Category: Infrastructure

Protecting wetlands helps communities reduce damage from hurricanes and storms

Protecting wetlands helps communities reduce damage from hurricanes and storms

By Siddharth Narayan, University of California, Santa Cruz and Michael Beck, University of California, Santa Cruz

2017 was the worst year on record for hurricane damage in Texas, Florida and the Caribbean from Harvey, Irma and Maria. We had hoped for a reprieve this year, but less than a month after Hurricane Florence devastated communities across the Carolinas, Hurricane Michael has struck Florida.

Coastlines are being developed rapidly and intensely in the United States and worldwide. The population of central and south Florida, for example, has grown by 6 million since 1990. Many of these cities and towns face the brunt of damage from hurricanes. In addition, rapid coastal development is destroying natural ecosystems like marshes, mangroves, oyster reefs and coral reefs – resources that help protect us from catastrophes.

In a unique partnership funded by Lloyd’s of London, we worked with colleagues in academia, environmental organizations and the insurance industry to calculate the financial benefits that coastal wetlands provide by reducing storm surge damages from hurricanes. Our study, published in 2017, found that this function is enormously valuable to local communities. It offers new evidence that protecting natural ecosystems is an effective way to reduce risks from coastal storms and flooding.

Coastal wetlands and flood damage reduction: A collaboration between academia, conservation and the risk industry.

The economic value of flood protection from wetlands

Although there is broad understanding that wetlands can protect coastlines, researchers have not explicitly measured how and where these benefits translate into dollar values in terms of reduced risks to people and property. To answer this question, our group worked with experts who understand risk best: insurers and risk modelers.

Using the industry’s storm surge models, we compared the flooding and property damages that occurred with wetlands present during Hurricane Sandy to the damages that would have occurred if these wetlands were lost. First we compared the extent and severity of flooding during Sandy to the flooding that would have happened in a scenario where all coastal wetlands were lost. Then, using high-resolution data on assets in the flooded locations, we measured the property damages for both simulations. The difference in damages – with wetlands and without – gave us an estimate of damages avoided due to the presence of these ecosystems.

Our paper shows that during Hurricane Sandy in 2012, coastal wetlands prevented more than US$625 million in direct property damages by buffering coasts against its storm surge. Across 12 coastal states from Maine to North Carolina, wetlands and marshes reduced damages by an average of 11 percent.

These benefits varied widely by location at the local and state level. In Maryland, wetlands reduced damages by 30 percent. In highly urban areas like New York and New Jersey, they provided hundreds of millions of dollars in flood protection.

Wetland benefits for flood damage reduction during Sandy (redder areas benefited more from having wetlands). Narayan et al., Nature Scientific Reports 7, 9463 (2017)., CC BY

Wetlands reduced damages in most locations, but not everywhere. In some parts of North Carolina and the Chesapeake Bay, wetlands redirected the surge in ways that protected properties directly behind them, but caused greater flooding to other properties, mainly in front of the marshes. Just as we would not build in front of a seawall or a levee, it is important to be aware of the impacts of building near wetlands.

Wetlands reduce flood losses from storms every year, not just during single catastrophic events. We examined the effects of marshes across 2,000 storms in Barnegat Bay, New Jersey. These marshes reduced flood losses annually by an average of 16 percent, and up to 70 percent in some locations.

Reductions in annual flood losses to properties that have a marsh in front (blue) versus properties that have lost the marshes in front (orange). Narayan et al., Nature Scientific Reports 7, 9463 (2017)., CC BY

In related research, our team has also shown that coastal ecosystems can be highly cost-effective for risk reduction and adaptation along the U.S. Gulf Coast, particularly as part of a portfolio of green (natural) and gray (engineered) solutions.

Reducing risk through conservation

Our research shows that we can measure the reduction in flood risks that coastal ecosystems provide. This is a central concern for the risk and insurance industry and for coastal managers. We have shown that these risk reduction benefits are significant, and that there is a strong case for conserving and protecting our coastal ecosystems.

The next step is to use these benefits to create incentives for wetland conservation and restoration. Homeowners and municipalities could receive reductions on insurance premiums for managing wetlands. Post-storm spending should include more support for this natural infrastructure. And new financial tools such as resilience bonds, which provide incentives for investing in measures that reduce risk, could support wetland restoration efforts too.

Improving long-term resilience

The dense vegetation and shallow waters within wetlands can slow the advance of storm surge and dissipate wave energy. USACE

Increasingly, communities are also beginning to consider ways to improve long-term resilience as they assess their recovery options.

There is often a strong desire to return to the status quo after a disaster. More often than not, this means rebuilding seawalls and concrete barriers. But these structures are expensive, will need constant upgrades as as sea levels rise, and can damage coastal ecosystems.

Even after suffering years of damage, Florida’s mangrove wetlands and coral reefs play crucial roles in protecting the state from hurricane surges and waves. And yet, over the last six decades urban development has eliminated half of Florida’s historic mangrove habitat. Losses are still occurring across the state from the Keys to Tampa Bay and Miami.

Protecting and nurturing these natural first lines of defense could help Florida homeowners reduce property damage during future storms. In the past two years our team has worked with the private sector and government agencies to help translate these risk reduction benefits into action for rebuilding natural defenses.

Across the United States, the Caribbean and Southeast Asia, coastal communities face a crucial question: Can they rebuild in ways that make them better prepared for the next storm, while also conserving the natural resources that make these locations so valuable? Our work shows that the answer is yes.


This is an updated version of an article originally published on Sept. 25, 2017.The Conversation Siddharth Narayan, Postdoctoral Fellow, Coastal Flood Risk, University of California, Santa Cruz and Michael Beck, Research professor, University of California, Santa Cruz. This article is republished from The Conversation under a Creative Commons license. Read the original article.

