According to a new study by researchers at the University of Southampton and the National Oceanography Center, the global climate is on the verge of a multi-decade temperature change. By combining data from two methods, they have shown that the Atlantic will begin cooling, which could last for several decades. This will likely result in drier summers in the United Kingdom and Ireland, accelerated sea rise on the coast of the Northeast United States, and drought in the Sahel region of Africa.
Sea-surface temperatures in the Atlantic fluctuate between warm and cold over multiple decades in what is called the Atlantic Multi-Decadal Oscillation (AMO), which can have an impact on the scale of 20-30 years. Negative AMO, like what we will be seeing in the near future, is caused by a weakening of the currents that bring warm water north, currents that are influenced by the same atmospheric conditions that determine the direction of the Atlantic jet stream.
The study is based on two sources. The first is RAPID, a system that has been collecting data from the Atlantic meridonal overturning circulation for about a decade. This data is useful, but it only provides a limited time scale, throughout which the strength of the currents has been declining. For a broader view, researchers turned to 100 years of data on sea level. This they got from the National Oceanographic Center’s study of mean sea level, a permanent feature that has been recording that data for a century.
By combining the two data sets, researchers have been able to link AMO to sea level at the coast for the first time. Doing so is an exciting development, as it allows us to learn more about the Atlantic. It also gives us information on sea level and water temperature changes before they happen. Being able to predict, for example, that the Sahel region will likely face droughts over the next few decades can help to prepare the people in that region and reduce starvation and loss of life.