What do we know about the climate extremes reached during 2023: air and ocean temperatures, and sea ice at the poles
If you only have a few seconds, read these lines:
- Some climate indicators have changed abruptly to limits never before recorded.
- The Earth’s average temperature has exceeded its previous record for 30 consecutive days, the ocean has been warmer than usual for 4 months, and the extent of sea ice in Antarctica is at historic lows despite it being winter in the southern hemisphere.
- The main reasons are the advancement of climate change and the natural phenomenon El Niño, although there is uncertainty and debate about more specific causes.
In July 2023, some key aspects of the climate system, such as global average temperature, ocean temperatures, and polar sea ice, have changed abruptly. Two main reasons for the extreme heat are the advancement of climate change and the effects of El Niño, a natural phenomenon that every few years overheats a part of the Pacific Ocean, influencing global climate. However, scientists are not certain about the exact reasons for ocean warming and the melting of ice in the southern hemisphere. We explain this to you and provide context.
Average air temperature
The global average temperature is not obtained through direct observation because measurement points are not evenly distributed across the planet. Reanalysis is used, a method that combines millions of available observations from satellites, radiosondes, buoys, aircraft, ships, and others, with estimates from mathematical models to create a comprehensive geographically-based database. Reanalysis also allows the study of climate evolution over the past decades by filling in missing data in the time series.
Although they have a margin of error, ‘different reanalysis products have proven to be quite useful when used with due care,’ explains this guide from the Corporation for Atmospheric Research. The Copernicus program of the European Union, the U.S. National Centers for Environmental Prediction (NCEP), NASA, and the Japan Meteorological Agency, among others, use reanalysis.
Retaining the format, since early July 2023, at least the NCEP reanalyses (visualized by the University of Maine in the United States) and those of Copernicus agree that the Earth’s average temperature is rising to unprecedented levels. These are not official figures, although the World Meteorological Organization has already documented this anomalous event. In the graph, we display the results from Copernicus, whose reanalysis incorporates more actual input data compared to the NCEP’s, making it more comprehensive.
The average air temperature at 2 meters above the planet’s surface, including land and oceans, had never exceeded 17°C, but according to Copernicus, starting from July 4th, it has accumulated 11 days above that threshold, as shown by the orange line in the upper graph. At least 30 consecutive days have surpassed the maximum of 16.7997°C recorded for August 13th, 2016, another El Niño year.
“If the increase in temperatures due to the burning of fossil fuels is the main driver of more intense heatwaves, this year El Niño is adding more fuel to the fire,” explained the Copernicus team to Maldita.es, a co-founding medium of Factchequeado.
In China, the national temperature record has been broken with 52.2°C; in Phoenix, Arizona, the average minimum temperature has been 32.7°C; and, despite it being winter in the southern hemisphere, Chile has set its second winter temperature record with 37°C, while in Argentina, temperatures are reaching up to 38°C, as reported by the World Meteorological Organization.
Average temperature at the ocean’s surface
The average temperature at the ocean’s surface is another variable obtained through reanalysis. At least in the region excluding the poles, different organizations are observing the same phenomenon: it has been warmer than the last 40 years since March. The year 2023 is represented in orange on the lower graph, which comes from Copernicus’ reanalysis.
As summarized by The Washington Post, scientists are not certain about what has exactly caused this rapid increase. Besides the well-known effects of El Niño, which itself is an abnormal warming of waters in the tropical Pacific Ocean, discussions have revolved around the influence of extreme air temperatures, the presence of weaker winds carrying less Sahara dust.
Also, the drastic reduction in sulfur dioxide emissions from ships, which polluted the air and harmed health, but also reflected sunlight, preventing the ocean from trapping more heat. In addition to the tropical Pacific, the warming is concentrated in three regions: the North Pacific, the North Atlantic, and the Mediterranean Sea. In the latter, the average temperature surpasses 28°C, with certain areas reaching 30°C on specific days.
Sea ice at the poles
In the case of icy surfaces, their extent is observed via satellite, at least as measured by the most commonly used source: the National Snow and Ice Data Center at the University of Colorado. In this case, the trend in sea ice surrounding Antarctica stands out (excluding the ice mass located on the continental shelf): despite being winter, its extent is the lowest in the entire record, which dates back to 1979. This is a very sudden change because there hadn’t been a clear decreasing trend until now.
It is still too early to directly attribute this drastic reduction in sea ice to climate change,” as experts from the Sea Ice and Snow Data Center told CNBC.
The opposite is happening in the Arctic Ocean, which this year remains at the lower limit of thawing and has been showing a continuous decline for years that is ‘unequivocally’ linked to anthropogenic climate change, according to the same experts.
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