Cover photo by NPS Everglades/Flickr (public domain)
Far-sighted adaptation to rising seas is blocked by just fixing eroded beaches

Far-sighted adaptation to rising seas is blocked by just fixing eroded beaches

By Andrew G. Keeler, East Carolina University; Dylan McNamara, University of North Carolina Wilmington, and Jennifer Irish, Virginia Tech

Coastal communities around the world are struggling to adapt to rising sea levels and increasingly severe coastal storms. In the United States, local governments are making investments to reduce those risks, such as protecting shorelines with seawalls, “nourishing” eroded beaches by adding sand and rerouting or redesigning roads and bridges.

In the short run, spending public money this way is economically rational. But in the long run, many people who live near coastlines will probably have to relocate as seas continue to rise.

We have studied this problem by combining insights from our work in economics, coastal geomorphology and engineering. As we have explained elsewhere, short-term actions to adapt to coastal flooding can actually increase risks to lives and property. By raising the value of coastal properties, these steps encourage people to stay in place and delay decisions about more drastic solutions, such as moving inland.

Keeping millions in harm’s way

According to recent estimates, a 1-foot increase (0.3 metres) in sea levels will put about 1 million people in the United States at risk, and 3 feet (0.9 metres) will threaten about 4 million people. Global sea levels currently are projected to rise 0.5 to 2.1 feet (0.15-0.64 metres) by 2050 and 1.0 to 8.2 feet (0.3-2.5 metres) by 2100.

As we see it, market forces and public risk reduction policies interact in unexpected ways, reducing incentives for communities to make long-term plans for retreating from the shore. Nourishing beaches and building seawalls signal to individuals and businesses that their risks are lower. This makes them more likely to build long-lasting structures in risky areas and renovate and maintain existing structures. As a result, their property values increase, which reinforces economic and political arguments for more risk-reduction engineering.

To illustrate this pattern, we compared a sample of houses in Nags Head and Kitty Hawk, North Carolina, two popular beach towns less than 10 miles apart on North Carolina’s Outer Banks. When we consulted county tax appraisal values, Nags Head beaches had routinely received sand from beach nourishment, whereas Kitty Hawk beaches had not. On average, homes in our Nags Head sample were worth over US$1 million, while homes in the Kitty Hawk sample were worth about $200,000.

Other researchers have found that in some locations, the threat of rising seas is eroding coastal property values. But this tends to be true for properties that are viewed as highly vulnerable – for example, homes that have already flooded. In contrast, homes that are elevated or have other flood-proofing features tend to have much higher values, so they are perceived as assets.

Subsidizing risky choices

Some amount of risk reduction makes sense. If people who benefited paid its full cost, and everyone involved understood how imminent the risk was and how much engineering solutions would cost, then market forces would likely produce reasonably efficient solutions.

As an example, flood-prone Norfolk, Virginia recently adopted an ordinance requiring almost all new homes and many major renovations to be elevated and include other flood-proofing features. This approach will help to price flood protection into the cost of homes and will tend to reduce demands to directly subsidize protective engineering, flood insurance and post-disaster assistance.

In our view, such solutions are a move in the right direction. But they will not break the positive feedback loop we describe as long as other public policies continue to skew perceptions of the long-term viability of coastal communities.

Engineering projects to slow shoreline retreat and reduce flooding generally receive smaller subsidies now than in past decades, but many communities still benefit. For example, beach nourishment in Ocean City, Maryland is cost-shared between the federal government, which pays about half, and state and local agencies. The Federal Emergency Management Agency helps pay to rebuild homes and public buildings damaged in major disasters. And allowing people to deduct local taxes on their federal tax forms partly subsidizes local tax financing for risk reduction.

Beach nourishment started at New York’s Coney Island a century ago. But with the sheer volume of sand needed to keep up with sea level rise, its costs could outweigh its benefits within a few decades.</small

Inaccurate perceptions of risk

Information and uncertainty are larger problems. Many coastal residents do not perceive medium- and long-term climate risk to be as serious as the scientific consensus suggests. Moreover, scientists are still analyzing how fast sea levels are likely to rise. Future storm frequency is uncertain, and could be affected by changes in global greenhouse gas emission trends.

On the positive side, engineering innovations such as designing storm-resistant homes could become more effective. But existing approaches like beach nourishment are likely to become more expensive as sand resources diminish and more communities compete for them. And growing uncertainty is likely to increase near-term demand for risk reduction engineering.

The most critical time for adaptation decisions is immediately after a storm or flood. Faced with expensive repairs or rebuilding, property owners face higher costs to return to the status quo. But if homeowners expect that public resources will be spent to protect them against future disasters, they are less likely to consider making big changes.

Federal or state financial rebuilding assistance creates a similar bias. If that money were used to subsidize relocation or other drastic adaptive actions, rebuilding patterns would be different. So far, however, programs for buying out flood-damaged properties have been largely unsuccessful. Many factors, including residents’ level of experience with disaster recovery and financial concerns, can make people unwilling to consider relocating.

Incentives to think long-term

There is no perfect formula for balancing near-term climate-proofing against more drastic steps to move people away from the coasts. But we believe that when communities focus excessively on reducing near-term threats, they risk inhibiting the successful adaptation that they are trying to promote.

We have three suggestions for breaking this cycle. First, local land use policies could be designed to discourage rebuilding homes to similar or higher property values after damage from storms. Second, communities could put increasing emphasis on adaptive engineering and large-scale planning practices – for example, sunsetting beach nourishment projects when sea level rise reaches some preannounced level.

