Tropical thunderstorms are set to grow stronger as the world warms



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A supercell thunderstorm in the US state of Oklahoma.
Hamish Ramsay, Author provided

Martin Singh, Monash University

Thunderstorms are set to become more intense throughout the tropics and subtropics this century as a result of climate change, according to new research.

Thunderstorms are among nature’s most spectacular phenomena, producing lightning, heavy rainfall, and sometimes awe-inspiring cloud formations. But they also have a range of important impacts on humans and ecosystems.

For instance, lightning produced by thunderstorms is an important trigger for bushfires globally, while the hailstorm that hit Sydney in April 1999 remains Australia’s costliest ever natural disaster.


Read more: To understand how storms batter Australia, we need a fresh deluge of data


Given the damage caused by thunderstorms in Australia and around the world, it is important to ask whether they will grow in frequency and intensity as the planet warms.

Our main tools for answering such questions are global climate models – mathematical descriptions of the Earth system that attempt to account for the important physical processes governing the climate. But global climate models are not fine-scaled enough to simulate individual thunderstorms, which are typically only a few kilometres across.

But the models can tell us about the ingredients that increase or decrease the power of thunderstorms.

Brewing up a storm

Thunderstorms represent the dramatic release of energy stored in the atmosphere. One measure of this stored energy is called “convective available potential energy”, or CAPE. The higher the CAPE, the more energy is available to power updrafts in clouds. Fast updrafts move ice particles in the cold, upper regions of a thunderstorm rapidly upward and downward through the storm. This helps to separate negatively and positively charged particles in the cloud and eventually leads to lightning strikes.

To create thunderstorms that cause damaging wind or hail, often referred to as severe thunderstorms, a second factor is also required. This is called “vertical wind shear”, and it is a measure of the changes in wind speed and direction as you rise through the atmosphere. Vertical wind shear helps to organise thunderstorms so that their updrafts and downdrafts become physically separated. This prevents the downdraft from cutting off the energy source of the thunderstorm, allowing the storm to persist for longer.

By estimating the effect of climate change on these environmental properties, we can estimate the likely effects of climate change on severe thunderstorms.

Stormy forecast

My research, carried out with US colleagues and published today in Proceedings of the National Academy of Sciences, does just that. We examined changes in the energy available to thunderstorms across the tropics and subtropics in 12 global climate models under a “business as usual” scenario for greenhouse gas emissions.

In every model, days with high values of CAPE grew more frequent, and CAPE values rose in response to global warming. This was the case for almost every region of the tropics and subtropics.

These simulations predict that this century will bring a marked increase in the frequency of conditions that favour severe thunderstorms, unless greenhouse emissions can be significantly reduced.

Change in frequency (in days per year) of favourable conditions for severe thunderstorms for 2081-2100, compared with 1981-2000 averaged across 12 climate models under the RCP8.5 greenhouse-gas concentration scenario. Stippling indicates regions where 11 of the 12 models agree on the sign of the change.
CREDIT, Author provided

Previous studies have made similar predictions for severe thunderstorms in eastern Australia and the United States. But ours is the first to study the tropics and subtropics as a whole, a region that is characterised by some of the most powerful thunderstorms on Earth.

What drives the increased energy?

Different climate models, constructed by different research groups around the world, all agree that global warming will increase the energy available to thunderstorms – a prediction underlined by our new research. But we need to understand why this happens, so as to be sure that the effect is real and not a product of faulty model assumptions.

My colleagues and I previously proposed that high levels of CAPE can develop in the tropics as a result of the turbulent mixing that occurs when clouds draw in air from their surroundings. This mixing prevents the atmosphere from dissipating the available energy too quickly. Instead, the energy builds up for longer and is released in less frequent but more intense storms.

As the climate warms, the amount of water vapour required for cloud formation increases. This is the result of a well-known thermodynamic relationship called the Clausius-Clapeyron relation. In a warmer climate this means the difference in the humidity between the clouds and their surroundings becomes larger. As a result, the mixing mechanism becomes more efficient in building up the available energy. This, we argue, accounts for the increase in CAPE seen in our model simulations.

In our new study, we tested this idea in a global climate model by artificially increasing the strength of the mixing between clouds and their surroundings. As expected, this change produced a large increase in the energy available to thunderstorms in our model.


