In earlier posts I explained why I think the International Panel on Climate Change (IPCC) has been exaggerating the world’s future temperature rise. See for example this
The IPCC likes to use their RCP8.5 projection as the “Business as Usual Case“, which projects horrendous temperature increases. However, this case uses unrealistically high fossil fuel resources (please see the post above for more details).
The IPCC studies use other projections, two of which are designated RCP6 and RCP4.6. These two use more reasonable fossil fuel resource burn rates. The groups preparing these cases weren’t too focused on the resources, they shifted emissions to meet IPCC target forcings (the 8.5 in RCP8.5 means the greenhouse gas forcing reaches 8.5 watts per square meter at the end of the 21st century).
RCP6 and RCP4.5 used ‘’more reasonable’’ emissions from fossil fuels purely by accident. But they are definitely better than RCP8.5. Below I’ll show a graph with the Hadley Center’s HADCRUT4 temperature anomaly data, updated through March 2016, and the temperature projections made by climate models using the three RCPs I mentioned. These three RCP climate model result curves were copied from a post at Climate Etc, but the original creator was Ed Hawkins. The HADCRUT4 data was downloaded from the Hadley center and dumped into Excel.
Hawkins likes to post these comparisons at Climate Lab Book. Here’s the latest I’ve seen
Figure 1. HADCRUT4 data and the three RCP projections,
or climate model ensemble results, copied from Ed Hawkins.
The graph shows the climate models’ temperature anomaly projections. As you can see, RCP4.5 and 6 are fairly close to each other. RCP8.5, the scary ‘’Business as Usual’’ case has a much higher temperature outcome.
The actual temperature data, the black line, has a very steep temperature increase in 2014-15-16. I believe most of this is attributable to the El Niño event we are experiencing.
The real temperature data could be a bit iffy. But let’s say the data is fine. Figure 1 shows that, until 2015-16, the models were overpredicting the temperature anomaly. The current temperature spike (if it’s real) would make the climate models look much better, if the world’s temperature anomaly were to stay up. However, as I write this there are indications the anomaly is coming down, and some climate centers say we should be entering a La Niña phase by September 2016. This would drop temperatures in a fashion similar to what was observed in 1998-99.
To see what the ‘’actual” data would look like if we had a repeat of the 98-2016 years, I created the analogue shown in Figure 2. The copied data was shifted up by 0.23 degrees C to mimic the step up in temperature seen in 1998-2000. If the temperature anomaly does follow a curve similar to this analogue’s, the temperature would be closer to the RCP4.5 and 6 cases, and fall away from the RCP8.5 case.
Figure 2. Same as Figure 1 but I added a copy of the 1999-2016
temperature anomaly data, shifted up 0.23 degrees C.
This analogue I’m using is bullshit, I’m just playing a what-if game. I don’t have a climate model, I don’t want to get one, and I don’t want to pay somebody to run one with my estimated fossil fuel burn rates. But I do think the temperature will move along closer, or slightly below, the RCP4.5 and 6 cases IF WE DO NOTHING ON THE POLICY FRONT. Fossil fuel depletion, the market, will dictate what happens even if the IPCC prescriptions are ignored.
The fact that fossil fuel resources are limited, will cost more to extract, and this will reduce demand, seems to be a no brainer. It also indicates that a properly planned shift away from oil will be useful. First because the oil price will be quite erratic as it rises, and this isn’t good for the economy. Second because the bulk of oil reserves are located in the Middle East, Venezuela, and Russia. Given the political environment, it’s pretty dumb to have a policy which makes the world rely more and more on countries which are probably going to be very unstable in the future.
Returning to Figure 2 before I close this, please note that, if the temperature rise in a market driven case (a do nothing case where the IPCC wonks are ignored) is closer to the RCP4.5 and 6 cases, then the benefit of the cut backs proposed by the IPCC is much lower than they project, because those benefits are estimated versus the totally bullshit RCP8.5 case.
Therefore, even if we believe the climate model’s math and physics, we have absolutely no reason to believe any of the economic estimates being made at this time. That work needs to be done using temperature projections based on reasonable emissions cases, not an exaggerated case based on surreal fossil fuel resource estimates.