NASA Confirms that 2023 was the Warmest Year on Record

Earth’s average surface temperature in 2023 was the warmest on record, according to an analysis by NASA. Global temperatures last year were around 2.1 degrees Fahrenheit (1.2 degrees Celsius) above the average for NASA’s baseline period (1951-1980), scientists from NASA’s Goddard Institute for Space Studies (GISS) in New York reported.

“NASA and NOAA’s global temperature report confirms what billions of people around the world experienced last year; we are facing a climate crisis,” said NASA Administrator Bill Nelson. “From extreme heat, to wildfires, to rising sea levels, we can see our Earth is changing. There’s still more work to be done, but President Biden and communities across America are taking more action than ever to reduce climate risks and help communities become more resilient – and NASA will continue to use our vantage point of space to bring critical climate data back down to Earth that is understandable and accessible for all people. NASA and the Biden-Harris Administration are working to protect our home planet and its people, for this generation – and the next.”

In 2023, hundreds of millions of people around the world experienced extreme heat, and each month from June through December set a global record for the respective month. July was the hottest month ever recorded. Overall, Earth was about 2.5 degrees Fahrenheit (or about 1.4 degrees Celsius) warmer in 2023 than the late 19th-century average, when modern record-keeping began.

“The exceptional warming that we’re experiencing is not something we’ve seen before in human history,” said Gavin Schmidt, director of GISS. “It’s driven primarily by our fossil fuel emissions, and we’re seeing the impacts in heat waves, intense rainfall, and coastal flooding.”

Though scientists have conclusive evidence that the planet’s long-term warming trend is driven by human activity, they still examine other phenomena that can affect yearly or multi-year changes in climate such as El Niño, aerosols and pollution, and volcanic eruptions.

Typically, the largest source of year-to-year variability is the El Niño – Southern Oscillation ocean climate pattern in the Pacific Ocean. The pattern has two phases – El Niño and La Niña – when sea surface temperatures along the equator switch between warmer, average, and cooler temperatures. From 2020-2022, the Pacific Ocean saw three consecutive La Niña events, which tend to cool global temperatures. In May 2023, the ocean transitioned from La Niña to El Niño, which often coincides with the hottest years on record.

However, the record temperatures in the second half of 2023 occurred before the peak of the current El Niño event. Scientists expect to see the biggest impacts of El Niño in February, March, and April.

Line graph with monthly temperature anomalies from each year from 1880 to 2023 growing across the graph to create a stacked bell shape. The Y-axis is labeled negative 3 degrees Celsius to 3 degrees Celsius and the X-axis has each month from January to December. As time goes on, the curved lines seem to stack higher and higher, and the colors of the lines change from white and light blue to light red, and then dark red. The 2023 line, a thicker red line than the others, rises high above the rest, especially starting in May and running through December, where there is space between it and the rest of the years.

Scientists have also investigated possible impacts from the January 2022 eruption of the Hunga Tonga-Hunga Ha’apai undersea volcano, which blasted water vapor and fine particles, or aerosols, into the stratosphere. A recent study found that the volcanic aerosols – by reflecting sunlight away from Earth’s surface – led to an overall slight cooling of less than 0.2 degrees Fahrenheit (or about 0.1 degrees Celsius) in the Southern Hemisphere following the eruption.

“Even with occasional cooling factors like volcanoes or aerosols, we will continue to break records as long as greenhouse gas emissions keep going up,” Schmidt said. “And, unfortunately, we just set a new record for greenhouse gas emissions again this past year.”

“The record-setting year of 2023 underscores the significance of urgent and continued actions to address climate change,” said NASA Deputy Administrator Pam Melroy. “Recent legislation has delivered the U.S. government’s largest-ever climate investment, including billions to strengthen America’s resilience to the increasing impacts of the climate crisis. As an agency focused on studying our changing climate, NASA’s fleet of Earth observing satellites will continue to provide critical data of our home planet at scale to help all people make informed decisions.”

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