"The instrumental record is generally considered not to be long enough to give a complete picture of climate variability... It is crucial, therefore, to extend the record of climatic variability beyond the era of instrumental measurements if we are to understand:
Jones et al., Science, April 27, 2001
- how large natural climatic variations can be
- how rapidly climate may change
- which internal mechanisms drive climatic changes on regional and global scales
- and what external or internal forcing factors control them"
Climate is one of the main influences on the landscape around us, and reconstructing past climate states and changes is a key part of understanding the current behavior of the climate system and predicting future climate changes. Understanding how quickly climate-driven changes in earth's surface occur, which changes or events triggered others, and when in the past significant changes have happened, all require measurement of time.
Geochronology is the fundamental underpinning of being able to determine when something happened, for how long, and how fast.
In the late Quaternary, radiocarbon is one of the most commonly used methods for dating records of climate change with a useful range up to the last ~50,000 years. Carbon-bearing materials from all potential depositional environments (lacustrine, marine, terrestrial) can be used to create age models for paleoclimate records or to date specific events (e.g., for neotectonics). Such materials should have a known provenance and relationship to the event, paleoclimate proxy, and understood within the depositional environment. In addition, the accumulation of rare isotopes such as 10Be, 26Al, and 36Cl in rocks exposed to cosmic rays at the earth's surface provides a clock for measuring the timing and pace of ice sheet retreat, waxing and waning of mountain glaciers, and the erosion and modification of landscapes by precipitation.
General background and information on the science of paleoclimate can be found at the:
- NOAA National Climatic Data Center: Paleoclimatology-data/Perspectives
- US Global Change Office: Abrupt Climate Change
- Intergovernmental Panel on Climate Change: IPCC AR5 Paleoclimate (Chapter 5)
There is significant intellectual and scientific overlap between CAMS' radiocarbon and cosmogenic isotope geochronology activities. Please check out the Earth System Processes competency for additional information.