World climate on the brink of large-scale change, says international study

By NewsGram Staff Writer

The global climate is on the verge of broad-scale change that could last for a number of decades, shows a study by British scientists.

The change is linked to cooling of the Atlantic, and is likely to bring drier summers in Britain and Ireland.

The study, which appeared in the journal Nature, is based on observational evidence of the link between ocean circulation and the decadal variability of sea surface temperatures called the Atlantic Multi-decadal Oscillation (AMO).

"Sea-surface temperatures in the Atlantic vary between warm and cold over time-scales of many decades. These variations have been shown to influence temperature, rainfall, drought and even the frequency of hurricanes in many regions of the world," said lead author Gerard McCarthy from the National Oceanography Centre (NOC).

These climatic phases are the result of the movement of heat northwards by a system of ocean currents. This movement of heat changes the temperature of the sea surface, which has a profound impact on climate on time-scales of 20-30 years.

The strength of ocean currents has been measured by a network of sensors, called the RAPID array, which have been collecting data on the flow rate of the Atlantic meridonal overturning circulation (AMOC) for a decade. The authors used 100 years of sea level data, maintained by the National Oceanography Centre's permanent service for mean sea level.

"By reconstructing ocean circulation over the last 100 years from tide gauges that measure sea level at the coast, we have been able to show, for the first time, observational evidence of the link between ocean circulation and the AMO," said co-author Ivan Haigh, lecturer in coastal oceanography at the University of Southampton.