With the summer solstice happening Friday, June 21 at 9:43 a.m. MDT, many meteorologists, atmospheric scientists, and climatologists are using the opportunity to share how temperatures have changed at their location over recent time.
This is accomplished by a simplified image, called the ‘warning stripes’ plot, for countries, states and cities. Each stripe represents a yearly temperature anomaly, representing how close or far a given year’s average temperature was from the 20th century average. Station data is from RCC-ACIS and state data is from NCDC Climate at a Glance data sets.
The graphics are designed to be as simple as possible. They are meant to start conversations about temperature trends. There are numerous sources of information which provide more specific details about how temperatures have changed, so these graphics fill a gap and enable communication with minimal scientific knowledge required to understand their meaning.
Many stations and states trend red (warmer than average) towards the data’s end in 2018. Locations in the southwest and northeast United States, and Alaska show a significant trend of being more above average over the most recent 15 to 20 percent of the analyzed years. While this tends to match the global data set, presented above, Colorado’s ‘warning stripes’ plots are a little different.
The plots for Colorado’s state-wide temperature anomaly, and that of Colorado Springs, show more of a mixture of cooler than average and warmer than average temperatures than many other locations and countries. The eye test does reveal that the last 20-to-25 years have been above average, and in the last decade some of the largest anomalies have occurred.
It’s important to note that comparing temperatures on the scale of a human life need to be carefully considered. The earth-ocean-atmosphere system is very complex and we continue to learn much about how the system is connected, and how changes in one part of the system impacts other parts of the system.
It’s also important to note that timescales for aspects of the system are often on the lengths of thousands, tens of thousands, and hundreds of thousands of years, or more! A human lifetime, or several generations of humans is literally the blink of an eye on a global time scale. This fact cannot be ignored. There are a number of periods where temperatures have been warmer and cooler than we are now.
The scientific community continues to learn more and more each year and decade about our past, the systems in our physical world and how they are all linked. Through that process we continue to learn about how modern life impacts the climate, but through that process are often faced with new questions.