pause to wonder. Leslie Hughes and Will Steffen are doing the data-driven work in this regard.
In other words, bringing climate and weather together can remind us that climate change is not only about abstract calculations on scales too big for our small and ultimately short-lived human forms to fathom.
Thinking about weather as part of climate underscores that we experience climate change with and on our bodies; climate change is lived by us at a very human scale, too.
The daily experience of weathering
So, what would it mean to harness the daily, mundane intrusions of weather as political? In contrast to terms like resilience (complicit with neoliberal incitements of bootstrapping) or sustainability (which suggests we get to keep something intact), weathering invites us to consider what we will lose along the way.
Weathered bodies, weathered houses, weathered cars, weathered clothes, weathered relationships, weathered dreams – these all bear scars of what has worn them down, and of what they have been asked to carry, to survive, and to hack.
Bringing this sense of lived climate change to our everyday perception is neither an easy nor comfortable thing. For one, discomfort is not a place we generally like to dwell for long. In a more political sense, though, paying attention to the weather as something in which we are intimately implicated, not just a disconnected backdrop to our human dramas, reminds us we are weather-makers too.
On a stable planet, nature provided a background against which the human drama took place; on the unstable planet we’re creating, the background becomes the highest drama.
This could be the epigraph for the Anthropocene.
Even in wealthy, climate-controlled places, weather inserts a reminder of one’s privilege, or luck, or vulnerability, or hardship, into those once mundane spaces. We may bemoan the slipping away of vacuous weather chats — “does everything have to be political?” — but perhaps noticing the weather can become an opening for everyday engagement in the politics of climate change instead.
In gender and cultural studies and the environmental humanities, rather than trying to leave weather-talk pregnant with fear, anticipation or political outrage, we are explicitly thinking with and through the weather to develop strategies for a rigorous and political response to climate change.
One way we are doing this is through a tactic or practice we call “weathering” – that is, cultivating attunement to how our own bodies, and bodies of others, experience weather. This includes how we and they manage it architecturally, technologically, professionally and socially.
We don’t all weather equally
Through the concept of “weathering”, our work forces a confrontation between large-scale climate data and embodied sociopolitical experiences that are too often treated as separate. It also underscores the politics and activism we hope this tactic can engender.
Such attentive acclimatisation reveals that, even though we’re all in the same planetary boat when it comes to global warming, we’re not all in it in the same way. This is something ecofeminists and environmental justice scholars have long known. Our work helps articulate how difference also marks our apparently banal encounters with the weather.
At a “Hacking the Anthropocence” symposium in Sydney this month, scholars, artists and activists are responding to the idea of “weathering”. The variety of experience that such a provocation reveals is astounding.
For Anne Werner’s and Genevieve Derwent’s work growing chickens on Autumn Farm and Cameron Muir’s reflections on life jackets for refugees, the weather holds a very different significance and function. Climate change is undoubtedly political – but all the more so because of these uneven individual and collective experiences of the weather.
Other kinds of bodily, socioeconomic, historical and geopolitical differences further complicate how we weather the world. When it comes to rising sea levels, or dried-up water holes, for example, racism, colonialism and gendered labour are all significant. Weathering as a concept thus asks us to think about what else, besides meteorological phenomena, one might be asked to weather.
Note that a more common meaning of “weathering” is as synonym for withstanding or enduring. Not only will different regions weather differently in a changing climate (drier, hotter in central Australia; more flooding on the US Atlantic coast; disappearing land in Pacific Islands), but people within those regions weather differently too.
Our human experiences of weather are linked to how the non-human world is weathering what we have forced it to carry. Artist Victoria Hunt will ask us to imagine with her “The Cry of Water”, while archaeologist Denis Byrne will explore the significance of seawalls, which are weathered by erosion. Human and non-human worlds weather together in a fraught and desirous intimacy.
The animal world is also constantly weathering. We know about catastrophic events such as the endangered bats that cannot cope with heat above 42℃. We’ve learned that the Great Barrier Reef is bleaching as water temperatures rise.
But what about the less-well-known water-holding frog or, indeed, ants and brine shrimp? How do they weather? At our symposium, Rebecca Giggs, Kate Wright and Emily O’Gorman (respectively) will let us know how, and suggest what we humans might learn about weathering the world differently.
These contributions invite us to explore how our experiences of the weather are highly mediated by a range of social, political and cultural forces. Anthropologist of institutions Tess Lea will investigate how bureaucracy (materialised as mountains of paperwork) orients different populations’ capacity to weather. Cli-fi expert and petrocultures scholar Stephanie LeMenager invites us to speculate on what a new kind of civic engagement might look like in this context.
Weathering directly connects human social, cultural and economic structures such as racism, colonialism and gender oppression to climate change. It insists that we think about global warming on a massive scale as always textured by acute experiences of social phenomena.
We recognise that the weight of a changing climate will not be borne equally by bodies – across geographies, economic status, or species.
So next time you curse a forgotten umbrella as the skies open up, or welcome the sun shining on your kid’s birthday party in the park, remember that when it comes to the weather, the personal is getting more and more political.
