Observational evidence of sensitivity of surface climate changes to land types and urbanization

Sensitivity of surface climate change to land types is investigated for the northern hemisphere by subtracting the reanalysis from the observed surface temperature (OMR). The basis of this approach is that while reanalysis represents the large-scale climate changes due to greenhouse gases and atmospheric circulation, it is less sensitive to regional surface processes associated with different land types.

OMR trends for two independent reanalyses (NNR and ERA40) show similar dependence upon land types, suggesting the attribution of the OMR to different land types is robust. OMR trends reveal 1) warming over barren areas is larger than most of other land types. 2) Urban areas with dominant human impact show a larger warming trend second only to barren areas. 3) Croplands with agricultural activity show a larger warming than natural broadleaf forests. 4) Needle-leaf tree areas show larger warming than low-latitudinal broadleaf and tropical forests. The overall assessment indicates surface warming is larger for areas that are barren, developed by human, or covered with needle-leaf forests. Results support that regional variety of OMR trends much more depend on land types, than small reanalysis errors.