Everything you need to know about floods and climate change | Explanatory

How does climate change affect flood risk?

How does climate change affect flooding? Well, climate change – driven by the burning of coal, oil and gas – means that all of today’s weather is happening in an atmosphere that has been rendered warmer, more humid and more energetic. Consider heating water in a saucepan: as it heats up, it begins to bubble (more energy) and produce steam (more moisture in the air).

This extra energy, heat, and humidity can mean several things:

  • A hotter the atmosphere can hold more moisture. In fact, for every degree of warming, the atmosphere can hold about 7% more moisture.
  • Continued humidity can then mean that more precipitation comes in the form of short, intense showers. This can increase the risk of flash floods.
  • the additional heat in the atmosphere means there is more energy for weather systems that generate intense precipitation.

Climate change is affecting our water cycle, which refers to how water moves around our planet. Generally speaking, wet areas get wetter and dry areas get drier. In addition, we receive more rain in the form of intense showers, which leads to a greater risk of flooding.

An illustration explaining how climate change affects flooding - in English

You can find this explanatory flood graphic in more languages, as well as more explanations for other extreme weather events, here.

Impacts of extreme rainfall and flooding

On the communities

Increasingly, we see communities being hit by one disaster after another, such as drought followed by fires followed by floods. The cumulative effect of these disasters takes a heavy toll.

The most recent IPCC report highlighted that repeated exposure to extreme events, such as floods and bushfires, is associated with decreased mental well-being in many ways. These mental health effects include loss of sense of identity and place, increased anxiety and risk of depression, as well as post-traumatic stress disorder and other adverse effects.

It’s important to take care of your mental health, both during extreme weather events and afterwards, during what can often be a long recovery period. You can find a guide to managing eco-anxiety here, and one for parents and children here. Flooding can also have a significant impact on domestic and native wildlife. You can read more about caring for animals during a flood here.

Health impacts

Heavy rains and flooding affect our health in many ways – contaminating water supplies, increasing mosquito-borne diseases such as dengue fever and the Ross River virus, and increasing psychological stress in communities, as explained here -above.

While intermediate levels of precipitation can cause property damage, heavy rains can cause casualties, as we have already seen in heartbreaking fashion during the 2022 floods.

Flooding can also impact critical infrastructure, which can have permanent effects on health and well-being. For example, floods frequently damage power transmission and sometimes power generation, which also has ripple effects such as depriving people of access to refrigeration or the internet. Extreme weather events such as intense rains and floods can reduce water quality and availability, compromising water security and affecting human health.

Economical consequences

Floods have constituted the largest proportion of economic damage caused by extreme weather in Australia over the past decade, followed by tropical cyclones and droughts. In fact, if emissions continue unabated, flooding could cost the Australian economy $40 billion a year by 2060.

The immediate impacts of flooding include property damage, destruction of crops and livestock, clean-up costs and emergency response.