Trends in the surface meridional temperature gradient

Given the presence of a meridional temperature gradient (MTG) across midlatitudes, large-scale eddies transport heat poleward, thereby shaping Earth's climate. Defining an MTG index here as the difference in surface temperature between the 30 degrees-35 degrees N belt and the 50 degrees-55 degrees N belt, we use a temperature record compiled from observations over a 110-year period to determine a trend in the MTG in the last century. We find a significant decreasing trend in the MTG over this period of 0.4 +/- 0.1 degrees C per 100 years, along with indications of substantial multidecadal variability.