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.

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Severe heatwaves show the need to adapt livestock management for climate



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Cows don’t do well in the heat.
Shutterstock

Elisabeth Vogel, University of Melbourne; Christin Meyer, Potsdam Institute for Climate Impact Research, and Richard Eckard, University of Melbourne

Climate change and extreme weather events are already impacting our food, from meat and vegetables, right through to wine. In our series on the Climate and Food, we’re looking at what this means for the food chain. The Conversation


During the recent heatwave in New South Wales, which saw record-breaking temperatures for two days in a row, 40 dairy cows died in Shoalhaven, a city just south of Sydney.

Climate change doubled the likelihood of this kind of record-breaking heatwave. And even the higher minimum temperatures we’ve recently experienced may soon be the “new normal” for this time of the year.

Farmers that already find it difficult to make a profit will need to adapt to these changing conditions, ensuring they mitigate the effects on their livestock. This could take the form of more shade and shelter, but also the selection of different breeds to suit the conditions.

What’s happening?

Cattle are vulnerable to changes in rainfall patterns (variability and extremes), temperature (average and extremes), humidity, and evaporation. These climactic changes can affect livestock directly, and also indirectly through pasture growth, forage crop quantity and quality, the production and price of feed-grain as well as spatial changes in disease and pest distribution.

The greatest risks stem from extreme events such as heatwaves and droughts, as they are less predictable and much more difficult to adapt to than gradual changes.

Dairy cows are particularly affected by heatwaves, which can not only reduce milk production, but, as the NSW heatwave illustrated, cause illness or death. Further, the effects on milk production and the protein content of the milk can last for several weeks.

Similar to humans, instances of high relative air humidity and little wind worsen the negative effects of high temperatures on livestock. When this occurs, the animals cannot easily offload excess heat through transpiration. This is compounded when there is little or no cloud cover, as the cattle are exposed to more solar radiation.

Milk production is also impacted by night-time temperatures and the timing of the heatwave. When night-time temperatures are high, cows cannot offload excess heat. If a heatwave occurs after the cows’ peak of lactation, milk production is less likely to recover and the impact is even worse.

The response of cattle to heat stress also depends on the breed. This can differ as a result of, among other things, differences in metabolic rate, sweating rate, coat texture and colour. Researchers have even identified a “slick hair gene”, responsible for producing cattle with shorter, slicker hair that reduces their vulnerability to direct radiative heat. The full benefits of the slick gene still require more research as a strategy for animals to cope in future climates.

Sheep are generally less affected by high temperatures than dairy cows. However, heatwaves with temperatures beyond 40℃ can cause heat stress. Hot days may have short-term impacts on rams’ fertility, and recently shorn sheep are at risk of sunburn if they are exposed to direct sunlight.

Factors that are unique to each individual animal, such as previous heat exposure and overall health and age, also play a role in how vulnerable they are to heat.

Mitigation

In the short run, farmers can mitigate the worst of these issues by providing high-quality water and shade (such as from trees, buildings, and shade cloth) in the heat, warm shelter in the cold, and by adjusting feed. During heatwaves, farmers can also adjust milking procedures and milk their cows very early in the morning or late at night. To provide immediate cooling they can also use sprinklers or misting systems. But care is needed to avoid simply increasing humidity around the animals.

Mitigation can be as simple as providing a bit of shade.
Shutterstock

A more long-term option is to selectively choose breeds that are better adapted to higher temperatures (such as breeds with lighter coat colour or Bos indicus types or crosses). Unfortunately, breeds adapted to warmer climates, such as the Brahman, tend not to be high milk producers or to do as well in feedlots as the traditional British beef breeds, so there will be a hit to productivity.

As the impact of climate change isn’t solely on the animals themselves, farmers will also have to adjust their work patterns and other aspects of their operations. To cope with heat, farmers themselves may need to consider working more during the cooler hours of the day. Farming both crops and livestock together can also provide a buffer against the impact of an extreme event. The combined production of wheat and wool is a typical example of spreading of risk on farm.

But for these strategies to really be effective, farmers need more information.

This includes accurate and timely forecasts of weather (temperature, rainfall, solar radiation) and heat (such as the temperature humidity index, THI) at daily, weekly and seasonal scales. Armed with this data, farmers and livestock managers can effectively plan and implement protection measures ahead of time.

A wide range of agricultural, climate and weather services exist. For example, the Bureau of Meteorology weather forecasts, seasonal outlooks of rainfall and temperature, and the current water balance and soil moisture information. There’s also the the Cool Cows website, the Dairy Forecast Service and the Cattle heat load toolbox.

We also need more research into improving our understanding of the climate system, to develop risk management plans for industries by regions, and more accurate and reliable forecasts, so that farmers and livestock managers can make management decisions and ensure the wellbeing of themselves and their animals.

