Bengaluru: The California-based non-profit Berkeley Earth, in its independent annual global temperature report for 2021, has stated that last year was the sixth warmest one on Earth since 1850, when record-keeping began.
The report is based on data collected from over 18,000 stations, making up 1,50,000 monthly averages for the year 2021. Also used is the sea surface temperature data from UK Met Office’s Hadley Center, which produced 20 million observations last year, using ships and buoys.
The last eight years, the report says, have been the eight warmest years on record. Additionally, 25 countries experienced their highest recorded annual average in temperatures, including China, Iran, North and South Korea, Saudi Arabia and Bangladesh.
An estimated 1.8 billion people experienced a record annual average high in temperatures last year, including most of the population of China, states the report.
Last year’s mean global temperature was 1.21 degrees Celsius above the average temperature from 1850-1900, the pre-industrial baseline for global temperature targets. The report states that 2020 was 0.15 °C warmer. As a result, 2021 was the sixth warmest year on record, while 2020 was the second warmest.
The warmest year so far has been 2016. The third, fourth, and fifth warmest years were 2019, 2017, and 2015, while the seventh warmest was 2018.
The role of La Niña
Due to a La Niña event in late 2021, the global mean temperatures dropped lower than 2020, the report stressed, but adds that the overall long-term trend remains consistent with ongoing global warming. This year, 2022, is also expected to be similar to or slightly warmer than 2021, but the average warming trend is expected to continue.
La Niña is a weather pattern that moves a large amount of heat across the planet. It leads to a cooling effect, appearing every few years and persisting for at least five months. Due to variations in ocean temperatures at the equatorial region, strong winds blow warm surface water across the Pacific, away from South America and towards Indonesia. As these warm waters move west, they are replaced by colder waters.
When it is active, the sea surface temperature across eastern Pacific Ocean drops by up to 5 degrees Celsius. It affects global weather on a large scale, including leading to an increase in Atlantic Ocean cyclones and a drop in Pacific Ocean cyclones.
Records for warmest temperature
In 2021, 87 per cent of the surface of Earth was “significantly” warmer than the average temperature between 1951 and 1980, 11 per cent had a similar temperature and 2.6 per cent was colder.
The report states 8.3 per cent of the Earth’s surface set a new local record for the warmest annual average temperature. No place on Earth recorded a coldest annual average.
Land areas warmed twice as fast as the ocean, with average land temperatures being 1.7°C above pre-industrial levels, and ocean averages being 0.83°C higher.
The Arctic’s rate of warming in 2021 also exceeded the Earth’s mean rate of warming, keeping with the same trend. This is caused due to the phenomenon known as Arctic amplification, a positive feedback loop where the more the white and reflective ice melts, the more sunlight gets absorbed, increasing warming further.
Last year also saw record highs of carbon dioxide in the atmosphere, which was measured to be 4.9 per cent higher than 2020.
Local events and trends
A host of extreme weather events, including wildfires on multiple continents, extreme flooding in many countries and increased cyclones were experienced in 2021.
A massive heat wave affected the Pacific coast of the US and Canada in June, which set temperature records in Canada for three consecutive days and was responsible for 798 deaths. The temperatures reached 45.9°C, beating 2020’s 45°C — itself a record high — a large margin.
The 25 countries experienced their highest recorded annual average temperatures were: Bangladesh, Bahrain, Benin, Bhutan, Burkina Faso, China, Ghana, Guinea, Iran, Kuwait, Liberia, Malta, Myanmar, Nigeria, North Korea, Oman, Qatar, Saudi Arabia, Senegal, Sierra Leone, South Korea, Togo, Tunisia, Turkmenistan and the United Arab Emirates. The report states that as a result, 1.8 billion people lived in areas that observed their locally warmest year.
China set a record high, exceeding 2°C above pre-industrial levels for the first time. This alone contributed to over a billion people experiencing their warmest year locally.
Despite 2021 being slightly cooler than 2020, data since 1850 clearly indicates that the average upward rising trend of temperatures is continuing, states the report.
Since 1980, the overall trend has shown a steep rise of 0.19°C every decade.
“At the current rate of progression, the increase in Earth’s long-term average temperature will reach 1.5°C above the 1850-1900 average by around 2033 and 2°C will be reached around 2060,” the report states.
(Edited by Saikat Niyogi)