Floods and drought

Heavy rain and extensive flooding occurred over large parts of Africa and Asia in 2020. Heavy rain and flooding affected much of the Sahel and the Greater Horn of Africa, triggering a desert locust outbreak. The Indian subcontinent and neighbouring areas, China, the Republic of Korea and Japan, and parts of South-East Asia also received abnormally high rainfall at various times of the year.

Severe drought affected many parts of the interior of South America in 2020, with the worst-affected areas being northern Argentina, Paraguay and the western border areas of Brazil. The estimated agricultural losses were near US$ 3 billion in Brazil, with additional losses in Argentina, Uruguay and Paraguay.

Long-term drought continued to persist in parts of southern Africa, particularly the Northern and Eastern Cape Provinces of South Africa, although winter rains helped in the continuing recovery from the extreme drought situation which peaked in 2018.
Greenhouse Gases

Concentrations of the major greenhouse gases continued to increase in 2019 and 2020. Globally averaged mole fractions of carbon dioxide (CO2) have already exceeded 410 parts per million (ppm), and if the CO2 concentration follows the same pattern as in previous years, it could reach or exceed 414 ppm in 2021, according to the report. The economic slowdown temporarily depressed new greenhouse gas emissions, according to UNEP, but had no discernible impact on atmospheric concentrations.

The Ocean

The ocean absorbs around 23% of the annual emissions of anthropogenic CO2 into the atmosphere and acts as a buffer against climate change. However, the CO2 reacts with seawater, lowering its pH and leading to ocean acidification. This in turn reduces its capacity to absorb CO2 from the atmosphere. Ocean acidification and deoxygenation have continued, impacting ecosystems, marine life and fisheries, according to IOC-UNESCO.

The ocean also absorbs more than 90% of the excess heat from human activities. 2019 saw the highest ocean heat content on record, and this trend likely continued in 2020. The rate of ocean warming over the past decade was higher than the long-term average, indicating a continued uptake of heat trapped by greenhouse gases, according to the EU’s Copernicus Marine Service.

Over 80% of the ocean area experienced at least one marine heatwave in 2020. The percentage of the ocean that experienced “strong” marine heat waves (45%) was greater than that which experienced “moderate” marine heat waves (28%).
Heat and fire

In a large region of the Siberian Arctic, temperatures in 2020 were more than 3°C above average, with a record temperature of 38°C in the town of Verkhoyansk. This was accompanied by prolonged and widespread wildfires.

In the USA, the largest fires ever recorded occurred in late summer and autumn. Widespread drought contributed to the fires, and July to September were the hottest and driest on record for the southwest. Death Valley in California reached 54.4°C on 16 August, the highest known temperature in the world in at least the last 80 years.

In the Caribbean, major heatwaves occurred in April and September. Cuba saw a new national temperature record of 39.7°C on 12 April. Further extreme heat in September saw national or territorial records set for Dominica, Grenada and Puerto Rico.

Australia broke heat records in early 2020, including the highest observed temperature in an Australian metropolitan area, in western Sydney, when Penrith reached 48.9°C.

The summer was very hot in parts of East Asia. Hamamatsu (41.1°C) equalled Japan’s national record on 17 August.

Europe experienced drought and heatwaves during summer 2020, although these were generally not as intense at in 2018 and 2019. In the eastern Mediterranean with all-time records set in Jerusalem (42.7°C) and Eilat (48.9°C) on 4 September, following a late July heatwave in the Middle East in which Kuwait Airport reached 52.1°C and Baghdad 51.8°C.