地 址：北京市朝阳区德胜门外祁家豁子华严里40号 竺南中心
Climate Change of 4°C Global Warming above Pre-industrial Levels[2018-08-17]
Using a set of numerical experiments from 39 CMIP5 climate models, we project the emergence time for 4 ℃ global warming with respect to pre-industrial levels and associated climate changes under the RCP8.5 greenhouse gas concentration scenario. Results show that, according to the 39 models, the median year in which 4 ℃ global warming will occur is 2084. Based on the median results of models that project a 4 ℃ global warming by 2100, land areas will generally exhibit stronger warming than the oceans annually and seasonally, and the strongest enhancement occurs in the Arctic, with the exception of the summer season. Change signals for temperature go outside its natural internal variabilities globally, and the signal-tonoise ratio averages 9.6 for the annual mean and ranges from 6.3 to 7.2 for the seasonal mean over the globe, with the greatest values appearing at low latitudes because of low noise. Decreased precipitation generally occurs in the subtropics, whilst increased precipitation mainly appears at high latitudes. The precipitation changes in most of the high latitudes are greater than the background variability, and the global mean signal-to-noise ratio is 0.5 and ranges from 0.2 to 0.4 for the annual and seasonal means, respectively. Attention should be paid to limiting global warming to 1.5 ℃, in which case temperature and precipitation will experience a far more moderate change than the natural internal variability. Large inter-model disagreement appears at high latitudes for temperature changes and at mid and low latitudes for precipitation changes. Overall, the intermodel consistency is better for temperature than for precipitation.
Wang, X., D. Jiang*, and X. Lang, Climate change of 4 ℃ global warming above pre-industrial levels, Advances in Atmospheric Sciences, 2018, 35(7), 757–770.
Figure. In the left-hand parts, dotted areas indicate the signal, contour lines the noise, and shading the signal-to-noise ratio (SNR), for the global annual mean (a) surface air temperature and (b) precipitation [units for signal: ℃ and %; noise: ℃ and mm d−1; SNR: ℃ ℃−1 and mm d−1 (mm d−1)−1, for (a) and (b), respectively] associated with a 4℃ global warming, calculated by the median of the 29 models under RCP8.5. In the right-hand parts, the vertical solid lines represent the globally averaged value for each variable; the other dashed lines show the zonal mean changes for the three variables over the globe (black), over the land (red) and over the ocean (blue); and the shading indicates one standard deviation of the projections from the 29 individual models.