The phoenix factor: what home gardeners can learn from nature’s rebirth after fire


Kingsley Dixon, Curtin University

A startling phenomenon occurs after a bushfire tears through a landscape. From the blackened soil springs an extraordinary natural revival – synchronised germination that carpets the landscape in flowers and colour.

So what is it in bushfires that gives plants this kiss of life? The answer is smoke, and it is increasingly transforming everything from large-scale land regeneration to nurseries and home gardening.

The mystery of seed germination

Burnt plants survive bushfires in various ways. Some are protected by woody rootstocks and bark-coated stems; others resprout from underground buds. But most plants awaken their soil seed bank, which may have lain dormant for decades, or even a century.

However, this smoke-induced seed germination is not easily replicated by humans trying to grow the plants themselves. Traditionally, many native Australian flora species – from fringe-lilies to flannel flowers and trigger plants – could not be grown easily or at all from seed.

The fringe-lily, the seed of which has been found to germinate after smoke treatment.
Flickr

In recent decades this has meant the plants were absent from restoration programs and home gardens, reducing biodiversity.

In 1989, South African botanist and double-PhD Dr Johannes de Lange grappled with a similar conundrum. He was trying to save the critically rare Audonia capitata, which was down to a handful of plants growing around Cape Town. The seed he collected could not be germinated, even after heat and ash treatments from fire. Extinction looked inevitable.

But during a small experimental fire, a wind change enveloped de Langer in thick
smoke. With watering eyes, he realised that smoke might be the mysterious phoenix factor that would coax the seeds to life. By 1990 he had shown puffing smoke onto soil germinated his rare species in astonishing numbers.

The technique is simple. Create a smouldering fire of dry and green leafy material and pass the smoke into an enclosed area where seed has been sown into seed trays or spread as a thin layer. Leave for one hour and water sparingly for ten days to prevent the smoke from washing out of the seed mix. The rest is up to nature.

Diagram showing the various ways that smoke is applied to seeds.
Supplied by Simone Pedrini

Taking smoke germination to the world

Soon after the de Lange discovery, I visited the Kirstenbosch National Botanic Garden in Cape Town. I was shown a few trays of seedlings out the back – some from seeds treated with smoke, some without. The difference was stark. Smoke-treated seeds produced a riot of green, compared to others that resulted in sparse, straggling seedlings.

A tray of seedlings where seed was treated with smoke, left, compared to a non-treated tray.
Supplied by author

But was smoke just an isolated African phenomenon, I wondered? Would 150 years of frustrated efforts to germinate some of Australia’s most spectacular and colourful species – from grevillea and fan-flowers to rare native heaths – also be transformed by smoke?

At first, the answer appeared to be no, as every attempt with Australian wildflower seed failed. But after many trials, which I oversaw as Director of Science at the Western Australian Botanic Garden, success came in 1993. Extra time in the smoke house and a serendipitous failure in the automated watering system resulted in the germination of 25 different species with seedlings. Some were thought to have never been germinated by humans before, such as wild-picked yellow bells (Geleznowia verrucosa) or the giant feather rush (Loxocarya gigas).




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This discovery meant for the first time smoke could be used for difficult-to-germinate species for the home gardener and cut flower growers. These days more than 400 species of native seeds, and potentially more than 1,000, respond to smoke treatment. They include kangaroo paw, cotton-tails, spinifex, native bush food tomatoes and fragrant boronias.

Highway plantings, mine site restoration and, importantly, efforts to save threatened plant species now also benefit greatly from the smoke germination technique. For example, smoke houses are now a regular part of many nurseries, which also purchase smoke water to soak seeds for sowing later.

Kangaroo paw seeds respond well to smoke treatment.
Supplied by the author

In mine site restoration, direct application of smoke to seeds dramatically improves germination performance. This translates into multimillion-dollar savings in the cost of seed.

Smoke is also a powerful research tool used to audit native soil seed banks, which includes demonstrating the adverse affects of prescribed burning in winter and spring on native species survival.

