WMO State of the Global Climate Report 2023: A Year of Unprecedented Heat and Hydrological Extremes

Here’s Quick Summary:

1. Global Climate Overview

• Temperature Records:
  • Hottest Year: 2023 was recorded as the hottest year on record, with a temperature increase of 1.45 °C above pre-industrial levels.
  • Climate Influences: The transition from La Niña to El Niño conditions and the positive phase of the Indian Ocean Dipole (IOD) were significant contributors to the extreme heat and associated weather impacts.

2. River Discharge Conditions

• General Trends:
  • The year 2023 saw predominantly drier-than-normal to normal river discharge conditions, continuing a trend from 2021 and 2022.
  • Over 50% of global catchment areas reported river discharge below normal.
• Regional Highlights:
  • North, Central, and South America:
    • Experienced severe drought conditions.
    • Record-low water levels were observed in the Mississippi and Amazon basins.
  • East Coast of Africa:
    • Recorded above- and much-above-normal discharge.
    • The Horn of Africa faced flooding after five consecutive dry rainy seasons.
  • Asia and Oceania:
    • Major river basins, including the Ganges, Brahmaputra, and Mekong, experienced lower-than-normal discharge.
    • The North Island of New Zealand and the Philippines exhibited much-above-normal discharge.
  • Northern Europe:
    • The UK, Ireland, Finland, and southern Sweden reported above-normal river discharge.

3. Reservoirs and Lakes

• Reservoir Inflows:

  • Inflows into reservoirs mirrored the global river discharge patterns, with below-normal inflows in India, North, Central, and South America, and parts of Australia.
  • Variability in reservoir storage was noted, influenced by water management practices.

• Lakes:

  • Lake Coari in the Amazon faced below-normal water levels, resulting in extreme water temperatures.
  • Lake Turkana, shared by Kenya and Ethiopia, experienced above-normal volumes following much-above-normal river discharge.

4. Groundwater Levels

• Above-Normal Levels:

  • South Africa, India, Ireland, Australia, and Israel observed above-normal groundwater levels due to above-average precipitation in recent years.

• Depletion:

  • Significant depletion was noted in North America and Europe, largely due to prolonged drought.
  • Chile and Jordan reported below-normal groundwater levels, attributed to over-abstraction rather than climatic factors.

5. Soil Moisture

• General Conditions:
  • Soil moisture levels were predominantly below normal across large territories globally, especially in North America, South America, North Africa, and the Middle East during the June–August period.
• Above-Normal Levels:
  • Regions such as Alaska, northeastern Canada, India, and parts of the Russian Federation reported much-above-normal soil moisture.
  • The northern and southeastern coasts of Australia, as well as New Zealand’s North Island, also experienced above-normal soil moisture due to wetter conditions and flooding.

6. Evapotranspiration (AET)

• Conditions in the Americas:
  • Central and South America, particularly Brazil and Argentina, faced much-below-normal AET in September–October–November.
  • Mexico experienced below-normal AET throughout most of 2023, reflecting severe drought conditions.

7. Snow Water Equivalent (SWE)

• Snow Conditions:
  • Most northern hemisphere catchments, with the exception of some in the northern United States and the Lena catchment in far eastern Russia, reported below- to much-below-normal SWE in March.
  • Seasonal peak snow mass was much above normal in North America but much below normal in Eurasia.

8. Glacier and Terrestrial Water Storage

• Glacier Loss:

  • Glaciers worldwide lost more than 600 gigatons (Gt) of water in 2023, marking the largest mass loss recorded in the last five decades.
  • This is the second consecutive year of ice loss in all glaciated regions globally, indicating significant melting trends.

• Terrestrial Water Storage (TWS):

  • Large parts of continents reported below-average TWS conditions in 2023.
  • Exceptions included sub-Saharan Africa, the Tibetan Plateau, and subregions of India, Australia, and northern South America.

9. High-Impact Hydrological Events

• Africa:

  • Experienced significant extreme hydrological events leading to human casualties, notably in Libya where two dams collapsed due to flooding, resulting in over 11,000 lives lost and affecting 22% of the population.
  • Additional impacts were felt in the Horn of Africa, Democratic Republic of the Congo, Rwanda, Mozambique, and Malawi, with over 1,600 deaths reported.

• Drought:

  • Regions including the southern United States, Central America, Argentina, Uruguay, Peru, and Brazil faced widespread drought conditions, leading to a 3% loss in GDP in Argentina and historically low levels in the Amazon River and Lake Titicaca.

10. Key Improvements in the 2023 Report

• Expanded Scope:

  • The report includes new chapters and hydrological variables such as lake volumes, reservoir volumes, and snow water equivalent, along with an extended chapter on glaciers.

• Increased Observational Data:

  • The number of river discharge measurement stations grew from 273 in 14 countries to 713 in 33 countries.
  • Groundwater data collection expanded to 35,459 wells in 40 countries, compared to 8,246 wells in 10 countries in the previous year.

• Model Validation:

  • Modelled river discharge values showed agreement with observed data in over 73% of validated basins, particularly in Central and Northern Europe, New Zealand, Australia, and selected basins in India, Myanmar, and South America.

11. Report Implications and Future Outlook

• Goals for Future Reports:

  • Enhance the accessibility and availability of observational data through improved monitoring and data sharing.
  • Further integrate relevant hydrological variables into future reports.
  • Encourage country participation to enhance understanding and reporting of water cycle dynamics.

• Anticipated Improvements:

  • The report aims to include more observational data supported by initiatives like the WMO Global Hydrological Status and Outlook System (HydroSOS) and collaborations with global data centers such as the Global Runoff Data Centre (GRDC), International Soil Moisture Network (ISMN), and others.