Category: flooding

Rivers flood, seas rise – and land faces erosion

Rivers flood, seas rise – and land faces erosion

By Tim Radford

Polar melting cannot be separated from farmland soil erosion and estuarine flooding. All are part of climate change.

Climate heating often ensures that calamities don’t come singly: so don’t forget what erosion can do.

In a warmer world the glaciers will melt ever faster to raise global sea levels ever higher. In a wetter world, more and more topsoil will be swept off the farmlands and downriver into the ever-rising seas.

And the pay-off of silt-laden rivers and rising sea levels could be catastrophic floods, as swollen rivers suddenly change course. Since many of the world’s greatest cities are built on river estuaries, lives and economies will be at risk.

Three new studies in two journals deliver a sharp reminder that the consequences of global heating are not straightforward: the world responds to change in unpredictable ways.

First: the melting of the ice sheets and the mountain glaciers. Researchers warn in the journal Nature Climate Change that if the loss of ice from Antarctica, Greenland and the frozen rivers continues, then climate forecasters and government agencies will have to think again: sea levels could rise to at least 17cms higher than the worst predictions so far.

“Avulsions are the earthquakes of rivers. They are sudden and sometimes catastrophic. We are trying to understand where and when the next avulsions will occur”

That means an additional 16 million people at hazard from estuarine floods and storm surges.

In the last 30 years, the flow from the Antarctic ice cap has raised sea levels by 7.2mm, and from Greenland by 10.6mm. Every year, the world’s oceans are 4mm higher than they were the year before.

“Although we anticipated the ice sheets would lose increasing amounts of ice in response to the warming of the oceans and the atmosphere, the rate at which they are melting has accelerated faster than we could have imagined,” said Tom Slater of the University of Leeds, in the UK, who led the research.

“The melting is overtaking the climate models we use to guide us, and we are in danger of being unprepared for the risks posed by sea level rise.”

Dr Slater and his colleagues are the third team to warn in the last month that observations of climate already match the worst-case scenarios dreamed up by forecasters preparing for a range of possible climate outcomes.

Erosion risk rises

The latest reading of glacial melt rates suggests that the risk of storm surges for many of the world’s greatest cities will double by the close of the century. But coastal cities – and the farmers who already work 38% of the terrestrial surface to feed almost 8bn people – have another more immediate problem.

In a warmer world, more water evaporates. In a warmer atmosphere, the capacity of the air to hold moisture also increases, so along with more intense droughts, heavier rainfall is on the way for much of the world. And the heavier the rain, or the more prolonged the drought, the higher the risk of soil erosion.

In 2015 the world’s farmers and foresters watched 43 billion tonnes of topsoil wash away from hillsides or blow away from tilled land and into the sea. By 2070, this burden of silt swept away by water or blown by wind will have risen by between 30% and 66%: probably more than 28 bn tons of additional loss.

This could only impoverish the farmland, according to a study by Swiss scientists in the Proceedings of the National Academy of Sciences. It could also impoverish people, communities and countries. The worst hit could be in the less developed nations of the tropics and subtropics.

But the flow of ever-higher silt levels into ever-rising seas also raises a new hazard: hydrologists call it river avulsion. It’s a simple and natural process. As conditions change, so rivers will naturally change their flow to spill over new floodplains and extend coastal lands.

Survival in question

But river avulsions can also be helped along by rising sea levels. Since 10% of humanity is crowded into rich, fertile delta lands, and since some of the deadliest floods in human history – two in China in 1887 and 1931 claimed six million lives – have been caused by river avulsions, the question becomes a matter of life and death.

US scientists report, also in the Proceedings of the National Academy of Sciences, that rising sea levels alone could make abrupt river avulsion more probable, especially as delta lands could be subsiding, because of groundwater and other extraction.

The dangers of avulsion are affected by the rate of sediment deposit in the river channels, and this is likely to rise with sea levels. This in turn raises the level of the river and eventually a breach of a levee or other flood defence will force the river to find a swifter, steeper path to the sea.

Cities such as New Orleans and the coastal communities of the Mississippi delta are already vulnerable. “Avulsions are the earthquakes of rivers,” said Michael Lamb, of California Institute of Technology, one of the authors.

“They are sudden and sometimes catastrophic natural events that occur with statistical regularity, shifting the direction of major rivers. We are trying to understand where and when the next avulsions will occur.” – Climate News Network


This article was originally posted on The Climate News Network.
250 million coastal dwellers will face rising floods

250 million coastal dwellers will face rising floods

By Tim Radford

Once again, researchers confirm that coastal dwellers can expect worse floods, more often and more expensively.

In the next 80 years flooding around the planet’s land masses is likely to rise by almost 50%, endangering many millions of coastal dwellers.

If humans go on burning ever greater volumes of fossil fuels, while destroying ever more natural forest, then another 77 million people could be at risk of flooding, a rise of 52%.

