Climate science: Sea temperatures rising for past 12,000 years

Global sea surface temperatures have been rising for the past 12,000 years, suggests a study published in Nature. The study helps to reconcile previous differences between climate models and data used to reconstruct historical changes in the climate during the Holocene.

Previous reconstructions of historical climate, based on preserved geological materials, have indicated a warm peak around 6,000 years ago, followed by a decrease in temperature until the industrial age. However, these reconstructions are at odds with long-term climate modelling, which suggests there was continual warming throughout the period.

Samantha Bova and colleagues re-interpret two recent climate reconstructions and found that most of the records represented seasonal temperatures rather than annual ones. To counter this, they developed a method of evaluating individual records for seasonal bias and used these to calculate the mean annual sea surface temperature. They identified that mean annual sea surface temperatures have been warming steadily for the past 12,000 years, which is in line with climate models for the period. They suggest that the warming is a result of retreating ice sheets 12,000 to 6,500 years ago and, more recently, of increasing greenhouse gas emissions. The authors conclude that current temperatures are the highest of the past 12,000 years and are similar to temperatures in the last interglacial period, around 125,000 years ago.