Read more: Australia faces a stormier future thanks to climate change


Another prediction of our hypothesis is that days with both high values of CAPE and heavy precipitation tend to occur when the atmosphere is least humid in its middle levels (at altitudes of a few kilometres). Using real data from weather balloons, we confirmed that this is the case across the tropics and subtropics.

What this means for future thunderstorms

The models predict that the energy available for thunderstorms will increase as the Earth warms. But how much more intense will storms actually become as a result?

The answer to that question is currently uncertain, and answering it is the next job for me, and other researchers around the world.

The ConversationBut it is clear that through our continued greenhouse gas emissions, we are increasing the fuel available to the strongest thunderstorms. Exactly how much stronger our future thunderstorms will ultimately become remains to be seen.

Martin Singh, Lecturer, School of Earth, Atmosphere and Environment, Monash University

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

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How TV weather presenters can improve public understanding of climate change



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David Holmes, Monash University

A recent Monash University study of TV weather presenters has found a strong interest from free-to-air presenters in including climate change information in their bulletins.

The strongest trends in the survey, which had a 46% response rate, included:

  • 97% of respondents thought climate change is happening;

  • 97% of respondents believed viewers had either “strong trust” or “moderate trust” in them as a reliable source of weather information;

  • 91% of respondents were comfortable with presenting local historical climate statistics, and just under 70% were comfortable with future local climate projections; and

  • 97% of respondents thought their audiences would be interested in learning about the impacts of climate change.

According to several analyses of where Australians get their news, in the age of ubiquitous social media TV is still the single largest news source.

And when one considers that social media and now apps are increasingly used as the interface for sharing professional content from news organisations – which includes TV news – the reach of TV content is not about to be challenged anytime soon.

The combined audience for primetime free-to-air TV in the five capital city markets alone is a weekly average of nearly 3 million viewers. This does not include those using catch-up on portable devices, and those watching the same news within the pay TV audience. And there are those who are getting many of the same news highlights and clips through their Facebook feeds and app-based push media.

Yet the ever-more oligopolistic TV industry in Australia is very small. And professional weather presenters are a rather exclusive group: there are only 75 such presenters in Australia.

It is because of this, rather than in spite of it, that weather presenters are able to command quite a large following. And they are highly promoted by the networks themselves – on freeway billboards and station advertising. This promotion makes weather presenters among the most trusted media personalities, while simultaneously presenting information that is regarded as apolitical.

At the same time, Australians have a keen interest in talking about weather. It tends to unite us.

These three factors – trust, the impartial nature of weather, and Australian’s enthusiasm for the weather – puts TV presenters in an ideal position to present climate information. Such has been the experience in the US, where the Centre for Climate Change Communication together with Climate Matters have partnered with more than 350 TV weathercasters to present simple, easy-to-process factual climate information.

In the US it is about mainstreaming climate information as factual content delivered by trusted sources. The Climate Matters program found TV audiences value climate information the more locally based it was.

Monash’s Climate Change Communication Research Hub is conducting research as a precondition to establishing such a program in Australia. The next step is to survey the audiences of the free-to-air TV markets in the capital city markets to evaluate Australians’ appetite for creating a short climate segment alongside the weather on at least a weekly basis.

As in the US, TV audiences are noticing more and more extreme weather and want to understand what is causing it, and what to expect in the future.

The Climate Change Communication Research Hub is also involved in creating “climate communications packages” that can be tested with audiences. These are largely based on calendar and anniversary dates, and show long-term trends using these dates as datapoints.

The calendar dates could be sporting dates, or how climate can be understood in relation to a collection of years based on a specific date, or the start of a season for fire or cyclones. There has been so much extreme weather in recent years that there are plenty of anniversaries.

Let’s take November 21, 2016 – the most severe thunderstorm asthma event ever to impact Melbourne. It saw 8,500 presentations to hospital emergency departments and nine tragic deaths.

There is no reason why this event can’t be covered this year in the context of climate as a community service message. As explained in the US program, just a small increase in higher average spring temperatures leads to the production of a higher count of more potent pollen. Also, as more energy is fed into the destructive power of storm systems, the prospect of breaking up pollen and distributing it efficiently throughout population centres is heightened.

The need to be better prepared for thunderstorms in spring is thus greater, even for those who have never had asthma before.

For its data, the Climate Change Communication Research Hub will be relying on the information from the Bureau of Meteorology and the CSIRO, but will call on the assistance of a wide range of organisations such as the SES, state fire services, and health authorities in conducting its research.