Finally, adaptation decisions could be planned and implemented at a multi-jurisdictional level, rather than town by town. This approach would help to avoid “rich towns get richer” dynamics that can develop when wealthier jurisdictions deploy sand resources and other protective measures in a way that reduces their own risk while ignoring or heightening threats to nearby locations.

Change is coming to coasts around the world. We believe that broader understanding of how markets and public policy interact is essential to minimize the social and economic costs of this change.The Conversation


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

Cover photo by Ashley Satanosky on Unsplash.
Coastal flooding in Europe ‘could cost up to €1 trillion per year’ by 2100

Coastal flooding in Europe ‘could cost up to €1 trillion per year’ by 2100

By Jocelyn Timperley, Carbon Brief

The economic damage from coastal flooding in Europe could reach almost €1 trillion per year by 2100 without new investment in adaptation to climate change, a new study finds.

The research looks at how rising sea levels and continued socioeconomic development will affect future coastal flood risk in 24 European countries.

In contrast to the past century, the main reason behind rising loses from coastal flooding will be global warming, rather than socioeconomic changes, the lead author tells Carbon Brief. The acceleration of loss is also unprecedented, he adds.

The UK would be the worst hit by far, the study finds, seeing up to €236bn in annual damages and 1.1 million people exposed to coastal flooding by 2100, if no upgrades are made to coastal protection.

Coastal damage

Europe’s coastline stretches to more than 100,000km. Many of its coastal zones are highly populated and developed.

This leaves it vulnerable to increased coastal flooding due to extreme sea levels. These arise from a combination of sea level rise, tides, and storm surges and waves due to cyclones.

Future damages due to coastal flooding will also be highly dependent on socioeconomic changes, which will impact the number of people moving to the coast and the extent of development.

The new study, published in Nature Climate Change, aims to combine modelling of both extreme sea levels and socioeconomic development to show what damages could look like this century without further adaptation efforts.

It projects that the economic damages from these extreme events will increase from €1.25bn per year today to between €93bn and €961bn per year by 2100, depending on how socioeconomic trends play out over the rest of this century. This is a 75- to 770-fold increase on today’s levels.

Three socioeconomic scenarios are considered, as set out below. (Carbon Brief recently published an explainer about these new scenarios, which are known as “Shared Socioeconomic Pathways” or SSPs.)

  • “Sustainability” (SSP1), where the world shifts gradually towards sustainability, with emphasis on more inclusive development that respects environmental boundaries. This is combined with a future emissions scenario known as RCP4.5, whereby greenhouse gas emissions level off by 2050 and global temperatures rise by 2-3C above pre-industrial levels by 2100. Expected annual damages from coastal flooding hit €156bn by 2100, the study finds.
  • “Fragmented world” (SSP3), where countries focus on achieving energy and food security goals within their own regions at the expense of broader-based development. This is combined with RCP8.5, a high emission and low climate policy scenario where global temperatures reach around 4-6C above pre-industrial levels by 2100. Expected annual damages from coastal flooding reach €93bn by 2100, the study finds.
  • “Fossil fuel-based development” (SSP5), where a push for economic and social development is seen alongside the exploitation of abundant fossil fuel resources. This is again combined with the RCP8.5 high emissions scenario. Expected annual damages from coastal flooding reach €961bn by 2100, the study finds.

The graph below shows how these annual damages for the different scenarios pan out across different European countries by 2100.

The graph below shows how these annual damages for the different scenarios pan out across different European countries by 2100.

Expected median annual damage from coastal flooding for 24 European countries by 2100. The scenarios included are: RCP4.5-SSP1 (“Sustainability”), RCP8.5-SSP3 (“Fragmented world”), and RCP8.5-SSP5 (“Fossil fuel based development”). Source: Vousdoukas et al. (2018). Chart by Carbon Brief using Highcharts.

It is worth noting that while emissions are the same for the “fragmented world” and “fossil-based development” scenarios, lower development and urbanisation leads to less economic exposure to extreme sea levels.

In all scenarios, the UK is the worst hit in absolute economic terms, followed by France and Norway. The UK – which today accounts for around a third of damages from coastal flooding – accounts for 22-28% of damages in Europe by 2100.

Dr Michalis Vousdoukas, an oceanographer at the European Joint Research Centre in Ispra, Italy, and lead author of the paper, tells Carbon Brief the high expected damages in the UK are due to its exposure to the oceanic waves of the North Atlantic. This is one of the most energetic areas in the world, he says, leading to more intense weather conditions than in Mediterranean countries, for example.

Dr Andra Garner, a postdoctoral fellow in sea-level research at Rutgers University in New Jersey, who was not involved with the research, says the results of the paper are “very telling”, although emphasises that any modelling study comes with caveats. She tells Carbon Brief:

“The results here indicate that, although socioeconomic choices can be important, rising sea levels ultimately dominate future flood risk in many regions, suggesting the need for swift action towards increasing adaptation measures and resilience planning in coastal communities.”

This is especially important, adds Garner, since the ocean responds slowly to a warming climate, which means that sea level rise impacts are likely to become even more severe beyond the end of the century.

Nearer-term damage

The authors also looked at damages from coastal flooding in the shorter term. By mid-century, the study shows these would reach €21bn, €13bn and €39bn for, respectively, the “sustainability”, “fragmented world” and “fossil fuel-based development” scenarios. This is a 10- to 32-fold increase compared to the annual damage in 2000.

The breakdown of these costs among different countries by 2050 is shown in the chart below. In all scenarios, the UK is again the most affected in absolute terms, followed by France and Italy.

