All climate computer games predict more global warming than is later measured, roughly double, on average, excluding one Russian model. Democrats claim the Russian model has colluded with President Trump to predict mild and harmless future global warming. Intermittent global warming HAS been mild and hatmless since the late 1690s. But never mind that.
The future climate can only be bad, or worse than that, according to leftists. Good climate news is impossible? And never mind the good climate news over the past 325 years, as the too cold Little Ice Age centuries were followed by gradual, harmless intermittent global warming. That people living in the 1690s would have loved. But never mind them, We've got multi-million dollar computer games here. And they will predict whatever their owners want predicted. Computers are great at following their "orders".
Always remember that the coming global warming "crisis", predicted for over 50 years so far, consists only of wild guess, nearly always wrong, predictions of the future climate, not reality.
Models can’t decide if cloud feedbacks are positive or negative. Half think they’re positive, the other half negative. Block et al., 2020
“Very intriguing is however, that 7 out of 13 models show positive ΔR [cloud feedbacks] in the Arctic while the other 6 have negative values. This implies that half of the models analyzed here simulate local runaway climate systems in which the gain of energy is larger than the loss of energy if advection is not taken into account. These models increase the initial radiative perturbation rather than to reduce it. On the other hand, models exhibiting little warmings tend to be dominated by the negative Planck feedback and can be brought back to radiative balance without the contribution of advection.”
Contrary to climate model claims that global warming causes perpetually rising positive feedbacks with water vapor (water vapor positive feedback, aka Runaway Global Warming), producing even more warming. But the observed “buoyancy effect” suggests higher atmospheric water vapor means outgoing long wave radiation (OLR) is enhanced, not reduced. This negative water vapor feedback stabilizes the Earth’s climate and prevents runaway warming. Yang and Seidel, 2020
“We propose that the vapor buoyancy effect can increase Earth’s OLR and helps stabilize Earth’s climate by regulating the atmosphere’s thermal structure. ... This is a negative feedback which can help to stabilize Earth’s climate.”
The climate computer games have no chance to model the Roman warm period, Medieval warm period, etc.. They need volcanoes to have cooler periods, and some extra CO2 in the atmosphere, or more solar radiation, for warmer periods. That's all they have. These are simple short term weather models that can not be converted into long term climate models ... but they were.
The CMIP6 output that each modeling center produces is loaded on a central web portal, managed by the Program for Climate Model Diagnosis and Intercomparison (PCMDI).
CMIP6 is bigger than CMIP5, and is running at least a year behind schedule. The 2021 IPCC AR6 report is currently being drafted. But it seems unlikely that all CMIP6 runs will be completed in time ... even though the modeling groups are supposed to coordinate their CMIP updates around the schedule of the IPCC assessment reports.
CMIP6, when completed, will be “runs” from about 100 computer games from 49 different modeling groups. The new computer games are running a number of new and updated CO2 emissions growth estimates, creating a much wider range of possible future outcomes than CMIP5.
Around 40 CMIP6 computer games published so far show more global warming from CO2 than CMIP5, which is puzzling, because the CMIP5 models already predicted too much global warming. About +0.4C more warming is predicted for this century than CMIP5 computer games.
The goal of CMIP is to generate a set of standard simulations that each model will run. This allows results to be directly comparable across different models, to see where models agree and disagree on future changes. One of the main sets of simulations run by models are future climate scenarios, where models are given a common set of future concentrations of greenhouse gases, aerosols and other climate variables, to project what might happen to the climate in the future.
IPCC AR5 had four Representative Concentration Pathways (RCPs) that -- different possible future greenhouse gas emissions. These scenarios – RCP2.6, RCP4.5, RCP6.0, and RCP8.5 – have new versions in CMIP6.
For
IPCC AR6, the energy modeling community developed a new set of
emissions scenarios -- “Shared Socioeconomic Pathways” (SSPs).
These updated scenarios are called SSP1-2.6, SSP2-4.5, SSP4-6.0, and SSP5-8.5
The are also new CO2 growth rate scenarios -- SSP1-1.9, SSP4-3.4, SSP5-3.4OS and SSP3-7.0.
CMIP6 has a brand new scenario – SSP3-7.0 – which lies right in the middle of the range of baseline outcomes produced by energy system models. Now modelers can examine worst case (SSP5-8.5), middle of the road (SSP3-7.0) and more optimistic (SSP4-6.0) outcomes when modeling how the world might warm in a world that fails to enact any climate policies.
SSP4-3.4 is another new scenario that tries to explore the space between scenarios that generally limit warming to below 2C (RCP2.6 / SSP1-2.6) and around 3C (RCP4.5 / SSP2-4.5) by 2100.
SSP5-3.4OS -- emissions follow a worst-case SSP5-8.5 pathway until 2040, after which they decline extremely rapidly with a lot of late-century use of negative emissions.
SSP1-1.9 is a scenario intended to limit warming to below 1.5C by 2100 above pre-industrial levels.
Equilibrium climate sensitivity (ECS) is the expected long-term warming after a doubling of atmospheric CO2 concentrations. CMIP6 models available so far tended to show higher ECS climate sensitivity to CO2 than CMIP5 models.
While only 40 CMIP6 models currently have the runs needed to calculate ECS, about one third have an ECS higher than the upper end of the likely range – +1.5C to +4.5C – provided in the IPCC AR5 (an unproven estimate from the 1970s). A quarter of the models have a higher ECS sensitivity than any of the models featured in CMIP5.
The transient climate response – a measure of shorter-term warming associated with increasing CO2 – is also higher in many CMIP6 models.
Two studies – one by Femke Nijsse and colleagues at the University of Exeter, and another by Dr Katarzyna Tokarska and colleagues at ETH Zurich, point out that the highest sensitivity climate models do a poor job of reproducing historical temperatures. ( But never mind that! )
