This provides a transfer function that enables the proxies to be used as predictors of past climate where proxy data are available in the absence of direct temperature measurements. (deepclimate.org)
The reconstruction was based on proxy data, most of which are not direct temperature measurements but may be indicative of temperature. (realclimate.org)
The problem is that some sets of tree - ring data suggest temperatures start falling towards the end of the 20th century, which direct temperature measurements show was not the case. (newscientist.com)