Does climate change increase the frequency and intensity of extreme weather, thus affecting more and more people?

The data is clear, less people are affected by extreme weather in the last two decades than in the previous two.

What is extreme weather?

Extreme weather refers to events significantly different from the average or usual weather patterns for a particular location and time period. These weather events may be unusually severe or intense and can cause significant damage to property, infrastructure, and human life.

Examples of extreme weather include hurricanes, tornadoes, blizzards, heat waves, droughts, floods, and severe thunderstorms. These weather events can have a variety of causes, including changes in atmospheric pressure, temperature, humidity, and wind patterns.

Extreme weather events can significantly impact the environment, human health, and the economy. They can lead to loss of life, damage to property and infrastructure, disruption of transportation and communication systems, and disruptions to the food supply chain.

What causes extreme weather?

Extreme weather can be caused by a variety of factors. Extreme weather events can be caused by natural disasters such as hurricanes, tornadoes, earthquakes, and volcanic eruptions. These events can cause extreme damage and loss of life, particularly when they occur in densely populated areas. Atmospheric conditions such as changes in air pressure, temperature, and humidity can cause extreme weather events such as thunderstorms, blizzards, and hailstorms. Human activities can also contribute to extreme weather events. For example, deforestation and urbanization can alter the landscape, making flooding and landslides more likely.

It is also claimed that climate change can exacerbate extreme weather conditions.

Climate change and extreme weather?

It is commonly claimed that climate change has a significant impact on extreme weather events. As global temperatures continue to rise, models predict the frequency, intensity, and duration of many types of extreme weather to increase. For example, climate models predict:

1. Heatwaves: Climate change will cause more frequent and severe heatwaves, particularly in urban areas. These heatwaves can cause dehydration, heat exhaustion, and even death, particularly among vulnerable populations such as the elderly and children.

2. Droughts: As temperatures rise, evaporation rates increase, causing more frequent and severe droughts. This can lead to crop failures, water shortages, and an increased risk of wildfires.

3. Floods: Warmer temperatures can increase the amount of water vapor in the atmosphere, leading to more frequent and severe precipitation events. This can cause flooding and landslides, particularly in areas with poor drainage systems.

4. Hurricanes and Typhoons: The warming of the oceans will cause more frequent and intense hurricanes and typhoons. These storms can cause significant damage to coastal communities, particularly in areas with inadequate infrastructure and housing.

5. Wildfires: Warmer temperatures and drier conditions can increase the risk of wildfires. This can lead to the widespread destruction of forests, wildlife habitats, and communities.

Overall, it is claimed that climate change is making extreme weather events more frequent, intense, and long-lasting, with significant impacts on human health, infrastructure, and the economy. However, it is difficult to examine past extreme weather events, particularly those before the late 90s, due to the lack of interconnectivity on our planet before the internet age. Thus, data before the late 90s suffer from under-reporting and is thus a minimum estimate (see figure below).

The figure above is from The International Disaster Database (https://www.emdat.be/), which states:

In 1988, the Centre for Research on the Epidemiology of Disasters (CRED) launched the Emergency Events Database (EM-DAT). EM-DAT was created with the initial support of the World Health Organisation (WHO) and the Belgian Government.

The main objective of the database is to serve the purposes of humanitarian action at national and international levels. The initiative aims to rationalise decision making for disaster preparedness, as well as provide an objective base for vulnerability assessment and priority setting.

EM-DAT contains essential core data on the occurrence and effects of over 22,000 mass disasters in the world from 1900 to the present day. The database is compiled from various sources, including UN agencies, non-governmental organisations, insurance companies, research institutes and press agencies.

If the above claims are true then surely more people would be affected by extreme weather today than in the past as warming and anthropogenic GHG emissions have continued to rise over the last several decades.

Are more people affected by extreme weather today than before?

In 2020 the CRED released a report comparing extreme weather disasters from the last two decades to those in the previous two. That report can be found here: https://www.emdat.be/cred-crunch-61-human-cost-disasters-2000-2019-0. This report claims that more people are being affected by extreme weather which is taken as direct evidence of the negative consequences of climate change and the need for immediate direct action.

The third paragraph states that 3.9 billion people were affected by extreme weather, including 510,837 deaths, from the time period 2000-2019. It also states that 3.2 billion people were affected by extreme weather, including 995,330 deaths, in the previous two decades (1980-1999). To compare these figures we need to account for population growth, so let’s take the global population for the middle of these two time periods (1990 and 2010). The global population in 1990 was 5.3 billion and in 2010 it was 6.9 billion (https://www.worldometers.info/world-population/world-population-by-year/).

In the 20 years beginning in 1980 extreme weather affected 60% of the global population, including 18% of the global population dying in extreme weather events. In the following 20-year period beginning in 2000, only 56% of the global population was affected by extreme weather, including only 7% dying due to extreme weather. In the last 20-year period, when more anthropogenic GHG emissions were added to the atmosphere than ever before, the number of people affected by extreme weather declined.