Hacking the Anthropocene II: Weathering (May 25-31) is supported by the Sydney Social Sciences and Humanities Advanced Research Centre (SSSHARC); the Australian Research Council Centre of Excellence for the History of Emotions; the Sydney Environment Institute at the University of Sydney; the Planetary Health Initiative at the University of Sydney; and the Seed Box: a MISTRA-FORMAS Environmental Humanities Collaboratory (hosted at Linkoping University, Sweden).
One of the worst instances of mangrove forest dieback ever recorded globally struck Australia’s Gulf of Carpentaria in the summer of 2015-16. A combination of extreme temperatures, drought and lowered sea levels likely caused this dieback, according to our investigation published in the journal Marine and Freshwater Research.
The dieback, which coincided with the Great Barrier Reef’s worst ever bleaching event, affected 1,000km of coastline between the Roper River in the Northern Territory and Karumba in Queensland.
About 7,400 hectares, or 6%, of the gulf’s mangrove forest had died. Losses were most severe in the NT, where around 5,500ha of mangroves suffered dieback. Some of the gulf’s many catchments, such as the Robinson and McArthur rivers, lost up to 26% of their mangroves.
The gulf, a remote but valuable place
The Gulf of Carpentaria is a continuous sweep of wide tidal wetlands fringed by mangroves, meandering estuaries, creeks and beaches. Its size and naturalness makes it globally exceptional.
An apron of broad mudflats and seagrass meadows supports thousands of marine turtles and dugongs. A thriving fishing industry worth at least A$30 million ultimately depends on mangroves.
Mangroves and saltmarsh plants are uniquely adapted to extreme and fickle coastal shoreline ecosystems. They normally cope with salt and daily inundation, having evolved specialised physiological and morphological traits, such as salt excretion and unique breathing roots.
But in early 2016, local tour operators and consultants doing bird surveys alerted authorities to mangroves dying en masse along entire shorelines. They reported skeletonised mangroves over several hundred kilometres, with the trees appearing to have died simultaneously. They sent photos and even tracked down satellite images to confirm their concerns. The NT government supported the first investigative surveys in June 2016.
In the end, the emails from citizen scientists nailed the timing: “looks like it started maybe December 2015”; the severity: “I’ve seen dieback before, but not like this”; and the cause: “guessing it may be the consequence of the four-year drought”.
Our investigation used satellite imagery dating back to 1972 to confirm that the dieback was an unparalleled event. Further aerial helicopter surveys and mapping during 2016, after the dieback, validated the severity of the event extending across the entire gulf. Mangrove dieback has been recorded in Australia in the past but over decades, not months.
Mysterious patterns in the dieback
We still don’t fully understand what caused the dieback. But we can rule out the usual suspects of chemical or oil spills, or severe storm events. It was also significant that losses occurred simultaneously across a 1,000km front.
There were also a number of tell-tale patterns in the dieback. The worst-impacted locations had more or less complete loss of shoreline-fringing mangroves. This mirrored a general loss of mangroves fringing tidal saltpans and saltmarshes along this semi-arid coast.
Mangroves were unaffected where they kept their feet wet along estuaries and rivers. This, as well as the timing and severity of the event, points to a connection with extreme weather and climate patterns, and particularly the month-long drop of 20cm in local sea levels.
Extreme weather the likely culprit
We believe the dieback is best explained by drought, hot water, hot air and the temporary drop in sea level. Each of these was correlated with the strong 2015-16 El Niño. Let’s take a look at each in turn.
First, the dieback happened at the end of an unusually long period of severe drought conditions, which prevailed for much of 2015 following four years of below-average rainfall. This caused severe moisture stress in mangroves growing alongside saltmarsh and saltpans.
Second, the dieback coincided with hot sea temperatures that also caused coral bleaching along the Great Barrier Reef. While mangroves are known to be relatively heat-tolerant, they have their limits.
The air temperatures recorded at the time of the mangrove dieback, particularly from February to September 2015, were also exceptionally high.
Third, the sea level dropped by up to 20cm at the time of the dieback when the mangroves were both heat- and moisture-stressed. Sea levels commonly drop in the western Pacific (and rise in the eastern Pacific) during strong El Niño years: and the 2015-2016 El Niño was the third-strongest recorded.
The mangroves appear to have died of thirst. Mangroves may be hardy plants, but when sea levels drop, reducing inundation, coupled with already heat-and-drought-stressed weather conditions, then the plants will die – much like your neglected pot plants.
We don’t yet know what role human-caused climate change played in these particular weather events or El Niño. But the unprecedented extent of the dieback, the confluence of extreme climate events and the coincidence with the bleaching of the Great Barrier Reef mean the role of climate change will be of critical interest in the global response to mangrove decline.
What future for mangroves?
The future for mangroves around the world is mixed. Thanks to climate change, droughts are expected to become hotter and more frequent. If the gulf’s mangroves experience further dieback in the future, this will have serious implications for Australia’s northern fisheries including the iconic prawn fishery, mudcrab and fin fish fisheries. All species are closely associated with healthy mangroves.
We don’t know whether the mangroves will recover or not. But there is now a further risk of shoreline erosion and retreat, particularly if the region is struck by a cyclone – and this may have already begun with recent cyclonic weather and flooding in the gulf. The movement of mangrove sediments will lead to massive releases of carbon uniquely buried among their roots.