Human influence on changes in the distribution of land precipitation

The evolution of the distribution of observed land precipitation over 1901–2010 and 1979–2010 is analyzed and compared with 14 simulations from the CMIP5 climate models. Firstly, two different quantile-based mapping methods are used to bias-correct the simulated monthly land precipitation. The results show a very slight difference in mean annual values between the two methods. Secondly, the comparison between observed and simulated land precipitation suggests that anthropogenic forcing most likely caused the redistribution of the repartition of land precipitation, decreasing the extent of arid area (area with precipitation range between 50 and 300 mm/yr), and increasing the extent of area with a precipitation range between 450 and 900 mm/yr. However, the observed changes are larger than estimated from model simulations. The future RCP8.5 (2010–2100) simulations are also analyzed. Therefore, all 14 model simulations show the same trend pattern, only slightly different from that found over 1979–2010 but with reduced spread.