World Water Day: Climate change and flash floods in Small Island Developing States

Pluvial flash flooding (otherwise known as flash flooding caused by rain) is a major hazard globally, but a particularly acute problem for Small Island Developing States (SIDS). Many SIDS experience extreme rainfall events associated with tropical cyclones (often referred to as hurricanes) which trigger excess surface water runoff and lead to pluvial flash flooding.

Following record-breaking hurricanes in the Caribbean such as Hurricane Maria in 2017 and Hurricane Dorian in 2019, the severe risk facing SIDS has been reaffirmed and labelled by many as a sign of the ‘new normal’ due to rising global temperatures under climate change. Nonetheless, in the Disaster Risk Reduction community there is a limited understanding of both current tropical-cyclone induced flood hazard and how this might change under different climate change scenarios, which inhibits attempts to build adaptive capacity and resilience to these events.

As part of the first year of my PhD research, I am applying rainfall data that has been produced by Emily Vosper and Dr Dann Mitchell in the University of Bristol BRIDGE group using a tropical cyclone rainfall model. This model uses climate model data to simulate a large number of tropical cyclone events in the Caribbean, which are used to understand how the statistics of tropical cyclone-induced rainfall might change under the 1.5C and 2C Paris Agreement scenarios. This rainfall data will be input into the hydrodynamic model LISFLOOD-FP to simulate pluvial flash flooding associated with hurricanes in Puerto Rico.

Investigating changes in flood hazard associated with different rainfall scenarios will help us to understand how flash flooding, associated with hurricanes, emerges under current conditions and how this might change under future climate change in Puerto Rico. Paired with data identifying exposure and vulnerability, my research hopes to provide some insight into how flood risk related to hurricanes could be estimated, and how resilience could be improved under future climate change.

————————————-
This blog is written by Cabot Institute member Leanne Archer, School of Geographical Sciences,  University of Bristol.
Leanne Archer

The uncertain world

J.G Ballard’s The Drowned World
taken from fantasticalandrewfox.com

Over the next 18 months, in collaboration with Bristol Green Capital 2015 artists, civic leaders and innovative thinkers, the Cabot Institute will be participating in  a series of activities in which we examine how human actions are making our planet a much more uncertain place to live.

Fifty years ago, between 1962 and 1966, J. G. Ballard wrote a trio of seminal environmental disaster novels: The Drowned World, The Burning World and The Crystal World.  These novels remain signposts to our future, the challenges we might face and the way people respond to rapid and unexpected change to their environment. In that spirit and coinciding with the Bristol Green Capital 2015, we introduce The Uncertain World, a world in which profound uncertainty becomes as much of a challenge to society as warming and rising sea levels.

For the past twenty years, the University of Bristol has been exploring how to better understand, mitigate and live with environmental uncertainty, with the Cabot Institute serving as the focus for that effort since its founding in 2010.  Uncertainty is the oft-forgotten but arguably most challenging aspect of mankind’s centuries-long impact on the environment.  We live our lives informed by the power of experience: our own as well as the collective experience of our families, communities and wider society. When my father started dairy farming he sought advice from my mother’s grandfather, our neighbours, and the grizzled veterans at the Middlefield auction house. Experience helps us make intelligent decisions, plan strategically and anticipate challenges.

Similarly, our weather projections, water management and hazard planning are also based on experience: tens to hundreds of years of observation inform our predictions of future floods, drought, hurricanes and heat waves. These records – this experience  – can help us make sensible decisions about where to live, build and farm.

Now, however, we are changing our environment and our climate, such that the lessons of the past have less relevance to the planning of our future.  In fact, many aspects of environmental change are unprecedented not only in human experience but in Earth history. As we change our climate, the great wealth of knowledge generated from human experience is losing capital every day.

The Uncertain World is not one of which we have no knowledge – we have high confidence that temperatures and sea level will rise, although there is uncertainty in the magnitude and speed of change. Nor should we view The Uncertain World with existential fear – we know that warm worlds have existed in the past.  These were not inhospitable and most evidence from the past suggests that a climate ‘apocalypse’ resulting in an uninhabitable planet is unlikely.

