The Gulf Stream is a small part of a large, global-scale ocean ‘conveyor belt’ of circulation, driven by winds and by differences in temperature and salinity, known as the ‘Atlantic Meridional Overturning Circulation’ (AMOC). The AMOC has been measured since 2004 by an international observation system called RAPID, in which the UK plays a leading role. These measurements have shown a slowing over the last decade, however much of this may be from natural variability.
A recent assessment by the Intergovernmental Panel on Climate Change (IPCC), published in the Special Report on Oceans and Cryosphere in a Changing Climate, found some evidence to indicate the AMOC has already weakened relative to the pre-industrial period (1850 – 1900), and finds it very likely that the AMOC will continue weakening over the rest of the 21st Century.
A large slowing of the AMOC would be expected to cause more winter storms over northern Europe, a decrease in marine biological productivity in the North Atlantic and changes in sea level. These effects would be superimposed on the effects of climate warming due to greenhouse gases, and they are included in the climate model projections used by the IPCC. At this stage we do not have evidence that the observed weakening of the AMOC has had a detectable impact on the UK climate.
The second Climate Change Risk Assessment (CCRA) published in 2017 identifies risks to flooding and coastal change as one of the UK’s top six risks from climate change. The second National Adaptation Programme (NAP) published in 2018, sets out a plan of actions across Government to address these risks (amongst others identified in the CCRA) over the following 5 years. In addition, updated UK Climate Projections (UKCP18) are a key tool to help the Government, businesses and the public understand the future climate and enable them to make climate-resilient decisions.