Focus 2 - Theme: Last 2 Millennia


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.


Key questions

What did the main patterns and modes of climate variability on sub-decadal to orbital timescales look and operate like?

How do climate variability and extreme events relate to the important primary forcing factors, namely orbital, solar and volcanic?

What feedbacks operated to modulate the climate response?


Working Groups

Work on the Last 2 Millennia Theme was undertaken primarily by the PAGES 2k Network.

Up until 2017, the 2k Network was made up of nine regional working groups. Each regional group collected and processesed 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).

 

 

References

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.