and Baliunas (2003) challenged the conclusion that the 20th century was the warmest at a hemispheric average scale. They surveyed regionally diverse proxy climate data, noting evidence for relatively warm (or cold), or alternatively dry (or wet) conditions occurring at any time within pre-defined periods assumed to bracket the so-called 'Medieval Warm Period' (and 'Little Ice Age'). Their qualitative approach precluded any quantitative summary of the evidence at precise times, limiting the value of their review as a basis for comparison of the relative magnitude of mean hemispheric 20th-century warmth (Mann and Jones, 2003; Osborn and Briffa, 2006)." This tells me that the "qualitative" approach precluded evidence of just how much warmer the MWP was than the late 20th century. On the other hand, S+B did provide compelling evidence that the MWP was a global phenomenon, which was actually the point they wanted to make. Is this the study you say "has been discredited"? If so, by whom? (Hopefully not by Mann and Jones, or Osborn and Briffa, members of the infamous "hockey stick" club). Do you have a link to the specific study "discrediting" this paper (or are you just making this up as you go along)? Please be more specific and provide links. Max tempterrain Max, You seem to have come up with a figure of $1 trillion per 0.05 degC to comabt AGW. Can you be a bit more specific and give us a link to the source of this? John Westman Thanks manacker for your lucid