GeoLog

natural hazards

A better framework for disasters

A better framework for disasters

The end of the Northern hemisphere summer tends to be a good time to regroup from natural hazards, as the frequency and intensity of storms, as well as the incidence of wildfires, tends to trail off. At the time of writing, however, Hurricane Willa had just crashed into Mexico, while Typhoon Yutu has just hit the Northern Mariana Islands so hard that any equipment designed to record wind-speed had been swept away. Both storms rapidly strengthened, and the latter was described by the US National Weather Service as ‘likely [to] become the new yard stick by which future storms will be judged.’

Super Typhoon Yutu (24 October 2018) making its way towards the Northern Mariana Islands, a territory of the United States. (Photo: Joshua Stevens/NASA Earth Observatory)

What if we changed the way we think about such events, though? What if, instead of focusing on the wind-speed of a typhoon or the magnitude of an earthquake, the first points of discussion were about the human aspect and impact associated with a specific event. How would this summer’s events be framed? It’s a crucial distinction; natural disaster is in some ways a paradox in terms – although the hazard, or physical manifestation, of a hurricane or earthquake is natural, the impacts, and thus the disaster, are entirely a result of human exposure and vulnerability. Let’s first explore some of the most dramatic themes from this summer’s disasters, and then try and put them in this new human context.

What links this summer’s events?

The recent Hurricanes – Yutu, Willa, Florence and Michael – encapsulate well the intensity and frequency at which we’ve seen disasters come over the last few months. Earthquakes, storms, droughts and wildfires have all caused havoc in a hugely diverse spectrum of locations, and while the specter of natural hazards is always present in many parts of the world, there seems to be something more intense and urgent with respect to this summer’s catastrophes, especially in the media coverage.

The availability of smartphones and the proliferation of social media use means we can see ever more easily from the safety of our homes what others experience in terror during disasters; who could forget the scarring imagery from the earthquake and tsunami in Lombok in September, as houses were tossed about like toys as the ground turned to liquid.

Elsewhere, Japan experienced a plethora of hazards as flooding, typhoons, landslides, earthquakes and drought brought a whole range of challenging conditions which caused a large number of fatalities, despite Japan’s status as one of the best prepared countries in the world for natural hazards.

Much of the media discussion related to disasters has focused on the links between hazards and climate change, and whether the severity of events like Hurricane Florence can be attributed in part to anthropogenic emissions. While it has historically proven difficult to attribute the strength of different storms to climate change, this summer marked the first time scientists attempted it in earnest while an event was taking place – some researchers argued that the rainfall forecast for Hurricane Florence was 50% higher than it would otherwise have been, although such estimates are still in their infancy. What is clearer from scientific predictions of future climate change is that storms will likely be stronger, wetter and slower moving, suggesting similar intense storms could become more normal.

Beyond tropical storms, records were broken by other catastrophes. The Northern hemisphere wildfire season was among the worst we’ve ever experienced on record, at least in terms of acreage burned. Californian fires were so intense that smoke was noticeable on the East Coast, while the extent of fire in western Canada was second only to the cataclysmic fires last year. Abnormally warm temperatures in Scandinavia prompted wildfires to break out north of the Arctic circle, an extremely rare and concerning occurrence.

A different way to think about catastrophes

While it’s interesting and important to discuss the potential for increased storm severity as a result of climate change, it seems that this should only form a part of the larger discussion: how will trends in climate co-evolve with trends in human exposure and vulnerability to hazards? Similarly, why focus on the numbers associated with a disaster – the earthquake magnitude, the depth of flooding, acres of forest burned – when we could instead look at who has been impacted, and how to prevent this in the future.

