In 2016, several regions in the world smashed their heat records for the third straight year in a row. Record warmth occurred in Europe, Australia, and parts of the Pacific. California also hit record high temperatures, including one of the worst droughts in history. So what's happening with our weather? Are high temperatures the new normal? Let's take a look at some statistical data from NASA to see how summer weather in the northern hemisphere has changed since 1950. Summer temperatures vary a lot even in a constant climate. But, if you take an average of summer temperatures from year to year, and plot them on a chart, you'll eventually see a pattern of numbers that resembles the shape of a bell. This is a normal distribution of temperatures, or what's known as the bell curve. In a constant climate, summer temperatures should fit this bell curve shape. With average temperatures occurring most often and extremely cold or extremely hot temperatures occurring less frequently. So statistically speaking, if the average temperature occurs here at zero, anything within one standard deviation from zero is considered statistically the same – or pretty much an average summer temperature.
But temperatures occurring two or three standard deviations away from zero are considered statistically extreme. So the hottest and coldest recorded temperatures would occur in these areas. Now let's take a step back and look at what summer temperatures looked like 50 years ago. We'll use this as our baseline for temperature comparison. in the 1950s, 60s and 70s summer mean temperatures were close to this type of bell-shaped distribution. but in each subsequent decade, the distribution of temperatures has shifted, with hotter temperatures becoming the new norm. Notice that as the distribution curve shifted to the right the probability of extreme heat greatly increased. The decade of 2001-2011 showed record temperatures nearly 5 standard deviations away from the normal temperatures of the 1950s, 60s and 70s. But also note that the decade of 2001-2011 continued to show temperatures of extreme cold. Some of the coldest temperatures were nearly 3 s standard deviations away from zero.
So even though the temperature pattern showed an increased tendency for unprecedented heat, due to variability in the weather, there were also brief burts of extreme cold. Still the periods of extreme heat today already far outweigh the periods of extreme cold. IN 2016 according to research from the National Center for Atmospheric Research there were roughly 4 times as many days with record highs, as days with record lows. So what's our takeaway from this? Well, it's important to realize that normal temperature patterns are shifting. If the temperature distribution curve continues to shift to the right we'll probably see some pretty extreme effects. Warmer summers will occur more often, and cooler summers will occur less often. Rising temperatures will lead to more extreme weather patterns. And the probability of extreme storms, heat waves, drought and floods will increase.
Of greater concerns are some projections made by climate change models. According to studies by the National Academy of Sciences, and the National Center for Atmospheric Research, the ratio of daily record highs to daily records lows in the lower 48 states could soar to 15 to 1 by mid-century, and 50-1 by 2100. .