In February 2018, the hub will hold a workshop with TV weather presenters as part of the Australian Meteorological and Oceanographic Society conference. At the conference the planning for the project will be introduced, with a pilot to be conducted on one media market to be rolled out to multiple markets in the second year.

The ConversationThe program is not intended to raise the level of concern about climate change, but public understanding of it. As survey after survey shows, Australians are already concerned about climate change. But more information is needed about local and regional impacts that will help people make informed choices about mitigation, adaptation and how to plan their lives – beyond tomorrow’s weather.

David Holmes, Director, Climate Change Communication Research Hub, Monash University

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

Explainer: how does the sea ‘disappear’ when a hurricane passes by?


Darrell Strauss, Griffith University

You may have seen the media images of bays and coastlines along Hurricane Irma’s track, in which the ocean has eerily “disappeared”, leaving locals amazed and wildlife stranded. What exactly was happening?

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These coastlines were experiencing a “negative storm surge” – one in which the storm pushes water away from the land, rather than towards it.


Read more: Irma and Harvey: very different storms, but both affected by climate change


Most people are familiar with the idea that the sea is not at the same level everywhere at the same time. It is an uneven surface, pulled around by gravity, such as the tidal effects of the Moon and Sun. This is why we see tides rise and fall at any given location.

At the same time, Earth’s atmosphere has regions where the air pressure is higher or lower than average, in ever-shifting patterns as weather systems move around. Areas of high atmospheric pressure actually push down on the ocean surface, lowering sea level, while low pressure allows the sea to rise slightly.

This is known as the “inverse barometer effect”. Roughly speaking, a 1 hectopascal change in atmospheric pressure (the global average pressure is 1,010hPa) causes the sea level to move by 1cm.

When a low-pressure system forms over warm tropical oceans under the right conditions, it can intensify to become a tropical depression, then a tropical storm, and ultimately a tropical cyclone – known as a hurricane in the North Atlantic or a typhoon in the northwest Pacific.

As this process unfolds, the atmospheric pressure drops ever lower and wind strength increases, because the pressure difference with surrounding areas causes more air to flow towards the storm.

In the northern hemisphere tropical cyclones rotate anticlockwise and officially become hurricanes once they reach a maximum sustained wind speed of around 120km per hour. If sustained wind speeds reach 178km per hour the storm is classed as a major hurricane.

Surging waters

A “normal” storm surge happens when a tropical cyclone reaches shallow coastal waters. In places where the wind is blowing onshore, water is pushed up against the land. At the same time the cyclone’s incredibly low air pressure allows the water to rise higher than normal. On top of all this, the high waves whipped up by the wind mean that even more water inundates the coast.

The anticlockwise rotation of Atlantic hurricanes means that the storm’s northern side produces winds blowing from the east, and its southern side brings westerly winds. In the case of Hurricane Irma, which tracked almost directly up the Florida panhandle, this meant that as it approached, the east coast of the Florida peninsula experienced easterly onshore winds and suffered a storm surge that caused severe inundation and flooding in areas such as Miami.

The negative surge

In contrast, these same easterly winds had the opposite effect on Florida’s west coast (the Gulf Coast), where water was pushed offshore, leading to a negative storm surge. This was most pronounced in areas such as Fort Myers and Tampa Bay, which normally has a relatively low tide range of less than 1m.

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The negative surge developed over a period of about 12 hours and resulted in a water level up to 1.5m below the predicted low tide level. Combined with the fact that the sea is shallow in these areas anyway, it looked as if the sea had simply disappeared.


Read more: Predicting disaster: better hurricane forecasts buy vital time for residents.


As tropical cyclones rapidly lose energy when moving over land, the unusually low water level was expected to rapidly rise, which prompted authorities to issue a flash flood warning to alert onlookers to the potential danger. The negative surge was replaced by a storm surge of a similar magnitude within about 6 hours at Fort Myers and 12 hours later at Tampa Bay.

The ConversationRising waters are the deadliest aspect of hurricanes – even more than the ferocious winds. So while it may be tempting to explore the uncovered seabed, it’s certainly not wise to be there when the sea comes rushing back.

Darrell Strauss, Senior Research Fellow, Griffith University

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

Australia’s record-breaking winter warmth linked to climate change


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This winter had some extreme low and high temperatures.
Daniel Lee/Flickr, CC BY-NC

Andrew King, University of Melbourne

On the first day of spring, it’s time to take stock of the winter that was. It may have felt cold, but Australia’s winter had the highest average daytime temperatures on record. It was also the driest in 15 years.