It’s especially important to frame the ‘cost’ of a given event in this context. Often, we think of cost in either loss-of-life or financial terms, but it’s worth considering those as functions of exposure and vulnerability. For example, Hurricane Florence, which recently made landfall on the US eastern seaboard, is likely to cost  40-50 billion US dollars. Compare this to Hurricane Maria, which devastated Puerto Rico in 2017; some estimates for the cost of the storm were around 100 billion US dollars. While Hurricane Maria cost roughly twice as much as Florence, the relative impact on Puerto Rico was far greater than that value would imply. The vulnerability of the economy of Puerto Rico to a disaster of that scale was far higher than the mainland US; with a GDP of over 10 trillion US dollars, the US economy can absorb shocks like Florence, but the GDP of Puerto Rico declined by a massive 8% in the aftermath of Maria. It is worth noting that Puerto Rico is in fact a territory of the US, and received federal funding to assist with recovery – so the economic impact might even have been more severe without it.

U.S. Customs & Border Protection & FEMA personnel deliver food and water to isolated Puerto Rico residents after their bridge was destroyed by Hurricane Maria in the mountains around Utuado, Puerto Rico (Photo: U.S. Air Force/Master Sgt. Joshua L. DeMotts via FEMA)

We can build the same framing for loss of lives; countries with well-developed disaster response and recovery mechanisms suffer significantly fewer fatalities in the face of a similar magnitude event to a poorly equipped country, all things being equal. This kind of social vulnerability to disaster is difficult to quantify, and encompasses a range of aspects including cultural awareness of natural hazards and healthcare expenditure, but it has to be considered alongside the trends in hazard intensity.

I would argue that coverage of (and research related to) disasters needs to shift away from the headline numbers, like skyrocketing costs or the increasing intensity of storms and wildfires, and instead discuss whether disasters are hitting harder in places that are more vulnerable, or whether the relative economic or human exposure to a given type of disaster is worsening or not. While it’s fascinating to see images of multiple hurricanes over a single basin, it’s an incomplete picture unless the risk is incorporated.

Flash flood impacts in Peru after torrential rain in 2013 (Photo: Galeria del Ministerio de Defensa del Perú via Flickr)

Reframing our vision of disasters would put the focus squarely on where inequality and climate change interact; if more vulnerable developing countries or regions are expected to be more exposed to disasters under a changing climate, then there is real potential for inequalities to be exacerbated – and this is indeed what the UN anticipates will occur. More fundamentally, reframing would help us shift away from a coldly analytical perspective of ‘disasters by the numbers’ and instead consider where the worst impacts would be, and who the people at risk are. While trends in the developed world indicate fewer and fewer deaths from disasters over the last 100 years, many countries don’t have the same capacity to absorb shocks.

The human tendency to dwell on the extraordinary, and the ephemeral nature of modern news coverage certainly encourages reporting to focus on the records broken by a given event. Perhaps it’s futile to add another voice to the many that have already asked for more context and temperance from such coverage, but it seems important to highlight that there may be other ways to cover disasters; those affected may benefit greatly, in both the long and short term.

Robert Emberson is a Postdoctoral Fellow at NASA Goddard Space Flight Center, and a science writer when possible. He can be contacted either on Twitter (@RobertEmberson) or via his website (https://robertemberson.com/)

Editor’s note: This is a guest blog post that expresses the opinion of its author, whose views may differ from those of the European Geosciences Union. We hope the post can serve to generate discussion and a civilised debate amongst our readers.

August GeoRoundUp: the best of the Earth sciences from around the web

August GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, major geoscience headlines, as well as unique and quirky research, this monthly column aims to bring you the latest Earth and planetary science news from around the web.

Major story

The south Indian state of Kerala has suffered unusually heavy monsoon rainfall this month, triggering the worst flooding the state has seen in more than a century.

Officials have reported nearly 500 deaths, while more than one million people have been evacuated to over 4,000 relief camps.

Between 1 and 19 August, the region received 758.6 milimetres of rain, 2.6 times the average for that season. In just two days (15-16 August), Kerala sustained around 270 milimetres of rainfall, the same amount of rainfall that the entire state receives in one month typically, said Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology and the National Oceanic and Atmospheric Administration, to BBC News.

