2021 was the sixth-hottest year on record: what happened in the other five?

Two new independent analyses by scientists at NASA and the National Oceanic and Atmospheric Administration (NOAA) found that 2021 ranks as the 6th hottest year since records began in 1880.

Collectively, the past eight years have been the warmest on record, indicating that our planet is indeed warming. Earth’s average land and ocean surface temperature in 2021 was 0.84 of a degree Celsius above the 20th-century average. 

Six different calculations ranked 2021 between the fifth and seventh hottest year since records began. NASA said last year tied with 2018 for sixth warmest, while NOAA puts it in sixth place by itself.

The fact that 2021 is not the warmest year on record has nothing to do with progress in tackling the heating of our planet, but it’s due to La Nina, the cooling phase of the El Nino-Southern Oscillation. This natural phenomenon, driven by changes in the winds across the Pacific Ocean, moves heat between the Pacific and the atmosphere, affecting climate patterns all over the world. A La Nina event in early 2021 led to a cooler year than it would otherwise have been, and its reappearance in late 2021 will likely cool temperatures again in 2022.

Based on NOAA calculations, here is what the five hottest years on record looked like.

1. 2016

2016 was the warmest year ever recorded, and the third consecutive year the planet reached a new record temperature.

While another El Nino event contributed to rising temperatures in the early months of the year, scientists said human activity was mostly responsible for the rise.

Research at the time showed that climate change had increased the risk of wildfires in the western US. It was also linked to extreme rainfall that caused deadly floods in China, and to South Africa’s drought and resultant food shortages. Scientists found no conclusive link between climate change and other weather phenomena experienced that year, such as severe drought in Brazil, record rains in Australia, and poor air quality in Europe.

2. 2020

This year saw a record number of tropical cyclones around the world – 103. Unusually high activity in the North Atlantic led to a violent hurricane season that left behind widespread destruction and more than 400 people dead. 

3. 2019

This year was marked by record heat waves in Europe. In June, the continent experienced the greatest heat wave in its history, with temperatures in southern France reaching an astonishing 46°C.

4. 2015

A year after 2014 became the hottest on record, 2015 became another record-smashing year. The El Nino event that appeared that year was classed as one of the three strongest ever alongside those in 1982-3 and 1997-98.

Climate change has been found linked to ten extreme weather events including heat waves in Europe, India, Pakistan, China, Indonesia, Japan, and Australia.

5. 2017

It became known at the time as the worst year for extreme weather on record, triggering a series of destructive events that affected poor developing countries in particular. Nearly 3,000 people were killed when Hurricane Maria hit Costa Rica. Sri Lanka suffered heavy landslides and flooding that killed more than 200 and displaced at least 600,000.