This complicates matters for scientists putting together a long-term, consistent estimate of how global temperatures are changing. Scientists must adjust the raw data to take into account all the differences in how, when and where measurements were taken.
These adjustments have long been a heated point of debate. Many climate sceptics like to argue that scientists “exaggerate” warming by lowering past temperatures and raising present ones.
Christopher Booker, a climate sceptic writing in the Sunday Telegraph in 2015, called them “the greatest scientific scandal in history”. A new report from the rightwing US thinktank, the Cato Institute, even claims that adjustments account for “nearly all the warming” in the historical record.
But analysis by Carbon Brief comparing raw global temperature records to the adjusted data finds that the truth is much more mundane: adjustments have relatively little impact on global temperatures, particularly over the past 50 years.
In fact, over the full period when measurements are available, adjustments actually have the net effect of reducing the amount of long-term warming that the world has experienced.
Source: Explainer: How data adjustments affect global temperature records – Carbon Brief
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