Is there a link between flooding and climate change?

We investigate the rising number of floods relating to the rising global temperatures

If you keep up to date with the news, you will know about the catastrophic floods that took place in Europe last year, as well as further across the world in America, Sudan, India and China, to name a few worst-struck areas. Whilst the landscapes and cultures of these impacted areas differ, one thing they have in common is the destruction left in the wake of sudden and unstoppable water, causing people to lose their homes and lives.

Both river and coastal flooding is becoming more common, but why?

Some suggest because of our Earth’s rising global temperature.

In general, scientists are wary of attributing specific extreme disasters, like flooding, to climate change. This is because, due to a lack of historical data, it’s impossible to say whether a global event wouldn’t have taken place if climate change wasn’t happening. Likewise, things like infrastructure, flood defences, soil quality and the condition of rives can also alter likelihood of floods and the level of damage. However, more and more research is being undertaken and links between climate change and flooding are being increasingly found.

Following the 2021 flooding that took place in Belgium and Germany, scientists from the World Weather Attribution (WWA) service backed up political assertions that ‘Europe had suffered a climate disaster’. The scientists said, according to news service Politico, that ‘the additional 1.2°C by which humans had warmed the planet since the Industrial Revolution had made such floods between 20 and 900 per cent more likely’ (politico.eu).

How can climate change lead to flooding?

Here is what scientists know so far.

Rising sea levels

As our global temperature climbs, ice sheets and glaciers are melting, contributing to the rising levels of our oceans. In fact, our oceans are approximately seven to eight inches higher than they were in 1900 (science2017.globalchange.gov), with levels currently rising by more than 3mm per year (theguardian.com). Scarily, the International Panel on Climate Change (IPCC) predict that seas around the world will rise anywhere from one foot to more than four feet above 2000’s levels by the end of the century. Although. in places like the East Coast of America, the National Oceanic and Atmosphere Association (NOAA) project that, due to regional factors (like currents bringing water to coastlines), the sea will rise to as much as 9.1 feet higher by 2100 (nrdc.org). As the oceans grow fuller, tides sweep higher and push into animal habitats and humanbuilt areas, and flooding occurs.

Heavier precipitation (rain)

A warmer atmosphere can hold more moisture, meaning that it can dump more, too. According to the IPCC, the atmosphere is roughly 0.75°C warmer now than it was at the start of the century, subsequently, the skies can now hold five to six per cent more moisture. Two meteorologists recently discovered that for every 1°C increase in temperature, the air can hold seven per cent extra water vapour (bbc.com). Whilst that doesn’t automatically guarantee more and heavier rainfall for the UK and elsewhere, it does mean that when it does rain, due to there being more water in the atmosphere, the volume of rain will increase (agu.org).

When we get the kinds of storms that bring about rapid cooling, you get heavier rain falling quickly out the clouds (bbc. com). Prof Piers Forster from the University of Leeds explains: “As temperatures are warmer, we get more intense rain, which by itself brings more floods, even if the number of storms hitting our shores don’t change. When coupled to warmer, wetter winters generally, as expected from climate change, the ground becomes more saturated so any rainfall will give a greater chance of flooding.” (bbc.com)

In a recent study, scientists predict that the UK will get warmer summers and wetter winters, with a 10-20 per cent increase in rainfall during the UK’s wettest days, so it is very possible that we will see more of this type of downpour throughout the remainder of winter (bbc.com).

More frequent hurricanes

Whilst hurricanes are not common in the UK, climate change is increasing the frequency of strong storms in places like America and the tropics, and it is predicted to continue to do so throughout the century. The IPPC forecasts that there will be an 80 per cent increase in frequency of category four and five hurricanes in the Atlantic basin in the next 80 years. With stronger storms, comes greater and more concentrated rainfall.

On top of this, a warmer atmosphere causes weakened atmospheric currents, which results in a slower storm that can dump more rain over a longer period of time. Experts predict that 2017’s Hurricane Harvey’s rainfall was made three times more likely and 15 times more intense because of climate change (carbonbrief.org).

One thing is certain: floods are becoming more common and more intense. If there is even a chance that, as the data and scientists suggest, climate change is making them worse, then we owe it to ourselves and future generations to do all that we can to halt Earth’s climbing temperatures.