2020 was one of the three warmest years on record, nearly matching 2016 for the top spot, according to a synthesis of five leading global datasets by the World Meteorological Organization (WMO). Despite a natural cooling phenomenon, La Niña, its impact was only felt toward the end of the year.
A Persistent Warming Trend
All five datasets analyzed by the WMO confirm that 2011–2020 was the warmest decade on record, reinforcing a long-term warming trend caused by human activity. The six warmest years have all occurred since 2015, with 2016, 2019, and 2020 ranking as the top three. The differences in global average temperatures over these three years are statistically insignificant.
In 2020, the global average temperature was approximately 14.9°C, or 1.2°C (± 0.1°C) above pre-industrial levels (1850–1900).
Climate Change and Its Impact
United Nations Secretary-General António Guterres emphasized the urgency of addressing climate change, stating:
“The confirmation by WMO that 2020 was one of the warmest years on record is yet another stark reminder of the relentless pace of climate change, which is destroying lives and livelihoods across our planet. We are already witnessing unprecedented weather extremes in every region and continent. We are headed for a catastrophic temperature rise of 3 to 5 degrees Celsius this century. Making peace with nature is the defining task of the 21st century and must be our top priority.”
Despite the cooling influence of La Niña, WMO Secretary-General Prof. Petteri Taalas highlighted the significance of 2020’s extreme heat:
“It is remarkable that 2020’s temperatures were nearly on par with 2016, despite the absence of a strong El Niño event that boosted warmth in 2016. This is clear evidence that the influence of human-induced climate change is now as strong as natural climate variations.”
Prof. Taalas also noted that each decade since the 1980s has been warmer than the previous one, with greenhouse gas concentrations remaining at record levels. The long-lasting presence of carbon dioxide (CO₂) in the atmosphere ensures continued warming in the coming years.
La Niña’s Cooling Effect and Future Projections
The La Niña event, which began in late 2020, is expected to continue into early to mid-2021. Historically, the impact of La Niña and El Niño events on global temperatures is most substantial in the second year of their occurrence. Whether La Niña’s continued influence in 2021 will temporarily offset the broader warming trend remains uncertain.
2020’s Extreme Weather Events
Several extreme weather events characterized 2020, including:
Record-breaking wildfires in Siberia and low Arctic sea ice extent
An unprecedented Atlantic hurricane season
Extreme heatwaves, floods, and storms globally
While global temperature is a primary indicator of climate change, other critical markers include:
Greenhouse gas concentrations
Ocean heat content
Ocean acidification
Global mean sea level rise
Glacial mass loss
Sea ice extent reduction
Increase in extreme weather events
Economic and Societal Impact
The effects of climate change had severe socio-economic consequences in 2020. For example, the United States reported a record-breaking 22 billion-dollar weather disaster, making it one of the costliest years on record.
International Temperature Monitoring
The WMO relies on multiple climate datasets from leading institutions, including:
NOAA (United States National Oceanic and Atmospheric Administration)
NASA GISS (Goddard Institute for Space Studies)
UK Met Office Hadley Centre & University of East Anglia (HadCRUT)
European Centre for Medium-Range Weather Forecasts & Copernicus Climate Change Service
Japan Meteorological Agency (JMA)
These datasets are based on millions of land, sea, and satellite observations and are used to track long-term temperature trends.
Ranking 2020 in the Climate Record
Different datasets ranked 2020 slightly differently:
NASA and Copernicus Climate Change Service: Joint warmest year with 2016
NOAA and HadCRUT (UK Met Office): Second warmest year, behind 2016
Japan Meteorological Agency (JMA): Third warmest year
The slight differences among these rankings are within the margin of error, confirming 2020 as one of the warmest years ever recorded.
Paris Agreement and Future Climate Goals
The Paris Agreement aims to limit global warming to below 2°C, ideally 1.5°C, above pre-industrial levels. However, 2020’s global average temperature (1.2°C above pre-industrial levels) is already dangerously close to the 1.5°C threshold.
The WMO Global Annual to Decadal Climate Update predicts a 20% chance that the global temperature will temporarily exceed 1.5°C by 2024.
Looking Ahead
The UK Met Office’s annual global temperature forecast for 2021 suggests that, despite the cooling effects of La Niña, the upcoming year will still be among the hottest on record. The long-term warming trend continues accelerating due to greenhouse gas emissions, requiring urgent global action to mitigate further climate-related disasters.
Mary Watson
