Climate change and wildfires – how do we know if there is a link?



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A firefighter runs after trying to save a home in Lakeport, California, suffering its biggest fires ever.
AP Photo/Noah Berger

Kevin Trenberth, National Center for Atmospheric Research

Once again, the summer of 2018 in the Northern Hemisphere has brought us an epidemic of major wildfires.

These burn forests, houses and other structures, displace thousands of people and animals, and cause major disruptions in people’s lives. The huge burden of simply firefighting has become a year-round task costing billions of dollars, let alone the cost of the destruction. The smoke veil can extend hundreds or even thousands of miles, affecting air quality and visibility. To many people, it has become very clear that human-induced climate change plays a major role by greatly increasing the risk of wildfire.

Yet it seems the role of climate change is seldom mentioned in many or even most news stories about the multitude of fires and heat waves. In part this is because the issue of attribution is not usually clear. The argument is that there have always been wildfires, and how can we attribute any particular wildfire to climate change?

As a climate scientist, I can say this is the wrong framing of the problem. Global warming does not cause wildfires. The proximate cause is often human carelessness (cigarette butts, camp fires not extinguished properly, etc.), or natural, from “dry lightning” whereby a thunderstorm produces lightning but little rain. Rather, global warming exacerbates the conditions and raises the risk of wildfire.

Even so, there is huge complexity and variability from one fire to the next, and hence the attribution can become complex. Instead, the way to think about this is from the standpoint of basic science – in this case, physics.

This year is proving to be another active wildfire season.
Climate Central, CC BY-NC

Global warming is happening

To understand the interplay between global warming and wildfires, consider what’s happening to our planet.

The composition of the atmosphere is changing from human activities: There has been over a 40 percent increase in carbon dioxide, mainly from fossil fuel burning since the 1800s, and over half of the increase is since 1985. Other heat-trapping gases (methane, nitrous oxide, etc.) are also increasing in concentration in the atmosphere from human activities. The rates are accelerating, not declining (as hoped for with the Paris agreement).

This leads to an energy imbalance for the planet.

The flows of energy through the climate system are schematically illustrated with numbers on the top-of-atmosphere values and net energy imbalance at the surface.
Trenberth et al 2009

Heat-trapping gases in the atmosphere act as a blanket and inhibit the infrared radiation – that is, heat from the Earth – from escaping back into space to offset the continual radiation coming from the sun. As these gases build up, more of this energy, mostly in the form of heat, remains in our atmosphere. The energy raises the temperature of the land, oceans and atmosphere, melts ice, thaws permafrost, and fuels the water cycle through evaporation.

Moreover, we can estimate Earth’s energy imbalance quite well: It amounts to about 1 watt per square meter, or about 500 terawatts globally.

While this factor is small compared with the natural flow of energy through the system, which is 240 watts per square meter, it is large compared with all other direct effects of human activities. For instance, the electrical power generation in the U.S. last year averaged 0.46 terawatts.

The extra heat is always the same sign and it is spread across the globe. Accordingly, where this energy accumulates matters.

Tracking the Earth’s energy imbalance

The heat mostly accumulates ultimately in the ocean – over 90 percent. This added heat means the ocean expands and sea level rises.

Heat also accumulates in melting ice, causing melting Arctic sea ice and glacier losses in Greenland and Antarctica. This adds water to the ocean, and so the sea level rises from this as well, rising at a rate of over 3 milimeters year, or over a foot per century.

Global ocean heat content for the top 2000 meters of the ocean, with uncertainty estimates by the pink region.
ScienceAdvances, CC BY-NC

On land, the effects of the energy imbalance are complicated by water. If water is present, the heat mainly goes into evaporation and drying, and that feeds moisture into storms, which produce heavier rain. But the effects do not accumulate provided that it rains on and off.

However, in a dry spell or drought, the heat accumulates. Firstly, it dries things out, and then secondly it raises temperatures. Of course, “it never rains in southern California” according to the 1970s pop song, at least in the summer half year.

So water acts as the air conditioner of the planet. In the absence of water, the excess heat effects accumulate on land both by drying everything out and wilting plants, and by raising temperatures. In turn, this leads to heat waves and increased risk of wildfire. These factors apply in regions in the western U.S. and in regions with Mediterranean climates. Indeed many of the recent wildfires have occurred not only in the West in the United States, but also in Portugal, Spain, Greece, and other parts of the Mediterranean.

