The 2k Network

Research on the last 1 to 2 ka has resulted in several multi-proxy reconstructions of global or hemispheric temperature (e.g., Rutherford et al., 2005; Mann et al., 2007; 2008). In addition, first attempts have been made to reconstruct other climatic parameters, at a high spatial and temporal resolution (e.g., Luterbacher et al., 2004). Despite significant progress over the last few decades, we still do not sufficiently understand the precise sequence of changes related to regional climate forcings, internal variability, system feedbacks, and the responses of surface climate, land-cover, and bio- and hydro-sphere. Furthermore, at the decadal-to-centennial timescale we do not understand how sensitive the climate is to changes in solar activity, frequency of volcanic eruptions, greenhouse gas and aerosol concentration, and land cover.

It is understood that, at the continental- to regional-scale, climate is strongly modulated by internal variability, e.g., the NAO and Atlantic Multidecadal Oscillation (AMO) in the Atlantic area; and the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillations (PDO) in the Pacific area. However, the interactions of key processes at different temporal and spatial scales are not fully understood (Bengtsson et al., 2006).

Further, many parts of the globe lack adequate paleorecords for comparison with model simulations, and high-resolution (spatially and temporally) instrumental datasets are sparse. This is particularly true for the southern hemisphere and the tropics.

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Regional working groups




The 2k Network is made up of 9 regional working groups. Each regional group collects and processes the best time series and spatial reconstructions of important state variables of the climate system (e.g., surface and 500 hPa geopotential, temperature and precipitation). The reconstructed maps and timeseries will be analyzed in combination with the best ensemble runs of existing ESMs.

> Africa2k (African climate of the last 2 millennia)
> Antarctica2k (Antarctic climate of the last 2 millennia)
> Arctic2k (Arctic climate of the last 2 millennia)
> Asia2k (Asian climate of the last 2 millennia)
> Aus2k (Australasian climate of the last 2 millennia)
> Euro-Med2k (European and Mediterranean climate of the last 2 millennia)
> LOTRED-SA (Long-Term Climate Reconstruction and Dynamics of South America)
> NAmerica2k (North American climate of the last 2 millennia)
> Ocean2k (Marine climate of the last 2 millennia)

If you would like to be involved in one or more of the 2k Regional Working Groups, please contact the working group leaders for that region.


Bengtsson, L., Hodges, K. I. and Roeckner, E. 2006: Storm tracks and climate change, Journal of Climate, 19: 3518-3543.
Luterbacher, J., Dietrich, D., Xoplaki, E., Grosjean, M. and Wanner, H., 2004: European seasonal and annual temperature variability, trends, and extremes since 1500, Science, 303: 1499-1503.
Mann, M.E., Zhang, Z., Hughes, M.K., Bradley, R.S., Miller, S.K., Rutherford, S. and Ni, F., 2008: Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia, Proceedings of the National Academy of Sciences, 105: 13252–13257.
Mann, M.E., Rutherford, S., Wahl, E. and Ammann, C., 2007: Robustness of proxy-based climate field reconstruction methods, Journal Geophysical Research, 112: doi: 10.1029/2006JD008272.
Rutherford, S., Mann, M.E., Osborn, T.J., Bradley, R.S., Briffa, K.R., Hughes, M.K. and Jones, P.D., 2005: Proxy-based Northern Hemisphere surface temperature reconstructions: Sensitivity to methodology, predictor network, target season and target domain, Journal of Climate, 18: 2308-2329.