Expected median annual damage from coastal flooding for 24 European countries by 2050. The scenarios included are: RCP4.5-SSP1 (“Sustainability”), RCP8.5-SSP3 (“Fragmented world”), and RCP8.5-SSP5 (“Fossil fuel based development”). Source: Vousdoukas et al. (2018). Chart by Carbon Brief using Highcharts.

According to the study, flood defences will need to be installed or reinforced to withstand increases in extreme sea levels of around 0.5m by 2050, and 1-2.5m by 2100, depending on the country.

GDP ratio

The researchers also calculate the expected annual damages from European coastal flooding as a share of combined total gross domestic product (GDP).

Depending on the scenario, they find that coastal flooding damages will account for 0.06-0.09% of Europe’s GDP by 2050. This rises to 0.29-0.86% of GDP by 2100. This is up from current average damage from coastal flooding in Europe today of around 0.01% of GDP.

Some countries are particularly hard hit, when viewed in this way. The study finds Norway would see damages equal to between 1.7-5.9% of its GDP, depending on the scenario, by 2100. Damages in Cyprus would equal 1.7-8.3% of its GDP and in Ireland it would be 1.8-4.9% of GDP.

A key point here is that river flooding in Europe is currently much more damaging than coastal flooding in GDP terms, the study says, with an average €6bn in annual damages, equivalent to around 0.04% of GDP.  This will change, according to the study, with flood risk increasingly dominated by coastal flood risk from 2050 onwards, unless flood-protection standards are upgraded. Vousdoukas tells Carbon Brief:

“In the future, the coastal flooding becomes four times more important than river flooding, because of the accelerating factor which is sea level rise basically. Coastal flooding will change so much, there will be so higher damages, that it will become more important. Then there needs to be spending there for protection.”

People affected

As well as looking at economic damages, the new study projects the number of people who will be affected by coastal flooding. This depends not only on the extent of increase in extreme events, but also how many are living in coastal zones. Therefore, as for economic damages, socioeconomic development will have a large impact alongside climate change.

The study finds the annual number of people in Europe exposed to flooding will rise from 102,000 today to between 530,000 and 740,000 by 2050 (again, in the absence of further adaptation measures). By 2100, 1.5 million Europeans would be affected by coastal flooding in the “fragmented world” scenario, the study finds, and 3.7 million in the “fossil fuel-based development” scenario.

The three graphs below show the projected number of people affected in each country for the three scenarios in 2100. Again, the UK is by far the most impacted across all three scenarios.

Expected median number of people affected by coastal flooding per year in 24 European countries in 2100. The scenarios included are: RCP4.5-SSP1 (“Sustainability”), RCP8.5-SSP3 (“Fragmented world”), and RCP8.5-SSP5 (“Fossil fuel-based development”). Source: Vousdoukas et al. (2018). Chart by Carbon Brief using Highcharts.

High uncertainty

It is important to remember that the projections in the study come with a very high uncertainty, Vousdoukas stresses.

The chart below shows the projected change of coastal flood impacts up to 2100 for the three scenarios. The dotted line show the median projections, as described above, while the coloured areas show the large potential range in the results.

Evolution of coastal flood impacts aggregated at European level for 24 countries under three socioeconomic scenarios: (a) shows the projected changes in expected annual damages and (b) the expected annual number of people exposed due to coastal flooding. The lines are the ensemble median projections and the coloured areas show the 5-95% quantile range confidence interval. Source: Vousdoukas et al. (2018)

Commenting on the paper, Dr Diego Rybski, deputy head of climate change and development group at the Potsdam Institute for Climate Impact Research tells Carbon Brief the paper “significantly contributes” to the understanding of coastal flood risk and sea level rise in Europe. However, he adds that such assessments of coastal flood risk are affected by further large uncertainties.

For example, he says, it is hard to know when the inundations are going to take place because coastal flood are very rare. The impact of a once-in-100-year event in the first half of the century could be very different than if it occured in the second half of the century. It is also possible that there is no such event, or more than one, during a given 100 years.


Vousdoukas, M, I. et al. (2018) Climatic and socioeconomic controls of future coastal flood risk in Europe, Nature Climate Change, . doi:10.1038/s41558-018-0260-4

This article originally appeared on Carbon Brief and is shared under a Creative Commons license. Read the original by clicking here.

Cover photo by grumpylumixuser/Wikimedia (CC BY 3.0): Flooding on Piazza San Marco, Venice, Italy.
Mumbai: the ‘rain ready’ city that floods every year

Mumbai: the ‘rain ready’ city that floods every year

By Devika Singh

This year, as in the years prior, the city of Mumbai was inundated by floodwater. Mumbai International, the country’s busiest airport was water logged and over a quarter of all flights were affected. The National Disaster Response Force and Indian Army were called upon to evacuate 2000 passengers stranded on the Mumbai-Vadodara train at Nalasopara and a further 400 salt pan workers and their families, stranded on a passenger train at Palghar. The severity of the impacts of flooding in the city demands an equivalent response, but this has not been forthcoming. The Brihanmumbai Municipal Corporation (BMC) is responsible for health, sanitation and water infrastructure spending in the city. Three years ago, after having spent INR 200 crore (USD 29.148 million) to build a new pumping station, the BMC proclaimed that Mumbai was now ‘rain ready’. To the contrary, Mumbai’s floods now reliably occur each year.

The BMC is India’s wealthiest civic body, with an annual budget often exceeding that of some states in the country. Its budget for 2017 was INR 25,141 crore (USD 3.664 billion). However, less than 18% of that budget was allocated to civic infrastructure (including upgradation of sewage and storm water drainage systems), in spite of the city’s much-publicised annual deluge.