And these floods – increasingly frequent and extending over greater areas – will put at risk cities, homes, resorts and industries valued at more than $14 trillion (£10.7tn).

This sum alone is worth 20% of global gross domestic product, the economist’s preferred indicator of economic health and wealth, according to a new study in the journal Scientific Reports.

The researchers built their argument on historic data from 681 tide-gauge stations around the world to model the growing hazard at 10,000 coastal locations.

“Compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change”

They conclude that the land area exposed to extreme flood will increase by more than 250,000 sq kms – an increase of 48% – to 800,000 sq kms, a threat to 252 million people.

“A warming climate is driving sea level rise because water expands as it warms, and glaciers are melting. Climate change is also increasing the frequency of extreme seas, which will further increase the risk of flooding,” said Ebru Kirezci of the University of Melbourne, Australia, who led the study.

“What the data and our model are saying is that compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change.”

None of this should come as a surprise to civic authorities, governments, hydraulic engineers and oceanographers: researchers have been warning for years that coastal floods driven by global heating will end up costing colossal and seemingly ever increasing sums.

On a global scale, and on regional examination, the story remains the same, and wealthy and developed societies in Europe and the US face the same rising tide of hazard as the world’s poorest in the crowded coastal cities of Africa and Asia.

Estimate too low?

A mix of more extreme storms and storm surges, combined with ever higher sea levels, will sweep away the world’s beaches and turn millions of comfortable US citizens into climate refugees.

It is even possible that researchers have under-estimated the hazard, simply because satellite-based measurements may have misread precise land elevation: in some cases, too, coasts are sinking independently of sea level rise.

The latest study identifies a series of flood “hotspots” around the world. These include south-eastern China, Australia’s Northern Territory, Bangladesh, West Bengal and Gujarat in India, the US states of North Carolina, Virginia and Maryland, and north-west Europe including the UK, northern France and northern Germany. The new map of risks takes no account of existing flood defences, but highlights the levels of threat to come.

“This is critical research from a policy point of view, because it provides politicians with a credible estimate of the risks and costs we are facing, and a basis for taking action,” said Ian Young, an engineer at the University of Melbourne, and a co-author.

“This data should act as a wake-up call to inform policy at global and local government levels so that more flood defences can be built to safeguard coastal life and infrastructure.” – Climate News Network


This article was originally posted on the Climate News Network.
Photo of New Orleans, after Hurricane Katrina had passed over. Image: By Master Sgt Bill Huntington, USAF  (public domain), via Climate Visuals
Rising heat affects Europe’s floods and droughts

Rising heat affects Europe’s floods and droughts

By Tim Radford

Patterns of Europe’s floods and droughts are starting to change: each could be more extreme, and far likelier with rising heat.

Climate change has begun to affect the pattern of Europe’s floods. The past three decades have seen “exceptional” flooding, say Austrian scientists who have worked their way through documentary records for the last 500 years.

At the same time, heat and drought affecting the continent are on the increase. The summer of 2018 broke all records for Germany, Austria and Switzerland, and by 2019 many trees in Europe’s forests were partly or entirely dead. And by 2085 rainfall could decline by a fifth, Swiss ecologists report, to alter the make-up of the forests dramatically.

Both findings are consistent with the big picture of climate change worldwide: wet seasons will become ever wetter; dry seasons too will become more extreme, according to US researchers in a third separate study.

All attempts to establish climate records involve careful interrogation of the past. Günter Blöschl of Vienna’s University of Technology and colleagues report in Nature that they sifted evidence from mountain lake beds, floodplains and 500 years of contemporary documents to identify decades more than usually rich in floods.

The floods of 1990 to 2016 in Western and Central Europe have been among the worst in history. To make sure of such a claim, the researchers identified periods of calamitous inundation across the whole region in the late 16th century and again in the 17th; and in the 18th and early 19th centuries.

“We should be preparing for the future by improving the technology to efficiently use water for crops”

If these episodes had anything in common, bygone floods happened when air temperatures were lower: fewer of them, too, happened in the summer.

“This finding seems to contradict the observation that, in some areas such as in the northwest of Europe, the recent warmer climate is aligned with larger floods,” Professor Blöschl said. “Our study shows for the first time that the underlying mechanisms have changed.

“While in the past floods have occurred more frequently under colder conditions, the opposite is the case now. The hydrological conditions of the present are very different from those in the past.”

Now, 55% of Central European floods happen in the summer, compared with 41% in previous centuries. It’s a message for planners, city chiefs and governments across the region: flood management is going to have to adapt.

So, too, is forest and woodland management, say scientists in Switzerland and Germany, who have been measuring changes in the canopies of their forests.

Growing vulnerability

For most of Europe, the single most extreme heatwave has been that of 2003: that is, until 2018. The sustained heat and aridity made temperatures in the growing season of 2018 on average 1.2°C higher than 2003, and 3.3°C higher than the average from 1961-1990.

