The feedback issue is just such a question as is the allocation of the late twentieth century temperature rise between its plausible causes. (judithcurry.com)
They concluded that few of the records showed anything particularly unusual about twentieth century temperatures, especially when compared with the so - called «Medieval Warm Period» a thousand years ago. (csicop.org)
«The causes of twentieth century temperature change in six separate land areas of the Earth have been determined by carrying out a series of optimal detection analyses. (skepticalscience.com)