"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 collection contains various model experiment output used in an analysis of whether the Little Ice Age climate could have been generated by one or more of the following factors: a weakening of the Atlantic thermohaline circulation; the persistence of a generally negative North Atlantic Oscillation; or reduced radiative forcing (by increased volcanic activity, reduced solar insolation and lower greenhouse gas concentrations relative to the present). 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.

Theme 5 - Cryosphere and Polar Oceans - of the National Centre for Earth Observation (NCEO) is aimed at resolving uncertainties in future climate and sea-level arising from behaviour of the cryosphere. Under this theme, 5 year time series Ice thickness data used by Katharine Giles, Seymour Laxon and Andy Ridout in their paper "Circumpolar thinning of Arctic sea ice following the 2007 record ice extent minimum" (Geophysical Research Letters, Vol. 35, L22502, doi:10.1029/2008GL035710, 2008) are presented.

"The Processes controlling dense water formation and transport on Arctic continental shelves". This Project was led by Prof Andrew Willmott of the Proudman Oceanographic Laboratory, with co-investigators at the Proudman Oceanographic Laboratory and Keele University. This dataset collection contains parameterisations for dense water production in polynyas for application in non-polynya resolving ocean circulation models, and results of the testing of these in a coupled sea ice-shelf sea POLCOMS-CICE model of the Barents Sea. The Barents Sea is an important site for the production of dense intermediate water. Up to one half of this intermediate water flows into the North Atlantic over the Scotland-Greenland Ridge, constituting an important branch of the global thermohaline circulation. The presence of numerous coastal polynyas and the relatively low river input into the Barents Sea explain why this region is a significant site for water for water mass transformation. Parameterisations for dense water production in polynyas for application in non-polynya resolving ocean circulation models, were developed and tested in a coupled sea ice-shelf sea model of the Barents Sea. The latter were used to study present day water mass transformation processes and to predict how they will change in a warmer climate. 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 Processes controlling dense water formation and transport on Arctic continental shelves". This Project was led by Prof Andrew Willmott of the Proudman Oceanographic Laboratory, with co-investigators at the Proudman Oceanographic Laboratory and Keele University. This dataset contains parameterisations for dense water production in polynyas for application in non-polynya resolving ocean circulation models, and results of the testing of these in a coupled sea ice-shelf sea POLCOMS-CICE model of the Barents Sea.

DESIRE (Dynamics of the Earth System and the Ice-Core Record) was part of QUEST (Quantifying and Understanding the Earth System) Theme 2. This dataset contains measurements of chemical traces and meteorological from the TOMCAT (Tropospheric Offline Model of Chemistry and Transport model), as part of the Work Package 1.3. The aim of this work package was to identify any atmospheric chemical signal preserved in the ice-core record that could be used to differentiate between the influences on atmospheric methane of changes in methane emissions and changes in oxidising capacity between the Last Glacial Maximum (LGM) and the pre-industrial era (PI). A series of experiments was carried out using the Cambridge parallelised-Tropospheric Offline Model of Chemistry and Transport (p-TOMCAT; v2.0 beta), the results to which are contained in this dataset.

This dataset contains measurements of sea ice content (HadISST1.1). Dataset include monthly mean gridded (1deg grid), global Ice content from 1870 to October 2015. This product replaced the GISST/GICE (Global Sea Surface Temperature/Global sea-Ice content) data sets ended in February 2003. The sea ice data are taken from a variety of sources including digitized sea ice charts and passive microwave retrievals. The sea ice fields are made more homogeneous by compensating satellite microwave-based sea ice concentrations for the impact of surface melt effects on retrievals in the Arctic and for algorithm deficiencies in the Antarctic, and by making the historical in situ concentrations consistent with the satellite data. SSTs near sea ice are estimated using statistical relationships between SST and sea ice concentration. From May 2007 the data set of in situ measurements used in HadISST has changed. The MOHSST data set, which was previously used has been discontinued, and HadSST2 is now being used in its place. The two systems ran in parallel for several months prior to the changeover and no significant differences were seen. The data were provided by the Hadley centre (Met Office). Important Notes: On 13th March 2015: Users have noticed that there is a minor discontinuity at the dateline in HadISST1 SST fields starting in 1982. It appears to only affect gridcells just to the east of the dateline. Please note that this can affect estimates of the mean and variability of SSTs in HadISST1 when analysed across this region. On 8th March 2011: The switch of satellite source data at the start of 2009 introduced a discontinuity in the fields of sea ice in both the Arctic and Antarctic. On 3rd December 2010: The SSM/I satellite that is used to provide the data for the sea ice analysis in HadISST suffered a significant degradation in performance through January and February 2009. The problem affected HadISST fields from January 2009 and probably causes an underestimate of ice extent and concentration. It also affected ses surface temperatures in sea ice areas because the SSTs are estimated from the sea ice concentration. As of 3rd December 2010, the Met Office Hadley Centre has reprocessed the data from January 2009 to the present using a difference sea ice data source. This is an improvement on the previous situation but users should still note that the switch of data source at the start of 2009 might introduce a discontinuity into the record.