However, investment in flood resilience is badly needed. On 24 June 2018, the city received over 150 mm of rainfall over a 24 hour period, 438% over Mumbai’s normal daily average. By July, the city received over half of the season’s rainfall quota, in just under 20 days. The severity of rainfall events is only one factor governing the impact of the floods. Poor urban planning, a lack of infrastructure investment, poor governance by the BMC, and unregulated development, all play their part.

Floods as a window into Mumbai’s past

In order to understand Mumbai’s current flood problems, it is helpful to look to the past. The city was originally composed of seven islands that were converted into the metropolis through extensive construction on reclaimed lands. Portions of the city are 6-8 metres below sea level, with large infrastructure developments dotting the coastline. Several buildings on reclaimed land are just above sea level, some way below high tide levels. Rampant development has taken place along the length of the Mithi river, its surrounding mangroves, wetlands, salt pan lands and flood plains. The wetlands served as a buffer zone, providing protection from flooding and rising tide levels.

Poorly planned construction in these areas has not only made the city more prone to flooding, but has also compromised the safety of the city and its people in the face of extreme events. What was originally Mumbai’s natural river drainage system has now been reduced to less than 50% of its original flow. It has, in effect, become a massive open sewer, carrying silt, waste and plastic through the heart of the city. Mumbai’s man-made drainage system does not fare much better. Built in 1860, during the British colonial era, the underground drainage system was constructed to support the 19th century population of the city and drain 25 mm of rainfall per hour, at low tide. Rainfall exceeding that limit, combined with high tide, results in the familiar picture of a flooded Mumbai.

Flooding’s deadly impact

In August 2005, Mumbai witnessed one of its most devastating floods. Around 500 people died over a matter of days. Some estimates of total economic losses reach up to INR 28 billion (407.9 million USD), INR 10 billion (145.6 million USD) was just infrastructure damage. Railway services, local trains, roads, and the airport were all inundated, and the city was brought to a standstill. The Mumbai airport, built on reclaimed land from the Mithi river, was inundated for three days.

Jump to August 2017: the city continues to struggle with flooding. Once again, the city’s critical infrastructure services such as transport and telecoms were disrupted. Floodwaters caused a Spice Jet flight to over shoot the runway and get stuck in the mud. The airport was closed for almost a day due to water logging. These scenes were repeated earlier this year, when an Air India flight overshot the runway, and flooding saw 89 arrivals and 319 departures from the Mumbai airport delayed.

In the wake of a flood disaster, it is the poor and slum dwellers who are worst affected. In 2005, the poor residents of Mumbai faced 60% more loss than their richer counterparts. Losing the little they have can cause irreversible damage to health, livelihood and life for these communities. In 2017, and now in 2018, the slum areas of the city remain the most affected.

The northern suburbs of Mumbai have faced a power cut for 37 hours, streets and railway lines have been water logged and cracks have been spotted on the Saket bridge. The city’s restricted drainage capacity is illustrated by Thane, a neighbouring district and part of the Mumbai Metropolitan Region. Thane flooded in spite of experiencing a 27% rainfall deficit this season (the only area in Mumbai to receive a deficit). This is indicative of the extent of under-capacity of the drainage systems, where even a lower than average rainfall incident can cause flooding. While overall rainfall amounts may have dropped, increased intensity of rainfall events in a short span can overwhelm the current drainage capacity of the metropolitan area.

The Brihanmumbai Municipal Corporation (BMC)

Every year before the rains hit, the BMC makes a last-minute attempt to de-silt and clean up the city’s natural and man-made drainage systems. And every year, the BMC fails. After the devastating floods of 2005, the BMC allocated INR 2500 crore for BRIMSTOWAD (USD 364.2 million) the Brihanmumbai Storm Water Disposal System. By 2017, the cost of the project had increased to INR 4500 crore (USD 655.74 million). Thirteen years after the drainage system was first approved, a majority of the city’s low-lying areas and slum settlements are yet to receive any respite from the annual deluge.

During the 2011 floods, the BMC commissioned 8 pumping stations along with 58 other projects. Today, in 2018, only 5 pumping stations are operational, and less than 30 of the planned flood protection projects are complete. In 2013, the BMC committed to spending INR 1400 crore (around USD 204.01 million) on setting up sewage treatment plants along the Mithi river. While the money has been spent, the Mithi remains an open sewer coursing through Mumbai. In 2015, having spent INR 200 crore (USD 29.148 million) to build a new pumping station, the BMC claimed that the city was now ‘rain ready’. And yet again, Mumbai flooded.

Climate change: What future for Mumbai?

One study of the Konkan coast from Dahanu to Vengurla (just north of Mumbai) over the past 20 years has shown a sea level rise of 5-6 cm. This has led to sea water intruding up to 1 km inland, causing damage to farm land and mangroves. Studies indicate tidal patterns are becoming more erratic, while precedent shows us that civic bodies and infrastructure are not prepared for these changes. The standard response has been the construction of bunds. These prove expensive and inefficient, costing around INR 60,000 per metre (USD 874.32) of bund construction. Further, they are built only in sections, thus providing limited protection against extreme events.

Some climate change projections indicate that around 40% of Greater Mumbai could be underwater by the end-century due to continuing sea level rise. Sea level rise is projected to increase by between 24 and 66 cm for Mumbai. Monsoon rainfall for the Konkan administrative division of Maharashtra (includes the Mumbai Metropolitan Region) is projected to increase by between 10% and 30% by mid-century (2021-2040). Annual mean temperatures for the same time period are projected to increase by 1.1°C-1.28°C. Warmer air can hold more water, increasing the likelihood of more intense rainfall events and longer dry spells between intense rainfall events.

