Greenhouse gas concentrations, global sea levels and ocean heat content reached record highs in 2021, according to the 32nd annual State of the Climate report.

The annual review of the world’s climate, led by scientists from NOAA’s National Centers for Environmental Information and published by the Bulletin of the American Meteorological Society, is based on contributions from more than 530 international scientists, including Rebecca Beadling, assistant professor in Temple University’s Department of Earth & Environmental Science.

The report 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.

Assembling a team of fellow Southern Ocean scientists, Beadling lead the Southern Ocean section for the Antarctic and Southern Ocean chapter of the report. The Southern Ocean—generally defined as the ocean surrounding Antarctica and below 30 degrees south latitude—is, according to Beadling, “a dominant player in the global climate system and monitoring its state is key to understanding how the climate is evolving.”

This region of the ocean is responsible for the majority of the oceanic anthropogenic heat and carbon uptake, plays a critical role in fertilizing global ocean biological productivity through the vast amount of nutrients upwelled and delivered northward, and exerts a strong influence on the melting of the Antarctic Ice Sheet.

“2021 was an exceptionally turbulent year in the Southern Ocean,” says Beadling, “and continued monitoring is vital to decipher whether the anomalies we observed are a harbinger of a changing ocean state as the climate warms.”

For the report, Beadling and the team focused on ocean properties that play a role in the heat and carbon budget of the region and for which a relatively long observational record exists. The year 2021 included enhanced ocean mixing to near-record-breaking depths, stronger ocean currents, high levels of biological productivity, and a continued uptake of heat from the atmosphere.

“The Southern Ocean is a vast sink for the excess heat and carbon trapped on our planet, yet its dynamics are changing,” says Beadling. “Exactly how this region responds as greenhouse gas concentrations rise is central to understanding the trajectory of our climate system.”

Beadling, who’s research interests include the assessment of how well models represent large-scale ocean circulation patterns and properties, joined EES in 2022. She earned a geosciences PhD from the University of Arizona, where her research focused on the ocean’s role in climate. She was a Climate and Global Change Postdoctoral Fellow at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory.

“In the EES Ocean Climate Connections lab,” explains Beadling, “we use observations in conjunction with climate model simulations to understand mechanisms that may be driving changes in the oceans state, how such changes influence the global climate, and how processes within the Southern Ocean will evolve throughout the 21st century and beyond.”

The State of the Climate report is a peer-reviewed series published annually as a special supplement to the Bulletin of the American Meteorological Society. Notable findings from the State of the Climate report include:

Earth’s greenhouse gases were the highest on record.
The major atmospheric greenhouse gas concentrations – carbon dioxide, methane and nitrous oxide – each rose once again to a new record high during 2021. The global annual average atmospheric carbon dioxide concentration was 414.7 parts per million (ppm). This was 2.3 ppm greater than 2020 amounts and was the highest ever measured in both the modern 63-year record as well as the highest in at least the last million years. The annual average atmospheric methane concentration was also the highest on record, and the year-over-year increase of 18 parts per billion (ppb) was the highest since measurements began. The annual increase in methane has significantly accelerated since 2014. The annual increase of 1.3 parts per billion (ppb) for nitrous oxide was the third highest since 2001, contributing to a global annual average atmospheric concentration of 334.3 ppb.

Earth’s warming trend continued.
A range of scientific analyses indicate that annual global surface temperatures were 0.38 - 0.50 degrees F (0.21–0.28 of a degree C) above the 1991 -2020 average. This places 2021 among the six warmest years since records began in the mid to late 1800s. The last seven years (2015–21) were the seven warmest years on record, and the average global surface temperature has increased at an average rate of 0.14–0.16 of a degree F (0.08–0.09 of a degree C) per decade since the start of record-keeping and at a rate more than twice as high since 1981 (0.32–0.36 of a degree F, or 0.18–0.20 of a degree C, per decade since 1981, according to a range of scientific analyses).

Ocean heat and global sea level were the highest on record.
The ocean stores about 91% of the energy that Earth’s climate system gained over the past half century. Global ocean heat content, measured from the ocean’s surface to a depth of more than 6,000 feet, continued to increase and reached new record highs in 2021. For the 10th consecutive year, global average sea level rose to a new record high and was about 3.8 inches (97.0 mm) higher than the 1993 average—the year that marks the beginning of the satellite measurement record.

La Niña conditions lowered sea surface temperatures.
La Niña conditions that began in mid-2020 continued for most of 2021. The annual global sea surface temperature in 2021 was lower than both 2019 and 2020 due in part to La Niña, but was still 0.52 degrees F (0.29 degrees C) higher than the 1991–2020 average. Approximately 57% of the ocean surface experienced at least one marine heatwave. Since the start of the 21st century, sea surface temperatures in the North Pacific have been warming at the fastest rate among all oceanic regions.

Temperatures were mixed in the Southern Hemisphere.
La Niña contributed to the warmest year on record for New Zealand, but also to the coolest year since 2012 for Australia. On Antarctica, cold air within a strong, stable polar vortex contributed to the coldest winter (from April through September) on record at the South Pole. On the Antarctic Peninsula two stations received persistent warm northerly winds; one station tied its highest annual temperature on record while the other experienced  its second highest recorded temperature.

The Arctic was cooler overall, but some records were set.
The Arctic had its coolest year since 2013, but 2021 was still the 13th warmest year in the 122 year record. Extreme heat events occurred during the summer. During a massive heat wave in western North America, a temperature of 103.8 degrees F (39.9 degrees C) was recorded at Fort Smith, Northwest Territories, Canada, on June 30; this was the highest temperature ever recorded above 60 degrees North latitude. A widespread melt event on the Greenland Ice Sheet on August 14, 2021—the latest on record—coincided with the first observed rainfall in the 33 year record at the Summit Station, which sits at more than 10,500 feet (3,200 meters) above sea level. While the Arctic minimum sea ice extent was the 12th smallest extent in the 43 year record, the amount of multiyear ice — ice that survives one or more summer melt seasons — remaining in the Arctic was the second lowest on record. This indicates the Arctic’s sustained transition to a younger, thinner ice cover, which is more likely to experience complete melting in the future.

Tropical cyclone activity was well above average.
There were 97 named tropical storms during the Northern and Southern Hemisphere storm seasons, well above the 1991–2020 average of 87. Seven tropical cyclones reached Category 5 intensity on the Saffir–Simpson Hurricane Wind Scale. The North Atlantic hurricane basin recorded 21 named storms, the third most for the basin, behind the record 30 cyclones in 2020 and 28 in 2005. Category 4 Hurricane Ida was the most impactful storm in the Atlantic. At $75 billion (U.S. dollars) in damage, Ida was the costliest U.S. disaster of 2021 and the fifth most expensive hurricane on record since 1980. Super Typhoon Rai was the third-costliest typhoon in the history of the Philippines, causing about $1 billion (U.S. dollars) in damages and more than 400 deaths.