Elisabeth Vogel, PhD Student, University of Melbourne; Christin Meyer, PhD student, Potsdam Institute for Climate Impact Research, and Richard Eckard, Professor & Director, Primary Industries Climate Challenges Centre, University of Melbourne

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

Climate change doubled the likelihood of the New South Wales heatwave


Sarah Perkins-Kirkpatrick, UNSW; Andrew King, University of Melbourne, and Matthew Hale, UNSW

The heatwave that engulfed southeastern Australia at the end of last week has seen heat records continue to tumble like Jenga blocks.

On Saturday February 11, as New South Wales suffered through the heatwave’s peak, temperatures soared to 47℃ in Richmond, 50km northwest of Sydney, while 87 fires raged across the state amid catastrophic fire conditions.

On that day, most of NSW experienced temperatures at least 12℃ above normal for this time of year. In White Cliffs, the overnight minimum was 34.2℃, a new record for the state’s highest observed minimum temperature.

On Friday, the average maximum temperature right across NSW hit 42.4℃, beating the previous February record of 42.0℃. The new record stood for all of 24 hours before it was smashed again on Saturday, as the whole state averaged 44.0℃ at its peak. At this time, NSW was the hottest place on Earth.

A degree or two here or there might not sound like much, but to put it in cricketing parlance, those temperature records are the equivalent of a modern test batsman retiring with an average of over 100 – the feat of outdoing Don Bradman’s fabled 99.94 would undoubtedly be front-page news.

And still the records continue to fall. Mungindi, on the border of NSW and Queensland, broke the Australian record of 50 days in a row above 35℃, set just four years ago at Bourke Airport, with the new record now at 52 days.

Meanwhile, two days after that sweltering Saturday we woke to find the fires ignited during the heatwave still cutting a swathe of destruction, with the small town of Uarbry, east of Dunedoo, all but burned to the ground.

This is all the more noteworthy when we consider that the El Niño of 2015-16 is long gone and the conditions that ordinarily influence our weather are firmly in neutral. This means we should expect average, not sweltering, temperatures.

Since Christmas, much of eastern Australia has been in a flux of extreme temperatures. This increased frequency of heatwaves shows a strong trend in observations, which is set to continue as the human influence on the climate deepens.

It is all part of a rapid warming trend that over the past decade has seen new heat records in Australia outnumber new cold records by 12 to 1.

Let’s be clear, this is not natural. Climate scientists have long been saying that we would feel the impacts of human-caused climate change in heat records first, before noticing the upward swing in average temperatures (although that is happening too). This heatwave is simply the latest example.

What’s more, in just a few decades’ time, summer conditions like these will be felt across the whole country regularly.

Attributing the heat

The useful thing scientifically about heatwaves is that we can estimate the role that climate change plays in these individual events. This is a relatively new field known as “event attribution”, which has grown and improved significantly over the past decade.

Using the Weather@Home climate model, we looked at the role of human-induced climate change in this latest heatwave, as we have for other events before.

We compared the likelihood of such a heatwave in model simulations that factor in human greenhouse gas emissions, compared with simulations in which there is no such human influence. Since 2017 has only just begun, we used model runs representing 2014, which was similarly an El Niño-neutral year, while also experiencing similar levels of human influence on the climate.

Based on this analysis, we found that heatwaves at least as hot as this one are now twice as likely to occur. In the current climate, a heatwave of this severity and extent occurs, on average, once every 120 years, so is still quite rare. However, without human-induced climate change, this heatwave would only occur once every 240 years.

In other words, the waiting time for the recent east Australian heatwave has halved. As climate change worsens in the coming decades, the waiting time will reduce even further.

Our results show very clearly the influence of climate change on this heatwave event. They tell us that what we saw last weekend is a taste of what our future will bring, unless humans can rapidly and deeply cut our greenhouse emissions.

Our increasingly fragile electricity networks will struggle to cope, as the threat of rolling blackouts across NSW showed. It is worth noting that the large number of rooftop solar panels in NSW may have helped to avert such a crisis this time around.

Our hospital emergency departments also feel the added stress of heat waves. When an estimated 374 people died from the heatwave that preceded the Black Saturday bushfires the Victorian Institute of Forensic Medicine resorted to storing bodies in hospitals, universities and funeral parlours. The Victorian heatwave of January 2014 saw 167 more deaths than expected, along with significant increases in emergency department presentations and ambulance callouts.

Infrastructure breaks down during heatwaves, as we saw in 2009 when railway lines buckled under the extreme conditions, stranding thousands of commuters. It can also strain Australia’s beloved sporting events, as the 2014 Australian Open showed.

These impacts have led state governments and other bodies to investigate heatwave management strategies, while our colleagues at the Bureau of Meteorology have developed a heatwave forecast service for Australia.

These are likely to be just the beginning of strategies needed to combat heatwaves, with conditions currently regarded as extreme set to be the “new normal” by the 2030s. With the ramifications of extreme weather clear to everyone who experienced this heatwave, there is no better time to talk about how we can ready ourselves.

We urgently need to discuss the health and economic impacts of heatwaves, and how we are going to cope with more of them in the future.