A satellite image of the Carr Fire in California. Drought conditions, in addition to a lot of dead trees and vegetation, are contributing to another year of severe wildfires.
NASA

The conditions can also develop in other parts of the world when strong high pressure weather domes (anticyclones) stagnate, as can happen in part by chance, or with increased odds in some weather patterns such as those established by either La Niña or El Niño events (in different places). It is expected that these dry spots move around from year to year, but that their abundance increases over time, as is clearly happening.

How big is the energy imbalance effect over land? Well, 1 Watt per square meter over a month, if accumulated, is equivalent to 720 Watts per square meter over one hour. 720 Watts is equivalent to full power in a small microwave oven. One square meter is about 10 square feet. Hence, after one month this is equivalent to: one microwave oven at full power every square foot for six minutes. No wonder things catch on fire!

Attribution science

Coming back to the original question of wildfires and global warming, this explains the argument: there is extra heat available from climate change and the above indicates just how large it is.

In reality there is moisture in the soil, and plants have root systems that tap soil moisture and delay the effects before they begin to wilt, so that it typically takes over two months for the effects to be large enough to fully set the stage for wildfires. On a day to day basis, the effect is small enough to be lost in the normal weather variability. But after a dry spell of over a month, the risk is noticeably higher. And of course the global mean surface temperature is also going up.

“We can’t attribute a single event to climate change” has been a mantra of climate scientists for a long time. It has recently changed, however.

As in the wildfires example, there has been a realization that climate scientists may be able to make useful statements by assuming that the weather events themselves are relatively unaffected by climate change. This is a good assumption.

Also, climate scientists cannot say that extreme events are due to global warming, because that is a poorly posed question. However, we can say it is highly likely that they would not have had such extreme impacts without global warming. Indeed, all weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be.

The ConversationIn particular, by focusing on Earth’s Energy Imbalance, new research is expected to advance the understanding of what is happening, and why, and what it implies for the future.

Kevin Trenberth, Distinguished Senior Scientist, National Center for Atmospheric Research

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

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Contrary to common belief, some forests get more fire-resistant with age


Philip Zylstra, University of Wollongong

An out-of-season bushfire raged through Sydney’s southwest at the weekend, burning more than 2,400 hectares and threatening homes.

As the fire season extends and heatwaves become more frequent, it’s vital to preserve our natural protections. My research, recently released in the journal Austral Ecology, contradict one of the central assumptions in Australian fire management – that forest accumulate fuel over time and become increasingly flammable.




Read more:
Ocean heat waves and weaker winds will keep Australia warm for a while yet


I looked at every fire in every forest in the Australian Alps National Parks and found that mature forests are dramatically less likely to burn. Perhaps surprisingly, once a forest is several decades old it becomes one of our best defences against large bushfires.

The English approach

Within decades of the first graziers taking land in the Australian Alps, observers noticed that English-style management had unintended consequences for an Australian landscape.

In the British Isles, grazing rangelands had been created in the moors by regular burning over thousands of years, and this approach was imported wholesale to Australia’s mountains.

By 1893, however, the botanist Richard Helms had observed that as little as a year after fires were introduced to clear the land, “the scrub and underwood spring up more densely than ever”.

It’s true that, as in the rest of the country, many shrubs in the Alps are germinated by fire. However, the Alps also lie in a climatic zone where many trees are easily killed by fire. As a result, fire produces dense regrowth, and in the worst cases, removes the forest canopy that is essential to maintaining a still, moist micro-climate. Fires burning in this regrowth have abundant dry fuel, and they are exposed to the full strength of the wind.




Read more:
New modelling on bushfires shows how they really burn through an area


Theoretically, that should make regrowth more flammable than old growth, but it is at odds with the widespread assumption that fuels accumulate over time to make old forests the most flammable. Which is the case then? Are old forests more or less flammable than regrowth?

36 million case studies

Looking back over 58 years of mapped fires in the 12 national parks and reserves that make up the Australian Alps National Parks, I asked a simple question: when a wildfire burnt the mountains, did it favour one age of forest over another? If there were equal amounts of forest burnt say, five years, 10 years or 50 years ago, did fires on average burn more in one of those ages than another?

It’s not an entirely new question; people have often studied what happened when a fire crossed into recently burnt areas.

