Suffering in the heat: the rise in marine heatwaves is harming ocean species



File 20190303 110119 1w5b8am.jpg?ixlib=rb 1.1
Recent marine heatwaves have devastated crucial coastal habitats, including kelp forests, seagrass meadows and coral reefs.
Dan Smale, Author provided

Dan Smale, Marine Biological Association and Thomas Wernberg, University of Western Australia

In the midst of a raging heatwave, most people think of the ocean as a nice place to cool down. But heatwaves can strike in the ocean as well as on land. And when they do, marine organisms of all kinds – plankton, seaweed, corals, snails, fish, birds and mammals – also feel the wrath of soaring temperatures.

Our new research, published today in Nature Climate Change, makes abundantly clear the destructive force of marine heatwaves. We compared the effects on ecosystems of eight marine heatwaves from around the world, including four El Niño events (1982-83, 1986-87, 1991-92, 1997-98), three extreme heat events in the Mediterranean Sea (1999, 2003, 2006) and one in Western Australia in 2011. We found that these events can significantly damage the health of corals, kelps and seagrasses.

This is concerning, because these species form the foundation of many ecosystems, from the tropics to polar waters. Thousands of other species – not to mention a wealth of human activities – depend on them.

We identified southeastern Australia, southeast Asia, northwestern Africa, Europe and eastern Canada as the places where marine species are most at risk of extreme heat in the future.




Read more:
Marine heatwaves are getting hotter, lasting longer and doing more damage


Marine heatwaves are defined as periods of five days or more during which ocean temperatures are unusually high, compared with the long-term average for any given place. Just like their counterparts on land, marine heatwaves have been getting more frequent, hotter and longer in recent decades. Globally, there were 54% more heatwave days per year between 1987 and 2016 than in 1925–54.

Although the heatwaves we studied varied widely in their maximum intensity and duration, we found that all of them had negative impacts on a broad range of different types of marine species.

Marine heatwaves in tropical regions have caused widespread coral bleaching.

Humans also depend on these species, either directly or indirectly, because they underpin a wealth of ecological goods and services. For example, many marine ecosystems support commercial and recreational fisheries, contribute to carbon storage and nutrient cycling, offer venues for tourism and recreation, or are culturally or scientifically significant.




Read more:
Australia’s ‘other’ reef is worth more than $10 billion a year – but have you heard of it?


.

Marine heatwaves have had negative impacts on virtually all these “ecosystem services”. For example, seagrass meadows in the Mediterranean Sea, which store significant amounts of carbon, are harmed by extreme temperatures recorded during marine heatwaves. In the summers of both 2003 and 2006, marine heatwaves led to widespread seagrass deaths.




Read more:
Seagrass, protector of shipwrecks and buried treasure


The marine heatwaves off the west coast of Australia in 2011 and northeast America in 2012 led to dramatic changes in the regionally important abalone and lobster fisheries, respectively. Several marine heatwaves associated with El Niño events caused widespread coral bleaching with consequences for biodiversity, fisheries, coastal erosion and tourism.

Mass die-offs of finfish and shellfish have been recorded during marine heatwaves, with major consequences for regional fishing industries.

All evidence suggests that marine heatwaves are linked to human mediated climate change and will continue to intensify with ongoing global warming. The impacts can only be minimised by combining rapid, meaningful reductions in greenhouse emissions with a more adaptable and pragmatic approach to the management of marine ecosystems.The Conversation

Dan Smale, Research Fellow in Marine Ecology, Marine Biological Association and Thomas Wernberg, Associate professor, University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisements

Heatwaves threaten Australians’ health, and our politicians aren’t doing enough about it


Paul Beggs, Macquarie University; Helen Louise Berry, University of Sydney; Martina Linnenluecke, Macquarie University, and Ying Zhang, University of Sydney

Extreme heat affects the mental health of Australians to the same degree as unemployment, yet Australia’s policy action on climate change lags behind other high-income countries such as Germany and the United Kingdom.

