SO&P: Project objectives & deliverables

Objectives

• The simulation of climate variations for the period AD 1500-2000 using two state-of-the-art GCM climate models, forced with very similar natural forcing histories (including volcanic aerosol loading, total solar irradiance changes and orbital changes) and separate simulations for the period AD 1750-2000 forced by combined natural and anthropogenic forcings (greenhouse gases, ozone and sulphate aerosols).

• Detailed statistical intercomparison of the simulations with one another, and with already available millennial-length control simulations (with constant external forcings), to enable:
  • the identification of robust climate responses to external forcing on global and regional scales; and
  • the quantification of the relative importance of forced and internally-generated climate variability.

• The production of an enhanced and integrated database of annually-resolved climate proxy records, by assembling many existing records (tree rings, ice cores, corals, etc.) and lower resolution records such as those from lake sediment, peat records and borehole temperature estimates.

• The construction of homogeneous sets of climate data, representing seasonal temperature, precipitation and atmospheric circulation variability over the last 500 years, involving the amalgamation (via appropriate calibration) of instrumental observations, documentary climate archival data and existing and the newly amalgamated palaeoclimate proxy evidence, to allow:
  • a detailed analysis (multiple variables for all seasons, or even at a monthly resolution) for the European region, possible because of the dense network of natural and documentary proxies available;
  • the improved definition of the characteristics and magnitude of natural climate variability during the last five centuries across the full Northern Hemisphere; and
  • the improved reconstruction of past variations in important atmospheric and ocean-atmosphere modes of climate variability, including the North Atlantic Oscillation (NAO, and the related Arctic Oscillation) and the El Niņo-Southern Oscillation (ENSO).

• Evaluation of the simulated climate variability, and the simulated climate response to external forcing, by quantitative comparison with the extended observed/reconstructed climate data.

• The use of the model simulations to aid in the interpretation of the real-world climate variability, specifically the use of signal detection techniques to test the extent to which the model response to external forcings is detectable in the observed/reconstructed climate data.

• The generation of improved estimates of natural climate variability, through synthesis of the simulated and observed/reconstructed data.

• The re-assessment of climate change prediction uncertainties and climate change signal detection uncertainty, in the light of these new estimates of natural variability.

• Comparison of estimates of sea level variation generated from the climate model simulations with a synthesised history of North Atlantic sea level changes, based on a combination of long tide gauge records and evidence from a number of ongoing tidal marsh sampling studies.

Deliverables