WP2 – Climate on land, at sea and impact on the biosphere

Leads: Philippe Gachon and Elizabeth Thomas

WP2 focuses on the analyses of all climate-related data to document the past and present climate variability on land and at sea and ecosystem changes (vegetation and marine productivity). The goals are multiple and include fundamental questions about the climate system. First, we aim at evaluating the role of the Arctic outflow to the NA through the East Greenland Current and Labrador Current on ocean circulation and hemispheric scale climate. Second, we aim at better understanding the long-term regional dynamics of sea ice, which is both a response to, and a driver of, climate changes. We also aim at evaluating the responses of the biosphere to long term changes at global scale versus regional-local scale events.       

The analyses of proxy-based estimates of climate parameters (surface air temperature, precipitation, sea-surface temperature, sea ice cover) will allow to address these questions:  

  1. How has regional climate changed during the late Holocene across the ASNA region?
  2. What could be the most determinant forcing and mechanisms accounting for climate variability locally and regionally?
  3. What was the interplay between climate and sea ice, and how did this influence ecosystem functioning, notably in coastal settings?

Main tasks

Synchronization of climate-related time series for space-time, multivariate and wavelet analyses to document the trends and modes of variability at local to regional scales. The proxy evidence will be binned/averaged over the same time intervals and analyzed with traditional multivariate and spectral analysis methods to document the common signals in the longterm changes, and millennial-scale variability. Furthermore, we will use resampling methods (e.g. bootstrap), to estimate the variance and biases, as well as systematic influences of specific subsets of proxies in the climate reconstructions.

Extract information from CERA-20C Coupled Reanalysis of the Twentieth Century in order to document the 1900-2010 CE intra- and inter-annual variations of climate parameters with a spatial resolution of ~ 100 km. The data will be used for making statistics on the pre-1950 CE variability to ongoing climate changes, and as calibration tool for paleoclimatic transfer functions. 

Confrontation of results from transient climate models such as those of TraCE-21ka (https://www.earthsystemgrid.org/project/trace.html) and proxies-inferred climate reconstructions (our compilation, in addition to new results from the project) in order to evaluate how the trends at global scale are correctly simulated in the study area and to identify critical parameters deserving more attention from data and/or modeling viewpoints.

Integration of multi-proxy data to assess biological productivity on land and at sea to evaluate how ecosystem functioning in target regions has changed through space and time.