However, instead of just looking at part of a fire, I looked at every hectare it had burnt as separate case study. Instead of only looking at recent fires, I looked at every recorded fire in every forest across the Australian Alps National Parks. Instead of a handful of case studies, I now had 36 million of them.

Consistent with all of the other studies, I found that forests became more flammable in the years after they were burnt; but this is where the similarity ended. Rather than stop there as the other studies have done, I pushed past this line and found something striking. Regardless of which forest I examined, it became dramatically less likely to burn when it matured after 14 to 28 years.

Alpine Ash forests become increasingly flammable until the trees are tall enough to avoid ignition, and the shrubs thin out.
Phil Zylstra, Author provided

The most marked response of these was in the tall, wet Ash forests. These have been unlikely to burn for about three years after a fire, but then the regrowth comes in. Until these trees are about 21 years old, Ash forests are one of the most flammable parts of the mountains, but after this, their flammability drops markedly. When our old Ash forest is burnt, it is condemned to two decades in which it is more than eight times as flammable.

https://cdn.knightlab.com/libs/juxtapose/latest/embed/index.html?uid=8818c198-4143-11e8-b263-0edaf8f81e27

The forests across the Alps have survived by constructing communities that keep fires small; but their defences are being broken down in the hotter, drier climate we are creating. Roughly the same area of the Victorian Alps was burnt by wildfire in the 10 years from 2003-2014 as had been burnt in the previous 50 years.




Read more:
To fight the catastrophic fires of the future, we need to look beyond prescribed burning


More fire means more flammable forests, which in turn mean more fire; it’s a positive feedback that can accelerate until fire-sensitive ecosystems such as the Ash collapse into permanently more flammable shrublands. Knowing this, however, gives us tools.

The ConversationOld forests are assets to be protected, and priority can be given to nursing older regrowth into its mature stages. It may be the eleventh hour, but we’re better placed now to stand with the forests and add what we can to their fight to survive climate change.

Philip Zylstra, Research Fellow, flammability and fire behaviour, University of Wollongong

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

How invasive weeds can make wildfires hotter and more frequent



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Mixed grill: burning combinations of invasive and native plants helps us understand how invasive plants make fires hotter and more likely.
Sarah Wyse, CC BY-ND

Tim Curran, Lincoln University, New Zealand; George Perry, and Sarah Wyse

Over the past year the global media has been full of reports of catastrophic fires in California, the Mediterranean, Chile and elsewhere. One suggested reason for increases in catastrophic wildfires has been human-induced climate change. Higher temperatures, drier weather and windier conditions all increase the impact of fires.

While climate change indeed raises the risk of wildfires, our research shows that another way humans can change patterns of fire activity is by introducing flammable plants to new environments.


Read more: How will Canada manage its wildfires in the future?


Plantations of highly flammable exotic species, such as pines and eucalypts, probably helped to fuel the recent catastrophic fires in Portugal and in Chile. In arid regions, such as parts of the US southwest, the introduction of exotic grasses has transformed shrublands, as fires increase in severity.

Invasive plants and fire

How do invasive plants change fire patterns? We burned species mixtures (aka “mixed grills”) on our plant barbecue to help find out.

Invasive plants are responsible for changing the patterns of fire activity in many ecosystems around the world. In particular, invasive species can lead to hotter and more frequent fires.

Invasive plants can also reduce fire frequency and fire intensity, but there are fewer examples of this occurring worldwide.

One of the main ways flammable invasive plants can have long-lasting impacts on an ecosystem comes from positive fire-vegetation feedbacks. Such feedbacks can occur when a flammable weed invades a less fire-prone ecosystem. By changing the available fuel the invader makes fires more likely and often hotter.

If the invading species has characteristics that allow it to outcompete native species after a fire, then it will further dominate the ecosystem. Such traits include thick bark, the ability to resprout following fire, or seeds that survive burning. This invasion will likely lead to more fires, changing the species composition and function of the ecosystem in a “fire begets fire” cycle. Extreme examples of this dynamic are where flammable grasses or shrubs invade forests, leading to loss of the forest ecosystems.

Mixed grills

We wanted to understand how invasive plants interact with other species when burned in combination. To explore the mechanisms underpinning such feedbacks, we examined how invasive plants might change the nature of a fire when burned together with native species.