Collaboration with research groups in the US, China, Europe and South America has expanded the use of smoke to germinate similarly stubborn seed around the world.

So what is smoke’s secret ingredient?

In 2013, an Australian research team made a breakthrough in determining which of the 4,000 chemicals in a puff of smoke resulted in such starting germination. They patented the chemical and published the discovery in the journal Science.

The smoke chemical, part of the butenolide group of molecules, was named karrikinolide, inspired by the local Indigenous Noongar word for smoke, karrik.

Karrikinolide is no shrinking violet of a molecule: just half a teaspoon is enough to germinate a hectare of bushland, which equates to 20 million seeds.




Read more:
How the land recovers from wildfires – an expert’s view


Smoke is sold to home gardeners and for commercial use in the form of smoke water, smoke-impregnated disks, or smoke granules. All contain the magical karrikinolide molecule.

Why not try it at home?

Home gardeners can try smoking their own seeds – but what you burn matters. Wood smoke can be toxic to seeds. Making your own smoke from leafy material and dry straw ensures you have the right combustible materials for germination.

At least 400 native seed species, and possibly up to 1,000, have been found to respond to smoke treatment.
Supplied by author

For the home gardener, having a bottle of smoke water on hand or constructing your own smokehouse can make all the difference to germinating many species – including those stubborn parsley seeds. To find out more, a webinar at this link shows you how to use smoke and even construct your own smoke apparatus.The Conversation

Kingsley Dixon, John Curtin Distinguished Professor, Curtin University

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

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Climate change is bringing a new world of bushfires


Dale Dominey-Howes, University of Sydney

Spring has barely arrived, and bushfires are burning across Australia’s eastern seaboard. More than 50 fires are currently burning in New South Wales, and some 15,000 hectares have burned in Queensland since late last week.

It’s the first time Australia has seen such strong fires this early in the bushfire season. While fire is a normal part of Australia’s yearly cycle and no two years are alike, what we are seeing now is absolutely not business as usual.




Read more:
Grim fire season looms but many Australians remain unprepared


And although these bushfires are not directly attributable to climate change, our rapidly warming climate, driven by human activities, is exacerbating every risk factor for more frequent and intense bushfires.

The basics of a bushfire

For some bushfire 101, a bushfire is “an uncontrolled, non-structural fire burning in grass, scrub, bush or forest”. This means the fire is in vegetation, not a building (non-structural), and raging across the landscape – hence, uncontrolled.

For a bushfire to get started, several things need to come together. You need fuel, low humidity (which also often means the fuel itself has a low moisture content and is easier to burn), and oxygen. It also helps to have an unusually high ambient temperature and winds to drive the fire forward.

In Australia, we divide bushfires into two types based on the shape and elevation of the landscape.

First are flat grassland bushfires. These are generally fast-moving, fanned by winds blowing across flattish open landscapes, and burn through an area in 5–10 seconds and may smoulder for a few minutes. They usually have low to medium intensity and can damage to crops, livestock and buildings. These fires are easy to map and fight due to relatively straightforward access.




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Second are hilly or mountainous bushfires. These fires are slower-moving but much more intense, with higher temperatures. As they usually occur in forested, mountainous areas, they also have more dead vegetation to burn and are harder to access and fight.

They burn slowly, passing through an area in 2-5 minutes and can smoulder for days. Fires in upper tree canopies move very fast. Mountainous bushfires actually speed up as they burn up a slope (since they heat and dry out the vegetation and atmosphere in front of the fire, causing a runaway process of accelerating fire movement).

Climate change and bushfire risk

To be clear, as previously reported, the current bushfires are not specifically triggered by climate change.

However, as bushfire risk is highest in warm to hot, dry conditions with low humidity, low soil and fuel load moisture (and are usually worse during El Niño situations) – all factors that climate change in Australia affects – climate change is increasing the risk of more frequent and intense bushfires.

