Did exaggerated records make global warming look worse?

"The panel will also examine ‘extrapolations’ – when the records include virtual figures from places where there is no actual measuring station, instead basing them on the figures of other stations in the same region. In some areas, such as the Arctic, these may be hundreds of miles away. Sceptics claim that the effect of the adjustments is usually to revise temperatures from decades ago downwards, and to increase recent readings, so that the warming trend of the past 150 years looks larger than it really is."