As Australia approaches another summer, we face the inevitability of deadly heatwaves. Our report published today in the Medical Journal of Australia concludes that policy inaction, particularly at the federal level, is putting Australian lives at risk.

The report, The MJA–Lancet Countdown on health and climate change: Australian policy inaction threatens lives, builds on an earlier publication in The Lancet medical journal, which concluded climate change is the biggest global health threat of the 21st century.




Read more:
Climate mitigation – the greatest public health opportunity of our time


Australia is the first to prepare its own country-level report. Developed in partnership with the Lancet Countdown – which tracks the global connections between health and climate change – it adopts the structure and methods of the global assessment but with an Australian focus.

How Australians’ health suffers

Australians are already facing climate change-related exposures that come from increasing annual average temperatures, heatwaves and weather-related disasters. Australian deaths during the 2014 Adelaide heatwave and Melbourne’s 2016 thunderstorm asthma event are examples of the risk climate poses to our health.




Read more:
Keeping one step ahead of pollen triggers for thunderstorm asthma


Our report was produced by a team of 19 experts from 13 universities and research institutes. We aimed to answer what we know about climate change and human health in Australia and how we are responding to this threat, if at all.

To do this, our team examined more than 40 indicators that enable us to track progress on the broad and complex climate change and human health issue. Health impact indicators included the health effects of temperature change and heatwaves, change in labour capacity, trends in climate-sensitive diseases, lethality of weather-related disasters and food insecurity and malnutrition.

We also developed an indicator for the impacts of climate change on mental health. This involved examining the association between mean annual maximum temperatures and suicide rates for all states and territories over the last ten years.

We found that, in most jurisdictions, the suicide rate increased with increasing maximum temperature. In Australia’s changing climate, we urgently need to seek ways to break the link between extreme temperature and suicide.

Across other indicators, we found workers’ compensation claims in Adelaide increased by 6.2% during heatwaves, mainly among outdoor male workers and tradespeople over 55 years.

And we found the length of heatwaves increased in 2016 and 2017 in Australia’s three largest cities – Sydney, Melbourne and Brisbane. Heatwave length varied from year to year, but between 2000 and 2017, the mean number of heatwave days increased by more than two days across the country.

Policy action we need

Australia’s slow transition to renewables and low-carbon electricity generation is problematic, and not only from a climate change perspective. Our report shows that pollutants from fossil fuel combustion cause thousands of premature deaths nationwide every year. We argue even one premature death is one too many when there is so much that we can do to address this.

Australia is one of the world’s wealthiest countries with the resources and technical expertise to act on climate change and health. Yet Australia’s carbon intensity is the highest among the countries we included in our comparison – Germany, United States, China, India and Brazil.

A carbon-intensive energy system is one of the main drivers behind climate change. Australia was once a leader in the uptake of renewables but other nations have since streaked ahead and are reaping the benefits for their economies, energy security and health.

Despite some progress increasing renewable generation, it’s time we truly pull our weight in the global effort to prevent acceleration towards dangerous climate change.

Policy leaders must take steps to protect human health and lives. These include strong political and financial commitments to accelerate transition to renewables and low-carbon electricity generation. The government lacks detailed planning for a clean future with a secure energy supply.




Read more:
What would a fair energy transition look like?


Our MJA-Lancet Countdown report will be updated annually. Now that Australia has begun systematically tracking the effects of climate change on health – and given its poor performance compared with comparable economies globally – further inaction would be reckless.The Conversation

Paul Beggs, Associate Professor and Environmental Health Scientist, Macquarie University; Helen Louise Berry, Professor of Climate Change and Mental Health, University of Sydney; Martina Linnenluecke, Professor of Environmental Finance; Director of the Centre for Corporate Sustainability and Environmental Finance, Macquarie University, and Ying Zhang, Associate Director, Teaching and Learning, Sydney School of Public Health, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Melbourne and Adelaide have been Australia’s most vulnerable major cities to killer heatwaves


Thomas Longden, University of Technology Sydney

Melbourne and Adelaide have been most prone to deadly heatwave conditions among Australia’s five largest cities, according to my new research published in Climatic Change.