Woodland foliage showed signs of drought stress. Leaves wilted, aged and dropped much earlier, and by 2019 many trees were dead, or partly dead. Those that survived were more vulnerable to beetle or fungal pests. Losses included beech, long considered the most drought-resistant.

Ten out of the 12 hottest growing seasons in the last 120 years have all happened this century. Climate forecasts already predict more of the same, with precipitation falling by a fifth by 2085. Foresters will have to think again about woodland design.

“Spruce was most heavily affected. But it was a surprise for us that beech, silver fir and pine were also damaged to this extent,” said Ansgar Kahmen of the University of Basel in Switzerland.

“We still need to study which tree species are good in which combinations, including from a forestry perspective. That will take time.”

Keeping Paris promise

And worldwide, farmers, foresters and water managers can also expect more of the same. As temperatures rise worldwide, dry seasons will tend to become drier, and wet seasons wetter.

US researchers report in the journal Nature Communications that they divided the world into nine land regions, and looked at annual rain or snowfall and how this fluctuated through the seasons in each of the nine from 1971 to 2000. They then looked at future temperature predictions for the rest of the century to see what happened to water availability.

The best outcome for relatively stable water supplies would be if nations could act to limit the planet’s average global temperature rise to no more than 2°C by 2100, in line with a promise made by 195 governments in Paris in 2015.

At higher temperatures the predicted scatter of flood and drought became more extreme. Once again, the message is: start planning. “We need to take precautions to optimally use how much water we have,” said Ashok Mishra of Clemson University in South Carolina.

“As the climate changes and population increases, we should be preparing for the future by improving the technology to efficiently use water for crops.” − Climate News Network


Cover photo by Villy, via Wikimedia Commons.
This article was originally posted on the Climate News Network.
Letting rivers run wild could reduce UK flooding – new research

Letting rivers run wild could reduce UK flooding – new research

By Neil Entwistle and George Heritage

The UK government currently spends £2.6 billion on flood defences in England, and that amount is set to double by 2026. Flooding in February 2020 showed how that’s likely to be a good investment, as climate change drives warmer and wetter weather each winter. But when it comes to managing rivers to prevent flooding in towns and cities downstream, we’re often our own worst enemy.

After the second world war, Britain embarked on a mission to reconstruct its rivers. Workers cut ditches to drain moorland, making it suitable for livestock farming. Looping rivers which once wound lazily through floodplains – flooding these areas once every two years or so – were straightened into rigid channels. River beds were dredged to deepen them and banks excavated to make them steeper, an unnatural situation that takes routine management to maintain.

The idea behind all of this was to reduce flooding by increasing the speed at which water moves downstream. But this also increased the power of rivers to move sediment. Gravels and cobbles dash along these modified and heavily managed rivers, accumulating where the water slows down, as it moves through towns and cities. Here, the river bed swells as sediment piles up, increasing local flood risk.

Flooding in Carlisle, December 2015. Environment Agency geomatics group, Author provided

Over 60% of the UK’s watercourses have been transformed in this way, changing the fundamental character of many British rivers – and the natural processes that would usually govern them – over just a few generations. In a new study, we found that doing nothing is often a better course of action for reducing flooding than these heavy handed attempts to mechanically alter rivers.

Going with the flow

We studied the River Caldew in Cumbria, which has caused three major floods in nearby Carlisle since 2010. Satellite data showed that straightening, deepening and embanking was common along the river between 2005 and 2016. Very little sediment was spotted in the river and across the floodplain, suggesting that almost all of it was being funnelled downstream towards Carlisle.

During this time, the channel through the city was widened in the hope that this would cause flood water to spread out and lose energy. But this only increased the problem of sediment building up within the river, creating a shallower channel through Carlisle that’s prone to overflowing.

A stretch of the Caldew near Mosedale in 2003. The channel is fairly rigid and surrounded by managed grassland. Google Earth, Author provided

Outside of the city, in parts where maintenance has been relaxed, the river has begun to return to a more natural state. Multiple “wandering” channels can now be seen alongside wide areas of deposited gravel. This is encouraging, as it suggests that the main river and its floodplain are reconnecting, allowing the sediment it transports to fall out of the channel and collect upstream.

We found that rivers which are allowed to behave more naturally are better at locking up sediment upstream, rather than letting it accumulate in unnaturally high quantities in flood-prone towns and cities. If more rivers are allowed to behave naturally and develop this way, it could help reduce future flooding.

The Caldew at Cummersdale in 2018. Note the variety of vegetation and increased gravel. Google Earth, Author provided

This hands-off approach to managing rivers is also much cheaper than hard engineering and brings a wealth of environmental benefits with it. The wandering channel system that’s evolving on the River Caldew has the greatest variety of features and habitats across the entire watercourse.

There are gravel bars, deep pools, floodplain wetlands, ponds and river cliffs. This diversity provides greater spawning habitat for fish, and cooler refuges for their fry. The open water habitats benefit amphibians, the trees and shrubs help kingfisher hunt and sand martins can nest in the river cliffs. Beetles and spiders scurry in the shingle, earning this wilder stretch of the Caldew a designation as a site of special scientific interest.