We would like to acknowledge Robert Smalley, Andrew Watkins and Karl Braganza of the Australian Bureau of Meteorology for providing observations included in this article. This article was amended on February 16, 2017, to include updated weather observations.

The Conversation

Sarah Perkins-Kirkpatrick, Research Fellow, UNSW; Andrew King, Climate Extremes Research Fellow, University of Melbourne, and Matthew Hale, Research Assistant, UNSW

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

A marine heatwave has wiped out a swathe of WA’s undersea kelp forest


Scott Bennett, Curtin University; Julia Santana-Garcon, and Thomas Wernberg, University of Western Australia

Kelp forests along some 100km of Western Australia’s coast have been wiped out, and many more areas damaged, by a marine heatwave that struck the area in 2011.

The heatwave, which featured ocean temperatures more than 2℃ above normal and persisted for more than 10 weeks, ushered in an abrupt change in marine plant life along a section of Australia’s Great Southern Reef, with kelp disappearing to be replaced by tropical species.

As we and our international colleagues report in the journal Science, five years on from the heatwave, these kelp forests show no signs of recovery.

Instead, fish, seaweed and invertebrate communities from these formerly temperate kelp forests are being replaced by subtropical and tropical reef communities. Tropical fish species are now intensely grazing the reef, preventing the kelp forests from recovering.

Kelp forest before (left) and after (right) the marine heatwave.
Author provided

Assessing the damage

We and our team surveyed reefs along 2,000km of coastline from Cape Leeuwin, south of Perth, to Ningaloo Reef between 2001 and 2015.

Up until 2011, temperate reefs were clearly defined by the distribution of kelp forests which formed dense, highly productive forests as far north as Kalbarri in WA’s Mid West.

Since 2011, the boundary between these temperate reefs of southern WA and the more tropical reefs (including Ningaloo) to the north has become less clear-cut. Instead, the sharp divide has been replaced by an intermediate region of turf-dominated reefs.

Infographic illustrating the impacts of the heatwave, kelp loss and tropicalisation of temperate reefs.
[Produced by Awaroo]((www.awaroo.com))

This has implications for the Great Southern Reef (GSR), which extends more than 8,000km around the southern half of Australia from the southern half of WA all the way to southern Queensland – a coastline that is home to around 70% of Australians.

Kelp forests are the GSR’s “biological engine”, feeding a globally unique collection of temperate marine species, not to mention supporting some of the most valuable fisheries in Australia and underpinning reef tourism worth more than A$10 billion a year.

But our research shows that on the GSR’s western side, kelp forests are being pushed towards Australia’s southern edge, where continued warming puts them at risk of losses across thousands of kilometres of coastline because there is no more southerly habitat to which they can retreat.

While the 2011 marine heatwave affected some 1,000km of Western Australia’s temperate coastline, it was a stretch of roughly 100km extending south of Kalbarri on the state’s Mid West coast that was most severely affected.

In this area alone an estimated 385 square km of kelp forest have been completely wiped out.

Further south, from Geraldton to Cape Leeuwin, the extent of kelp loss was less severe, despite an estimated total area of 960 square km having been lost in the region.

Northern regions towards Kalbarri were more severely affected because these kelp forests were closer to their limit, and also because this area is closer to the tropical regions like Ningaloo Reef, meaning that tropical species could more easily move in.

A school of tropical rabbitfish moves through the affected area.
Thomas Wernberg, Author provided

The problem was exacerbated by the southward-flowing Leeuwin Current, which helps tropical species move south while making it harder for temperate species to move north and recolonise the affected areas of the GSR.

The combination of these physical and ecological processes set within a background warming rate roughly twice the global average, compounds the challenges faced by kelp forests in the region.

The plight of WA’s kelp forests provides a strong warning of what the future might hold for Australia’s temperate marine environment, and the many services it provides to Australians.

The Conversation

Scott Bennett, Marie Curie Fellow at the Spanish National Research Council (CSIC), Curtin University; Julia Santana-Garcon, Postdoctoral research associate in Marine Ecology, and Thomas Wernberg, ARC Future Fellow in Marine Ecology, University of Western Australia

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

Australia: Heat Continues


The link below is to an article reporting on the continuing heat of a summer that just won’t end.

For more visit:
http://www.smh.com.au/environment/weather/a-summer-that-refuses-to-throw-in-the-towel-20130308-2fpyq.html

Australia: The Heat is On


The link below is to an article reporting on the current heatwave being experienced in Australia.

For more visit:
http://www.theage.com.au/environment/weather/temperatures-off-the-charts-as-australia-turns-deep-purple-20130108-2ce33.html

Australia: Western Australia – Ocean Heatwave Changed Environment


The link below is to an interesting article concerning an ocean heatwave off the Western Australian coast. It changed the ecology of the area dramatically.

For more visit:
http://www.newscientist.com/article/dn22090-heatwave-transformed-australian-marine-life.html