Widespread drought conditions, very low humidity, higher than average temperatures in many places, and strong westerly winds driven by a negative Southern Annular Mode (all made worse by human-induced climate change) have collided right now over large areas of the eastern seaboard, triggering extremely unusual bushfire conditions – certainly catching many communities unawares before the start of the official bushfire season.




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Different regions of Australia have traditionally experienced peak bushfire weather at different times. This has meant that individual households, communities and the emergency services have had specific periods of the year to prepare. These patterns now seem to be breaking down, and bushfires are happening outside these regular places and times.

Map of bushfire seasons.
Bureau of Meteorology

New challenges for the emergency services

While experts recently forecast a worse-than-average coming bushfire season, the current emergency has essentially exploded out of nowhere.

Many Australian communities do know how to prepare but there is always some apathy at the start of bushfire season around getting households and communities bushfire-ready. When it’s still relatively cold and feeling like the last whisps of winter are still affecting us, bushfire preparation seems very far off.

Compounding our worsening bushfire conditions, we are increasingly building in bushfire-prone areas, exposing people and homes to fire. This tips the scales of risk further in favour of catastrophic losses. Sadly too, these risks always disproportionately affect the most vulnerable.




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With such extensive fires over wide areas, the current emergency points to an extremely frightening future possibility: that emergency services become more and more stretched, responding to fires, floods, storms, tropic cyclones and a myriad other natural hazards earlier in each hazard season, increasingly overlapping.

Our emergency services do an amazing job but their resources and the energy of their staff and volunteers can only go so far.

Regularly the emergency services of one area or state are deployed to other areas to help respond to emergencies.

But inevitably, we will see large-scale disasters occurring simultaneously in multiple territories, making it impossible to share resources. Our emergency management workforce report they are already stressed and overworked, and losing the capacity to share resources will only exacerbate this.

Immediate challenges will be to continue funding emergency management agencies across the nation, ensuring the workforce has the necessary training and experience to plan and respond to a range of complex emergencies, and making sure local communities are involved in actively planning for emergencies.The Conversation

Dale Dominey-Howes, Professor of Hazards and Disaster Risk Sciences, University of Sydney

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

Grim fire season looms but many Australians remain unprepared



Burnt out cars in Tingha, New South Wales, in February 2019.
AAP/Dave Hunt

Richard Thornton, Bushfire and Natural Hazards CRC

Bushfires are predicted to be worse than normal across much of Australia this summer but research shows many people, especially those in high-risk areas, remain unprepared.

The latest Australian Seasonal Bushfire Outlook shows the 2019-20 fire season has the potential to be an active season across the country, following a very warm and dry start to the year.

The east coast of Queensland, New South Wales, Victoria and Tasmania, as well as parts of southern Western Australia and South Australia, face above-normal fire potential. It means communities in those areas, and across Australia, should start planning their emergency fire response.

The ingredients for a bad fire season

Above-normal bushfire potential refers to the ability of a large fire to take hold. It takes into account recent and predicted weather for a particular area, the dryness of the land and forests, and recent fire history.

The year to date has been unusually warm and dry for large parts of Australia. In fact it has been the fifth-driest start to the year on record, and the driest since 1970. Some areas, such as New South Wales into southeastern Queensland, are into their third year of dry conditions.

Vast areas of Australia, particularly the east coast, have an above-normal fire potential this season.
BNHCRC

The warming trend means that above average temperatures now tend to occur in most years, and 2019 has followed this pattern. These high temperatures further dry the landscape and vegetation.




Read more:
The summer bushfires you didn’t hear about, and the invasive species fuelling them


An early start to the fire season has been declared in many areas across eastern Australia. The dry landscape means that any warm and windy conditions are likely to see elevated fire risk. However in some drought-affected areas, poor growth of grass and annual plants means that vegetation loads are reduced, which may lower the fire risk.

The climate outlook for the next few months is also a crucial factor. Of particular interest are the future tendencies of Pacific sea surface temperature associated with the El Niño-Southern Oscillation, as well as the Indian Ocean Dipole, major climate drivers over Australia.