We collected 70cm shoots of four globally invasive species (of both high and low flammability) and burned them in pairwise combinations with New Zealand native trees and shrubs to determine which characteristics of a fire could be attributed to the invasive plants.

Samples of Hakea sericea (foreground) and Kunzea robusta (rear) arranged on the grill of our plant barbecue.
Sarah Wyse, CC BY-ND

We found that overall flammability was largely driven by the most flammable species in the mixture, showing how highly flammable weeds could set in motion fire-vegetation feedbacks.

We established that a greater difference in flammability between the two species led to a larger influence of the more flammable species on overall flammability. This outcome suggests weeds that are much more flammable than the invaded community can have larger impacts on fire patterns.

Importantly, we also showed the influence of the highly flammable species was independent of its biomass, meaning highly flammable weeds may impact community flammability even at low abundances.

When we looked closer at the different components of flammability (combustibility, ignitability, consumability and sustainability) we found some important nuances in our results.

While the maximum temperature reached in our burns (combustibility) and the ignition speed (ignitability) were both most influenced by the more flammable species, consumability (the amount of biomass burned) and sustainability (how long the fire burns) were equally influenced by both the more flammable and less flammable species.

In short, more flammable weeds will cause a fire to ignite more quickly and burn hotter.

However, less flammable species can reduce the duration of a fire compared to when a more flammable species is burnt alone. These results could have important ecological implications, as the longer a fire burns the more likely it is to kill plants: low-flammability plants could reduce this impact.

Measuring how long a fire burns on our plant barbecue.
Tom Etherington, CC BY-ND

Managing weeds to reduce fire impacts

Even low abundances of highly flammable invasive weeds could set in motion positive fire-vegetation feedbacks that lead to drastic changes to ecosystems. If this result holds when our shoot-scale experiments are repeated using field trials, then land managers should work quickly to remove even small infestations of highly flammable species, such as gorse (Ulex europaeus) and prickly hakea (Hakea sericea).

Conversely, the role of low flammability plants in extinguishing fires further supports the suggestion that the strategic planting of such species across the landscape as “green firebreaks” could be a useful fire management tool.

The ConversationIn any case, our “mixed grill” study further highlights the role of exotic plants in fuelling hotter wildfires.

Tim Curran, Senior Lecturer in Ecology, Lincoln University, New Zealand; George Perry, Professor, School of Environment, and Sarah Wyse, Early Career Research Fellow, The Royal Botanic Gardens, Kew and Research Fellow, School of Environment

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

To fight the catastrophic fires of the future, we need to look beyond prescribed burning



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AAP Image/ Darren Pateman

James Furlaud, University of Tasmania and David Bowman, University of Tasmania

California is burning – a sentence we’ve heard far too often this year. Sydney is currently on bushfire alert, as firefighters battle a fire in the Hunter Valley region and temperatures are set to top 40℃.

A cocktail of factors, from climate change to centuries of ignoring indigenous burning practises, means that catastrophic fires are likely to become more common.


Read more: Dry winter primes Sydney Basin for early start of bushfire season


One of Australia’s favourite fire prevention measures is prescribed burning – using carefully controlled fires to clear out flammable materials. We’re almost obsessed with it. Indeed, it seems the outcome of every major inquiry is that we need to do more of it.

The Royal Commission inquiry that followed Victoria’s 2009 Black Saturday fires recommended that 5% of all public land in Victoria be treated per year – a doctrine that was subsequently dropped due to impracticality.

Yet our research, published today in the International Journal of Wildland Fire, modelled thousands of fires in Tasmania and found that nearly a third of the state would have to be burned to effectively lower the risk of bushfires.

The question of how much to burn and where is a puzzle we must solve, especially given the inherent risk, issues caused by smoke smoke and shrinking weather windows for safe burning due to climate change.

Why use computer simulations?

The major problem fire science faces is gathering data. Landscape-scale experiments involving extreme fire are rare, for obvious reasons of risk and cost. When a major bushfire happens, all the resources go into putting it out and protecting people. Nobody has the time to painstakingly collect data on how fast it is moving and what it is burning. We are therefore restricted to a few limited data sources to reconstruct the behaviour and impact of fire: we can analyse the scar on the landscape after a fire, look at case studies, or run simulations of computer models.

Most research on the effectiveness of prescribed burning has been at a local scale. We need to start thinking bigger: how can we mitigate the effect of multiple large fires in a region like Tasmania or Southeastern Australia? What is the cumulative effect of different prescribed burning strategies?

