While graphs of gradual change in average temperature dominate mainstream narratives on climate science, a recent study warns that changes in the daily and annual temperature ranges may have a greater effect on some organisms than higher average temperatures.


Jennifer Hushaw, Applied Forest Scientist for Manomet’s Climate Smart Land Network (CLSN), explained the findings of this new study in CSLN’s weekly bulletin designed to inform foresters in the network about important climate change research.  


According to the study, there has been a ‘flattening’ of the global temperature profile. Temperature cycles experienced at higher latitudes are becoming more like the tropics as their daily ranges are becoming wider and annual ranges are narrowing.  Higher latitude areas have a greater annual temperature range because of their harsh winters, but changes in global climate have lessened the severity of the winter lows. In terms of daily temperature, there has been some suggestion that the observed range expansion is the result of more sunlight hitting the surface due to changes in the amount of pollution or cloud cover in the atmosphere, but the exact reason for this observed trend is still up in the air.       



Hushaw emphasizes that this study only looks at how temperature ranges are changing and not why they may be changing. The results revealed through this global analysis differed from previous research, which raises some interesting open-ended questions. In fact, there are a number of different factors that could drive these kinds of changes in temperature range and more study will be needed to get at the “why” question.   However, just the fact that ranges are changing is what is important to the people on the ground.


For foresters, this study matters because these changes will affect the life cycle and population dynamics of various pests and diseases. Pests, like the hemlock woolly adelgid, may be able to expand their ranges to higher latitudes because of the milder winters in areas like New England while some specialized organisms that can only survive in narrow temperature ranges may suffer.      


“Foresters in the network found this new information very relevant to their business,” said Climate Services Leader Eric Walberg. “This is very encouraging because that is the purpose of the bulletin: to make complex climate science clear and useful to our partners.”


Learn more about the study and it’s implications from Jennifer Hushaw here.