I had tried to extract the temperature and precipitation from WRF model data for the Higher Himalayan region but found no significant difference in both scenarios, though they are both extreme scenarios.
Here, Prof. Dieter Scherer, Meteorology of TU Berlin, can certainly assist you! Manfred
Now I have data set only up to 2050, therefore I am currently working till this period. GHGs emission is expected to increase up to 1300 ppm in 8.5 scenario as far as I know. I am surprising when I extract the data for both scenario. I could not see any extreme difference between them.
I have not seen the temperature trends but I would assume that the two extreme scenario simulations will start to strongly deviate from each other after around 2050. While both simulations may significantly deviate from today's temperature, they do not necessarily deviate from each other yet around 2050. One reason is that the system needs time to warm up and does not instantaneously react on the strong CO2 increase, think e.g. about the inertia of the ocean etc.
I'm not sure exactly what it is you're asking, because the scenarios you discuss are certainly different; at 2100 RCP4.5 gives 1.1-2.6 & RCP8.5 gives 2.6-4.8, all according to IPCC. There's not even an overlap.
But if you're doing a regional downscaling, you only use one model and for sure the models are different (that's why there's a span) and they also have slightly different circulation patterns, so regional difference, which are large also within any model, is even larger for an ensemble of models, especially for precipitation.
Hence, analyze the change for your region from the global model first. If that changes between the scenarios, then your regional results should be scenario dependent. If it isn't you made a mistake somewhere in specifying the boundary conditions or WRF must develop a discontinuity at the boundary. Also recall you're changing the radiative forcing in the global model; consequently you must do the same change in WRF.
If you're looking at results from the near future I agree with a previous response; most of what drives climate change in the near future has already been emitted and it is not until 2040 that RCP4.5 and 8.5 emission scenarios start to really deviate. And then it takes some time...
Hi Michael,
he only seems to look into the period until 2050. That means only half way to the final emission scenarios at 2100. It looks not surprising to me that there is not a significant difference between RCP4.5 and 8.5 yet according to the figure linked below from AR5.
http://www.easterbrook.ca/steve/wp-content/IPCC-AR5-Fig-12.5.png
OK; that was unclear to me. However, the figure you show indicates one could find a model that for RCP8.5 is about the same globally as some other model for RCP2.6(!), all the way up to 2060-2070. But those would be two different models and the question is what any single given model might do in the near term. The shading is incorporating both internal variability in each model and several different models with differing climate sensitivity.
Still, I tend to agree; the change in relation to the noise between the two scenarios looking at before 2050, especially looking for a smaller region, would render the two results insignificantly different. But there should be some differences...
Dear Michael and Frederik
Thank you very much for your very elaborated response. Yea, In my case I am working on very smaller river basin (200 -15000 sq.km). Therefore, it is the case I could not observe the difference also the time in which I am working is only up to 2050.
It would better If I can analyze the global first then regional and local from different model in the future. But right now I don't have data set of different GCMs and RCMs. Also it would better to have data after 2050 period just to confirm whether trend will match or not. Thank you very much again all for your response.
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