Record thunderstorm losses and deadly earthquakes: the natural disasters of 2023

North America once again recorded the highest losses worldwide, although this year its share of global losses was smaller than usual (40%; five-year average 57%). Natural disasters destroyed assets worth US$ 100bn, of which around US$ 67bn was insured. In spite of the large number of severe thunderstorms, the loss amount for all natural disasters was less than that of the previous year (overall losses US$ 160bn, with US$ 100bn insured).

The hurricane season in the USA was comparatively mild. Although Hurricane Idalia, one of the most severe storms of the year, hit the US mainland, the affected region in northwest Florida is sparsely populated.

However, the hurricane season in the North Atlantic was more active than average with 20 named storms, including seven hurricanes, three of which were major hurricanes, as high water temperatures offset the dampening effect of El Niño. However, most of the storms did not reach land but raged over the sea.

Two thunderstorm outbreaks in the USA in March (Midwest) and in June (Texas) numbered among the year’s costliest natural disasters worldwide in terms of insured losses. These thunderstorm series alone caused combined overall losses of US$ 17bn, of which around US$ 12bn was insured.

A devastating fire fanned by strong winds swept across Hawaii in August, destroying large parts of the coastal town of Lahaina on the island of Maui. Like the Marshall Fire in Colorado in December 2021, this event shows that grassfires in high wind conditions can spread rapidly and cause significant losses. Overall losses are estimated at US$ 5.5bn, of which roughly US$ 3.5bn was insured.

Losses from natural disasters in Europe came to US$ 83bn (€77bn), largely due to the earthquake in Turkey. Insured losses came to around US$ 19bn (€18bn). In particular, storms in the Alpine region and in the Mediterranean area contributed to the record thunderstorm losses. In July and August, hailstones measuring up to 19 cm in diameter caused billions of dollars of losses in northern Italy and several other regions. They were the result of the high prevailing temperatures and the accompanying risk of severe storms as a result of increased evaporation. There is scientific evidence that climate change is promoting the development of conditions like these.

Torrential rainfall in countries along the Adriatic coast caused widespread flooding in May and August. A low-pressure system at the start of September triggered severe flooding, particularly in Greece, and then intensified over the Mediterranean to a cyclone, Medicane Daniel. Losses from these events in Europe amounted to US$ 17bn, of which US$ 2bn was insured.

In December, sustained rainfall caused heavy flooding in many parts of northern Germany. As the floods were still ongoing in early 2024, the volume of losses could not be accurately estimated at the time of writing.    

In the Asia-Pacific and Africa region, the overall losses in 2023 of US$ 64bn were slightly lower than in the previous year (US$ 66bn). Approximately US$ 8bn of this amount was insured (previous year: US$ 11bn). Japan, a country highly exposed to natural hazards, was largely spared major damage in 2023.

While Typhoon Doksuri was the year’s costliest disaster in terms of overall losses, two major catastrophes in New Zealand together accounted for the highest insured losses in Asia-Pacific (around US$ 4bn). In early February, there were massive floods in and around Auckland, New Zealand’s biggest city, causing insured losses of nearly US$ 2bn and overall losses of US$ 2.9bn. In mid-February, Cyclone Gabrielle hit New Zealand’s North Island and Norfolk Island, resulting in huge damage. Losses from the cyclone were at a similar level to those from the floods.

In Africa, Medicane Daniel made landfall in Libya in September, and was accompanied by torrential rainfall. Dams in the city of Derna collapsed. More than 4,000 people lost their lives in the ensuing floods.

Also in September, around 3,000 people were killed in a 6.8-magnitude earthquake in Morocco. It was the strongest earthquake in Morocco for well over 100 years. The destructive power of the quake produced overall losses of some US$ 7bn. Very little was protected, with insured losses totalling around US$ 0.3bn.

At the start of the year, Cyclone Freddy triggered a humanitarian disaster in southeast Africa. Freddy formed off the Australian coast, before crossing the entire southern Indian Ocean, covering a distance of more than 8,000 kilometres. It now holds the record for the longest cyclone ever registered (five weeks). It made landfall on the island of Madagascar and then meandered back and forth between Madagascar and Mozambique. As a result, Mozambique was impacted twice over by the tropical cyclone. More than 1,400 people were killed in Mozambique and neighbouring countries.

In the northeast of Australia, severe flooding occurred in mid-December as a result of tropical storm Jasper in the state of Queensland. According to media reports, there was more than 800 mm of rain in just one day. This is roughly equivalent to the average annual rainfall in Germany. Numerous rivers burst their banks. It is still too early to reliably quantify the damage.

As in other regions, ENSO conditions influence weather extremes in Asia, in addition to climate change. The El Niño ENSO expression peaked at the end of the year and will most likely subside by mid-year. Australia can therefore hope for a mild cyclone season overall, lasting until the end of April. In contrast, the risk of forest fires is likely to be increased as the lush vegetation of recent months begins to dry out, increasing flammability. If El Niño turns into its counterpart, La Niña, in the second half of 2024, the risk of flooding for eastern Australia could increase.

The outlook for the typhoon season in the northwest Pacific remains unclear due to the uncertainty of ENSO development in the second half of the year. In the event of a La Niña phase, typhoon activity in the northwest Pacific could be below average. However, more storms could hit the Philippines, as storms under La Niña conditions tend to move westwards rather than northwards.