The last 75 years have seen many UK rivers change beyond recognition. The way we manage them in future must look very different. Relaxing our iron grip and allowing natural processes to flourish on rivers once more could be our best hope for reducing flooding, while reviving lost ecosystems rich in native wildlife.


This article was originally posted on The Conversation.

Cover photo from Wikimedia Commons.

Managed retreat: Moving 1 million US homes out of flood zone could save $1 trillion dollars

Managed retreat: Moving 1 million US homes out of flood zone could save $1 trillion dollars

By Will Bugler

A US-government study has found that the country could save $1 trillion dollars by removing around a million homes from flood-prone areas. The report indicates that government schemes to buy and demolish homes at high risk of repeated flooding, moving residents to higher ground, should be expanded. The report notes that climate change will drive flood risk to real estate even higher in the coming decades and warns that without action financial losses will climb substantially.

The report says that buyout programmes are essential to minimise exposure to flood risk. However, existing schemes operated by the Federal Emergency Management Agency (FEMA) are hampered due to funding shortages and the reluctance of homeowners to move.

“Flooding is the country’s biggest risk, and we just have all of these homes in the floodplain that keep getting repetitive losses,” said Keith Porter, one of the study’s authors and a structural engineering researcher at the University of Colorado. “We never should have been building in the floodplain in the first place. It’s time to solve that problem.”

According to the report, while a nationwide buyout programme would cost around $180 billion, it could save around nine times that amount – $1.6 trillion – over a 100-year period. Savings would accrue thanks to reduced costs to public disaster programmes and avoiding property damage reducing pay-outs through federally subsidised flood insurance schemes.

The report found that moving properties out of the flood zone through a buyout scheme was by far the most cost-effective way to reduce risk, saving $6.50 for every $1 spent. Other flood related protection measures such as levees and home adaptations still represented value, but were much more costly, saving $2 for every $1 spent.

The findings are important, as federal agencies consider the best course of action to reduce climate risks, faced with mounting costs from properties that are flooded repeatedly. FEMA’s National Flood Insurance Program ensures that homeowners that would otherwise be refused flood insurance can continue to insure their properties. However, “repetitive-loss properties” (those that flood repeatedly, year after year) are becoming increasingly burdensome to the programme. The government has resisted cutting funding for the flood insurance programme, as that would increase premium pay-outs considerably, or leave homes uninsurable.

A copy of the report can be found here.


Cover photo by Sandra Seitamaa on Unsplash
US coasts face far more frequent severe floods

US coasts face far more frequent severe floods

By Tim Radford

A new study of high-water levels on US coasts in 200 regions brings ominous news for those who live in vulnerable towns and cities.

By 2050, floods expected perhaps once every 50 years will happen almost every year in nearly three fourths of all the coasts under study.

And by 2100, the kind of extreme high tides that now happen once in a lifetime could wash over the streets and gardens of 93% of these communities, almost every day.

The message, from researchers led by the US Geological Survey, is that sea levels will go on rising steadily by millimetres every year, but the number of extreme flooding events could double every five years.

Researchers outline their argument in the journal Scientific Reports. They looked at the data routinely collected from 202 tide gauges distributed around the US coasts and then extended the tidal levels forward in time in line with predictions based on global sea level rise that will inevitably accompany ever-increasing global average temperatures, driven by greenhouse gas emissions from fossil fuel use.

“The impact of this finding bears repeating: sea level rise will likely cause ‘once-in-a-lifetime’ coastal flooding events to occur nearly every day before 2100”

Other scientists have warned that the damage from coastal flooding, storm surges and marine invasion will rise to colossal levels by the century’s end, that routine high-tide floods will become increasingly common, and that up to 13 million US citizens now in coastal settlements could become climate refugees.

But researchers based in Chicago, Santa Cruz and Hawaii wanted more than that: they wanted to know what sea level rise will do, as the waters lap ever higher, from year to year.

“Sea level rise is slow, yet consequential and accelerating,” they point out. “Upper end sea level rise scenarios could displace hundreds of millions of people by the end of the 21st century. However, even small amounts of sea level rise can disproportionately increase coastal flood frequency.”

The researchers selected 202 sites, most of them in sheltered harbours or bays, for their tide data: that way their record reflected the highest tides and storm surges, but not the haphazard readings of waves.

They concentrated on what they called “extreme water-level events” of the kind that happened once every 50 years, because most US coastal engineering work is based on that kind of hazard frequency. And then they started doing the calculations.

Exponential hazard growth

For nine out of 10 locations, the difference between the kind of flood that happened every 50 years and the sort that occurred maybe once a year was about half a metre. For 73% of their chosen tide gauges, the difference between the daily highest tide and the once-every-50-years event was less than a metre. Most projections for sea level rise worldwide by the end of the century are higher than a metre.