A large fuel reduction burn off on Hobart’s eastern shore.
Flickr/Mike Rowe, CC BY-NC

To answer these questions, we create models using mathematical equations to simulate the behaviour of fires across actual landscapes. These models include the effects of vegetation type, terrain and fuel loads, under specific weather conditions. If we simulate thousands of these fires we can get an idea of where fire risk is the highest, and how effective prescribed burning is at reducing that risk.

The island of Tasmania offers the perfect study system. Self-contained, with a wide array of vegetation types and fire regimes, it offers an ideal opportunity to see how fire behaves across a diverse landscape. Perhaps more interestingly, the island contains large areas of flammable landscape surrounding globally unique ecosystems and numerous towns and villages. Obviously, we cannot set fire to all of Tasmania in real life, but computer simulations make it possible!

So, encouraged by the Tasmanian Fire Service, who initiated our research, we simulated tens of thousands of fires across Tasmania under a range of prescribed burning scenarios.

Prescribed fire can be effective, in theory

The first scenario we looked at was the best-case scenario: what happens if we perform prescribed burning on all the vegetation that can handle it, given theoretically unlimited resources? It is possible this approximates the sustained and skillful burning by Tasmanian Aboriginal peoples.

Wildfire simulations following this scenario suggested that such an approach would be extremely effective. Importantly, we saw significant reductions in fire activity even in areas where prescribed burning is impossible (for example, due to the presence of people).

Unfortunately, this best-case approach, while interesting from a theoretical perspective, would require prescribed burning over more than 30% of Tasmania in one year.

We also analysed the effects of 12 more realistic scenarios. These realistic plans were less than half as efficient as the best-case scenario at reducing fire activity.

On average, 3 hectares of prescribed burning would reduce wildfire extent by roughly 1ha in grasslands and dry forests.

In other flammable Tasmanian vegetation types like buttongrass sedgelands and heathlands, the reduction in wildfire was even smaller. This is obviously better than no prescribed burning, but it highlights the fact that this is a relatively inefficient tool, and given the costs and potential drawbacks, should be used only where it is most needed.

This is a fundamental conundrum of prescribed burning: though it is quite effective in theory, the extent to which we would need to implement it to affect fire behaviour across the entire state is completely unachievable.

Therefore, it is imperative that we not just blindly burn a pre-ordained fraction of the landscape. Rather, we must carefully design localised prescribed burning interventions to reduce risk to communities.

We need a multi-tool approach

Our study has shown that while prescribed burning can be quite effective in certain scenarios, it has serious constraints. Additionally, while we analysed these scenarios under bad fire weather, we were not able to analyse the kind of catastrophic days in which the effect of prescribed burning is seriously reduced, with howling dry winds and stupefying heat.

Unfortunately, due to climate change, we are going to see a lot more catastrophic days in the future in Tasmania and indeed globally.

In Hobart this is of particular concern, as the city is surrounded by tall, wet eucalypt forests that have had fifty years grow dense understoreys since the 1967 Black Tuesday fires. These have the potential to cause some of the most intense fires on the planet should conditions get dry enough. Prescribed burning is impossible in these forests.


Read more: Where to take refuge in your home during a bushfire


To combat fire risk we must take a multi-pronged approach that includes innovative strategies, such as designing new spatial patterns for prescribed burning, manually removing fuels from areas in which prescribed burning is not possible, improving the standards for buildings and defensible spaces, and most importantly, engaging the community in all of this.

The ConversationOnly by attacking this problem from multiple angles, and through close collaboration with the community and all levels of government, can we effectively face our fiery future.

James Furlaud, PhD Student in Fire Ecology, University of Tasmania and David Bowman, Professor, Environmental Change Biology, University of Tasmania

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

Was Tasmania’s summer of fires and floods a glimpse of its climate future?


Alistair Hobday, CSIRO; Eric Oliver, University of Tasmania; Jan McDonald, University of Tasmania, and Michael Grose, CSIRO

Drought, fires, floods, marine heatwaves – Tasmania has had a tough time this summer. These events damaged its natural environment, including world heritage forests and alpine areas, and affected homes, businesses and energy security.

In past decades, climate-related warming of Tasmania’s land and ocean environments has seen dozens of marine species moving south, contributed to dieback in several tree species, and encouraged businesses and people from mainland Australia to relocate. These slow changes don’t generate a lot of attention, but this summer’s events have made people sit up and take notice.

