Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
World map of tree-ring sites, International Tree-Ring Data Bank

Dendrochronology and its role in global change studies.

As the impact of human activities on the environment becomes more marked, 
there is increased concern about the scale and implications of the changes 
caused by these activities. Climatic changes that occur as a result of 
anthropogenic activities will be superimposed upon the natural climatic 
variability. A key to detection and/or prediction of future global changes 
lies in understanding the causes and characteristics of variability in the past.

Dendrochronology contributes to the study of global change in many ways. 
Tree-ring research has produced long-term reconstructions of climate which can be used to:

    Evaluate current variability and trends in climate in the context of past years.

    Identify periods of time or locations of anomalous climate change in the past 
    that may provide clues about the potential behavior of climate and areas that 
    may be particularly sensitive to climate change in the future.

    Study the climatic impact of volcanic eruptions, solar cycles, or El Nino events 
    prior to the advent of instrumental records. 

Tree-ring chronologies can provide excellent, exactly dated estimates of climate 
variability for hundreds or even thousands of years during the Holocene, 
and therefore are vital for the study of global change.

This map shows the locations of many of the tree-ring chronologies that exist today. 
Note that most are located in the Northern Hemisphere, specifically in North America 
and Europe, and that few chronologies have been developed for much of Asia. 
The temperate forests of the Southern Hemisphere also contain trees suitable 
for dendrochronology, although few chronologies currently exist for these areas. 
Recent research has indicated that a few select tree species growing in tropical 
areas that experience wet and dry seasons may also contain annual rings 
and be useful for dendrochronological studies.

Photo Credits:
Wendy Gross and Connie Woodhouse
NOAA Paleoclimatology Program