Chocolate Easter eggs and climate change

IN his recent letter, Mr Peter Hancock demonstrates his profound ignorance regarding the changes in sea levels and sea temperatures which have been largely driven by anthropogenic global warming.

If Mr Hancock cares to visit the US Environmental Protection Agency (EPA) website, he will be able to read there that average sea surface temperature has increased during the 20th century and continues to rise. In the period 1901 to 2020, sea surface temperature rose at an average rate of 0.08oC (0.14°F) per decade.

Furthermore, the NASA website reports that the heat content of the ocean in the top 2,000 metres has increased by 360 zettajoules since 1955 (zetta is the SI prefix for 10 to the power 21), the last 10 years were the ocean’s warmest decade since at least the 1800s, and the year 2023 was the oceans’ warmest year on record. The temperature of the world’s seas and oceans is increasing because they have absorbed 90% of the atmospheric warming that has occurred in recent decades due to the increase in greenhouse gases caused by human activity.

The NASA and EPA websites also provide data on rises in sea level which completely refute the suggestion made Mr Hancock that ‘high tide still comes in to exactly the same point it always has’. These authorities explain that sea level rise is caused primarily by two factors related to global warming: through the expansion of seawater as it warms, and by the added water from melting ice sheets and glaciers.

Between 1900 and 2018, global average sea level has risen by more than 200mm, but the rate of rise is accelerating and data collected by satellite between 1993 and 2023 record a rise of 104mm.

In addition, Mr Hancock clearly doesn’t understand the relationship between chocolate prices and climate. Chocolate is mostly made from cocoa grown in West Africa, which has a yield that is highly sensitive to climate change. This year a humid heatwave, which climate scientists demonstrate has been made 10 times more likely by human-induced climate change, has massively cut yields and has raised the price of a tonne of cocoa by approximately 50%, thus leading to much more costly Easter eggs. Professor Bruce Webb

Exeter, Devon