My study shows that between 2001 and 2015, Melbourne and Adelaide suffered the most exposure to temperatures beyond a crucial threshold of 7.26℃ above the average. Above this threshold, deaths are more likely because people are not acclimatised to the extreme weather.

I estimated that there were 151 deaths in Melbourne and 144 in Adelaide due to extreme heatwaves – those above this 7.26℃ threshold – between 2001 and 2015.

Heatwaves can cause significant numbers of deaths, especially among vulnerable groups of people who are not prepared for or acclimatised to extreme hot temperatures.

Even though Melbourne and Adelaide are located in more temperate areas (in comparison with more northerly cities such as Brisbane), they have been periodically hit by severe heatwaves.




Read more:
We’ve learned a lot about heatwaves, but we’re still just warming up


In my research, I looked at the “Excess Heat Factor”, a measure used by the Bureau of Meteorology as part of its heatwave forecasts. It is the difference between the 3-day average temperature and the 30-day average, and is therefore a measure of how “unusually hot” it is during a heatwave. It captures how much residents are likely to struggle to cope with the heat.

The graphs below show the frequency of excessively hot or cold weather for each of Australia’s major cities from 2001 to 2015. These charts show that most days had temperatures where the 3-day average was 2℃ higher or lower than the 30-day average.

A grey dashed line shows the extreme heat threshold that my study found was associated with higher deaths, relative to moderately warm and cool days.
I then estimated the threshold at which there is a significantly increased risk of deaths.

The death rate (per 100,000 people) that coincides with the extreme heat acclimatisation measure is shown as a black line on each of the graphs. This is an average impact of temperature on death rates, adjusted for different cities’ population sizes and baseline death rates.

Between 2001 and 2015, most of the events above the 7.26℃ extreme heat threshold occurred in Adelaide, Melbourne and Perth. Brisbane and Sydney had fewer days above this threshold.

Figure 1 – Histograms of the Excess Heat Index for major Australian cities between 2001 and 2015.

The importance of acclimatisation

Several previous studies have linked excessive heat to adverse events such as deaths (see here, here and here), and emergency department visits and ambulance call-outs (see here, here and here). But my study is the first to solely focus on the extreme heat index acclimatisation measure, and to identify a temperature threshold in this way. This measure is important, as it identifies the times when residents of cities with different background climates begin to struggle with the heat.

The Bureau of Meteorology does not currently use the 7.26℃ threshold identified in my paper. Doing so may improve predictions of which heatwaves are most likely to turn deadly for significant numbers of people living in our major cities.

Implications for policy

Since the severe heatwaves of 2009, many states and territories have implemented or revised their heatwave response plans, or conducted awareness campaigns to educate people about the health risks. But more can be done to make vulnerable people aware of upcoming heatwave events.

A 2016 review proposed that heatwave response plans and early warning systems should be evaluated and updated at least every five years, to ensure that they remain effective, and to incorporate up-to-date knowledge about population-level vulnerability to heat stress.

While my research has focused on Australia’s five largest cities, this does not mean that extreme heat is any less dangerous in other areas. Nor is the danger limited to prolonged heatwaves – individual hot days can catch people out too. A NSW study found that emergency hospital admissions due to dehydration and other heat-related injuries rose significantly on individual hot days, as well as during hot spells lasting at least three days.

This suggests that we need to develop more complex heat risk management plans, with targeted responses for different health issues based on the longevity of extreme heat events.

Implications for the future

We also need to consider the patterns of extremely hot temperatures that we are likely to encounter in the future. Recent research found that changes in the frequency and duration of heatwaves will be larger in the north of Australia than the south. But the same study also found that “heatwave amplitude” – the intensity of the hottest day of the hottest heatwave – will increase more in southern parts of Australia.

