CMIP6 Future Scenario Emission Data Analysis And Climate Change Projection Experiments

This paper includes the analysis of characteristics of the emission datasets of CMIP6 scenarios and the projection of future climate change.In the first part,we analyze the emission datasets of several major greenhouse gases and aerosols under the eight SSPx-y scenarios adopted CMIP6,including emission intensities in the reference year(i.e.,2015),the spatial and temporal variations of future emission intensities,and the time variant emission intensities for the selected six typical sub-regions.In the second part,we conduct two sets of experiments by NCAR CESM2 to project climate change under the SSP1-2.6scenario and the SSP5-8.5 scenario.Based on evaluating the simulation performance of NCAR CESM2 on historical surface air temperature and precipitation,we analyze simulation results of surface air temperature and precipitation from 2015 to 2044under the SSP1-2.6 scenario and the SSP5-8.5 scenario.The main conclusions are as follows:(1)The strongest emission intensities of carbon dioxide(CO₂),methane(CH₄), black carbon(BC)and sulfur dioxide(SO₂)of the SSPx-y scenarios,are mainly distributed in East Asia and South Asia in 2015.Compared to the reference year, variations of CO₂ and CH₄ emission intensities in 2100 have significant differences between in the high and low radiative forcing scenarios.Moreover, the mean global emission intensities of BC and SO₂ in 2100 are weaker than that of the reference year under all scenarios.(2)In terms of temporal variation,as the development of bioenergy with carbon capture and storage,the values of CO₂ emission intensities in all sub-regions turn negative in 2100 for four low radiative forcing scenarios(i.e.,radiative forcing values?3.4 W/m²).On the other hand,the net negative emission intensity in South America is-0.3 kg/m²/yr under the SSP5-3.4 scenario in 2100, which is lower than all other sub-regions.Finally,by comparing the variations of emission intensities in East Asia and South Asia,it implies that actions of emission reduction in East Asia play more effective role than in South Asia described in every scenario in the future time.(3)By comparing historical simulations of NCAR CESM2 to the avail observations, we found that spatial-temporal characteristics of surface air temperature and precipitation of the historical period is captured by NCAR CESM2.The global mean surface air temperature and the global mean precipitation intensity in the 2015-2044 time frame for the SSP1-2.6 and SSP5-8.5 simulated by NCAR CESM2 are continuously increase.In the 2015-2034 time frame,increment speeds of global mean surface air temperature and global mean precipitation intensity for SSP1-2.6 are higher than that for SSP5-8.5.In the 2035-2044 time frame,increment speeds of global mean surface air temperature and global mean precipitation intensity for SSP5-8.5 are higher than that for SSP1-2.6.Relative to 2005-2014,the increases of global mean surface air temperature for the period 2015-2044 are projected to always less than 1.5?for SSP1-2.6.The increase of global mean surface air temperature for SSP5-8.5 is projected to exceed 1.5?by 2043.(4)The results of simulations show that the increase of surface air temperature is a global phenomenon,and the increase of precipitation intensity is a regional phenomenon.The highest warming is mainly distributed in high latitudes of the northern hemisphere.The degree of warming of land is generally higher than the ocean.On land,the highest warming is distributed in eastern North America.The spatial distribution of precipitation intensity for SSP1-2.6 and SSP5-8.5 has the following common characteristics:the equatorial Pacific and mid-high latitudes are projected to experience an increase in precipitation intensity,the subtropical regions is projected to experience a decrease in precipitation intensity.(5)The analysis of simulations of six typical sub-regions shows that each one of the sub-regions's trend rates of future surface air temperature for SSP5-8.5 is higher than that for SSP1-2.6.For the SSP1-2.6 scenario,the trend rates in North America is 0.4?/10a,which is higher than all other sub-regions.For the SSP5-8.5 scenario,the trend rates in North America and East Asia are 0.7?/10a, which are higher than other sub-regions.For the trend rates of precipitation intensity,there are significant differences between the six typical sub-regions under the SSP1-2.6 and SSP5-8.5 scenarios.