Back at the start of winter the Bureau of Meteorology forecast a warm, dry season. That proved accurate, as winter has turned out both warmer and drier than average.


Read more: Australia’s dry June is a sign of what’s to come


While we haven’t seen anything close to the weather extremes experienced in other parts of the world, including devastating rainfalls in Niger, the southern US and the Indian subcontinent all in the past week, we have seen a few interesting weather extremes over the past few months across Australia.

Much of the country had drier conditions than average, especially in the southeast and the west.
Bureau of Meteorology

Drier weather than normal has led to warmer days and cooler nights, resulting in some extreme temperatures. These include night-time lows falling below -10℃ in the Victorian Alps and -8℃ in Canberra (the coldest nights for those locations since 1974 and 1971, respectively), alongside daytime highs of above 32℃ in Coffs Harbour and 30℃ on the Sunshine Coast.

During the early part of the winter the southern part of the country remained dry as record high pressure over the continent kept cold fronts at bay. Since then we’ve seen more wet weather for our southern capitals and some impressive snow totals for the ski fields, even if the snow was late to arrive.

This warm, dry winter is laying the groundwork for dangerous fire conditions in spring and summer. We have already had early-season fires on the east coast and there are likely to be more to come.

Climate change and record warmth

Australia’s average daytime maximum temperatures were the highest on record for this winter, beating the previous record set in 2009 by 0.3℃. This means Australia has set new seasonal highs for maximum temperatures a remarkable ten times so far this century (across summer, autumn, winter and spring). The increased frequency of heat records in Australia has already been linked to climate change.

Winter 2017 stands out as having the warmest average daytime temperatures by a large margin.
Bureau of Meteorology

The record winter warmth is part of a long-term upward trend in Australian winter temperatures. This prompts the question: how much has human-caused climate change altered the likelihood of extremely warm winters in Australia?

I used a standard event attribution methodology to estimate the role of climate change in this event.

I took the same simulations that the Intergovernmental Panel on Climate Change (IPCC) uses in its assessments of the changing climate, and I put them into two sets: one that represents the climate of today (including the effects of greenhouse gas emissions) and one with simulations representing an alternative world that excludes our influences on the climate.

I used 14 climate models in total, giving me hundreds of years in each of my two groups to study Australian winter temperatures. I then compared the likelihood of record warm winter temperatures like 2017 in those different groups. You can find more details of my method here.

I found a stark difference in the chance of record warm winters across Australia between these two sets of model simulations. By my calculations there has been at least a 60-fold increase in the likelihood of a record warm winter that can be attributed to human-caused climate change. The human influence on the climate has increased Australia’s temperatures during the warmest winters by close to 1℃.

More winter warmth to come

Looking ahead, it’s likely we’re going to see more record warm winters, like we’ve seen this year, as the climate continues to warm.

The likelihood of winter warmth like this year is rising. Best estimate chances are shown with the vertical black lines showing the 90% confidence interval.
Author provided

Under the Paris Agreement, the world’s nations are aiming to limit global warming to below 2℃ above pre-industrial levels, with another more ambitious goal of 1.5℃ as well. These targets are designed to prevent the worst potential impacts of climate change. We are currently at around 1℃ of global warming.

Even if global warming is limited to either of these levels, we would see more winter warmth like 2017. In fact, under the 2℃ target, we would likely see these winters occurring in more than 50% of years. The record-setting heat of today would be roughly the average climate of a 2℃ warmed world.

While many people will have enjoyed the unusual winter warmth, it poses risks for the future. Many farmers are struggling with the lack of reliable rainfall, and bad bushfire conditions are forecast for the coming months. More winters like this in the future will not be welcomed by those who have to deal with the consequences.


Climate data provided by the Bureau of Meteorology. For more details about winter 2017, see the Bureau’s Climate Summaries.

The ConversationYou can find more details on the specific methods applied for this analysis here.

Andrew King, Climate Extremes Research Fellow, University of Melbourne

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

Southeast Europe swelters through another heatwave with a human fingerprint



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Searching for respite from the heat in one of Rome’s fountains.
Max Roxxi/Reuters

Andrew King, University of Melbourne

Parts of Europe are having a devastatingly hot summer. Already we’ve seen heat records topple in western Europe in June, and now a heatwave nicknamed “Lucifer” is bringing stifling conditions to areas of southern and eastern Europe.