Nonetheless, increasing uncertainty arising from human-induced changes to our global environment should cause deep concern.  Crucial details of our climate remain difficult to predict, and it undermines our ability to plan for our future. We do not know whether many regions of the world will become wetter or dryer. This uncertainty propagates and multiplies through complex systems: how do we make sensible predictions of coastal flood risk when there is uncertainty in sea level rise estimates, rainfall patterns and the global warming that will impact both?  We can make predictions even in such complex systems, but the predictions will inevitably come with a degree of uncertainty, a probabilistic prediction.  How do we apply such predictions to decision making? Where can we build new homes, where do we build flood defences to protect existing ones, and where do we abandon land to the sea?

Perhaps most worrying, the consequences of these rapid changes on biological and chemical systems, and the people dependent upon them, are very poorly understood. For example, the synergistic impact of warmer temperatures, more acidic waters, and more silt-choked coastal waters on coral reefs and other marine ecosystems is very difficult to predict. This is particularly concerning given that more than 2.6 billion people  depend on the oceans as their primary source of protein. Similarly, warming of Arctic permafrost could promote the growth of CO2-sequestering plants or the release of warming-accelerating methane – or both. Warm worlds with very high levels of carbon dioxide did exist in the past and these do provide some insight  into the response of the Earth system, but we are accelerating into this new world at a rate that is unprecedented in Earth history, creating additional layers of uncertainty.

During late 2014 and 2015, the Cabot Institute will host a variety of events and collaborate with a variety of partners across Bristol and beyond to explore this Uncertain World and how we can live in it. How do we better explain uncertainty and what are the ‘logical’ decisions to make when faced with uncertainty? One of our first events will explore how uncertainty in climate change predictions should motivate us to action: the more uncertain our predictions the more we should employ mitigation rather than adaptation strategies. Future events will explore how past lessons from Earth history help us better understand potential future scenarios; how future scenario planning can inform the decisions we make today; and most importantly, how we build the necessary flexibility into social structures to thrive in this Uncertain World.

This blog is by Prof Rich Pancost, Director of the Cabot Institute at the University of Bristol.

Prof Rich Pancost

Pearls of wisdom: The importance of knowledge exchange when facing environmental uncertainty

Dame Pearlette Louisy at the Living
at the Sharp End of Environmental
Uncertainty Conference, Bristol, 17
July 2014. Image credit: Amanda
Woodman-Hardy
On 17 July 2014, Dame Pearlette Louisy, Governor-General of Saint Lucia, came to the University of Bristol to give a keynote talk on the challenges and strategies on environmental uncertainty from Saint Lucia and the Caribbean.  Her visit marked the start of a Cabot Institute funded conference at the university, Living at the Sharp End of Environmental Uncertainty, where members of Small Island States (SIS) came together with academics and stakeholders to thrash out the problems facing SIS in a world of global environmental uncertainty.  This blog post captures some of the key points from Dame Pearlette’s talk.

Defining environmental uncertainty

 
Defining ‘environmental uncertainty’ is a tricky prospect.  What does the term actually mean?  It’s embedded into the Cabot Institute’s strapline of ‘Living with environmental uncertainty’ but it can be hard to define.  Dame Pearlette felt there were two principle components to ‘environmental uncertainty’ – a lack of knowledge and a lack of knowledge about how an environmental system will change in the future. 

Environmental challenges in the Caribbean

 
Hurricane Tomas, 2010. Image credit: Ryder Busby
The challenges facing the Caribbean are strongly based around environmental uncertainty.  It is an area highly prone to devastating natural disasters like hurricanes, earthquakes, landslides and volcanoes.   Being a small geographical area its vulnerability is increased especially as its dependence on tourism and agriculture for income can ruin its resilience by the occurrence of one natural event.  The limited capacity to develop, coupled with limited human resources and a fragile ecosystem means that the Caribbean’s ability to implement disaster risk reduction is relatively low.
One of the key things that stood out for me in Dame Pearlette’s talk was that the locals are noticing the effects of climate change already.  A little rhyme they use about the hurricance season goes like this:

June – Too Soon
July – Standby
August – You must
September – Remember

October – It’s all over

What is shocking is that hurricane season now lasts six months (June to November) leaving communities on tenterhooks for half of the year.  Comparing this to the old rhyme, it is clear to see that this is a much longer season than it used to be.
Sadly communities in the Caribbean are particularly vulnerable to all sorts of environmental impact.  Those living on reclaimed land or at sea level are prone to flooding by high water tides.  Communities also rely heavily on coastal and marine resources leaving them vulnerable when these are damaged by environmental events.  There is also the problem of getting insured in the Caribbean.  The islands are classified as high risk which has led to very high insurance premiums for people who can ill afford them.  This has led to communities not redeveloping after disasters.

