Rapid Climate Change: past; present; future

Key findings from an ambitious research project that provided the first ‘early detection system’ for climate changes in the Atlantic Ocean are highlighted today at a conference in London.

Most climate models predict gradual future changes to climate, related to the steadily increasing greenhouse gas concentrations. But ice and sediment core records reveal that, in the past, climate has changed abruptly – possibly in as little as 10 to 20 years. Such rapid change in the future could make prevention and adaptation strategies difficult and expensive to implement.

The need to understand the fundamental ocean processes that cause this abrupt change inspired the Natural Environment Research Council (NERC) to set up the £20m Rapid Climate Change programme.

A major part of the international programme involved deploying an array of instruments across the Atlantic from the Saharan coast of Africa to the Bahamas. It was risky – this type of monitoring had never been done before so there were no guarantees of success. But the risk was worth taking as, for the past four years, the instruments have provided scientists with a continuous and accurate record of the Atlantic’s Meridional Overturning Circulation (MOC), often referred to as the ‘Atlantic heat conveyor’, that moves warm water northwards and helps to maintain Europe’s mild climate.

Speaking at today’s conference, Ian Pearson, Minister for Science & Innovation, said, “We have made significant advances in the science that allows us to understand climate change, but governments still need more accurate climate predictions globally and regionally on timescales of months, years and decades.

“The Rapid Climate Change programme is vital in providing this data. Better knowledge of the state of the oceans will reduce uncertainty and improve regional climate predictions, particularly for north-west Europe.”

Research results from the programme revealed that, around 8,000 years ago, Newfoundland, the UK and northern Europe experienced extreme cold and dry conditions. Greenland temperatures were almost 6°C colder than present day. The shift to colder temperatures took only a few decades and lasted for about 160 years. It is thought that a rush of melt-water into the North Atlantic caused the slowdown of the Atlantic conveyor, leading to the colder conditions.

By combining data from past records with the new measurements obtained from the instrument array, the scientists have been able to reconstruct the behaviour of the Atlantic conveyor over the past 50 years. The reconstruction is helping them to understand recent climate changes. It also allows them to gauge the accuracy of the current climate models and the future predictions of change.

Professor Alan Thorpe, Chief Executive of NERC, said, “The RAPID programme has provided the first evidence of large, natural variability in the Atlantic circulation, much greater knowledge of how and why abrupt changes happened in the past, and the means to improve climate models. We now need to look to the future. The programme has already proved how valuable the continuous monitoring record is to current understanding of climate change and to future climate models. As a result, NERC has made a commitment to fund the observing system for a further six years, until 2014.”

The next phase of the Rapid Climate Change programme is known as RAPID-WATCH. NERC is providing &pound16m to continue monitoring the Atlantic conveyor, and to assess the scientific and broader benefits of having a more permanent operational system. Matching funds have been committed by the National Science Foundation and the National Oceanic & Atmospheric Administration in the United States, to complete the transatlantic monitoring array.

The research will involve scientists from the UK, Canada, Germany and the USA, working in close collaboration with the Met Office Hadley Centre to feed results from the programme into the Centre’s decadal prediction system.

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