Due to the heavy downpours, rivers have overflowed, water from several dams has been released, and lethal landslides have swept away rural villages.

“Officials estimated about 6,000 miles (10,000km) of roads had been submerged or buried by landslides,” reported the Guardian. “Communications networks were also faltering, officials said, making rescue efforts harder to coordinate.”

Experts report that the event’s severity stems from many factors coming together.

For instance, a recent study led by Koll has shown that in the past 50-60 years, monsoon winds have weakened, delivering less rain on average in India. However, the distribution of rainfall is uneven, with long dry spells punctuated by heavy rainfall events. Koll’s research suggests that central India has experienced a threefold rise in the number of widespread extreme rain events during 1950-2012. In short, it doesn’t rain as often; but when it rains, it pours.

Scientists also say that increased development in the region had exacerbated the monsoon’s impact.

For example, usually when storms release heavy rainfall, much of that water is absorbed or slowed down by vegetation, soil, and other natural obstacles. However, scientists point out that “over the past 40 years Kerala has lost nearly half its forest cover, an area of 9,000 km², just under the size of Greater London, while the state’s urban areas keep growing. This means that less rainfall is being intercepted, and more water is rapidly running into overflowing streams and rivers.”

To make matters worse, increased development can also change how effectively rivers handle heavy downpours. For instance, canals and bridges can make rivers more narrow and can create sediment build-up, which slows water flow. “When there is a sudden downpour, there is not enough space for the water so it floods the surrounding area,” explains Nature.

Some experts have added that badly-timed water management practices are also partly to blame for the flood’s devastation on local communities.

“A contributing factor is that after the heavy rain, authorities began to release water from several of the state’s 44 dams, where reservoirs were close to overflowing. The neighbouring state of Tamil Nadu also purged water from its over-filled Mullaperiyar dam, which wreaked yet more havoc downstream in Kerala,” Nature adds.

While floodwaters began to recede in late August, rescue teams are still searching submerged neighborhoods to deliver aid and evacuate survivors.

What you might have missed

Water on moon confirmed

Recent research published this month suggest that there is almost certainly frozen water on the moon’s surface.

The image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right). Blue represents the ice locations, plotted over an image of the lunar surface, where the gray scale corresponds to surface temperature (darker representing colder areas and lighter shades indicating warmer zones). (Credit: NASA)

“Previous observations indirectly found possible signs of surface ice at the lunar south pole, but these could have been explained by other phenomena, such as unusually reflective lunar soil,” NASA officials said in a published statement.

Now, scientists involved with the new study claim that they’ve found definitive evidence that ice is located within craters on the moon’s north and south poles.

During daylight hours, the moon’s surface can be brutally hot, often reaching temperatures as high as 100 degrees Celsius. However, due to the moon’s axial tilt, some parts of the lunar poles don’t receive sunlight. Scientists estimate that some craters situated within these permanently dark polar regions are cold enough to sustain pockets of water-ice.

Because the moon’s poles are so dark, scientists have had a hard time studying the lunar craters. But Shuai Li, a planetary researcher at the University of Hawaii at Manoa and lead author of the study, and his colleagues tried a creative way to shed some light on shadowed craters, using data collected from India’s Chandrayaan-1 lunar probe ten years ago.

“They peered into dark craters using traces of sunlight that had bounced off crater walls,” reports the New York Times. “They analyzed the spectral data to find places where three specific wavelengths of near-infrared light were absorbed, indicating ice water.”

As of now, the researchers still aren’t sure how much ice there is, or how it found its way to the moon’s poles. But if enough accessible ice exists close to the lunar surface, the water could be used as a resource for future missions to the moon, from a source of drinking water to rocket fuel.

Mapping Earth’s winds from above

Also this month, scientists from the European Space Agency launched a satellite that will profile the world’s winds, in hopes that the data will greatly improve weather forecasts and provide insight for long-term climate research. The satellite, named Aeolus after the celestial keeper of the winds in Greek mythology, was sent to orbit from French Guiana on Wednesday 22 August.

