World Meteorological Day: 23 March 2021
The theme of this year’s World Meteorological Day is ‘The Ocean, our Climate and Weather.’
This reflects the understanding of the importance of the oceans to the planet:-
- Oceans cover 70% of the Earth's surface area
- 90% of the World’s trade is carried by the ocean
- The oceans directly sustain the 40% of humanity who reside within 100km of coasts
It also forms part of the World Meteorological Organisation’s (WMO) contribution to the United Nations Decade of Ocean Science for Sustainable Development (2021-2030).
The influence of the oceans on Earth’s heat balance
- Most of the sun’s incoming radiation is absorbed by the ocean
- The ocean is responsible for transferring huge quantities of absorbed heat around the globe in a network of large-scale currents
- The pattern of these is itself influenced by heat absorption and any changes may have significant local and regional impacts
- 90% of the extra heating caused by human-produced emissions of CO2 is absorbed by the oceans, whereas only 2.3% directly heats the atmosphere and the rest goes towards warming land surfaces
- Therefore, the oceans act as a store of heat. This will eventually be released to the atmosphere over forthcoming decades and centuries, which is why the warming effects of CO2 emitted so far are already built-in to the future
- Warm ocean temperatures tend to promote stronger and more frequent tropical storms. Recent studies have shown that ocean heat content reached record levels in 2020 and this coincided with a record-breaking Atlantic Hurricane season and some particularly severe tropical cyclones in the Indian and South Pacific Oceans
Other ocean-related climate issues
- Ocean warming results in expansion of the water and therefore sea-level rise. Over the past 30 years, average sea levels have already risen by around 9cm. This may sound quite small, but we must remember that the occasional extremes which arise are likely to be considerably greater and therefore potentially far more damaging to coastal and low-lying communities
- Warmer water necessarily contains less dissolved oxygen. This impacts the sustainability of marine ecosystems, including coral reefs, and will impact fishing industries
- If there is more CO2 in the atmosphere, then more will be absorbed by the oceans. This will reduce the alkalinity of the water which will, in turn, affect the growth of species such as shellfish
The choice of theme for World Meteorological Day enables focus to be directed towards enhancing the understanding of the ocean’s responses to anthropogenic CO2 increases and improving humanity’s ability to predict and mitigate these. But it also highlights the importance of better monitoring and further study of the oceans, the need for a more sustainable approach to their use and the encouragement of collaboration with other organisations, such as the International Maritime Organisation (IMO) in the pursuit of improved safety of life at sea and around the coasts.
To view a short video produced by WMO, please click below.