Detection of Greenhouse Gas and Aerosol Influences on Changes in Temperature Extremes

Detection/attribution analyses of temperature extremes were carried out by comparing a new gridded observational dataset of daily maximum/minimum temperatures (HadGHCND) and the simulation of MIROC3.2. It was shown that significant anthropogenic warming is detectable in the annual warmest night, and the coldest day and night from 1950 to 1999, while human influence was not detected in the warmest day. These findings are in agreement with a previous study that examined the simulation of HadCM3. Human influence is also identified in the decrease in the number of frost days, but not with the increase in the number of summer days. Furthermore, it was suggested that half of the warming trend due to rising greenhouse gas concentrations is canceled out by other factors, predominantly aerosol cooling. It is expected that a rapid decline of aerosol emissions coupled with rising greenhouse gas concentrations would induce larger changes in temperature extremes in the future.