If climate change will produce conditions that we have never seen before, did Tasmania just get a glimpse of this future?

Hot summer

After the coldest winter in half a century, Tasmania experienced a warm and very dry spring in 2015, including a record dry October. During this time there was a strong El Niño event in the Pacific Ocean and a positive Indian Ocean Dipole event, both of which influence Tasmania’s climate.

The dry spring was followed by Tasmania’s warmest summer since records began in 1910, with temperatures 1.78℃ above the long-term average. Many regions, especially the west coast, stayed dry during the summer – a pattern consistent with climate projections. The dry spring and summer led to a reduction in available water, including a reduction of inflows into reservoirs.

Left: September-November 2015 rainfall, relative to the long-term average. Right: December 2015-February 2016 temperatures, relative to the long-term average.
Bureau of Meteorology, Author provided

Is warmer better? Not with fires and floods

Tourists and locals alike enjoyed the clear, warm days – but these conditions came at a cost, priming Tasmania for damaging bushfires. Three big lightning storms struck, including one on January 13 that delivered almost 2,000 lightning strikes and sparked many fires, particularly in the state’s northwest.

By the end of February, more than 300 fires had burned more than 120,000 hectares, including more than 1% of Tasmania’s World Heritage Area – alpine areas that had not burnt since the end of the last ice age some 8,000 years ago. Their fire-sensitive cushion plants and endemic pine forests are unlikely to recover, due to the loss of peat and soils.

Meanwhile, the state’s emergency resources were further stretched by heavy rain at the end of January. This caused flash flooding in several east coast towns, some of which received their highest rainfall ever. Launceston experienced its second-wettest day on record, while Gray recorded 221 mm in one day, and 489 mm over four days.

Flooding and road closures isolated parts of the state for several days, and many businesses (particularly tourism) suffered weeks of disruption. The extreme rainfall was caused by an intense low-pressure system – the Climate Futures for Tasmania project has predicted that this kind of event will become more frequent in the state’s northeast under a warming climate.

Warm seas

This summer, an extended marine heatwave also developed off eastern Tasmania. Temperatures were 4.4℃ above average, partly due to the warm East Australian Current extending southwards. The heatwave began on December 3, 2015, and was ongoing as of April 17 – the longest such event recorded in Tasmania since satellite records began in 1982. It began just days after the end of the second-longest marine heatwave on record, from August 31 to November 28, 2015, although that event was less intense.

Anatomy of a marine heatwave. Top left: summer sea surface temperatures relative to seasonal average. Top right: ocean temperature over time; red shaded region shows the ongoing heatwave. Bottom panels: duration (left) and intensity (right) of all recorded heatwaves; the ongoing event is shown in red.
Eric Oliver

As well as months of near-constant heat stress, oyster farms along the east coast were devastated by a new disease, Pacific Oyster Mortality Syndrome, which killed 100% of juvenile oysters at some farms. The disease, which has previously affected New South Wales oyster farms, is thought to be linked to unusually warm water temperatures, although this is not yet proven.

Compounding the damage

Tasmania is often seen as having a mild climate that is less vulnerable to damage from climate change. It has even been portrayed as a “climate refuge”. But if this summer was a taste of things to come, Tasmania may be less resilient than many have believed.

The spring and summer weather also hit Tasmania’s hydroelectric dams, which were already run down during the short-lived carbon price as Tasmania sold clean renewable power to the mainland. Dam levels are at an all-time low and continue to fall.

The situation has escalated into a looming energy crisis, because the state’s connection to the national electricity grid – the Basslink cable – has not been operational since late December. The state faces the prospect of meeting winter energy demand by running 200 leased diesel generators, at a cost of A$43 million and making major carbon emissions that can only exacerbate the climate-related problems that are already stretching the state’s emergency response capability.

Is this summer’s experience a window on the future? Further study into the causes of climate events, known as “detection and attribution”, can help us untangle the human influence from natural factors.

If we do see the fingerprint of human influence on this summer, Tasmania and every other state and territory should take in the view and plan accordingly. The likely concurrence of multiple events in the future – such as Tasmania’s simultaneous fires and floods at either end of the island and a heatwave offshore – demands that governments and communities devise new strategies and mobilise extra resources.

