Post-glacial climatic change and variability - The Global Climate System: Patterns, Processes, and Teleconnections - page 210

of the data sets. The reasons for these fluctuations before AD 1850 have been
defined as variations in solar radiation (linked to sunspots) and volcanic activity
leading to changes in dust concentration in the stratosphere and lower
troposphere. Other forcing factors may be changes in ocean circulation and
atmosphere-ocean interactions and variations between the ice packs and the
ocean. The expansion and contraction of the circumpolar vortex in each hemi-
sphere has an important role. After AD 1850, human influences such as green-
house warming must be included to properly explain the variations.
The 8200-year cooling event appears to be global, but is more evident in the
NH. The global existence of the MWP and LIA is debatable, but many data sets
show some indication of appropriate warming or cooling, although starting and
ending dates, and the temporal scale, vary. Further assessment of current data
and the development of new data sets will lead to increased knowledge and
understanding about past climate variability and more accurate predictions for
the future.
6.6 Examples of paleoclimate websites
The World Data Center for Paleoclimatology (WDC-A) is based at the US
National Oceanographic and Atmospheric Administration in Boulder, Colorado,
USA, and has lots of excellent programs and data sets: www.ngdc.noaa.gov/
paleo/paleo.html.
The Byrd Polar Research Center at Ohio State University (USA) focuses
on paleoclimatic research from ice cores in polar regions and Peru: www-
bprc.mps.ohio-state.edu/Icecore/frontpage.html.
The Quaternary Palaeoenvironments Group at the University of Cambridge
(UK) researches a range of paleoenvironmental aspects over the last 2.6 million
years: www-qpg.geog.cam.ac.uk/.
The University of Washington (USA) Quaternary Research Center studies
Earth systems interactions over the past 2 million years, including high-resolution
climatic change in Antarctic ice cores: depts.washington.edu/qrc/index.cgi.
The Climate System Research Center at the University of Massachusetts
(USA) focuses on the climate system, climate change, climate variability, and
global change issues: eclogite.geo.umass.edu/climate/climate.html.
The Climate Change Research Center at the University of New Hampshire
(USA) studies global climate change and forcing mechanisms, linking data sets
from different locations around the world: www.ccrc.sr.unh.edu.
6.7 References
Alley, R. B. et al., 1995. Changes in continental and sea-salt atmospheric loadings in central
Greenland during the most recent deglaciation: Model-based estimates. Journal of
Glaciology, 41, 503-514.