Several countries are grappling with the effects of this extreme heat, which include wildfires and water restrictions.

Temperatures have soared past 40℃ in parts of Italy, Greece and the Balkans, with the extreme heat spreading north into the Czech Republic and southern Poland.

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Some areas are having their hottest temperatures since 2007 when severe heat also brought dangerous conditions to the southeast of the continent.

The heat is associated with a high pressure system over southeast Europe, while the jet stream guides weather systems over Britain and northern Europe. In 2007 this type of split weather pattern across Europe persisted for weeks, bringing heavy rains and flooding to England with scorching temperatures for Greece and the Balkans.

Europe is a very well-studied region for heatwaves. There are two main reasons for this: first, it has abundant weather observations and this allows us to evaluate our climate models and quantify the effects of climate change with a high degree of confidence. Second, many leading climate science groups are located in Europe and are funded primarily to improve understanding of climate change influences over the region.

The first study to link a specific extreme weather event to climate change examined the record hot European summer of 2003. Since then, multiple studies have assessed the role of human influences in European extreme weather. Broadly speaking, we expect hotter summers and more frequent and intense heatwaves in this part of the world.

We also know that climate change increased deaths in the 2003 heatwaves and that climate change-related deaths are projected to rise in the future.

Climate change’s role in this heatwave

To understand the role of climate change in the latest European heatwave, I looked at changes in the hottest summer days over southeast Europe – a region that incorporates Italy, Greece and the Balkans.

I calculated the frequency of extremely hot summer days in a set of climate model simulations, under four different scenarios: a natural world without human influences, the world of today (with about 1℃ of global warming), a 1.5℃ global warming world, and a 2℃ warmer world. I chose the 1.5℃ and 2℃ benchmarks because they correspond to the targets described in the Paris Agreement.

As the heatwave is ongoing, we don’t yet know exactly how much hotter than average this event will turn out to be. To account for this uncertainty I used multiple thresholds based on historically very hot summer days. These thresholds correspond to an historical 1-in-10-year hottest day, a 1-in-20-year hottest day, and a new record for the region exceeding the observed 2007 value.

While we don’t know exactly where the 2017 event will end up, we do know that it will exceed the 1-in-10 year threshold and it may well breach the higher thresholds too.

A clear human fingerprint

Whatever threshold I used, I found that climate change has greatly increased the likelihood of extremely hot summer days. The chance of extreme hot summer days, like this event, has increased by at least fourfold because of human-caused climate change.

Climate change is increasing the frequency of hot summer days in southeast Europe. Likelihoods of the hottest summer days exceeding the historical 1-in-10 year threshold, one-in-20 year threshold and the current record are shown for four scenarios: a natural world, the current world, a 1.5℃ world, and a 2℃ world. Best estimate likelihoods are shown with 90% confidence intervals in parentheses.
Author provided

My analysis shows that under natural conditions the kind of extreme heat we’re seeing over southeast Europe would be rare. In contrast, in the current world and possible future worlds at the Paris Agreement thresholds for global warming, heatwaves like this would not be particularly unusual at all.

There is also a benefit to limiting global warming to 1.5℃ rather than 2℃ as this reduces the relative frequency of these extreme heat events.

As this event comes to an end we know that Europe can expect more heatwaves like this one. We can, however, prevent such extreme heat from becoming the new normal by keeping global warming at or below the levels agreed upon in Paris.


The ConversationYou can find out more about the methods used here.

Andrew King, Climate Extremes Research Fellow, University of Melbourne

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

Another attack on the Bureau, but top politicians have stopped listening to climate change denial


Michael J. I. Brown, Monash University

Has the Australian climate change debate changed? You could be forgiven for thinking the answer is no.

Just this week The Australian has run a series of articles attacking the Bureau of Meteorology’s weather observations. Meanwhile, the federal and Queensland governments continue to promote Adani’s planned coal mine, despite considerable environmental and economic obstacles. And Australia’s carbon dioxide emissions are rising again.

So far, so familiar. But something has changed.

Those at the top of Australian politics are no longer debating the existence of climate change and its causes. Instead, four years after the Coalition was first elected, the big political issues are rising power prices and the electricity market. What’s happening?


Read more: No, the Bureau of Meteorology is not fiddling its weather data.