Once the researchers had set their algorithms to work, they found that even in median sea-level rise scenarios, the hazards grew exponentially. They found that all tidal stations would by 2050 be recording what remain for the moment 50-year events, every year. When they set the timetable to 2100, 93% of their locations would be recording a once-in-50-years flood every day.

“The impact of this finding bears repeating: sea level rise will likely cause ‘once-in-a-lifetime’ coastal flooding events to occur nearly every day before 2100,” they warn.

This would have profound consequences for what they call extreme events. And even in ordinary circumstances, beaches are increasingly likely to be washed away, and cliffs eroded.

The researchers conclude: “Our society has yet to fully comprehend the imminence of the projected regime shifts in coastal hazards and the consequences thereof.”


This article was originally posted on the Climate News Network.
Cover image: October 2012: Hurricane Sandy visits Manhattan. Image: By Beth Carey, via Wikimedia Commons
Even looking at flood maps can’t convince coastal residents their homes will be underwater

Even looking at flood maps can’t convince coastal residents their homes will be underwater

By Risa Palm and Toby W. Bolsen

Advertisers understand that providing consumers with the facts will not sell products. To get people to stop and pay attention, successful advertising delivers information simply and with an emotional hook so that consumers notice and, hopefully, make a purchase.

Climate communication scientists use these same principles of messaging—visual, local, and dramatic—to provide facts that will get the public’s attention. Such messaging is intended to help people understand risk as it relates to them, and perhaps change their behavior as a result.

As social scientists studying the effectiveness of climate change communication strategies, we became curious about a particular message we found online. Some houses advertised for sale in South Florida were accompanied by banner ads with messages such as “Flooding hurts home value. Know more before you buy. Find out for free now.” The ads were sponsored by the First Street Foundation through its website FloodIQ.com. The nonprofit foundation provides detailed aerial photos of present and future flooding as a consequence of rising sea level.

My colleague and I decided to survey residents of coastal South Florida to better understand how information affected their attitudes and opinions. Did these messages developed by a nonprofit organization change the perceptions of coastal residents who live in low-lying areas about the threat of coastal flooding as a result of sea-level rise?

Defining the danger to property by zip code

Many studies of climate change communication and response have been based on national surveys or more local reviews of counties and states susceptible to a range of coastal flooding. We focused our survey on a single region and a population at greatest risk: those who live in zip codes along the South Florida coast where the probability of flooding in local neighborhoods is extremely high.

Maps can be a way to see potential flood risk. [Image: floodiq/courtesy of the author]

With permission of the First Street Foundation to reproduce their maps that represent what flooding in the future might look like, we developed a survey to understand the effectiveness of tailored messages. How would this messaging impact residents’ beliefs about climate change and sea-level rise? We also asked if residents believed their communities and homes were at risk.

We surveyed more than 1,000 residents living in 166 zip codes in South Florida between October and December of 2018. All those surveyed were at risk from either the direct or indirect effects of flooding to their homes, including a decrease in property values, as coastal property is perceived as a less desirable destination.

We sampled residents of seven metropolitan areas, including Tampa-Saint Petersburg-Clearwater, Fort Myers, Key West, Miami-Dade County, Fort Lauderdale, West Palm Beach and Palm Beach, and Vero Beach. Half the sample received a map of their own city, rendered at a scale so that their city block was visible. The maps illustrated what could happen just 15 years from now at the present rate of sea-level rise if there were a Category 3 hurricane accompanied by storm-surge flooding.

[Photo: Asael Peña/Unsplash]

Does visual information make a difference?

The study was intended to assess how residents might perceive the vulnerability of their property and their communities to severe storms. We asked residents about their political affiliation and their support for policies such as zoning laws, gasoline taxes, and other measures to address climate change.

Surprisingly, we found that those who had viewed the maps were, on average, less likely to say they believed that climate change was taking place than those who had not seen the maps.

Further, those who saw the maps were less likely than those survey respondents who had not seen the maps to believe that climate change was responsible for the increased intensity of storms. Respondents who classified themselves as Republicans had the strongest negative responses to the maps.

Those who saw the maps were no more likely to believe that climate change exists, that climate change increases the severity of storms, or that sea level is rising and related to climate change. Even more dramatically, exposure to the scientific map did not influence beliefs that their own homes were susceptible to flooding or that sea-level rise would reduce local property values.

Consistent with national surveys, party identification was the strongest predictor of general perceptions of climate change and sea-level rise. However, the majority of homeowners denied that there was a risk to their property values, regardless of political affiliation.

What does it take to change minds?

We believe that the motivation of our respondents, their underlying beliefs when forming an opinion, is important when reflecting on these survey results. Specifically, people often process information or learn in a way that protects their existing beliefs or their partisan leanings.

