· Greenhouse gas concentrations
Levels reached a new global high in 2020 and continued to increase in 2021, with the concentration of carbon dioxide reaching 413.2 parts per million globally, a 149% increase on pre-industrial levels.
· Ocean heat
Another record high. The upper 2,000m depth of ocean water continued to warm in 2021 and it is expected that it will continue to warm in the future – a change which is irreversible on centennial to millennial time scales, and affects deeply marine ecosystems such as coral reefs.
· Ocean acidification
Because of the excess carbon dioxide (CO2) the ocean is absorbing (some 23% of annual emissions), its waters are increasingly acidifying.
This has consequences for organisms and ecosystems, and also threatens human food security and tourism.
The decreasing PH level also means the ocean’s capacity to absorb CO2 from the atmosphere also decreases.
· Sea-level rise
Sea level increased a record of 4.5 mm per year over the period 2013-2021, mainly due to the accelerated loss of ice mass from the ice sheets.
This has major implications for hundreds of millions of coastal dwellers and increases vulnerability to tropical cyclones.
UNEP GRID Arendal/Glenn Edney
A school of Moorish Idols cruise over the coral reef, Ha’apai, Tonga.
· Cryosphere
The world’s glaciers that scientists use as a reference have thinned by 33.5 meters since 1950, with 76% happening since 1980.
In 2021, glaciers in Canada and the US Northwest had a record ice mass loss because of heatwaves and fires in June and July.
Greenland also experienced an exceptional mid-August melt and the first-ever recorded rainfall at its highest point.
· Heatwaves
The heat broke records across western North America and the Mediterranean in 2021. Death Valley, California reached 54.4 °C on 9 July, equalling a similar 2020 value as the highest recorded in the world since at least the 1930s, and Syracuse in Sicily reached 48.8 °C.
A heatwave in British Columbia, Canada caused more than 500 deaths and fuelled devastating wildfires.
· Flooding and Droughts
Flooding caused economic losses of US$17.7 billion in Henan province of China, as well as 20 billion in Germany. It was also a factor leading to heavy loss of life.
Droughts affected many parts of the world, including the Horn of Africa, South America, Canada, the western United States, Iran, Afghanistan, Pakistan and Turkey.
The drought in the Horn of Africa has intensified through 2022. Eastern Africa is facing the very real prospect that the rains will fail for a fourth consecutive season, placing Ethiopia, Kenya and Somalia into a drought of a length not experienced in the last 40 years.
· Food security
The compounded effects of conflict, extreme weather events and economic shocks, further exacerbated by the COVID-19 pandemic, undermined decades of progress towards improving food security globally.
Worsening humanitarian crises in 2021 have also led to a growing number of countries at risk of famine. Of the total number of undernourished people in 2020, more than half live in Asia (418 million) and a third in Africa (282 million).
· Displacement:
Hazards related to water events continued to contribute to internal displacement. The countries with the highest numbers of displacements recorded as of October 2021 were China (more than 1.4 million), the Philippines (more than 386,000) and Viet Nam (more than 664,000).