A few years ago, rejection of climate science was part of the Australian political mainstream. In 2013, the then prime minister Tony Abbott repeated a common but flawed climate change denial argument:

Australia has had fires and floods since the beginning of time. We’ve had much bigger floods and fires than the ones we’ve recently experienced. You can hardly say they were the result of anthropic [sic] global warming.

Abbott’s statement dodges a key issue. While fires and floods have always occurred, climate change can still alter their frequency and severity. In 2013, government politicians and advisers, such as Dennis Jensen and Maurice Newman, weren’t shy about rejecting climate science either.

The atmosphere is different in 2017, and I’m not just talking about CO₂ levels. Tony Abbott is no longer prime minister, Dennis Jensen lost preselection and his seat, and Maurice Newman is no longer the prime minister’s business advisor.

Which Australian politician most vocally rejects climate science now? It isn’t the prime minister or members of the Coalition, but One Nation’s Malcolm Roberts. In Australia, open rejection of human-induced climate change has moved to the political fringe.

Roberts has declared climate change to be a “fraud” and a “scam”, and talked about climate records being “manipulated by NASA”. He is very much a conspiracy theorist on climate, as he is on other topics including banks, John F. Kennedy, and citizenship. His approach to evidence is frequently at odds with mainstream thought.

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This conspiratorial approach to climate change is turning up elsewhere too. I was startled by the author list of the Institute of Public Affairs’ new climate change book. Tony Heller (better known in climate circles by the pseudonym Steven Goddard) doesn’t just believe climate change is a “fraud” and a “scam”, but has also promoted conspiracy theories about the Sandy Hook school massacre. This is a country mile from sober science and policy analysis.

So where is the Australian political mainstream? It’s not denying recent climate change and its causes, but instead is now debating the policy responses. This is exemplified by political arguments about the electricity market, power prices, and the Finkel Review.


Read more: What I learned from debating science with trolls


While this is progress, it’s not without serious problems. The debate may have rightly moved on to policy rather than science, but arguments for “clean coal” power are at odds with coal’s high CO₂ emissions and the failure thus far of carbon capture. Even power companies show little interest in new coal-fired power plants to replace those that have closed.

The closure of the Hazelwood power station was politically controversial.
Jeremy Buckingham/flickr

History repeating?

Have those who rejected global warming and its causes changed their tune? In general, no. They still imagine that scientists are up to no good. The Australian’s latest attacks on the Bureau of Meteorology (BoM) illustrate this, especially as they are markedly similar to accusations made in the same newspaper three years ago.

This week, the newspaper’s environment editor Graham Lloyd wrote that the BoM was “caught tampering” with temperature logs, on the basis of measurements of cold temperatures on two July nights at Goulburn and Thredbo. For these nights, discrepant temperatures were in public BoM databases due to automated weather stations that stopped reporting data. The data points were flagged for BoM staff to verify, but in the meantime an amateur meteorologist contacted Lloyd and the Institute of Public Affairs’ Jennifer Marohasy.

In 2014, Lloyd cast doubt on the BoM’s climate record by attacking the process of “homogenisation,” with a particular emphasis on data from weather stations in Rutherglen, Amberley and Bourke. Homogenisation is used to produce a continuous temperature record from measurements that may suffer from artificial discontinuities, such as in the case of weather stations that have been upgraded or moved from, say, a post office to an airport.

The Tuggeranong Automatic Weather Station.
Bidgee/Wikimedia Commons

Lloyd’s articles from this week and 2014 are beat-ups, for similar reasons. The BoM’s ACORN-SAT long-term temperature record is compiled using daily measurements from 112 weather stations. Even Lloyd acknowledges that those 112 stations don’t include Goulburn and Thredbo. While Rutherglen, Amberley and Bourke do contribute to ACORN-SAT, homogenisation of their data (and that of other weather stations) does little to change the warming trend measured across Australia. Australia has warmed over the past century, and The Australian’s campaigns won’t change that.

In 2014, the government responded to The Australian’s campaign by commissioning the Technical Advisory Forum, which has since reviewed ACORN-SAT and found it to be a “well-maintained dataset”. Prime Minister Abbott also considered a taskforce to investigate BoM, but was dissuaded by the then environment minister Greg Hunt.

The ConversationHow will Malcolm Turnbull’s government respond to The Australian’s retread of basically the same campaign? Perhaps that will be the acid test for whether the climate debate really has changed.

Michael J. I. Brown, Associate professor, Monash University

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