"The Role of Air-Sea Forcing in Causing Rapid Changes in the North Atlantic Thermohaline Circulation" project was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 1 - NER/T/S/2002/00427 - Duration 16 Feb 2004 - 15 Oct 2007) led by Dr Simon Josey of National Ocenaography Centre, with co-investigators also at the National Oceanography Centre. This dataset collections contains analysis of coupled model output of surface forcing variability in ocean circulation. The main aims of this proposal were to determine the role that surface forcing variability plays in causing rapid changes in the ocean circulation and to examine the effect of such changes on climate. These issues are addressed through a combined analysis of coupled model output and observational datasets. The focus of the analysis was in the North Atlantic thermohaline circulation (THC) although the results have been interpreted in the broader context of the global climate system. Variations in the air-sea fluxes of surface heat and freshwater have the potential to cause rapid changes in the ocean circulation eg through their influence on deep convection. However, the relationship between surface forcing variability and rapid changes in the ocean remains to be properly determined; our goal was to significantly improve understanding of this area. Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation

Data from "The Predictability of rapid climate change associated with the Atlantic thermohaline circulation" project. This was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 2 - NE/C509174/1 - Duration 1 Jan 2005 - 18 Sep 2008) led by Prof Rowan Sutton of the University of Reading, with co-investigators at the University of Oxford and at the National Oceanography Centre. The dataset identifies the dominant sources of uncertainty in General Circulation Model predictions of the Thermohaline Circulation. This dataset contains meteorology model output from the HadCM3 control ensemble. Forecasts of the future behaviour of the Atlantic Thermohaline Circulation (THC) are needed to inform policy on climate change. Such forecasts must be probabilistic taking into account the principal sources of uncertainty. It is not possible to sample exhaustively all sources of uncertainty because the number of degrees of freedom is too great. Consequently a future forecasting system will be reliant on strategies to identify those dimensions of uncertainty that are most important. This project developed an objective methodology to identify the dominant sources of uncertainty in General Circulation Model predictions of the THC. Perturbations to oceanic initial conditions and climate model parameters that generate the most rapid change in the THC and related aspects of climate were identified. These perturbations were used to produce an early probabilistic forecast for the behaviour of the THC up to 2100. The results were also feed directly into the next generation of ensemble climate predictions being developed at the UK Hadley Centre. Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

"The Assimilation in ocean and coupled models to determine the thermohaline circulation" project was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 2 - NE/C509058/1 - Duration 1 Sep 2005 - 30 Sep 2009) led by Prof Keith Haines of the University of Reading, with co-investigators at the National Oceanography Centre. This dataset collection contains Atlantic Ocean Thermohaline Circulation (ATOC) model measurements. To make the best use of the historical research ship records as well as new observations from autonomous ocean profiling floats and special observing programs such as Rapid climate change, it was proposed to assimilate all of the available data from the past 40 years into a high quality ocean circulation model that can represent complete fields of ocean properties. In this way derived quantities such as the north-south mass and heat transports which are vital to understanding the oceans role in controlling climate, could be determined. The project also put into context the various timeseries of observations that have been compiled from local regions which suggest that important changes in ocean circulation and transports have been ongoing in the past decades. These timeseries have been put into a basin scale and global scale context of ongoing change. The program determined the relationship between hydrographic signals in different parts of the ocean basins (particularly the N Atlantic). The program provided a method for assimilating data from the thermohaline monitoring arrays into an ocean model that could then be used as part of a coupled climate model for multi-annual climate prediction. Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

"The Mass balance and freshwater contribution of the Greenland ice sheet: a combined modelling and observational approach" project, which was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Joint International Round - NE/C51631X/1 - Duration 1 Jun 2005 - 30 Nov 2008) led Prof Jonathan Bamber of the University of Bristol, with co-investigators at the Nansen Environmental & Remote Sensing Center, Norway, the Royal Netherlands Meteorology Institute and Dr MR van den Broeke, University of Utrecht, Netherlands. The dataset quantifies how, where and when the Greenland ice sheet has fed fresh water through iceberg calving, subglacial melting and meltwater runoff into the surrounding ocean during the last half century. This dataset collection contains precipitation, evaporation and run off model outputs. The thermohaline circulation is a global ocean circulation, driven by differences in the density of the sea water that is controlled by temperature (thermal) and salinity (haline). In the north Atlantic, the thermohaline circulation transports warm and salty water to the north, where it, together with the North Atlantic Drift (the north-eastern most extension of the Gulfstream), contributes to the warm sea surface along the coast of western Europe and to the relatively mild European winters. From ice cores drilled in Greenland, there is evidence that rapid climate changes took place during the last glacial (the period roughly from 100,000 to 20,000 years before present): over a period of just several decades, northern European winter temperature dropped by as much as 10 degrees for periods typically lasting 1000 years. The present explanation is that large, pulse-like freshwater fluxes (probably from icebergs that originated from the continental ice sheets) were released into the north Atlantic where they weakened or shut down the thermohaline circulation. In a warmer greenhouse climate, it is also likely that the freshwater flux into the north Atlantic will increase; using a scenario of doubling CO2 within the next 70 years, most atmospheric models predict an increase in precipitation in high latitudes. One of the great uncertainties in these projections is the role of the Greenland ice sheet, which is situated in the middle of the area of interest. We know so little about the variability in its meltwater production and its sensitivity to regional warming that its contribution to the problem of the north Atlantic thermohaline circulation is often ignored, in spite of the fact that the Greenland ice sheet contains enough water to rise global sea level by 6 m! In this proposed research we quantifyed in detail how, where and when the Greenland ice sheet has fed fresh water through iceberg calving, subglacial melting and meltwater runoff into the surrounding ocean during the last half century. The melting and runoff was calculated using a coupled snow - atmosphere model that is run over Greenland at very high resolution (11 km in the horizontal), which took about 1 year on a supercomputer to run! Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