The ConversationThis research suggests that cities south of Brisbane will experience the most severe temperature spikes beyond what their residents are used to dealing with.

Thomas Longden, Senior Research Fellow, University of Technology Sydney

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

It’s a savage summer in the Northern Hemisphere – and climate change is slashing the odds of more heatwaves


Andrew King, University of Melbourne and Ben Henley, University of Melbourne

In Australia we know about sweltering summer heat. We all remember the images of burned koala paws, collapsing tennis players and, far more seriously, the tragic events of Black Saturday.

Aussies may scoff at Britain’s idea of a heatwave, but this time it’s the real deal and it’s no laughing matter.

Extreme heat has hit locations throughout the Northern Hemisphere, in places as far apart as Montreal, Glasgow, Tokyo and Lapland. In the past few weeks heat records have tumbled in a wide range of places, most notably:




Read more:
Why hot weather records continue to tumble worldwide


Heat has not been the only problem. Much of northern Europe is experiencing a very persistent drought, with little to no measurable rainfall in months. This has caused the normally lush green fields of England and other European countries to turn brown and even reveal previously hidden archaeological monuments.

There have also been major wildfires in northern England, Sweden and, most recently and devastatingly, Greece. The Greek wildfires came off the back of a very dry winter and spring.

What’s behind the widespread extreme heat?

The jet stream, a high-altitude band of air that pushes weather systems around at lower altitudes, has been weaker than normal. It has also been positioned unusually far to the north, particularly over Europe. This has kept the low-pressure systems that often drive wind and rain over northern Europe at bay.

The jet stream has remained locked in roughly the same position over the Atlantic Ocean and northern Europe for the past couple of months. This has meant that the same weather types have remained over the same locations most of the time.

Weather is typically more transient than it has been recently. Even when we do have blocking high-pressure systems associated with high temperatures in northern Europe, they don’t normally linger as long as this.

Is it driven by climate change?

Although climatologists have made great strides in recent years in the field of event attribution – identifying the human climate fingerprint on particular extreme weather events – it is hard to quantify the role of climate change in an event that is still unfolding.

Until the final numbers are in we won’t be able to tell just how much climate change has altered the likelihood or intensity of these particular heat extremes.

Having said that, we can use past analyses of extreme heat events, together with future climate change projections, to infer whether climate change is playing a role in these events.

We also know that increasing numbers of hot temperature records are being set, and that the increased probability of hot temperature records can indeed be attributed to the human influence on the climate.

In Europe especially, there is already a large body of literature that has looked at the role of human-caused climate change in heat extremes. In fact, the very first event attribution study, led by Peter Stott from the UK Met Office, found that human-caused climate change had at least doubled the likelihood of the infamous European heatwave of 2003.

For all manner of heat extremes in Europe and elsewhere, including in Japan, a clear and discernible link with climate change has been made.

Research has also shown that heat extremes similar to those witnessed over the past month or two are expected to become more common as global temperatures continue to climb. The world has so far had around 1℃ of global warming above pre-industrial levels, but at the global warming limits proposed in the Paris climate agreement, hot summers like that of 2003 in central Europe would be a common occurrence.

At 2℃ of global warming, the higher of the two Paris targets, 2003-like hot summers would very likely happen in most years.

Similarly, we know that heat exposure and heat-induced deaths in Europe will increase with global warming, even if we can limit this warming to the levels agreed in Paris.




Read more:
Yes, the Arctic’s freakishly warm winter is due to humans’ climate influence


But summers have always been hot, haven’t they?

For most parts of the world summers have got warmer, and the hottest summer on record is relatively recent – such as 2003 in parts of central Europe and 2010 in much of eastern Europe. One exception is central England, where the hottest summer remains 1976, although it may be challenged this year.

While extreme hot summers and heatwaves did happen in the past, they were less common. One big difference as far as England is concerned is that its extreme 1976 heatwave was a global outlier, whereas this year’s isn’t.

