A major new study says that the cost to meet the UN Paris Agreement’s target of limiting global warming to 1.5 degrees C is a whopping three times the cost to limit it to 2 degrees. That is a huge cost for a very small difference.

This big cost finding puts the UN Intergovernmental Panel on Climate Change (IPCC) into a serious bind. As I explained in this article, the IPCC is tasked with producing a report showing that the 1.5 degree target is reasonable. Given this new huge cost estimate they will have to dream up huge damages that exceed it. That is, the difference in global damages between the 2 degree target and the 1.5 degree target must exceed this great cost difference.

Mind you this is all just a game played with computer models, so we need to look at it that way. It is entirely possible that humans are not causing global warming, in which case this computer model exercise is really just a game. But if this game becomes global government policy the cost is ruinous.

Also keep in mind that we are not talking about 1.5 versus 2 degrees of future global warming. The IPCC assumes that one degree of warming has already occurred, so we are talking about just 0.5 versus 1.0 degrees of future warming.

On the computer game side the first problem the IPCC faces is called “lukewarming.” This is the idea that small warming is harmless or even on the whole beneficial. My colleague Pat Michaels has a whole book on this subject, titled “Lukewarming: The New Climate Science That Changes Everything.”

In fact one of the top computer models is a lukewarmer, which the IPCC will have a hard time ignoring. It is Richard Tol’s FUND model, which is what is called an Integrated Assessment Model (IAM). IAMs are monster models that project global economic impacts from global warming and climate change.

The US EPA uses three IAMs and FUND is one of them. Unlike the other two, FUND says that small warming, such as in the 0.5 to 1.0 degree range that the IPCC is looking at, is on the whole net beneficial. In other words it says that the Paris Agreement’s 1.5 degree target is a bad plan.

The IPCC’s second problem is that some of the climate change models say that the 1.5 degree target is impossible to achieve. This is because these models include a long lag time from when our CO2 emissions occur until when all of the global warming that they supposedly cause actually occurs. According to these models our past emissions are already enough to cause global warming to exceed the 0.5 degrees of future warming allowed under the 1.5 degree Paris target. Not surprisingly, these are called “hot” models.

Even the models that are not so hot say that it will be extremely difficult to hold warming to the 1.5 degree target and this is where the huge cost in the new study comes from. One climate policy expert is quoted as putting it rather graphically, saying this:

“Our face is already against the wall; we don’t have anywhere to move. 1.5C is so close to becoming unfeasible, just before it becomes unfeasible the costs will go to ridiculously high levels.”

So some computer models say that small warming is a good thing. Others say it is either impossible to stop or it will be ridiculously expensive to do so. Then there is the pesky fact that we do not even know that humans are causing global warming. These computer models are just big games.

Given all of this, the Paris target of trying to hold future warming to 0.5 degrees is clearly ridiculous, as is the entire UN Paris Agreement.