Heat from Euro summer not seen for 100,000 years: So, how do we infer prehistoric temperatures?
Heat Record: Unprecedented Heat: Temperatures Reach Levels Not Seen in 100,000 Years.
In the previous blog, we referred to Samantha Burgess from the European Centre for Medium-Range Weather Forecasts, the organisation responsible for Copernicus, spoke to AFP and emphasised the exceptional extent of the current warming. Ms Burgess noted:
“Humans have not experienced temperatures as high as today for, likely, the past 100,000 years”.
August 2026 was 1.65°C hotter than the average temperature before major industrialisation. According to Copernicus, it was the hottest August on record, with records going back to 1940.
So, how do we know what temperatures were like before 1940?
Modern temperature records only go back around 80-90 years. So how can scientists say today’s temperatures are unusual compared with periods thousands or even hundreds of thousands of years ago?
The answer is climate evidence preserved in nature.
How do we measure pre-historic temperatures?
Our Chief Scientist, Dr Les Strezov has noted the following:
It is important to remember that scientists are not measuring the ancient temperature directly. They are using a well-tested chemical indicator, or proxy, that changes predictably with temperature. Ice core samples are used to directly measure the ratio of isotope oxygen-18 to oxygen-16 in the ice. A higher proportion of oxygen-18 indicates warmer conditions, while a lower indicates colder conditions. These measurements are usually crosschecked with measuring the same ratio in ocean and seafloor sediments. Ice core samples also contain tiny bubbles of ancient air.
These allow for measurements of past concentrations of gases such as carbon dioxide and methane. The bubbles therefore provide information about the atmosphere at the same time that the isotope measurements provide information about temperature. While pinpointing the exact temperature with isotope method is not easy, it is reliable and robust for showing whether the climate was warmer or colder at a given period.
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