Disaster management in the Caribbean

 
Haiti after Hurricane Tomas had passed through.
Image credit: DVIDSHUB
Caribbean disaster management is difficult as the people who live there cannot manage disaster responses by themselves.  However there are fantastic organisations across the Caribbean who are key to managing risk and are helping to build a resilient and sustainable future:

 

Dame Pearlette was keen to point out that enhanced international cooperation is needed if we are to improve sustainable development in the Caribbean region.  

New approaches to Saint Lucia’s landslide problem

 
Saint Lucia is volcanic in origin and it has steep slopes. Most flat land there is situated in a narrow belt, which is where most settlement is located.  Hurricane Tomas hit Saint Lucia in 2010 and it had a large impact on the community and its financial health.  Two years later there was a landslide on the main arterial road Barre de L’Isle.  This cut the island in two and caused substantial damage to infrastructure, buildings, the East Coast Road, slopes and water catchments including the Roseau Dam which collected a lot of silt.  Saint Lucia are still trying to desilt the dam which is causing water shortage problems this year. 
It is particularly difficult to reforest slopes after landslides as all the soil is swept away leaving bare rock.  Landslide disaster risk is increasing and new approaches to designing and delivering landslide risk reduction measures on-the-ground are urgently needed.  In response to that challenge, researchers at the Cabot Institute developed a novel methodology, Management of slope stability in communities (Mossaic), the vision for which is to provide low cost, community-based solutions, such as low cost drains and other related measures to reduce landslide hazard.  
 
You can read more about how the Cabot Institute has been working with St Lucia on this poster and this powerpoint presentation

Strategies for the Saint Lucia government

 
Dame Pearlette outlined some key strategies that Saint Lucia is implementing to improve its resilience to natural hazards and environmental uncertainty including a climate change adaptation policy; a strategic programme for climate resilience; a special programme on adaptation to climate change; a pilot programme for climate resilience; and a national environmental education policy and strategy.
However there is one key challenge and that is of funding. Saint Lucia has debts and what is troubling is that it is now difficult to borrow because lenders are not sure of Saint Lucia’s ability to pay their loans back which means the country continues to depend on external assistance of NGOs.  Although not an ideal situation, there is interesting work being funded by NGOs.  One such NGO is UNDP who are working with communities to achieve environmental sustainability with emphasis on the poor to build capacity.

Education for sustainable development – the future of environmental management?

 
At the end of Dame Pearlette’s talk, she shared her thoughts on the best way forward.  She strongly felt  that Education for Sustainable Development (ESD) is the best way to bring about environmental change.  Even though no Caribbean policy for ESD exists, there are many groups trying to embed ESD into their institutes of learning.  Dame Pearlette said that knowledge management is the management of an organisation’s knowledge assets for the purpose of creating value.  The key principle of uncertainty is about lack of knowledge.   Therefore knowledge creation and knowledge sharing is paramount for managing sustainability and thus it is the individual or country’s responsibility to ensure it keeps learning to reduce its environmental uncertainty.
Here at the University of Bristol, we also believe that ESD is a worthwhile ambition to embed sustainable development into our own curriculum. At the Cabot Institute we have appointed an intern to undertake a Community Based Learning project to place environmental postgraduate students with organisations in the local community.  By embedding our environmental knowledge and sharing it with our communities, we can help build a more sustainable world and more resilient communities to what seems to be a growing plight of environmental uncertainty.
 
This blog is by Amanda Woodman-Hardy (@Enviro_Mand), Cabot Institute, University of Bristol.
 
Amanda
Woodman-Hardy