In 1976 northwestern Europe had higher temperature anomalies than almost anywhere else on the globe. In June 2018 the same region was unusually warm, but so was most of the rest of the Northern Hemisphere.

The ConversationSo while the persistent weather patterns are driving much of the extreme heat we’re seeing across the Northern Hemisphere, we know that human-caused climate change is nudging the temperatures up and increasing the odds of new heat extremes.

Andrew King, ARC DECRA fellow, University of Melbourne and Ben Henley, Research Fellow in Climate and Water Resources, University of Melbourne

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

Full response from the Climate Council for an article on heatwaves and hot days in Australia



File 20170619 5844 1phovhx
Climate Council CEO Amanda McKenzie, speaking on Q&A.
Q&A

Lucinda Beaman, The Conversation and Michael Courts, The Conversation

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?

Climate change is making hot days and heatwaves more frequent and more severe. Since 1950 the annual number of record hot days across Australia has more than doubled and the mean temperature has increased by about 1°C from 1910.

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.

The accumulating energy in the atmosphere is affecting all extreme weather events. Climate change is driving global warming at a rate 170 times faster than the baseline rate over the past 7,000 years.

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.

The ConversationRead the article here.

Lucinda Beaman, FactCheck Editor, The Conversation and Michael Courts, Editor, The Conversation

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

Are heatwaves ‘worsening’ and have ‘hot days’ doubled in Australia in the last 50 years?


Andrew King, University of Melbourne

The release of the Finkel report has refocused national attention on climate change, and how we know it’s happening.

On a Q&A episode following the report’s release, Climate Council CEO Amanda McKenzie said we’ve seen:

… worsening heatwaves, hot days doubling in Australia in the last 50 years.

Excerpt from Q&A, June 12, 2017. Quote begins at 2:12.

Her comment provides the perfect opportunity to revisit exactly what the research says on heatwaves and hot days as Australia’s climate warms.

Examining the evidence

When asked for sources to support McKenzie’s assertion, a Climate Council spokesperson said:

Climate change is making hot days and heatwaves more frequent and more severe. Since 1950 the annual number of record hot days across Australia has more than doubled and the mean temperature has increased by about 1°C from 1910.

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.

You can read full response from the Climate Council here.

How do we define ‘heatwaves’?

Internationally, organisations use different definitions for
heatwaves.

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.

We can also characterise heatwaves by looking at their their intensity, frequency and duration.

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:

We’ve seen a trend towards more heatwave days over Australia. Trends are shown for 1950-2013 in units of heatwave days per decade. Stippling indicates statistical significance at the 5% level.
Adapted from Perkins-Kirkpatrick et al. (2017)

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.

https://datawrapper.dwcdn.net/wsR9Z/1/

The following map shows the trend in the number of days per year above 35 °C from 1957–2015:


Bureau of Meteorology

A 2010 Bureau of Meteorology/CSIRO report found record hot days had more than doubled between 1960 and 2010. That data was collected from the highest-quality weather stations across Australia.

Number of record hot day maximums at Australian climate reference stations, 1960-2010.
Bureau of Meteorology 2010
Number of days in each year where the Australian area-averaged daily mean temperature is extreme. Extreme days are those above the 99th percentile of each month from the years 1910-2015.
Bureau of Meteorology

Why are heatwaves worsening, and record hot days doubling?

The trend in rising average temperatures in Australia in the second half of the 20th century is likely to have been largely caused by human-induced climate change.

Recent record hot summers and significant heatwaves were also made much more likely by humans’ effect on the climate.

The ConversationThe human influence on Australian summer temperatures has increased and we can expect more frequent hot summers and heatwaves as the Earth continues to warm.

Andrew King, Climate Extremes Research Fellow, University of Melbourne

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

Severe heatwaves show the need to adapt livestock management for climate



Image 20170227 27378 u8yry6
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.