Principal indicators of past climates - Climate Change: Biological and Human Aspects - page 61

palaeo-indicators of climate have made it possible to begin to establish a picture
of how the climate has changed in the past, even if this picture is more detailed in
some places than others. Nonetheless, we now have a sufficiently good picture of
climate change on the global scale going back the past few glacial-interglacial cycles
at the decadal-to-century scale to begin to inform us about possible future climate
change.
At the regional level in many places we also have a detailed understanding of the
palaeoclimate with resolutions of a year or less going back many thousands of years.
On timescales of back many millions of years we have a coarse understanding at the
mid-latitude continental level and with resolutions of fractions of millions of years.
Several palaeoclimatic proxies taken together can prove to be a powerful tool. One
such multiple proxy index is the North Atlantic Oscillation index and such indices can
be used to reconstruct large-scale hemispheric changes in temperature. Consequently
not only is a picture of global climate change beginning to emerge but also - given
that carbon dioxide is a principal forcer of climate - an appreciation of how the
carbon cycle has broadly changed over the past few hundred years is beginning to
emerge: although this, and palaeoclimatology itself, is still the focus of a considerable
research effort in many countries.
2.7 References
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