This will require unprecedented coordination and cooperation between governments at all levels, and between governments, citizens, and community and business groups. Done well, the island state could show other parts of Australia how to prepare for a future with no precedent.

The Conversation

Alistair Hobday, Senior Principal Research Scientist – Oceans and Atmosphere, CSIRO; Eric Oliver, Postdoctoral Fellow (Physical Oceanography and Climate), University of Tasmania; Jan McDonald, Professor of Environmental Law, University of Tasmania, and Michael Grose, Climate Projections Scientist, CSIRO

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

Bushfires are pushing species towards extinction


Tim Doherty, Deakin University; Emma Burgess, The University of Queensland; Martine Maron, The University of Queensland, and Robert Davis, Edith Cowan University

Massive bushfires in recent months have tragically claimed people’s lives and destroyed their homes. These events are becoming more common as our warming and drying climate increases the frequency, intensity and extent of fires.

But these impacts aren’t just restricted to humans. Our native animals and plants are also affected by fire. Some species have even been pushed to the verge of extinction by the way fire patterns have changed. The International Union for the Conservation of Nature’s Red List identifies “fire and fire suppression” as a threat to more than 100 threatened species in Australia.

Recent bushfires in Victoria, Western Australia and Tasmania have all taken a devastating toll on threatened species and unique ecosystems.

Plant species threatened by fire (L to R): Andersonia pinaster, Athrotaxis cupressoides, and Banksia verticillata.
L to R: Sarah Barrett, brewbrooks/flickr (CC BY-SA 2.0, https://flic.kr/p/7g7BGb), Sarah Barrett

Burning biodiversity

Cape Arid National Park on WA’s south coast is home to the only known population of the critically endangered Western Ground Parrot. The parrot lives in unburned heathland, and its distribution has shrunk rapidly in recent decades.

Before last year’s fires, only 140 birds were thought to remain. Then in October and November a series of bushfires burned 90% of the species’ known habitat. It is not known how many birds may have survived the fires.

Also late last year, fires at Two People’s Bay Nature Reserve destroyed habitat of the critically endangered Gilbert’s Potoroo (the world’s rarest marsupial), as well as habitat of the threatened Noisy Scrub Bird, Western Bristlebird, Western Ringtail Possum, Quokka, and the plant Andersonia pinaster. Four populations of the rare Banksia verticillata were also burned in November at the nearby Torndirrup National Park.

These extreme fire events are also impacting species in southeastern Australia. In December, 2,500 hectares were burned in Victoria’s Otway Ranges. Native mammal populations in this region have been declining over recent decades, including that of the vulnerable New Holland Mouse. Such fires could worsen the outlook for these species, especially since foxes in the Otways are attracted to and increase their consumption of some mammals in recently burned areas.

The current burning of World Heritage forests in Tasmania is an equally concerning conservation catastrophe, and may be doing irreversible damage to these unique ecosystems.

Animal species threatened by fire (clockwise from top left): New Holland Mouse (Pseudomys novaehollandiae), Western Ground Parrot (Pezoporus flaviventris), Gilbert’s Potoroo (Potorous gilbertii), and Mallee Emu Wren (Stipiturus mallee).
Clockwise from top-left: Doug Beckers (flickr, CC BY-SA 2.0, https://flic.kr/p/6jpWxN), Alan Danks, Dick Walker and Gilbert’s Potoroo Action Group, Ron Knight (flickr, CC BY 2.0, https://flic.kr/p/diYjwY)

As part of its Threatened Species Strategy, the federal government has identified 20 threatened bird and 20 threatened mammal species for priority conservation action.

The list includes many species threatened by inappropriate fire regimes, such as Gilbert’s Potoroo, Western Ground Parrot, Mallee Emu Wren, South-eastern Red-tailed Black-Cockatoo, Western Ringtail Possum, Malleefowl, and Leadbeater’s Possum.

Halting extinction

But since these species evolved in a fire-prone environment, why is fire a problem for them now?

Not only are fires becoming more severe and frequent in parts of Australia, but for many species there is not much habitat left. Such species have already declined and are often reliant on habitat that hasn’t been burned for a long time, so a single fire can wipe out entire populations.

This creates complex ecological challenges for land managers and conservationists – especially where prescribed burning is used to reduce fire risk to people and their property.