In the case of our respondents’ general beliefs about climate change and its connection to sea-level rise, those who belonged to the Republican Party may have dismissed the maps either because they challenged their party’s stance on the issue or because they did not view the information as credible given their prior views. In the case of our respondents’ views about the future effects of sea-level rise on property values, all of the homeowners we surveyed, regardless of their partisanship, may have been motivated by their personal financial interests to reject the notion that sea-level rise would reduce their own property values.

It is important to emphasize that targeted information about climate change may lead to unintended effects. While accurate and easily absorbed information is important, it will take a much more nuanced approach to change the way people understand information. As advertisers well know, it takes more than facts to sell any product.


This article was originally published on The Conversation.
Cover photo by Epicurrence on Unsplash
The flooding emergency in Northern England is a policy failure not a freak of nature

The flooding emergency in Northern England is a policy failure not a freak of nature

By Will Bugler

Last week the government declared a national emergency as devastating floods affected parts of Northern England. Communities living on the River Don were particularly badly affected. The speed of the river’s response to a period of very intense rainfall seemingly caught authorities off guard. People were forced to evacuate their homes, businesses were forced to close their doors, and one person lost their life. The tragedy of these floods is compounded by the fact that they were both predicted and preventable. Their impacts represent a failure of policy.

Residents living in the flood affected areas have been in this position before. The River Don has burst its banks on several occasions, causing devastating flooding in 2007, then again in 2012

The previous severe floods provided ample warning of the vulnerability of communities to flood risk. This was reinforced by the UK Government’s own Climate Change Risk Assessments in 2012 and 2017. In 2012, Acclimatise led the work for part of the Risk Assessment, the document explicitly warns that “we currently expect a shift towards generally wetter winters, and a greater proportion of precipitation to fall as heavy events.” Flooding was also identified as a top risk for each of the sectors analysed in the report. Five years later in 2017, the UK Climate Change Risk Assessment Evidence Report presented “compelling evidence that climate change may lead to increases in heavy rainfall and significantly increased risks from fluvial and surface flooding”.

Image 1: The Adaptation Sub-Committee’s assessment of the top six areas of inter-related climate change risks for the UK. Source: Committee on Climate Change (2016) UK Climate Change Risk Assessment 2017 Synthesis Report, www.theccc.org.uk/uk-climate-change-risk-assessment-2017/synthesis-report/

One of the businesses flooded this year was the Meadowhall Shopping Centre in Sheffield. The Centre was featured in a 2007 Acclimatise report on climate risks to commercial property after it was badly flooded that year. The risks that flooding poses are not just foreseeable, they are foreseen and even experienced.

Image 2: An excerpt from Acclimatise’s report Understanding the investment implications of adapting to climate change (2007) which featured the Meadowhall Shopping Centre as a case study. http://www.acclimatise.uk.com/wp-content/uploads/2018/01/Acclimatise_USS_Commercial_Property_Final_Report_Oct09.pdf

Data from the UK Met Office shows the amount of rain from extremely wet days has increased by 17%, when comparing 2008-17 records with those from 1961-90. They calculate that an extended period of extreme winter rainfall in the UK is now about seven times more likely because of climate change.

A lack of action

Despite these repeated warnings, government action on flooding has been piecemeal. According to the government’s official advisers, the Committee on Climate Change there were no areas where the government was preparing properly for climate impacts. This is evident from the reduction in staff numbers working in key departments. In 2013 the number of staff working directly on climate adaptation at Defra was counted in dozens, by 2018 only around five remained. Government support for important services including the UK Climate Impacts Programme, the Environment Agency’s Climate Ready programme and the Regional Climate Change Partnerships was also cut, and reporting on adaptation, mandatory in 2011, has since been made voluntary.

This year’s Committee on Climate Change’s progress report on the government’s record on flooding was damning. It found that “vulnerability and exposure to climate change are increasing across a range of priority areas; including terrestrial and freshwater habitats; development in flood risk areas; risks to health from heat and cold; and risks to health from changes in air quality. Urban greenspace, which has a host of benefits for reducing flood and heat risks, continues to decline, from 63% of urban area in 2001 to 55% in 2018. The proportion of impermeable surfacing in towns and cities, which increases flood risk, has risen by 22% since 2001.”

Building flood resilience

As implied by the Committee on Climate Change’s report, dealing with flood risk requires a systemic approach in order to be truly effective. After severe flood events in the UK, there are a lot of calls for measures such as flood walls and levees to be constructed and for rivers to be dredged. Treating the symptoms of flooding in this way is unlikely to be effective in the face of climate change.

In a 2014 report on dredging as an approach for flood management, the Chartered Institute of Water and Environmental Management (CIWEM) said that “claims that the widespread use of dredging can act as a flood prevention measure are not only unsupported by both science and evidence, they are a cruel offer of false hope to those living in flood prone communities.”

Dredging targets just one small part of the hydrological system (the river), temporarily increases capacity and the speed of flow of the water. This can have serious unintended consequences for towns as flood waters move faster through them.

