Extreme weather events have increased fivefold over the last 50 years

Extreme Weather Events and Socioeconomic Impacts – WMO World Weather Research Programme

Extreme weather events cause significant socioeconomic impacts. WMO reports that the number of weather-related disasters has increased by a factor of five over the past 50 years, claiming, on average, the lives of 115 people and causing US$ 202 million in losses daily (WMO, 2021).

As attribution science continues to improve, evidence of the link between human-induced climate change and observed extremes, such as heatwaves, heavy precipitation and tropical cyclones, has strengthened (IPCC 2021). And while extreme weather events can impact anyone, it is the world’s most vulnerable populations, particularly those living in poverty and marginalized communities, that suffer the most.

Extreme weather events in 2022

Tropical Storm Ana and Tropical Cyclone Batsirai

Figure 1. Tropical Cyclone Batsirai off the coast of Madagascar in the south-west Indian Ocean.

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The 2021/2022 south-west Indian Ocean tropical cyclone season was very active with 12 named storms – five of which reached intense tropical cyclone status. Tropical Storm Ana was the first storm of the season, bringing strong winds, heavy rain, and widespread flooding to Madagascar, Malawi, Mozambique and Zimbabwe in late January 2022. It was followed by Batsirai, an even stronger tropical cyclone, shown in Figure 1.

The storms caused severe humanitarian impacts across the region – one of the poorest and most vulnerable in the world. In Mozambique, for example, nearly 64% of the population lives in extreme poverty, and in Madagascar, 42% of children under the age of five suffer from chronic malnutrition (World Bank, 2021; World Food Programme, 2021). As a result of these storms, tens of thousands of people were displaced, infrastructure was destroyed, and flooded farmlands further exacerbated food insecurity (Otto et al., 2022).

Using published peer-reviewed methods, the World Weather Attribution initiative found that climate change likely increased the intensity of rainfall associated with these storms (Otto et. al., 2022). As the atmosphere becomes warmer, it holds more water, which, on average, makes wet seasons and events wetter. With further emissions and rising temperatures, heavy rainfall episodes, like those associated with Ana and Batsirai, will become more common.

Vulnerable populations, such as those impacted by Ana and  Batsirai, are hit hardest by extreme weather events because they have the fewest resources to respond, recover and adapt to a changing climate. When disasters strike, they set back progress towards achieving the Sustainable Development Goals and exacerbate existing poverty and inequality. However, effective adaptation, such as the implementation of early warning systems, can reduce climate risks, minimize losses and damages and climate resilient development (See Chapter: Early Warning Systems: ing Adaptation and Disaster Risk Reduction) (IPCC, 2022).

Flooding in eastern Australia

Figure 2. Flooding in Corinda and Oxley, suburbs of Brisbane, Australia, on 1 March 2022 (Getty Images/Bradley Kanaris/Intermittent).

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Throughout 2022, successive spells of heavy rainfall over eastern Australia resulted in major floods. In late February and early March 2022, an atmospheric river transported large amounts of moisture to the Australian coast, leading to a record-breaking rainfall event and some of the worst flooding in the country’s history. Brisbane, the third largest city in Australia, experienced three consecutive days with rain totals greater than 200 mm – the first such occurrence since routine weather observations began. Subsequently, spells of heavy rain continued to hit the rain-soaked region from March to July 2022, leading to additional severe flooding (Figure 2).

The rapidly rising floodwaters resulting from this extreme rainfall caused widespread devastation and economic losses. Communities in Australia are generally better equipped to respond, recover and adapt compared to communities in lower-income countries, however, the floods still highlighted socioeconomic inequalities that exacerbate vulnerability. For example, in the devastated town of Lismore, marginalized Aboriginal communities were particularly hard hit as well as lower-income families who are more likely to live in flood-prone locations and to be unable to afford flood insurance (Williamson, 2022).

The varied nature of the extreme rainfall, with some areas experiencing persistent heavy rain for several days and others receiving short but very intense rain, makes defining how the event may be connected to human-caused climate change challenging. Climate science indicates an increasing risk of short-duration, but extreme, rainfall with continued human-induced warming. Additional factors, such as the underlying La Niña also increased the chances of wetter than average conditions across the region.

European heatwaves

In June and July 2022, Europe was affected by two extreme heat waves resulting from warm air in northern Africa spreading to the north and east, reaching Central Europe and the United Kingdom. Daily maxima exceeded 40 °C in parts of Iberia, which was 7–12 °C above normal for that time of year. In Portugal, a peak temperature of 47.0 °C was measured, exceeding the national July record of 46.5 °C (1995). Additionally, for the first time on record, temperatures in the UK exceeded 40 °C with a provisional record temperature of 40.3 °C recorded in Coningsby on 19 July, beating the previous record of 38.7 °C set in 2019. According to the World Weather Attribution initiative, human-caused climate change made the heatwave in the UK at least 10 times more likely (Zachariah et al., 2022). Figure 3 shows heatwaves across southwestern Europe from 1950 to July 2022.

Summer heatwaves pose a significant risk to human and ecosystem health. The elderly and people with chronic health conditions are particularly vulnerable, but other factors – such as socioeconomic conditions, work conditions, urbanization, and levels of preparedness – can also increase vulnerability. In London, for example, the urban heat island made the city significantly warmer than surrounding areas and high levels of inequality exacerbated vulnerability (Zachariah et al., 2022). Across Europe, first reports indicate that the heatwaves led to several thousand deaths, although it is too early to know the full human toll of these extreme events. Additionally, a coinciding marine heatwave led to devastating consequences for marine life and an extended drought across large parts of Europe impacted freshwater and other aquatic ecosystems through low river waters, plant stress and forest fires.

Figure 3. Heat waves in southwestern Europe (Portugal, Spain, southern , eastern Italy) from 1950 to 21 July 2022 in dependency of their duration (x-axis) and intensity (average anomaly, y-axis). The size of the bubbles (radius) show the spatial extension of the heat waves, annotations indicate their starting and ending dates. Bubble colours highlight the year of occurrence: blue: 2022, green: most recent before 2022, red: 21st century, orange: 20th century (Deutscher Wetterdienst (DWD)).