The Past, the Future, the Now: Floods and the Need to be Adapted

According to the last Intergovernmental Panel on Climate Change report on Global Warming (2018), if we continue living the way we currently are (also known as “business as usual”), the sea-level is expected to rise by 18 cm by 2030, and 44 cm by 2070 [i]. While 44 cm may not sound like a significant change, especially scattered in 50 years, this increase is enough to cause disruptions, affecting directly coastal areas and islands.

In global terms, this would mean:

1. Reduction of habitable land,

2. The disappearance of vital natural reservoirs and parks located at the shorelines,

3. Extensive damages to all properties close to the coast, including harbours, hotels and apartments, and, of course, …

4. The increased number of climate migrations around the world.

For the record, all this is already happening worldwide.

Although the sea-level rise is expected to affect primarily the group of countries known as “Small Island Developing States — SIDS”, however, they are not the only ones. Most of the capitals and the most important cities of the world are located by the sea, such as New York city, Stockholm, Copenhagen, Cape Town, Singapore and Hong Kong, among many others. Countries with people living in coastal areas and floodplains should also be aware of the imminent consequences of climate change.

“Sea-level rise is not the only threat, and many capital cities may be exposed in the near future if adaptation is not taking place.

Sea-level rise is not the only water-related threat to be worried about. More specifically, climate change is expected to intensify and increase the frequency of natural hazards, which translates to more dangerous storms, fluvial (riverine flooding), pluvial (flash floods and surface water), and coastal floods (storm surge).

Flood risk in Europe: The past and the future

With the aim to project the flood risk in Europe in the near future, I analysed potential flood-prone area extent data, which delineates the areas that are flooded once every 100 years. For example, the probability of flooding is 1% assuming that flooding is unrestricted [ii] (as of 2019) and the total amount of days with high and very high severity floods from 1980 to 2013[iii] from the European Environmental Agency. The map below shows the results from combining both data sets, which presents some interesting insights, explained below.[iv]

Past disruptions and future risks due to floods in Europe

First, Spain stands out as the country most affected by high and very high severity-level flooding in the past, with a total of 1,311 days (the equivalent of more than three years and a half) of severe disruptions due to floods in 33 years. Spain is, however, not the wettest country in Europe, and it is not the one with the heaviest precipitation levels. So, the question here is, why is Spain the most affected country on the continent? Some reasons that explain these considerable number of disruptions are, among others, land-use change, river channels modifications, increased activities in areas vulnerable to floods, and the increase of impermeable surfaces[v].

The countries that follow the list are Germany and Poland, with 922 days and 690 days respectively. These numbers highly contrast with Luxembourg, the Netherlands and Sweden, which in 33 years had 0 days of high or very high severe floods. The European average of days with high and very high severity-level flooding for the period 1980–2013 is 193, which denotes a significant variance between the countries in Europe.

“Spain stands out as the most affected European country by severe disruptions due to floods from 1980–2013, despite not being the wettest country in the continent.

Another information that the map provides us is the location of floodplains (which are areas of low-lying ground adjacent to a river, formed mainly of river sediments and subject to flooding) with a 1% probability of being flooded. It is interesting to see that there is no clear correlation between the number of days of disrupted floods and floodplains at risk. For countries such as Sweden (0 days of disruptions), Finland (17 days), Hungary (11 days) and Serbia (30 days), with very low or non-disrupted days due to floods, most of their floodplains are expected to be flooded if no adaptation measures are taken. On the other hand, Denmark (with 60 days) has almost no floodplains at risk.

However, climate change implies much uncertainty in the possible impacts of future storms since there are many variables (mainly greenhouse gasses emissions). Considering that future storms will increase in intensity and frequency, those countries with more floodplains at risk may see disruptions due to floods in the future if adaptation and prevention measures are not implemented. Definitively, more variables need to be considered to assess the damages and risks, such as the terrain’s elevation around those floodplain areas at risk and the distribution of population density. Hence, the less elevation of the land and the more population density, the more probability of damage. The same applies to countries that have experienced significant disruptions in the past due to floods.

“The less elevation of the land and the more population density in coastal areas and floodplains, the more probability of damage.

Conclusions

While it is true that past data cannot explain the future, past disruptions due to floods constitute a good indicator of climate change preparedness and adaptation.

On the one hand, given that storms will be more frequent and severe due to climate change, those countries that were struggling with less frequent and less intense storms will see more damaging disruptions in the coming future if nothing is changed (from greenhouse gas emissions to increased protection mechanisms of those areas most at risk).

“Those countries that were struggling with less frequent and less intense storms will see more damaging disruptions in the coming future if nothing is changed.

On the other hand, most of the countries in Europe, especially the North, South and South-East, are expected to see increased damages and disruptions in the potential flood-prone areas, which can change the experience these countries had in the past with floods. Again, if nothing is done to prevent all these damages.

To sum up, not only the most vulnerable countries are exposed to the risks of climate change. Climate change affects every single country and, although differently, resulting in critical losses that can be prevented if we act now.

Acknowledgements

I would like to acknowledge Santiago Lema Burgos for his inputs and editorial work.

References:

[i] R. Warrick, J. Oerlemans, IPCC Special Report: Global Warming of 1.5º — Chapter 9: Sea Level Rise. Available at: https://www.ipcc.ch/site/assets/uploads/2018/03/ipcc_far_wg_I_chapter_09.pdf

[ii] For more explanation on this data, please go to: https://water.discomap.eea.europa.eu/arcgis/rest/services/Flood/Potential_flood_prone_area/MapServer

[iii] For more information, please go to: https://www.eea.europa.eu/data-and-maps/data/european-past-floods/flood-phenomena

[iv] For the background of the map: https://server.arcgisonline.com/ArcGIS/rest/services/World_Terrain_Base/MapServer/tile/{z}/{y}/{x}

[v] Centre for Climate Adaptation, Spain: River Floods in Spain (March, 2021). Available at: https://www.climatechangepost.com/spain/river-floods/#:~:text=The%20direct%20anthropogenic%20causes%20include,coastal%20urbanization%20has%20been%20extensive.