Only a small proportion of water in a river basin is held in the river itself. An effective flood prevention strategy should take a whole systems approach, implementing measures that slow the flow of water as it moves through the catchment. These might include tree planting in upland areas, more green spaces in cities, more water stores and floodable areas outside of towns, and improved farming practices to prevent runoff.

The floods on the River Don this year were made a lot worse by poor land management in the Peak District and the upland areas in the Pennines. Over the past decades the areas have seen huge amounts of peat cutting, drainage and heather burning. With nothing to stop it the water now runs very quickly from the hills into stream and river channels. Flooding remains one of the most significant climate risks to the UK. Without significant investment in systemic flood resilience building, events like those experienced by the residents living along the River Don will continue.


Cover photo of The River Don, in Attercliffe Sheffield. Photo from Dan Cook Archived on Flickr
From droughts to floods: the cost of climate change for India continues to mount

From droughts to floods: the cost of climate change for India continues to mount

By Devika Singh

India is one of the most climate vulnerable countries on Earth. A land of such diverse topography and microclimates, it is exposed to a wide spectrum of climate risks. The seemingly endless oscillation from extreme heat and drought to extreme rain and floods, has left the country counting the cost of climate change in lost lives, livelihoods and in dollars. In India, economic losses from weather related events have doubled over the last thirty years. In the ten years from 2008 to 2017 the country suffered losses of US$ 45 billion, compared with US$ 20 billion from 1988-1997. In 2017, damages from climate related events globally reached a record high of US$ 330 billion, 55% higher than the year before (US$ 184 billion).

In India, most of the losses come from an increase in flood events and cyclones, which are projected to increase in magnitude and frequency with climate change. India faces high exposure to climate-related disasters, and is one of the most vulnerable countries in the world to extreme weather events in the world. Its vulnerability is compounded by high population density, unplanned development and urbanisation, socioeconomic conditions, and environmental degradation.

India’s vulnerability is in part due to its sensitivity to a wide range of climate impacts including droughts, floods, storms, landslides and extreme temperatures. Droughts occur less frequently, but impact the highest number of people in the country, affecting 680 million people between in the 20 years to 2017. Floods, on the other hand, are the most economically damaging climate impact, costing more than all other disaster events combined. Between 1998-2017, 10 of the 14 extreme weather-related disasters to hit the country were floods, causing economic damage of approximately US$ 45 billion, killing over 27,000 people and affecting more than 370 million people.

Southwest monsoon and flooding in India

In 2018, a prolonged southwest monsoon over the state of Kerala resulted in one of the worst floods in 100 years, causing estimated losses of US$ 4.25 billion. Over 800,000 people were displaced and 400 lives lost over a span of 2 weeks. Up to 1% of the state’s GDP is estimated to have been lost, with the service sector, agriculture and industry all witnessing a slow down from the flood impacts.

This year, many states across the country have witnessed severe drought conditions, followed by a delayed monsoon, which made up for by spells of high intensity rainfall resulting in heavy flooding across the country. The delayed onset of the southwest monsoon and disruption caused by the formation of Cyclone Vayu over the Arabian Sea caused a country-wide monsoon deficit of 44%, and exceeding 80% in some districts till 18th June. However, by the first week of July, a number of rainfall deficit districts in the states of Bihar and Assam were hit by multiple spells of high intensity rainfall (greater than 124.4mm), resulting in flash floods.

By the first week of August, the situation was repeated across the states of Kerala, Karnataka, Andhra Pradesh, Gujarat, Goa and Maharashtra. Between June and July, multiple regions in the country were affected by over 18 instances of high intensity rainfall. Kodagu district in Karnataka, home to the Cauvery river and a main component of India’s coffee economy transitioned from drought in May, to receiving more than double (920mm) of its average rainfall over a span of 9 days. Many districts in the state of Karnataka received an untimely burst of rainfall, with some crossing 3000% above its normal range in a single day – 8th August. While half the state is reeling under the impact of floods, there are districts which still have a monsoon deficit crossing 40%.

The impact


The floods in Bihar affected 7.2 million people and resulted in the death of over 100 people. Floods across the state have killed over 20 people and affected agriculture, infrastructure and property. The flooding in Kerala has claimed over 120 lives since 8th August, while Maharashtra and Gujarat lost 79 lives. Across the north Indian states of Rajasthan, Himachal Pradesh, Punjab and Uttarakhand, more than 70 lives have been lost in this year’s flooding. Millions have been evacuated and the National Disaster Response Force (NDRF), Army, Navy and Air Force have been deployed in rescue operations across the country.

Economic impacts

The Centre and State Disaster Relief Funds (NDRF and SDRF) have already issued over US$ 9.6 billion for flood relief across 8 of the affected states, compared to the US$ 7.7 billion released towards post-disaster relief measures between 2015-2017. Financial assistance from the government budget is directed towards relief, while banks and financial institutions also provide relief and rehabilitation support in the form of loans, rescheduling existing loans and sanctioning fresh loans in the face of natural disasters. As a result, loan recovery in the face of natural calamities becomes increasingly difficult, with the Indian banking sector reflecting an increase in agricultural and non-agricultural Non-Performing Assets (NPAs). Between 2012-2017, agricultural NPAs increased by 2.5 times, partly due to crop damage from weather-related events. After the Kashmir floods of 2014, non-agricultural NPAs increased from 8% of total NPAs in 2015 to 14% by 2016.

