Prediction Of Winter Haze In Beijing-Tianjin-Hebei Under Global Warming Of 1.5? And 2.0?

Global warming has become one of the most emerging challenges to human being,it has also important impacts on the formation and development of haze weather events.To avoid more serious effects.the Paris Agreement proposed to control the global warming to 2.0?at the end of 21th century and strive to limiting to 1.5?relative to the pre-industrial level.Therefore,it is of great scientific significance and application value to accurately quantify the changes of winter haze weather events in China under global warming of 1.5?and 2.0?.This paper uses CESM ensemble model output and Model E2-YIBs simulation output to estimates the changes and attributions of winter haze activity in the Beijing-Tianjin-Hebei region under global warming of 1.5?and 2.0.The study used the haze weather index and the simulation experiments,combined with ensemble average,difference analysis,sensitivity analysis,correlation analysis,relative change analysis,etc.,to predict the future changes of winter haze activities in the Beijing-Tianjin-Hebei region and the impacts of various climate factors.Based on the output of CESM ensemble model and the predictions of the haze weather index,it is shown that:(1)compared with present day,the global temperature will increase by 0.71?and 1.28?under global warming of 1.5?and 2.0?respectively;(2)compared with the global warming of 1.5,0.5?additional warming.will make the sensitivity of winter temperature and winter relative humidity in Beijing-Tianjin-Hebei region change significantly in sensitivity up to 96%and-44%,respectively;(3)compared with present day,the average of future haze daily intensity will increase by0.197 and 0.202 under the global warming of 1.5?and 2.0?,respectively,and the occurrence frequency of HWI large values will show an increase trend;(4)compared with present day,the future winter days of HWI>0 will increase by 14.5%under global warming of 1.5?,and the future winter days of HWI>0 will increase by 26.9%under global warming of 2.0?;(5)compared with present day,the future winter haze events of lasting 4-7 days for HWI>0 will increase by 0.1 case/year(1.5?scenario)and 1.4case/year(2.0?scenario),respectively;(6)850h Pa meridional wind(V850),500h Pa zonal wind(U500)and the temperature difference between the upper troposphere and the lower troposphere(!T)is all the reasons for the increase in winter days of HWI>0,and the contribution ratio is showed!T>U500>V850;(7)from the overall results about CESM estimate,the results at 2.0?scenario will be greater than the results of 1.5?scenario.Based on the simulation results of Model E2-YIBs fixed emissions show that:(1)compared with present day,the future global temperature will increase by 0.63°C and1.10°C under global warming of 1.5°C and 2.0°C,which is slightly less than the predicted result of CESM output;(2)compared with global warming of 1.5?,0.5?additional warming will especially make Beijing-Tianjin-Hebei winter temperature more sensitive(increased by 110%);(3)compared with present day,the future winter PM_2.5concentration in Beijing-Tianjin-Hebei will decrease by 0.75(?)g/m3 and 0.90(?)g/m3under global warming of 1.5°C and 2.0°C,respectively;(4)from the view of climatic factors,a large increase of winter precipitation may be the main reason for the decline of winter PM_2.5concentration;(5)from the chemical composition of winter PM_2.5concentration,the decrease of winter PM_2.5concentration under global warming of 1.5?is mainly caused by the reduction of dust aerosols,while the decrease of winter PM_2.5concentration under global warming of 2.0?is mainly caused by the reduction of nitrate and the salts of ammonium.The conclusions obtained by two research methods are inconsistent.The main reason may be that the definition of the haze weather index does not consider the impact of precipitation.In addition,the research shows that reducing pollutant emissions is still the preferred method for haze control.