The rocket was due to lift off on Tuesday, but the launch was postponed – ironically – due to high altitude winds,” reports BBC News.

Aeolus profiling the word’s winds (Credit: ESA)

Equipped with a Doppler wind lidar, Aeolus will send powerful laser pulses down to Earth’s atmosphere and measure how air molecules and other particles in the wind scatter the light beam.

Researchers expect that wind data from Aeolus will greatly improve current efforts to forecast storms, especially their severity over time. While scientists have many ways to measure wind behavior, current methods are unable to capture wind movement from all corners of the Earth. Aeolus will be the first mission to monitor winds across the entire globe.

Using data collected by Aeolus, experts estimate that the quality of forecasts will increase by up to 15% within the tropics, and 2-4% outside of the tropics.

“If we improve forecasts by 2%, the value for society is many billions of dollars,” said Lars Isaksen, a meteorologist at the European Centre for Medium-Range Weather Forecasts (ECMWF), to Nature.


Learn how Earth’s wind is generated and why we need to measure it. (Credit: ESA

Links we liked

The EGU story

Do you enjoy the EGU’s annual General Assembly but wish you could play a more active role in shaping the scientific programme? Now is your chance! Help shape the scientific programme of the 2019 General Assembly.

Before the end of today (6 September), you can suggest:

This month we released two press releases from research published in our open access journals. Take a look at them below:

Landslides triggered by human activity on the rise

More than 50,000 people were killed by landslides around the world between 2004 and 2016, according to a new study by researchers at UK’s Sheffield University. The team, who compiled data on over 4800 fatal landslides during the 13-year period, also revealed for the first time that landslides resulting from human activity have increased over time. The research is published today in the European Geosciences Union journal Natural Hazards and Earth System Sciences.

Deadline for climate action – Act strongly before 2035 to keep warming below 2°C

If governments don’t act decisively by 2035 to fight climate change, humanity could cross a point of no return after which limiting global warming below 2°C in 2100 will be unlikely, according to a new study by scientists in the UK and the Netherlands. The research also shows the deadline to limit warming to 1.5°C has already passed, unless radical climate action is taken. The study is published today in the European Geosciences Union journal Earth System Dynamics.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

GeoTalk: Severe soil erosion events and how to predict them

GeoTalk: Severe soil erosion events and how to predict them

Geotalk is a regular feature highlighting early career researchers and their work. In this interview we speak to Matthias Vanmaercke, an associate professor at the University of Liège in Belgium who studies soil erosion and land degradation across Europe and Africa. At the EGU General Assembly he received the 2018 Soil System Sciences Division Outstanding Early Career Scientists Award.

Thanks for talking to us today! Could you introduce yourself and tell us about your career path so far?

Hi! So I am Matthias Vanmaercke. I’m from Belgium. I’m studied physical geography at the University of Leuven in Belgium, where I also completed my PhD, which focused on the spatial patterns of soil erosion and sediment yield in Europe. After my PhD, I continued working on these topics but with a stronger emphasis on Africa. Since November 2016, I became an associate professor at the University of Liege, Department of Geography where I continue this line of research and teach several courses in geography.

At the 2018 General Assembly, you received a Division Outstanding Early Career Scientists Award for your contributions towards understanding soil erosion and catchment sediment export (or the amount of eroded soil material that gets effectively transported by a river system).

Could you give us a quick explanation of these processes and how they impact our environment and communities?

We have known for a long time that soil erosion and catchment sediment export pose important challenges to societies. In general, our soils provide many important ecosystem services, including food production via agriculture. However, in many cases, soil erosion threatens the long term sustainabilty of these services.

Several erosion processes, such as gully erosion, often have more direct impacts as well. These include damage to infrastructure and increased problems with flooding. Gullies can also greatly contribute to the sediment loads of rivers by directly providing sediments and also by increasing the connectivity between eroding hill slopes and the river network. These high sediment loads are in fact the off-site impacts of soil erosion and often cause problems as well, including deteriorated water quality and the sedimentation of reservoirs (contributing to lower freshwater availability in many regions).