Climate change doesn’t create bushfires, but can make them worse

Heat, drought, flood and fire are not new phenomena for Australia. What is different now is that there is an underlying 1℃ increase in average temperatures since industrial times began – the result of climate change – which means that the variability of normal events sits on top of that. So climate change alone doesn’t create a bad fire season, but can make the weather conditions conducive to very large and destructive fires.

A bushfire threatened homes near Lake Macquarie in August this year.
AAP/Darren Pateman

Weather records are routinely being broken and all indications are that temperatures will continue to increase.

We cannot be sure what this means for extreme hazards like bushfire. This is an area in critical need of further research into weather prediction, land planning, infrastructure development, population trends and community awareness.

Firefighting resources are finite

The distribution and readiness of firefighting resources are also considered when calculating fire potential.

In Victoria’s East Gippsland, for example, forests have been extremely dry for many years. If a fire were to start under bad conditions, there is a high likelihood it would grow too large for local resources, and they would need to call for extra support from elsewhere.




Read more:
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Fire seasons are lengthening and overlapping across states, and indeed across the globe. So we need to think of new ways of dealing with bushfires, floods, cyclones, and heatwaves. The old ways of sharing resources such as aerial firefighting equipment, and fire fighters between Australian states and other countries, may not always be possible. So we need to discover better ways to manage all our resources.

Overlapping fire seasons means the sharing of fire crews and equipment between states may not always be possible.
AAP

Be prepared, and get your kids involved

Research has identified significant trends of vulnerability linked to demographic changes, such as a growing and ageing population. For example, the population of those aged over 85 is predicted to double in the next 25 years. The general population is also increasingly shifting into traditionally hazard-prone areas such as forested or coastal rural areas.

Our research is consistently showing that many Australians, especially those in high risk areas, are not sufficiently ready for fire and have not established fire plans well ahead of time. For example, people may underestimate the risks to life and property if the fire danger is not rated as “catastrophic”. The research showed many properties were under-insured and some people overestimated the response capacity of fire services.

Experts say all Australians, not just those in high-risk areas, should prepare for the bushfire season.
AAP

So, make sure you’ve got a plan, talk about it with your family and ensure you have back up plans B, C and D. Include your children in planning to help them prepare, and don’t forgot about your pets and animals too.

Backed by the research, emergency warnings to people under the threat of a fire have been transformed in recent years. But do not wait for a warning, as it might be too late. Everyone should be aware of their surroundings.

The latest outlook report is the work of the Bureau of Meteorology and fire and land management agencies around the country, brought together by the Bushfire and Natural Hazards Cooperative Research Centre.

For more information on how to prepare and be ready for the fire season, consult your local fire service website.The Conversation

Richard Thornton, Chief Executive Officer, Bushfire and Natural Hazards CRC

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

The Amazon is on fire – here are 5 things you need to know



Huge fires are raging across multiple regions of the Amazon Basin.
Guaira Maia/ISA

Danilo Ignacio de Urzedo, University of Sydney

Record fires are raging in Brazil’s Amazon rainforest, with more than 2,500 fires currently burning. They are collectively emitting huge amounts of carbon, with smoke plumes visible thousands of kilometres away.

Fires in Brazil increased by 85% in 2019, with more than half in the Amazon region, according to Brazil’s space agency.

This sudden increase is likely down to land degradation: land clearing and farming reduces the availability of water, warms the soil and intensifies drought, combining to make fires more frequent and more fierce.




Read more:
Amazon rainforests that were once fire-proof have become flammable


1. Why the Amazon is burning

The growing number of fires are the result of illegal forest clearning to create land for farming. Fires are set deliberately and spread easily in the dry season.

The desire for new land for cattle farming has been the main driver of deforestation in the Brazilian Amazon since the 1970s.

Ironically, farmers may not need to clear new land to graze cattle. Research has found a significant number of currently degraded and unproductive pastures that could offer new opportunities for livestock.

