One of the frequent claims of climate change skeptics is that climate scientists are making up or falsifying data to make it appear that the Earth is warming. You may have heard this from some of your own clients who based their beliefs on stories promoted in some media outlets. However, this “zombie theory” has been widely debunked by experts who look at the details of how climatologists put together long records of temperature and precipitation for their studies. (A “zombie” theory is one that has been proven false but continues to live on in some popular media outlets.)
In fact, climatologists need to “clean up” the data to correct for missing or incorrect values, account for changes in the location of stations, and other quality control measures. Some of the corrections they have made actually have reduced the effective rate of warming rather than increased it. You can read stories about the controversy and the methods used by climatologists to improve the record by Politifact.com (link) and FactCheck.org (link). Both of these news sources provide excellent explanations of how climate records are corrected for errors and how those changes affect the trends in temperature over time. The Guardian also had a story recently on this topic.
Below is a graph of US annual average temperatures from the National Climatic Data Center using data corrected using the methods described in the articles above. You can make your own graphs like this for your region and time period at https://www.ncdc.noaa.gov/cag (the Climate At a Glance tool).