Apart from the direct loss of life, economic losses in 2019 from impacts on road and other transport infrastructure, water and electricity infrastructure, agriculture, and industries are yet to be estimated. Recognising the importance of building resilience in addition to relief and rehabilitation measures, the Government of India is spearheading the Coalition for Disaster Resilient Infrastructure (CDRI), proposed at the Hamburg G20 in 2017. The government has pledged US$ 70 million to fund the Coalition which aims to pool resources and best practices for technical and financial assistance in disaster-resilient rebuilding of core infrastructure sectors (transport, energy, construction, telecommunications and water).

Through disaster risk reduction and climate change adaptation efforts, India has made significant progress in minimising mortality from natural disasters, while the economic losses from damage to property and infrastructure have been dramatically increasing. The CDRI is an important step towards building resilience and minimising losses from climate-related disasters to local infrastructure and the economy.


Cover photo by Barry Pousman from Wikimedia Commons and republished under Creative Commons 2.0 licensing.
New York’s poor and ethnic minority neighbourhoods to be hit hardest by climate change finds NYC Panel on Climate Change

New York’s poor and ethnic minority neighbourhoods to be hit hardest by climate change finds NYC Panel on Climate Change

By Will Bugler

The New York City Panel on Climate Change (NYCPCC), released last month, its 2019 report on the science of climate change and its implications for New York City. The report finds that climate change is affecting everyday life in New York today, and that climate impacts will continue to increase over the coming decades, hitting the poorest neighbourhoods hardest.

The NYCPCC, which has been helping NYC prepare for climate change since 2008, found that extreme weather events are becoming more pronounced, high temperatures in summer are rising, and heavy downpours are increasing. The report finds that areas with lower incomes and the highest percentages of African American and Hispanic residents are consistently more likely to suffer the impacts of climate change. The panel advises that community engagement is critical for more effective and flexible adaptation efforts in the most at-risk communities.

The report serves as a “further wakeup call on the need to move urgently and take action on climate change” according to New York’s mayor Bill de Blasio. “This [report] shows what New Yorkers learned acutely during Sandy – climate change is real and an existential threat,” he said.

Records show that maximum daily summer temperatures have been rising at rates of 0.5°F per decade at JFK Airport and 0.7°F per decade at LaGuardia Airport since 1970. Sea level recorded at The Battery in lower Manhattan continues to rise at a rate of 0.11 inches per year since 1850. These changes are broadly in line with the climate change projections made by the NPCC in 2015.

The report also emphasises that climate change is already affecting the daily life of NYC residents, especially for those who live in coastal communities where nuisance flooding is becoming more frequent and for those who operate and use the city’s critical infrastructure during heatwaves and heavy downpours. Economic losses from hurricanes and floods have significantly increased in past decades and are likely to increase further in the future from more intense hurricanes and higher sea level rise.

“Recent scientific advances have allowed the NPCC to better detail climate vulnerabilities in the city, such as where nuisance floods might occur more frequently,” says William Solecki, co-chair of the NPCC. “This improved knowledge has, in turn, helped the panel craft new sets of tools and methods, such as a prototype system for tracking these risks and the effectiveness of corresponding climate strategies.”

One of those tools is the Antarctic Rapid Ice Melt Scenario, which the NPCC created to model the effects of melting ice sheets on sea level rise around NYC. The model predicts that under a high-end scenario, monthly tidal flooding will begin to affect many neighbourhoods around Jamaica Bay by the 2050s and other coastal areas throughout the city by the 2080s.

“The NPCC 2019 report tracks increasing risks for the city and region due to climate change,” says Cynthia Rosenzweig, co-chair of the NPCC and senior research scientist at Columbia University’s Earth Institute. “This report, the third by the NPCC in ten years, continues to lay the science foundation for development of flexible adaptation pathways for changing climate conditions.”

To help manage the dynamic climate and public policy contexts, the NPCC 2019 report recommends that the city put in place a coordinated indicator and monitoring system to enable the city and its communities to better monitor climate change trends, impacts, vulnerability, and adaptation measures. The report also notes that property insurance can be a catalyst for infrastructure resilience by encouraging investment in adaptation measures prior to a disaster through a reduction in premiums.

Other NPCC recommendations include:

  • continuing broad assessments of climate change across the metropolitan region with federal, state, and regional partners (for example, NOAA’s Consortium for Climate Risk in the Urban Northeast);
  • using updated methods for the next set of NPCC climate change projections; and
  • hosting a NYC Climate Summit once during every mayoral term.

Photo by Tommaso Ripani on Unsplash