In 2014, the Maharashtra State Action Plan on Climate Change identified that a repeat occurrence of the 2005-like rainfall event would flood a number of areas (especially the low-lying areas) in the Mumbai Metropolitan Region, even after the drainage capacity is expanded. This goes to show that the steps taken by the BMC towards flood resilience are not sufficient to prepare the city for future climate-related extreme events. The BMC needs to integrate climate change adaptation strategies into its policy decisions, if it wants to avoid a repetition of the 2005 flood impacts. The State Action Plan has a number of recommendations to improve Mumbai’s adaptive capacity to floods and extreme rainfall. Foremost amongst these are strengthening of the storm water drainage network and improving ground water percolation. Improving coordination between identified implementation agencies such as the Disaster Management Department, Storm Water Drainage Department and the BMC would go some way towards making Mumbai ‘rain ready’.

Rising sea levels will result in increasing salinity of coastal groundwater, endanger wetlands and inundate valuable land, directly affecting the lives and livelihood of coastal communities. Projections made by an ADB study indicates that total losses in Mumbai could as much as triple by 2080 as compared to the present. Another study estimates that the probability of a flood event (similar to the 2005 incident) is likely double, with a tripling of losses (direct and indirect), amounting to $690-1890 million by 2080. And these estimates do not consider potential loss of life.

The historical trends and future projections all point to increasing intensity of rainfall, rising sea levels and an increase in extreme weather events. The high population density of Mumbai, growing development on reclaimed lands, under-capacitated drainage systems overburdened with garbage and plastics, combine to exacerbate the effects of rainfall events and climate change. These factors suggest that a recurrence of the 2005 floods is a matter of ‘when’ not ‘if’. The city has some tough decisions to take, but to begin with, improving the drainage system alone can reduce losses by as much as 70%. In addition, extending insurance coverage could halve the indirect losses that emanate from Mumbai’s annual floods.


Cover photo by Paasikivi/Wikimedia (CC BY-SA 4.0): Flooding in Mumbai, India in 2017.
Flooded internet is possible by 2035

Flooded internet is possible by 2035

By Tim Radford

Information now travels along the internet. But what happens when sea levels rise and leave a flooded internet, its vital cables and traffic hubs under water?

US engineers have identified a problem nobody had ever expected to confront so soon: the approach of the flooded internet, caused by worldwide sea level rise. Within 15 years seawater could be lapping over buried fibre optic cables in New York, Seattle, Miami and other US coastal cities, according to a new study.

The consequences for global communications are unknown. But, as the glaciers melt, and the water in the oceans continues to expand as temperatures rise, the chances of urban flooding will increase.

And that means water where nobody expected it – over buried cables, data centres, traffic exchanges, termination points and other nerve centres of the physical internet, according to a team from the University of Wisconsin-Madison and the University of Oregon.

“Most of the damage that’s going to be done in the next 100 years will be done sooner than later,” said Paul Barford, the computer scientist who led the study and presented it to a meeting of network scientists. “That surprised us. The expectation was we’d have 50 years to plan for it. We don’t have 50 years.”

“Keeping the sea at bay is hard. We can probably buy a little time, but in the long run it’s just not going to be effective”

In fact, such buried infrastructure is usually sheathed in water-resistant protection, but water-resistant is not the same as waterproof. And while submarine cables are fashioned to withstand extended seawater corrosion and pressure, urban services don’t have quite the same level of future-proofing.

But city managers already have the awful lessons of massive flooding in New York  from Superstorm Sandy, or of New Orleans from Hurricane Katrina, or of Houston from Hurricane Harvey.

The message from climate science for the last five years has been simple: expect more coastal flooding.

Risk easily increased

The US scientists looked only at the challenges for the US. They calculate that by 2033 an estimated 4,000 miles (6,400 kms) of buried fibre optic conduit will be under water. More than 1,100 traffic hubs – internet exchange points that handle massive quantities of information at colossal speeds – will be surrounded by water.

Many of the conduits at risk are already at or near sea level, and only a very slight further rise could bring extra risk, especially at those places where the submarine cables come ashore.

“The landing points are all going to be underwater in a short period of time,” Professor Barford believes. “The first instinct will be to harden the infrastructure. But keeping the sea at bay is hard. We can probably buy a little time, but in the long run it’s just not going to be effective.”

And, he told academics and industry scientists at an Applied Network Research Workshop: “This is a wake-up call. We need to be thinking about how to address this issue.”


This article originally appeared on Climate News Network and can be accessed here.

Cover photo from Pixabay.
Climate gentrification to impact real estate market

Climate gentrification to impact real estate market

By Caroline Fouvet

While an ocean view from a balcony often implies higher property prices, this trend seems to be reversed as sea level rise and climate-change-triggered flooding unfold. In 2016, in the United States alone, four inland flooding events amounted to US$ 4 billion, in a country where inundations are the costliest and most common natural disaster. Coastal cities such as Miami and New York City are even more vulnerable to flooding, and are ranked first and second in the list of places most at risk from climate change and sea-level rise.

Such effects are likely to cause displacements, reshaping urban settlements and the socioeconomic status of neighbourhoods. This is what a new Harvard study that looked at climate change impacts on property markets in Miami-Dade County, Florida, suggests. The authors found a correlation between the higher elevation of single-family properties and their rate of price appreciation. Similarly, the research demonstrates that since 2000 the price appreciation of homes at lower elevations was inferior to that higher properties.