"To what extent was the Little Ice Age a result of a change in the thermohaline circulation?" project. This was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Joint International Round - NE/C509507/1 - Duration 1 Aug 2005 - 31 Jul 2008) led by Dr Tim Osborn of the University of East Anglia, with co-investigators at the University of East Anglia and Royal Netherlands Meteorology Institute. The dataset contains positive North Atlantic Oscillation model output from the HadCM3 model.

"Improving our ability to predict rapid changes in the El Nino Southern Oscillation climatic phenomenon" project, which was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 1 - NER/T/S/2002/00443 - Duration 1 Jan 2004 - 30 Sep 2007) led by Prof Alexander Tudhope of the University of Edinburgh, with co-investigators at the Scottish Universities Environment Research Centre, Bigelow Laboratory for Ocean Sciences, and the University of Reading. This dataset collection contains meteorology and ocean model outputs from the Coupled Hadley-Isopycnic Model Experiment (CHIME). The objective was to use a combination of palaeoclimate reconstruction from annually-banded corals and the fully coupled HadCM3 atmosphere-ocean general circulation model to develop an understanding of the controls on variability in the strength and frequency of ENSO, and to improve our ability to predict the likelihood of future rapid changes in this important element of the climate system. To achieve this, we targeted three periods:0-2.5 ka: Representative of near-modern climate forcing; revealing the internal variability in the system.6-9 ka: a period of weak or absent ENSO, and different orbital forcing; a test of the model's ability to capture externally-forced change in ENSO.200-2100 AD: by using the palaeo periods to test and optimise model parameterisation, produce a new, improved, prediction of ENSO variability in a warming world. Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

"To what extent was the Little Ice Age a result of a change in the thermohaline circulation?" project. This was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Joint International Round - NE/C509507/1 - Duration 1 Aug 2005 - 31 Jul 2008) led by Dr Tim Osborn of the University of East Anglia, with co-investigators at the University of East Anglia and Royal Netherlands Meteorology Institute. The dataset contains fresh water hosing model output from the LAR experiment run by the HadCM3 model. The freshwater was added to the North Atlantic basin to a larger area north of the CMIP (between latitudes 50°N and 70°N) area.

The Assimilation in ocean and coupled models to determine the thermohaline circulation" project was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 2 - NE/C509058/1 - Duration 1 Sep 2005 - 30 Sep 2009) led by Prof Keith Haines of the University of Reading, with co-investigators at the National Oceanography Centre. This dataset collection contains Atlantic Ocean Thermohaline Circulation ORCA1 model data.

"The Role of Air-Sea Forcing in Causing Rapid Changes in the North Atlantic Thermohaline Circulation" project was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 1 - NER/T/S/2002/00427 - Duration 16 Feb 2004 - 15 Oct 2007) led by Dr Simon Josey of National Ocenaography Centre, with co-investigators also at the National Oceanography Centre. This dataset collections contains analysis of coupled model output of surface forcing variability in ocean circulation from the Fast Ocean Rapid Troposphere Experiment (FORTE). Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

"Improving our ability to predict rapid changes in the El Nino Southern Oscillation climatic phenomenon" project, which was a Natural Environment Research Council (NERC) RAPID Climate Change Research Programme project (Round 1 - NER/T/S/2002/00443 - Duration 1 Jan 2004 - 30 Sep 2007) led by Prof Alexander Tudhope of the University of Edinburgh, with co-investigators at the Scottish Universities Environment Research Centre, Bigelow Laboratory for Ocean Sciences, and the University of Reading. This dataset collection contains meteorology and ocean model outputs from the FORTE2 model. The objective was to use a combination of palaeoclimate reconstruction from annually-banded corals and the fully coupled HadCM3 atmosphere-ocean general circulation model to develop an understanding of the controls on variability in the strength and frequency of ENSO, and to improve our ability to predict the likelihood of future rapid changes in this important element of the climate system. To achieve this, we targeted three periods:0-2.5 ka: Representative of near-modern climate forcing; revealing the internal variability in the system.6-9 ka: a period of weak or absent ENSO, and different orbital forcing; a test of the model's ability to capture externally-forced change in ENSO.200-2100 AD: by using the palaeo periods to test and optimise model parameterisation, produce a new, improved, prediction of ENSO variability in a warming world. Rapid Climate Change (RAPID) was a £20 million, six-year (2001-2007) programme for the Natural Environment Research Council. The programme aimed to improve the ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.