Prescribed burning can be a valuable tool in protecting habitat from wildfire, but it must be science-based and carefully targeted. Until recently, Victoria had a policy to burn 5% of its land area every year, a practice that was threatening sensitive ecosystems and species, such as the endangered South-eastern Red-tailed Black Cockatoo. The recent lifting of the policy is therefore a major step away from arbitrary management targets and – hopefully – towards science-based conservation.

Other threats may have started the declines and made species more vulnerable to fire. These include habitat loss, disease and introduced predators.

Therefore, it is vital that conservation plans consider interactions between threats. When a species has only a handful of individuals remaining, captive breeding and the creation of insurance populations are sometimes necessary.

Climate change is expected to make fire patterns worse for wildlife in the future. We need political leadership on climate action if we are to understand and mitigate these impacts. Otherwise, we risk robbing future generations of the opportunity to see much of our amazing native wildlife that is currently threatened with extinction.

Only 1,500 South-eastern Red-tailed Black-Cockatoos remain, and too much fire is a major threat. © Bob McPherson

The authors acknowledge the Friends of the Western Ground Parrot Group, Gilbert’s Potoroo Action Group, and Sarah Barrett of the WA Department of Parks and Wildlife for photos and information.

The Conversation

Tim Doherty, Research Fellow, Deakin University; Emma Burgess, Researcher, The University of Queensland; Martine Maron, Associate Professor of Environmental Management, The University of Queensland, and Robert Davis, Senior Lecturer in Vertebrate Biology, Edith Cowan University

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

Fires are increasing in warming world, but a new model could help us predict them


Ritaban Dutta, CSIRO

Over the past decade, the frequency of bushfires in Australia has increased. The Forest Fire Danger Index – which measures the frequency and severity of the weather most conducive to fire – has increased dramatically since the 1970s, and particularly in the 1990s and 2000s. This – along with a great deal of other evidence – indicates that a major change in the climate is looming.

In a study published today in Royal Society Open Science, we show that bushfire frequency has increased by 40% over the past five years.

This is part of our work to better predict bushfires using weather information. We developed a model that can predict bushfires over a week-long period with an accuracy of 91%. While we can’t yet use this to predict fires definitively, it is a big step forward in planning for and predicting fires.

There is an urgent need for scientific research that can contribute to Australia’s future bushfire preparedness. The knowledge gained from this research could help save lives and property, underpin effective building codes and help land-management decisions.

Fire forecasting gets smart

We wanted to find bushfire “hotspots” – places where a bushfire might happen in the future based on recent weather patterns. They don’t show that a bushfire will definitely happen, and similarly we need to be careful that people don’t assume a fire won’t happen if there is no hotspot.

To do this we developed a model that combined data on fires (from satellite images) with data on climate, including soil moisture, dry fuel load, wind speed, temperature and humidity.

We are using a machine learning approach to model future bushfire hotspots – in short, a form of artificial intelligence that allows the model to learn on its own. Our model used other forms of learning to produce maps of bushfire hotspots.

Map showing predicted hotspots (green) and real fires (purple). Red dots show fires not predicted by the model.
Ritaban Dutta

Predicting hotspots

We tested our model by looking at bushfires retrospectively. Our predictions achieved 91% global accuracy. The analysis also indicates that, on a week-by-week basis, the frequency of Australian bushfires, particularly during summer months, has increased by 40% over the past five years.

We conducted extensive research in Australian bushfire history, to make sure the data on the conditions and behaviour of 36 major fires were correct.

Two types of Australian vegetation are prone to fire: grasslands and forests. We found that our model could predict both.

Fighting fires

Although new technologies are being developed to manage the growing number of unplanned bushfires in Australia, we do not have, and are never likely to have, a way to avert natural fire disasters.

The recent history of Australian bushfires indicates that the most effective way to save lives is early planned evacuation, combined with timely advice and alerts to the people potentially at risk.

Early estimation of the likely frequency of future bushfires, and accurate hot-spot estimation of the locations most likely to be affected could provide great support to land managers, and assist in reducing the damage caused.

But as yet, our system exists only as a research model. Its impact and effectiveness could only be fully evaluated if a real system were implemented as a decision support tool for land managers and emergency services, to accurately forecast the most likely bushfire hot spots, at a detailed and fine-grained resolution and a timely scale.

The Conversation

Ritaban Dutta, Senior Research Scientist and Research Project Leader, Data61, CSIRO

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