For a palaeoclimate proxy to be effective it needs to

1) be internally consistant

2) have known quantified uncertainties and

3) give results that are consistant with other proxies.

In regard to 3) CLAMP has been shown to yield the same or very similar results to geochemical proxies from the Cretaceous to the Neogene, and where differences exist they are systematic and consistant. For more details on this topic click here. Internal consistancy (requirement 1) in CLAMP is achieved through standardized collecting and scoring protocols coupled with the use of defined and publicly available 'open source' calibration data sets and methodologies. With respect to quantifying uncertainties (requirement 2) the CLAMP methodology automatically incorporates and quantifies a range of uncertainties. This page explores these in more detail.

CLAMP uncertainties arise from the way climate data are recorded and gridded, climate alters over time, variations in local microclimates and how plants respond to them, and how well leaf physiognomy data from a given site are collected and converted to the CLAMP scoring scheme. Uncertainties introduced through the processes of fossilization (taphonomy) and fossil collection are largely unknown and unquantifiable, but the multivariate nature of CLAMP has been shown to confer a high degree of robustness to taphonomic data loss. Unlike many proxies CLAMP has been subject to a wide range of studies examining its reliability and precision, either through experiment or by inter-proxy comparison.

Before looking at the way uncertainties are measured in CLAMP and its reliability it is worth considering the sources of uncertainties in any plant-based palaeoclimate proxy. These uncertainties can be divided into four broad categories:

1. Taphonomic - the extent to which the features being measured in the fossil assemblage are altered during the process of transport, deposition and fossilization.
2. The errors associated with the way climate, used to calibrate the proxy, is measured.
3. Uncertainties related to the natural ‘noise’ that arises from individual responses to environmental constraints.
4. Uncertainties that arise from errors in measuring the plant characteristics underpinning the proxy.