New technical developments also offer the possibility of transforming extensive cattle ranches into more compact and productive farms – offering the same results while consuming less natural resources.

2. Why the world should care

The devastating loss of biodiversity does not just affect Brazil. The loss of Amazonian vegetation directly reduces rain across South America and other regions of the world.

The planet is losing an important carbon sink, and the fires are directly injecting carbon into the atmosphere. If we can’t stop deforestation in the Amazon, and the associated fires, it raises real questions about our ability to reach the Paris Agreement to slow climate change.

The Brazilian government has set an ambitious target to stop illegal deforestation and restore 4.8 million hectares of degraded Amazonian land by 2030. If these goals are not carefully addressed now, it may not be possible to meaningfully mitigate climate change.

3. What role politics has played

Since 2014, the rate at which Brazil has lost Amazonian forest has expanded by 60%. This is the result of economic crises and the dismantling of Brazilian environmental regulation and ministerial authority since the election of President Jair Bolsonaro in 2018.

Bolsonaro’s political program includes controversial programs that critics claim will threaten both human rights and the environment. One of his first acts as president was to pass ministerial reforms that greatly weakened the Ministry of the Environment




Read more:
Amazon deforestation, already rising, may spike under Bolsonaro


Regulations and programs for conservation and traditional communities’ rights have been threatened by economic lobbying.

Over the last months, Brazil’s government has announced the reduction and extinction of environmental agencies and commissions, including the body responsible for combating deforestation and fires.

4. How the world should react

Although Brazil’s national and state governments are obviously on the front line of Amazon protection, international actors have a key role to play.

International debates and funding, alongside local interventions and responses, have reshaped the way land is used in the tropics. This means any government attempts to further dismantle climate and conservation policies in the Amazon may have significant diplomatic and economic consequences.

For example, trade between the European Union and South American trading blocs that include Brazil is increasingly infused with an environmental agenda. Any commercial barriers to Brazil’s commodities will certainly attract attention: agribusiness is responsible for more than 20% of the country’s GDP.

Brazil’s continued inability to stop deforestation has also reduced international funding for conservation. Norway and Germany, by far the largest donors to the Amazon Fund, have suspended their financial support.

These international commitments and organisations are likely to exert considerable influence over Brazil to maintain existing commitments and agreements, including restoration targets.




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5. There is a solution

Brazil has already developed a pioneering political framework to stop illegal deforestation in the Amazon. Deforestation peaked in 2004, but dramatically reduced following environmental governance, and supply change interventions aiming to end illegal deforestation.

Environmental laws were passed to develop a national program to protect the Amazon, with clearing rates in the Amazon falling by more than two-thirds between 2004 and 2011.

Moreover, private global agreements like the Amazon Beef and Soy Moratorium, where companies agree not to buy soy or cattle linked to illegal deforestation, have also significantly dropped clearing rates.

We have financial, diplomatic and political tools we know will work to stop the whole-sale clearing of the Amazon, and in turn halt these devastating fires. Now it is time to use them.




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The Conversation


Danilo Ignacio de Urzedo, PhD candidate, University of Sydney

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

Catastrophic Queensland floods killed 600,000 cattle and devastated native species


Gabriel Crowley, James Cook University and Noel D Preece, James Cook University

In February, about 600,000 cattle were killed by catastrophic flooding across north Queensland’s Carpentaria Gulf plains.

The flood waters rose suddenly, forming a wall of water up to 70km wide. Record depths were reached along 500km of the Flinders River, submerging 25,000 square kilometres of country. Cattle were stranded. Many drowned.




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Even though cattleman Harry Batt lost 70% of his herd, he was more concerned about the wildlife. He said, “all the kangaroos, and bloody little marsupial mice and birds, they couldn’t handle it”.

Harry was right to be concerned. As our research, published today in Austral Ecology, reveals, floods sweeping Australia’s plains have disrupted native species for millions of years. Now, as climate change drives more intense flooding, we will see this effect intensify.

