Title: Examining trends in multiple parameters of seasonally‐relative extreme temperature and dew point events across North America

Authors: Cameron C. Lee, Omon Obarein, Scott C. Sheridan, Erik T. Smith, Ryan Adams

Journal: International Journal of Climatology

URL: https://doi.org/10.1002/joc.6852


When people talk about the topic of ‘Climate Change’ usually the first thing that comes to mind is ‘Global Warming’. While an increase in the average global temperature is a great – and simple – indicator of how our climate is changing, an average temperature has relatively little impact on society compared to changes in extreme temperatures. Furthermore, temperature is not the only characteristic of the atmosphere that is changing; things like humidity, rainfall, wind and others are also changing. In particular, the combination of temperature and humidity affects human health. With this in mind, this research investigates how extreme temperature events and extreme humidity events in North America have changed over the last several decades.

This research shows extreme heat and humidity events have been occurring more often and across larger areas, while extreme cold events have become smaller and less frequent. Extreme dry-air events were also found to be increasing in the southwestern US and northern Mexico. However, there were also some more-surprising findings. First, there are some areas of the western US that are actually having more frequent extreme cold events in autumn. This is one example of how some results can be ‘washed-out’ if you do not break-down extreme events by season. Secondly, the places where average temperatures are known to be increasing the most (for example, in the Arctic), do NOT necessarily have the greatest increase in extreme heat events. Third, just because extreme heat events are significantly increasing, does NOT necessarily mean that extreme cold events are decreasing in that same place. These last two last findings suggest that, in addition to averages, it is very important to also examine how the variability of temperature and humidity are changing, along with how extreme events are changing.

In summary, focusing exclusively on changes in averages, without investigating extremes, runs the risk of overlooking aspects of our changing climate that might be even more impactful on humans than averages.