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Politics : Mainstream Politics and Economics -- Ignore unavailable to you. Want to Upgrade?

To: Jorj X Mckie who wrote (2704)	9/26/2011 12:17:20 AM
From: Wharf Rat	Respond to of 85487

"Can you show me that our current global average temperature is outside of normal cyclical variations?" Can you show me that the range of normal cyclical variations are capable of supporting human civilization? 4-5 degrees C are within the norms, but what might we expect with that? Here's the official Brit version... Globally, a 4C temperature rise would have a catastrophic impact. According to the government's 2006 Stern review on the economics of climate change, between 7 million and 300 million more people would be affected by coastal flooding each year, there would be a 30-50% reduction in water availability in Southern Africa and the Mediterranean, agricultural yields would decline 15 to 35% in Africa and 20 to 50% of animal and plant species would face extinction guardian.co.uk = I think you also have to agree that there is a pretty strong likelihood that we are at the end of the interglacial period and that the next glacial period is right around the corner. :>) I think you have to agree I'll probably never agree with statements like that, even if our CO2 wasn't a factor. These two factors, orbit and tilt, are weak and are not acting within the same timescale – they are out of phase by about 10,000 years. This means that their combined effect would probably be too weak to trigger an ice age. You have to go back 430,000 years to find an interglacial with similar conditions, and this interglacial lasted about 30,000 years. skepticalscience.com Temps... probably more here than you want to know, but there is a lag time with heating. We still have a lot more in the pipeline, even if we kept CO2 at current levels. the projected temperature increase as a response to a doubling of the CO2 contents within the next 70 years, stable thereafter Figure 9.1: Global mean temperature change for 1%/yr CO2 increase with subsequent stabilisation at 2xCO2 and 4cCO2. The red curves are from a coupled AOGCM simulation (GFDL_R15_a) while the green curves are from a simple illustrative model with no exchange of energy with the deep ocean. The "transient climate response", TCR, is the temperature change at the time of CO2 doubling and the "equilibrium climate sensitivity", T2x, is the temperature change after the system has reached a new equilibrium for doubled CO2, i.e., after the "additional warming commitment" has been realised Figure 1.Projected temperature increase after 70 years of 1% annual increases of CO2 in the atmosphere. This gives a doubled CO2 content after 70 years. Note that the temperature levels off very fast after a stabilization of the CO2-level. The time to 50% of the remaining temperature increase is according to this graph around 40 years. Source: http://www.grida.no/climate/ipcc_tar/wg1/345.htm#fig91 According to this graph IPCC assumes around 3,5 degrees C increase after a doubling of the CO2 contents from today's 380 to 760 ppm. Before that we have had close to one degree C increase after 100 ppm increase from 280 to 380 ppm. Thus, IPCC assumes that in total an increase of 480 ppm will result in a temperature increase of 4,5 degrees C or around 1 degree C per 100 ppm CO2. Figure 2 shows the thermal response to a peak (not a step function, though) according to the same organisation: Although the increase in CO2 is not a step function but a ramp the time to 50% of temperature increase looks to be around 50 years, quite in line with the projections made in Figure 1.. Figure 2. Calculated thermal response to a somewhat slower reduction of annual CO2 outlet than assumed in Figure 1. hir.nu skirsch.com grida.no