Paleo Slide Set: Tree Rings: Ancient Chronicles of Environmental Change
The Giant sequoia (Sequoiadendron giganteum) is the largest tree species on earth.

Tree rings record the fluctuation of environmental factors that influence tree growth 
during the life of the tree. In many cases, trees grow to be hundreds or even thousands 
of years old and thus are an important source of information about environmental change. 
Instrumental records of climate or other types of environmental variations exist for 
less than 100 years in most parts of the world. This length of record is not sufficient 
to answer questions such as: Is current global warming unusual, or is it part of the 
natural climate variability that we can expect over the long term? What is the range 
of precipitation variability that can be expected over centuries and millennia? 
With the climate information stored in tree rings, we can begin to answer such questions.

Photo Credits:
Peter Brown
Rocky Mountain Tree-Ring Research, Ft. Collins, CO