Detection and Attribution of Human Influence on the Global Diurnal Temperature Range Decline

A decline in the global diurnal temperature range (DTR) and its implications for human and natural systems have been widely reported, yet it remains unclear whether humans have a detectable influence on the DTR and to what extent anthropogenic greenhouse gases (GHG) may be driving such changes. Results indicate that the effect of anthropogenic forcing on the DTR is detectable separately from natural forcing across the globe and in many regions. GHG is the dominant contributor to DTR changes and caused the global DTR to decrease by -0.32 degrees C during 1951-2018, close to the observed change of -0.41 degrees C. Decreased anthropogenic aerosols (AER) increased the DTR in Europe, while increased AER decreased the DTR in Asia. If greenhouse gas emissions continue to rise, further decreases in the DTR are likely to be observed in the future. Plain Language Summary Contrary to rising temperatures, the diurnal temperature range has been decreasing over the past several decades. Although the impacts of humans on global warming have been widely demonstrated, formal detection and attribution of the impacts of human-made greenhouse gases (GHG) and aerosols on the DTR are still lacking. Our results suggest that human impacts on the DTR are clearly detectable, separately from natural changes. Human-made greenhouse gases are the dominant factor controlling decreases in the DTR worldwide. In contrast, anthropogenic aerosols (AER) are the dominant contributor for Europe and have led to an abnormal increase in the DTR in this region. If human emissions continue, we expect to see further decreases in the DTR in most regions. Our first quantification of human impacts on the global and regional DTR has significant implications for climate change assessments and future climate projections.

Automated summary

The study reveals that human activities have a detectable influence on the decline in the global diurnal temperature range (DTR). The dominant contributor to DTR changes is anthropogenic greenhouse gases (GHG), which caused a decrease in the global DTR. However, anthropogenic aerosols (AER) have different effects on the DTR in Europe and Asia. Future emissions are expected to further decrease the DTR in most regions.