This imbalance demonstrates that the perception of flood risks is likely to shift consumer preferences and trigger relocation. As a result, the question arises how vulnerable communities can move to flood-risk-free zones, given the increases of property values in those areas. This situation illustrates the issue of climate gentrification, or how property value fluctuations based on a building’s climate resilience can lead to speculation and investment, forcing lower-income population out of climate proof areas.

The research points out three ways for climate gentrification to manifest:

  1. The “superior investment pathway” is a situation where high-income households opt for safer locations, as illustrated in the study.
  2. Under the “cost-burden pathway” assumption, only richer segments of the population can afford to live in climate vulnerable areas and to pay the associated costs of insurance and repair.
  3. Lastly, the “resilience investment pathway” relates to engineering and infrastructure investments in homes, that drive up property value and exclude those who cannot provide for it.

Climate change impacts on the real estate market are a topic not only for local authorities and urban planners to watch, but also for investors. Part of the methodology designed by Acclimatise, UNEP FI and 16 leading banks for banks to assess climate risks to their loan book covers real estate and estimates the potential changes in property values and loan-to-value ratios due to extreme weather events. A complex interplay of factors, including risk perception, are considered in the analysis. Evidence shows for instance that updating flood risk maps changes beliefs around the riskiness of newly designated flood-prone areas, driving down properties’ sale prices by 12% to 23%. Moreover, the report describes that the value of unaffected properties can increase compared to that of affected properties in the same area, as well as the value of homes that have undergone maintenance and resilience enhancement works following an extreme event.

As both the incremental and acute impacts of a changing climate manifest themselves globally, so do their financial costs. The real estate sector is already impacted, and future trends seem to point toward increasing damages. Improving the resilience of homes is a necessary adaptation measure, but this must go hand-in-hand with careful consideration of communities’ socioeconomic status to avoid a two-tier system for urban development.


Cover photo by Ryan Parker on Unsplash.
The heat is on: Northern Hemisphere experiences sweltering summer temperatures

The heat is on: Northern Hemisphere experiences sweltering summer temperatures

By Elisa Jiménez Alonso

Large parts of the Northern Hemisphere are currently experiencing unusually high temperatures giving us a taste of what climate change looks like in our day-to-day lives, and highlighting the need for adaptation.

Worldwide heat

Temperature records have been breaking across the United Kingdom, Glasgow for example had its hottest day ever recorded with 31.9C, and Scotland broke its temperature record with 33.2C in Motherwell. While these temperatures are not nearly as bad as elsewhere, they are out of the ordinary and are causing infrastructure problems.

Buckled rails and signal failures have led to widespread cancellations and delays. Additionally, the Met Office has activated a Level 3 – Heatwave Action across southern, central, and western England, encouraging people to check on any elderly family members or friends and other vulnerable persons.

In Canada, where Montreal broke its temperature record with 36.6C, up to 54 deaths have been linked to the heatwave in southern Quebec. Temperatures rose to 35C with high humidity and a smog advisory. Most victims were over 50 years old.

Most frightening of all, however, the temperature in the town of Quriyat in Oman never dropped below 42.6C for a full 24 hours in June.

Trends of the new millennium

The warming trend is clear, according to the US National Oceanic and Atmospheric Administration (NOAA), all 18 years of the 21st century have been among the 19 warmest on record with 2016 being the hottest year ever recorded. The five hottest years ever recorded have occurred since 2010.

Many countries have experienced what these trends can lead to. The notorious 2003 European heatwave is estimated to have caused anywhere between 20,000 and 70,000 premature deaths. In 2006, California saw a ten-day heatwave that was linked to 140 deaths. In Canada, the summer heatwave of 2010, one of the hottest on record, killed about 280 people.

A hot new normal without political will to change

The warming trends are clearly linked to increasing greenhouse gas concentrations in the atmosphere. While renewable energy use is growing, 80% of global energy use is from fossil fuels. The transition to a low-carbon economy is proving to be a slow one, thus, adaptation to climate change will be, and already is, essential.

National infrastructure, especially related to water supply, will need a lot of attention, as will housing standards. But, as we are seeing in the UK right now, transportation will need to be updated as well to deal with higher temperatures. There are also considerations for national healthcare and land management – adaptation truly needs to happen across all sectors.

However, as the political climate in the Northern Hemisphere heats up as well, climate change is rarely top of the agenda. This, of course, is a major mistake, as climate change will put even more pressure on any problems we are already facing undermining prosperity, progress, and economic growth.


Photo by Garry Knight/Flickr (CC BY 2.0): Summer in Regent’s Park.
Dominican Republic city braces for 2018 hurricane season

Dominican Republic city braces for 2018 hurricane season

By Georgina Wade

The Dominican Republic’s second largest city is preparing for the upcoming hurricane season with a new evacuation plan following last year’s storms that killed around 90 people.

Santiago de los Caballeros is still struggling with the economic toll from hurricanes Maria and Irma, two category 4 storms that left trails of destruction as they crashed through the Caribbean in September of last year.

The fifth largest metro area in the Caribbean, Santiago de los Caballeros has experienced rapid and disorganized urbanisation and physical expansion leading to an increase in informal settlements  that are poorly or illegally connected to official infrastructure and services.

Amongst rising fears in many island nations that infrastructure and economies could be devastated by even more powerful storms in the future, authorities are taking measures to mitigate the potential damage caused with the unveiling of its 87-page resilience strategy

As a member of the Rockefeller Foundation’s 100 Resilient Cities initiative, Santiago de los Caballeros has prioritised disaster preparedness, alongside developing infrastructure, improving transport and reducing domestic violence.

However, Maria Isabel Serrano Dina, the Chief Resilience Officer for 100 Resilient Cities, says the city is faced with limited resources that are preventing the full implementation of the plan.

