The summer of 2023 was the hottest since the Roman Empire, concerns for 2024

Researchers have revealed that the summer of 2023 was the hottest in the Northern Hemisphere in the past two millennia, with temperatures nearly 7.2°F (4°C) higher than the coldest summer during the same period.


The year 2023 has been declared the hottest on record, but instrumental evidence only dates back to 1850, often with data limited to certain regions.

By using ancient climate information derived from tree rings over two millennia, scientists from the universities of Cambridge and Johannes Gutenberg in Mainz demonstrated the exceptional nature of the summer of 2023.

Even accounting for natural climate variations, the summer of 2023 remains the hottest since the peak of the Roman Empire, surpassing extremes of natural climate variability by 0.9°F (0.5°C). These findings also indicate that the 2015 Paris Agreement, which aimed to limit warming to 2.7°F (1.5°C) above pre-industrial levels, has already been exceeded in the Northern Hemisphere.

Tree rings reveal that the coldest periods of the past two millennia, such as the ancient little ice age in the 6th century and the little ice age at the beginning of the 19th century, followed large sulfur-rich volcanic eruptions. The coldest summer of the last 2,000 years, in 536 AD, followed such an eruption and was 7.1°F (3.93°C) colder than the summer of 2023.

Warmer periods can be attributed to the El Niño climate phenomenon, which affects global weather conditions due to the weakening of trade winds in the Pacific Ocean and often leads to hotter summers in the Northern Hemisphere.

El Niño events become even stronger due to global warming caused by greenhouse gas emissions, leading to hotter summers. The current El Niño event is expected to continue until the beginning of summer 2024, making it likely that this summer will again break temperature records.