DESIRE (Dynamics of the Earth System and the Ice-Core Record) was part of Theme 2 QUEST (Quantifying and Understanding the Earth System) programme. This dataset collection contains chemical traces, sea conditions and meteorological measurements from the Tropospheric Offline Model of Chemistry and Transport (TOMCAT) model and MITgcm (MIT General Circulation Model). The project involved an Anglo-French collaboration between QUEST and INSU (Institut national des sciences de l'univers). The project responded to a call to “explain the major changes in atmospheric carbon dioxide and methane concentration over glacial-interglacial timescales”. The project had three strands. In the first strand, tools to improve understanding and modelling of methane were worked on; this included improvements to models, as well as new constraining datasets. In the second strand, similar improvements for CO2 were to be made. The third strand included model simulations and a major data compilation covering the 800,000 year ice core period. Much of the early research in this project used the simple Earth system model GENIE, which generally yields robust results. For example, CO2-forced transient simulations over 650,000 years reproduced Antarctic temperature anomalies with a high correlation, broadly capturing the QUEST Final Report, June 2011 22 magnitude of glacial-interglacial temperature changes. This study found that warm peaks in interglacials are consistent with changes in the meridional overturning circulation.

Data from HasISST contains measurements of sea surface temperature (SST) and also global sea ice coverage (HadISST1.1). Dataset include: - Global Ocean Surface Temperature (HadISST_1.1_SST), a set of SST data in monthly 1° area grids, for 1870 to October 2015. - Global sea-Ice content, (HadISST_1.1_ICE), monthly 1° grids of ice coverage for 1870 to October 2015. In situ sea surface observations and satellite derived estimates at the sea surface are included in the analysis. SST bucket corrections have been applied to gridded fields from 1870 through 1941. And a blend of satellite AVHRR (for SST), SSMI (for ice) and observations are used in the modern periods. This data product replaces the GISST/GICE (Global Sea Surface Temperature/Global sea-Ice content) data sets ended in February 2003. The data were provided by the Hadley Centre (Met Office). Updates are available from the Hadley Centre.

This dataset contains measurements of sea surface temperature (SST) (HadISST1.1). Dataset include monthly mean gridded (1deg grid), global SSTs from 1870 to October 2015. This product replaced the GISST/GICE (Global Sea Surface Temperature/Global sea-Ice content) data sets ended in February 2003. The SST data are taken from the Met Office Marine Data Bank (MDB), which from 1982 onwards also includes data received through the Global Telecommunications System (GTS). In order to enhance data coverage, monthly median SSTs for 1871-1995 from the Comprehensive Ocean-Atmosphere Data Set (COADS) (now ICOADS) were also used where there were no MDB data. The sea ice data are taken from a variety of sources including digitized sea ice charts and passive microwave retrievals. HadISST1 temperatures are reconstructed using a two stage reduced-space optimal interpolation procedure, followed by superposition of quality-improved gridded observations onto the reconstructions to restore local detail. The sea ice fields are made more homogeneous by compensating satellite microwave-based sea ice concentrations for the impact of surface melt effects on retrievals in the Arctic and for algorithm deficiencies in the Antarctic, and by making the historical in situ concentrations consistent with the satellite data. SSTs near sea ice are estimated using statistical relationships between SST and sea ice concentration. From May 2007 the data set of in situ measurements used in HadISST has changed. The MOHSST data set, which was previously used has been discontinued, and HadSST2 is now being used in its place. The two systems ran in parallel for several months prior to the changeover and no significant differences were seen. The data were provided by the Hadley centre (Met Office). Important Notes: On 13th March 2015: Users have noticed that there is a minor discontinuity at the dateline in HadISST1 SST fields starting in 1982. It appears to only affect gridcells just to the east of the dateline. Please note that this can affect estimates of the mean and variability of SSTs in HadISST1 when analysed across this region. On 3rd December 2010: The SSM/I satellite that is used to provide the data for the sea ice analysis in HadISST suffered a significant degradation in performance through January and February 2009. The problem affected HadISST fields from January 2009 and probably causes an underestimate of ice extent and concentration. It also affected ses surface temperatures in sea ice areas because the SSTs are estimated from the sea ice concentration. As of 3rd December 2010, the Met Office Hadley Centre has reprocessed the data from January 2009 to the present using a difference sea ice data source. This is an improvement on the previous situation but users should still note that the switch of data source at the start of 2009 might introduce a discontinuity into the record.

DESIRE (Dynamics of the Earth System and the Ice-Core Record) was part of QUEST (Quantifying and Understanding the Earth System) Theme 2. This dataset contains measurements of sea temperature, salinity and elevation from the MITgcm (MIT General Circulation Model) model, as part of the Work Package 2.3. These experiments were conducted to investigate the role of changing the vertical tracer diffusivity on Drake Passage Transport (DPT) and the meridional overturning circulation (MOC).