Flooding causes major disruptions to gene flow

February’s flood came ten years to the day after a far bigger flood on the adjoining river systems that submerged an area larger than Ireland. It was this flood that first drew our attention to the plight of native species.

Noel was asked by Northern Gulf Resource Management Group to survey wildlife in areas affected by the 2009 flood. Over the following four years, he found almost no ground-dwelling reptiles, despite them occurring elsewhere in the region. They appeared to have been washed away or drowned.

Biologists have long known that many species’ ranges are interrupted by the Gulf Plains. Hence, these floodplains are considered one of Australia’s most important biogeographic barriers: the Carpentarian Gap.

Many closely related species with a common ancestor are separated by this Gap, including the Golden-shouldered Parrot of Cape York Peninsula and the Hooded Parrot of the Northern Territory. They are thought to have separated around 7 million years ago.




Read more:
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The Gap also separates many other species, including birds, mammals, reptiles and butterflies, at the subspecies or genetic level. Even more species found on either side are just absent from the Gulf Plains.

Huge flooding across the Gulf Plains, including the Norman and Flinders Rivers, in February 2009.
NASA Worldview, CC BY-SA

Flood impacts are immense and under-appreciated

When biologists first tried to find a reason for these patterns, they only considered aridity. They proposed Australia’s arid zone expanded to the Gulf of Carpentaria during ice ages.

There is no evidence for this, but the misunderstanding is completely understandable.

Any dry-season visitor to the Gulf Plains will find a dry, inhospitable environment with few trees or shrubs for shade, cracked clay soils, and lots of flies. European explorers described the region as “God-forsaken”.

But it can be quite a different place in the wet season.

Rains in the Gulf are caused by the summer monsoonal troughs or cyclones. About once a decade, these generate massive downpours. Historical records show at least 14 major floods since 1870.

So, to us, it seemed floods rather than aridity could be the cause of the odd distributions of plants and animals.

We set out to see whether Noel’s findings could have been caused by flooding or whether other factors such as soil, vegetation or climate were more important.

We also wanted to know what other effects floods might have on the region’s ecosystem. Could floods, by eliminating trees and shrubs, be responsible for the hostile appearance of the region? Could ground-dwelling reptiles and birds be underrepresented, not just at Noel’s sites, but on floodplains across the area?

To find out, we divided the area into floodplains and higher-altitude land, and generated 10,000 random sites across the Gulf Plains. We extracted soil, vegetation and rainfall data from national information sources, and examined the patterns.

We found trees and shrubs were significantly less common on floodplains than on land above the flood zone, regardless of soil or rainfall, and tree cover was further reduced on cracking clays. We concluded the plain’s open, hostile appearance is caused by a combination of soils and flooding.

We then examined all gecko, skink and bird records from the Atlas of Living Australia.

We found ground-living reptiles and birds were much less common on the floodplains, regardless of vegetation or soil. As expected, reptiles were more sensitive to flooding than birds, which can fly to safety during floods.

Finally, we found the sites affected by the 2009 flood had significantly fewer geckos and skinks than other sites across the Gulf Plains.

Increased flooding from climate change could have major consequences

Our findings have evolutionary significance that extends into the future. Repeated disruption of species across their distributions affects gene flow and ultimately produces new species. If floods become more frequent, as expected under climate change, so might the rates at which new species form.

They also have serious land management implications. Climate change planning emphasises conserving river corridors as safe refuges from arid conditions. However, periodic scouring of many of the nation’s floodplains – expected to increase under climate change – means that this approach needs rethinking.




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We conclude that on the most arid occupied continent on Earth, unpredictable floods may cause the most disruption to the Australian plant and animal life.The Conversation

Gabriel Crowley, Adjunct Principal Research Fellow, James Cook University and Noel D Preece, Adjunct Asssociate Professor, James Cook University

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

Heatwaves and flash floods: yes, this is Britain’s ‘new normal’


Hayley J. Fowler, Newcastle University

“It’s hard to believe, isn’t it, that we had a heatwave just last week?”

