The findings are published in the 34th annual State of the Climate report. The international annual review of the world’s climate, led by scientists from NOAA’s National Centers for Environmental Information (NCEI) and published by the Bulletin of the American Meteorological Society (BAMS), is based on contributions from nearly 600 scientists in 60 countries. It provides the most comprehensive update on Earth’s climate indicators, notable weather events and other data collected by environmental monitoring stations and instruments located on land, water, ice and in space.

Dr Stephen Blenkinsop, Senior Lecturer at Newcastle University’s School of Engineering contributed a section to the annual report.

He said: “In 2023 we continued to see the planet warming and with this we saw notable extreme rainfall events that were associated with significant loss of life and damage to homes and infrastructure. Some of these events were made more likely or more severe by human-caused warming. It remains vital that we adapt our societies to these increasing risks.”

Notable findings from the State of the Climate Report include:

Record temperatures notable across the globe. A range of scientific analyses indicate that the annual global surface temperature was 0.99 to 1.08 of a degree F (0.55 to 0.60 of a degree C) above the 1991–2020 average. This makes 2023 the warmest year since records began in the mid to late 1800s, surpassing the previous record in 2016.

Earth’s greenhouse gas concentrations were the highest on record. Carbon dioxide, methane and nitrous oxide — Earth’s major atmospheric greenhouse gases — once again reached record high concentrations in 2023.

El Nino conditions contributed to record-high sea surface temperatures. El Nino conditions in the equatorial Pacific Ocean emerged in boreal spring 2023 and strengthened throughout the year. The mean annual global sea-surface temperature in 2023 was record high, surpassing the previous record of 2016 by 0.23 of a degree F (0.13 of a degree C). Each month from June to December was record warm.

Ocean heat and global sea level were the highest on record. Over the past half-century, the oceans have stored more than 90 percent of the excess energy trapped in Earth’s system by greenhouse gases and other factors. The global ocean heat content, measured from the ocean’s surface to a depth of 2000 meters (over 6,500 feet), continued to increase and reached new record highs in 2023. Global mean sea level was record high for the 12th-consecutive year, reaching about 4.0 inches (101.4 millimeters) above the 1993 average when satellite altimetry measurements began.

Heatwaves and droughts contributed to massive wildfires around the world. During late spring and a record-warm summer, approximately 37 million acres burned across Canada, an area more than twice the size of Ireland and more than double the previous record from 1989. Approximately 232,000 people were evacuated due to the threat of wildfires, and smoke from the wildfires impacted regions across Canada, the heavily populated cities of New York City and Chicago and even areas of western Europe.

The Arctic was warm and navigable. The Arctic had its fourth-warmest year in the 124-year record, with summer (July to September) being record warm.

Antarctica sea ice set record lows throughout 2023. Eight months saw new monthly mean record lows in sea ice extent (coverage) and sea ice area, and 278 days in 2023 set new daily record-low sea ice extents. On February 21, Antarctic sea ice extent and sea ice area both reached all-time record lows, surpassing the previous record lows that were set just a year earlier in February 2022.

Tropical cyclone activity was below average, but storms still set records around the globe. There were 82 named tropical storms last year, which was below the 1991–2020 average of 87. Seven tropical cyclones reached Category 5 intensity on the Saffir–Simpson Hurricane Wind Scale. Globally, the accumulated cyclone energy — a combined measure of the strength, frequency, and duration of tropical storms and hurricanes — rebounded from the lowest in the 43-year record in 2022 to above average in 2023.

Adapted with thanks from the American Meteorological Society.

Read the full report.