“One of the biggest challenges is money. What can you do with a little budget? You have to be creative,” she said.

Working with businesses to sponsor local parks or to take responsibility for street lights is a cost-effective way of funding schemes and giving private sector companies a vested interest in protecting their areas, she said.

Additionally, public education and outreach programmes can help communities get more involved in resilience efforts.

Major challenges to the city currently include improving the drinking water supply and waste management system.


Cover photo by Greifen/Wikimedia Commons (CC BY-SA 3.0): View of Santiago de los Caballeros, Dominican Republic.
Low awareness of climate risks hampering resilience of critical infrastructure sectors claims new study

Low awareness of climate risks hampering resilience of critical infrastructure sectors claims new study

Low levels of awareness of climate risks and the availability of climate services are significant barriers to climate adaptation in the electricity sector, according to new research from Germany. However, the research also finds that the underlying market opportunity for climate services remains strong.

Damage to a critical infrastructure, its destruction or disruption by for example natural disasters, will have a significant negative impact on the security of the EU and the well-being of its citizens. Focussing on the German electricity sector, the report found that stakeholders in the sector claimed to need seasonal forecasts and decadal predictions, the latter aligning closely with energy companies’ time frames for strategic planning. However, despite this, there is currently a low level of demand for climate services from the sector.

The report found that four major barriers prevented the uptake of climate services:

  1. low awareness of the climate-related risks,
  2. low awareness of the benefits climate services can provide,
  3. mismatches between the required and the available timescales and spatial resolution of data and
  4. a lack of trust in the reliability of data.

In order to overcome these hurdles, the report recommends that considerable work needs to be done in the first instance to increase the visibility of the climate services industry and how it can contribute to the climate resilience of key sectors. It proposes that a ‘Climate Service Provider Store’ is created to provide information about where appropriate climate service providers are available.

Additionally, the case study recommends that work continues to ensure that seasonal and decadal forecast become ever-more accurate and that regional cooperation between industry networks and climate services providers are strengthened.

The case study was led by the non-profit research organization HZG under the MArket Research for a Climate Services Observatory (MARCO) programme of which Acclimatise is a proud partner. MARCO, a 2-year project coordinated by European Climate-KIC, hopes that research such as this will help to remove the barriers to the growth of the climate services industry across Europe.


Download the full case study “Critical Energy Infrastructureshere.

Download an infographic highlighting the key findings of the case study here.

Cover photo from pxhere (public domain).
Tokyo’s massive flood protection facility might not be “enough” due to climate change

Tokyo’s massive flood protection facility might not be “enough” due to climate change

By Elisa Jiménez Alonso

In Tokyo, an enormous underground flood protection system pumps excess water out of the metropolitan area into the sea and has reduced flood occurrences massively. But, climate change might take it to its limits.

When you look at a photograph of the Metropolitan Area Outer Underground Discharge Channel, or G-Cans, you might be reminded of J.R.R. Tolkien’s Mines of Moria and the terrifying Balrog that lived there. However, it is the world’s largest underground flood water diversion infrastructure, built on the outskirts of Tokyo.

The numbers associated with this cavernous super structure are truly impressive: 50 metres beneath the surface, five containment silos, each 65 metres high and with a diameter of 32 metres, are connected by a 6.3-kilometre network of tunnels. The silos are so big, they could fit the Statue of Liberty inside. The structure also has a large cistern, the “Underground Temple”, 18 metres high, 78 metres wide, and 177 metres long with 59 massive pillars and connected to the drainage facility of the system which consists of 4 pumps that can pump a total of 200 cubic metres of water per second.

Concept drawing of G-Cans. Source: Edo River Office, Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transportation, and Tourism.

The underground system was built in 2006 and cost roughly $2 billion. Now, climate change threatens to erode the capacity thresholds of G-Cans. According to the Japanese Meteorological Agency, Japan, already one of the wettest areas of the world, will see even more rainfall. Additionally, sea level rise is threatening Tokyo, which is further exacerbated by subsidence. In 2015, heavy rainfall caused by a typhoon filled Tokyo’s flood protection system with almost 19 million cubic metres of water – which could roughly fill 7600 Olympic size pools – and took four days to be pumped out.

For the time being, the facility remains crucial to Tokyo’s flood defences. However, in the face of climate change and possibly looking at a future where this structure alone will not be able to protect Tokyo’s 38 million inhabitants from floods, Nobuyuki Tsuchiya, former chief civil engineer of Tokyo’s Edogawa ward, said to the New Statesman that current flood protection measures “are not enough.” Kuniharu Abe, who heads the Metropolitan Area Outer Underground Discharge Channel, further adds he is “not sure Japan can build something like this again.”

It begs the question if attempting another infrastructure project of such enormous proportions (literally and financially) even is the correct way forward. Concrete defences often offer a very obvious and visible form of flood protection and can attract more people to flood-prone areas. This is what happened to Saitama, where the G-Cans facility has reduced floods significantly. Many businesses settled in the area and might face a future when frequent flooding returns.

It is important to emphasise that the Metropolitan Area Outer Underground Discharge Channel is by no means a story of failure, it has already avoided many floods and will, at the very least, continue to alleviate them in the future. But it tells a story about the fact that adaptation to increasing flood risk, or any climate risk for that matter, is never one-dimensional. No single project will remove the risk. It is important to consider many aspects from infrastructural solutions, zoning and land use, to public risk awareness and preparedness.


Cover photo by Kunitaka NIIDATE/Wikimedia Commons: Metropolitan Area Outer Underground Discharge Channel Kasukabe, Saitama, Japan