Those words were spoken by a BBC news presenter, in front of graphic images of fire service rescues, as heavy rain caused floods and landslides which closed many roads and railway lines. In recent days there have dramatic floods across the north of England, particularly around Manchester, the Peak District and Yorkshire.

For me, this is personal, as I am from the worst affected area. I went to high school where people spent the night in their Civic Hall. Three miles away from where I grew up, a dam holding back Toddbrook Reservoir has been at risk of collapse and the town of Whaley Bridge was evacuated. But I’m not surprised that we are seeing flash flooding and I expect it to get worse in the future.

I am a professor at Newcastle University, where I lead a large research group focused on understanding changes to intense rainfall events and flash floods. Over the past eight years we’ve been working closely with colleagues at the UK Met Office to develop new very high-resolution climate models that can simulate these very intense summer storms and therefore predict what might happen in a warming climate.

Our models tell us that by 2080 summers in the UK will be much hotter and drier. Heatwaves will be more common. In fact a report released by the Met Office on the same day as the latest flash floods tells us that heatwaves are already happening more often. When Cambridge recently hit 38.7℃, the UK became one of 12 countries to break its national temperature record this year.

The world is warming. But although UK average summer rainfall is predicted to decrease, our models tell us that when it does rain it will be more intense than has been the case. Flash flooding in the UK is generally caused by intense rainstorms, where more than 30mm falls in an hour. Climate models predict these will happen five times more often by 2080.

Part of the reason for this is the simple fact that warmer air can hold more moisture. But that’s too simple: the availability of moisture also increases in areas close to warm oceans – warmer sea surface temperatures cause more moisture to be evaporated into the atmosphere, providing additional fuel for these intense storms. And here’s the scary bit: the Atlantic Ocean provides a vast source of moisture for storms in the UK.

But that’s not the whole story. Heavy, short rain storms are intensifying more rapidly than would be expected with global warming (what we call the Clausius-Clapeyron relationship). Research also suggests that more intense storms can themselves grow bigger, and with both the intensity of the rainfall and the spatial footprint of the storm increasing, the total rainfall in an “event” could double.

What’s more, the larger storms seem to have an ability to draw in more moisture from the surrounding area and become even more intense: the additional energy (heating) fuelling the uplift of air within the storm’s core draws in even more moisture from the surface, allowing them to grow even larger, with more potential for flooding. These also provide the perfect ingredients for large hail storms.

So, it is entirely consistent that we might expect both more heatwaves and more intense summer thunderstorms in a warmer climate. We also know which areas of the country are already susceptible to these flash floods from our analysis of historical records of flooding. Newspapers have reported on the dramatic impacts of these floods for centuries and this has allowed my team to reconstruct a flash-flooding history of the UK.

Certain parts of the country are highly vulnerable as their rivers respond quickly to rainstorms. These rivers tend to be found in steep, upland catchments underlain by non-permeable rocks, mainly in the north and west of the UK. High-risk catchments also include urban areas where the ground is also non-permeable, for entirely different reasons.

Many of the towns reported to have suffered “biblical” flooding recently have suffered repeated flooding through history, but perhaps not within living memory. For example, Whaley Bridge is mentioned twice in the flood chronologies for events in June 1872 and July 1881:

On 19th [June 1872] the Goyt was 12 to 14 feet above its normal level. At Whaley Bridge houses near the river were completely flooded and people were taken into the chapel and inns … in Macclesfield a woman and child were drowned when the river Bollin overflowed. Two reservoirs burst in the vicinity.

This rich archive of knowledge, including the prevalence of flooding in certain towns, even specific roads, is something we should draw upon in planning both the emergency response to these flash floods and for reducing their future impact. We can learn a lot from the past in how to manage the greater risks of flooding the future will bring.The Conversation

Hayley J. Fowler, Professor of Climate Change Impacts, Newcastle University

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