2023 WMO Report on Global Sea-Level Rise and Implications: Key Facts and Figures

 April 2023 saw the release of 2023 WMO Report on Global Sea-Level Rise and Implications: Key Facts and Figures. It was based on:

WMO flagship reports
•    Global State of the Climate 2020 and
•    Provisional state of the Global climate 2021 and
IPCC Reports:
•    The physical Science Basis 2021 Summary for Policy Makers and
•    Special Report on the Ocean and Cryosphere in a Changing Climate 2019.

Key Messages:

• Sea-level rise threatens several low-lying small islands and high-population coastal cities.
• It is a major threat for countries like Netherlands, Bangladesh, India and China some of which comprise large coastal populations.
• Several big cities on all continents are threatened, such as Shanghai, Dhaka, Bangkok, Jakarta, Mumbai, Maputo, Lagos, London, Copenhagen, New York, Los Angeles, and Buenos Aires.
• There are significant specific impacts and challenges to those populations faced with sea-level rise living in coastal urban areas in least developed and low-middle income countries.
• It is a major economic, social and humanitarian challenge.
• Sea-level rise threatens coastal farmlands and water reserves and resilience of infrastructures as well as human lives and livelihoods.
• The impacts of average sea-level rise are boosted by storm surges and tidal variations.
• The speed of the melting of the largest global ice mass Antarctica has uncertainties.
• Human influence was very likely the main driver of these sea-level increases since at least 1971.
• The global ocean has warmed faster over the past century than since the end of the last deglacial transition (around 11,000 years ago).
• Thermal expansion explained 50% of sea-level rise during 1971–2018. Ice loss from glaciers contributed 22%, ice sheets 20% and changes in land-water storage 8%.
• The rate of ice-sheet loss increased by a factor of four between 1992–1999 and 2010–2019.
• Sea-level will continue to rise over the 21st century but sea-level rise is not globally uniform and varies regionally.
• Over the next 2000 years, global mean sea-level will rise by about 2 to 3 m if warming is limited to 1.5°C, 2 to 6 m if limited to 2°C and 19 to 22 m with 5°C of warming
• Continued sea-level rise will increase risks to food security in vulnerable regions between 1.5 C and 2 C Global warming level.
• Sea-level rise poses a distinctive and severe adaptation challenge as it implies dealing with slow onset changes and increased frequency and magnitude of extreme sea-level events which will escalate in the coming decades.