Matthias Vanmaercke, recipient of the 2018 Soil System Sciences Division Outstanding Early Career Scientists Award. Credti: Matthias Vanmaercke.

What recent advances have we made in predicting these kinds of processes?

Given that we live in an increasingly globalised and rapidly changing world, there is a great need for models and tools that can predict soil erosion and sediment export as our land use and climate changes.

However, currently our ability to predict these processes, foresee their impacts and develop catchment management and land use strategies remains limited. This is particularly so at regional and continental scales and especially in Africa. For some time, we have been able to simulate processes like sheet and rill erosion fairly well. However, other processes like gully erosion, landsliding and riverbank erosion, remain much more difficult to simulate.

Nonetheless, the situation is clearly improving. For example, with respect to gully erosion, we already know the key factors and mechanisms that drive this process. The rise of new datasets and techniques helps to translate these insights into models that will likely be able to simulate these processes reasonably well. I expect that this will become feasible during the coming years.

 

What is the benefit of being able to predict these processes? What can communities do with this information?

These kinds of predictions are relevant in many ways. Overall, soil erosion is strongly driven by our land use. However, some areas are much more sensitive than others (e.g. steep slopes, very erodible soil types). Moreover, many of these different erosion processes can interact with each other. For example, in some cases gully formation can entrain landslides and vice versa.

Models that are capable of predicting these different erosion processes and interactions can strongly help us in avoiding erosion, as they provide information that is useful for planning our land use better. For instance, these models can help determine which areas are best reforested or where soil and water conservation measures are needed.

They also help with avoiding and mitigating the impacts of erosion. Many of these processes are important natural hazards (e.g. landsliding) or are strongly linked to them (e.g. floods). Models that can better predict these hazards contribute to the preparedness and resilience of societies. This is especially relevant in the light of climate change.

However, there are also impacts on the long-term. For example, many reservoirs that were constructed for irrigation, hydropower production or other purposes fill up quickly because eroded sediments that are transported by the river become deposited behind the dam. Sediment export models are essential for predicting at what rate these reservoirs may lose capacity and for designing them in the most appropriate ways.

At the Assembly you also gave a presentation on the Prevention and Mitigation of Urban Gullies Project (PREMITURG-project). Could you tell us a bit more about this initiative and its importance?

Urban mega-gullies are a growing concern in many tropical cities of the Global South. These urban gullies are typically several metres wide and deep and can reach lengths of more than one kilometre. They typically arise from a combination of intense rainfall, erosion-prone conditions, inappropriate city infrastructure and lack of urban planning and are often formed in a matter of hours due to the concentration of rainfall runoff.

Urban gully in Mbuji-Maji, Democratic Republic of Congo, September 2008. Credit: Matthias Vanmaercke

Given their nature and location in densely populated areas, they often claim casualties, cause large damage to houses and infrastructure, and impede the development of many (peri-)urban areas.  These problems directly affect the livelihood of likely millions of people in several countries, such as the Democratic Republic of Congo, Nigeria, and Angola. Due to the rapid growth of many cities in these countries and, potentially, more intensive rainfall, this problem is likely to aggravate in the following decades.

With the ARES-PRD project PREMITURG, we aim to contribute to the prevention and mitigation of urban gullies by better studying this problem. In close collaboration with the University of Kinshasa in the Democratic Republic of Congo (DRC) and several other partners and institutes, we will study this underestimated geomorphic hazard across several cities in DRC. With this, we hope to provide tools that can predict which areas are the most susceptible to urban gullying so that this can be taken into account in urban planning efforts. Likewise, we hope to come up with useful recommendations on which techniques to use in order to prevent or stabilise these gullies. Finally, we also aim to better understand the societal and governance context of urban gullies, as this is crucial for their effective prevention and mitigation.

Interview by Olivia Trani, EGU Communications Officer