highlights
hydrological limit
2023 was the hottest year on record. The transition from La Niña to El Niño conditions in mid-2023 and the positive phase of the Indian Ocean Dipole (IOD) influenced extreme weather events.
Africa was the most affected region in terms of human casualties. In Libya, severe floods in September 2023 caused two dams to collapse, killing more than 11,000 people and affecting 22% of the population. Floods also affected the Greater Horn of Africa, the Democratic Republic of the Congo and Rwanda, Mozambique and Malawi.
The southern United States, Central America, Argentina, Uruguay, Peru and Brazil were affected by widespread drought, with Argentina experiencing a 3% decline in gross domestic product and the Amazon and Lake Titicaca experiencing their lowest water levels on record.
river discharge
The year 2023 was characterized by drier-than-normal or largely-than-normal river flow conditions compared to historical periods. As in 2022 and 2021, more than 50% of the world’s watersheds will experience abnormal conditions, with most in the red. Few basins showed conditions above normal.
In 2023, large areas of North, Central, and South America experienced severe drought, reducing river flows. Record low water levels were seen in the Mississippi and Amazon River basins. In Asia and Oceania, below-normal conditions occurred across most of the vast Ganges, Brahmaputra, and Mekongri river basins.
Africa’s east coast experienced far above normal flows and flooding. New Zealand’s North Island and the Philippines saw far above normal annual runoff. In Northern Europe, above-normal spills were seen across the UK and Ireland, as well as Finland and southern Sweden.
2023: Rivers will dry up in half of the world
reservoirs and lakes
Inflows into reservoirs followed a pattern similar to global river runoff trends, with parts of India, North and South, Central America, and Australia experiencing below-normal inflows. The amount of water stored in the entire basin fluctuated significantly, reflecting the effects of water management, and in some basins, such as the Amazon and Paraná, where river flows in 2023 were significantly below normal, they were significantly higher than normal.
Lake Coari in the Amazon has experienced extremely warm water temperatures below normal. Lake Turkana, which straddles Kenya and Ethiopia, had higher than normal water levels due to river flow conditions that were well above normal.
groundwater level
In South Africa, as in India, Ireland, Australia and Israel, most wells showed above-normal groundwater levels due to above-average rainfall. Due to prolonged drought, a significant decrease in groundwater availability was observed in parts of North America and Europe. Groundwater levels in Chile and Jordan are below normal and have declined over time due to over-extraction rather than climate factors.
Soil moisture and evapotranspiration
Soil moisture levels were primarily below or well below normal in large parts of the world, with North America, South America, North Africa, and the Middle East experiencing a particularly dry period from June to August. In Central and South America, especially Brazil and Argentina, actual evapotranspiration was significantly below normal from September to October to November. In Mexico, this situation lasted almost all year round due to drought.
In contrast, soil moisture levels were well above normal in certain regions, including Alaska, northeastern Canada, India, parts of Russia, parts of Australia, and New Zealand.
Snow water equivalent amount
In most basins in the Northern Hemisphere, snowwater equivalents in March were below or well below normal. Peak snowfall for the 2023 season was well above normal in parts of North America, but well below normal in Eurasia.
glacier
Preliminary data from September 2022 to August 2023 shows the glacier’s water volume has declined by more than 600 gigatonnes, the worst on record in 50 years. This severe decline is mainly due to extreme melting in western North America and the European Alps, where Swiss glaciers are located. Approximately 10% of the remaining volume has been reduced over the past two years. Snowfall in the Northern Hemisphere has been decreasing from late spring to summer, with May 2023 having the eighth lowest snowfall on record (1967-2023). In North America, snowfall in May was the lowest for the same period.
Summer ice mass loss over the past few years has caused glaciers in Europe, Scandinavia, the Caucasus, northern western Canada, western South Asia, and New Zealand to exceed their peak water flow (the maximum melting rate of retreating glaciers), resulting in subsequent water storage and (leading to a decrease in available capacity) has been exceeded. ), while melting rates still appear to be increasing in the southern Andes (mostly in the Patagonia region), the Russian Arctic, and Svalbard.
Glaciers are retreating: Glaciers are experiencing their biggest mass loss in 50 years
