In Part 1, I explained how the course of Erika was an example of how climate change could affect both sides of the debate. In this post, I will be explaining the concept of evidence. Point? There is evidence to support most sides of this. It’s how we choose and weigh the evidence that is what people are arguing about. And how Google Maps is a microcosm of climate model debate.
Evidence is Simple
What is “evidence?” It is defined as the available body of facts or information indicating whether a belief or proposition is true or valid. People are often familiar with the legal side of evidence. People understand circumstantial evidence, verbal testimony, DNA evidence. In a court of law, there are rules of evidence that are based upon trustworthiness. A judge will rule on the admissibility of evidence based upon these rules of trustworthiness. This means that there is much evidence that a jury will never hear or see.
But in the court of public opinion, there is a whole different game. Hence OJ can be regarded as a killer in public but be acquitted of the crime. Even courts have different standards. The prosecution could not prove beyond a reasonable doubt that OJ was a murdered. A civil litigator, though, did prove by a preponderance of the evidence that OJ was liable for the killings. Hence we see an example of how there can be enough evidence of something in one setting but not enough evidence for another. In public, we see people who have higher standards of proof, as well. It is not wrong of them. It just is what it is.
In a courtroom, there are attorneys. Each one takes up an adversarial position, putting evidence before the jury and arguing what the effect of that evidence is. They seek to put in their own evidence and keep out the opposing side’s evidence. The lawyers argue that their evidence is strong and the other side’s evidence is weak. In the closing argument, there is a no holds barred appeal to the jury that the evidence clearly fits with their narrative and the opposing evidence just doesn’t matter. It is left to the jury to make sense of it all and figure out what happened. “The evidence has shown X.”
Regardless of the arguments, there has likely never been a contested trial where there was no evidence put forth by one side. Each side has evidence supporting its position. If evidence was a sheet of paper, one side may have 100 sheets of paper. The other side may have 101. The jury or judge – or both – tries to make sense of it. Because, yes, the evidence did show X. The evidence also showed A through Z.
Types of Climate Evidence
In the climate arena, there are several different evidence sources. There are even many evidence types:
Raw data; Adjusted/processed data; Paleo Data; Paleo reconstruction data; Computer Model data; etc. A great compilation of this can be found at http://www.realclimate.org/index.php/data-sources/ . Most people, it seems, would trust their observations. If one wants to know the temperature outside and one has a thermometer, one would look at it and see what the temperature is. This is raw data. This person may also know that the thermometer runs a degree hot, so a reading of 95 degrees would mean it is actually 94 degrees. Reconstructions take that analysis a few extra steps.
The last type – computer models – dominate climate science policy, since they are the only sources of evidence for what the future may hold. This evidence is useful in terms of scenarios that are based on a starting state and on assumptions of future. We do use computer models all the time. I want to be at Rockefeller Plaza at 10:00 a.m. I am leaving from Newark Liberty Airport. We plug it into Google Maps and we have a known distance, presumed route and estimated time.
Climate Models are Not Meant to Be Testable Predictions
Climate models show some pretty amazing scenarios. But, like Google Maps, they are based on assumptions. A climate model is a fine extrapolation so long as the assumptions (which can number in the hundreds) are correct. Google maps gives you a route, distance and time. It works out fine, but all it takes is a fender bender to mess up the time or the route. Imagine a climate model. All it takes is twenty years where volcanic activity is less or more than expected and the model will be off.
We don’t curse Google maps for failing to project a wreck. We expect that unknown variables arise in a chaotic system. Same with a climate model. For the “denier” side, treating models as failed predictions that are useless causes credibilty issues. For the “alarmist” side, pointing to models as predictions of what will happen similarly lacks credibility.
Note: this is vast oversimplification of a climate model. But stripped down, it should aid in explanation for the public.
What does the Evidence Show?
The evidence shows lots of things. Did warming pause in 1998? According to some data sets, it did not. According to some data sets, i.e. GISTEMP and HADCRUT4, 1998 was not the warmest year globally. There is evidence, therefore, that warming did not pause.
On the other hand, according to some data sets, i.e., RSS and UAH (which are satellite data), 1998 was the warmest year globally. There is evidence, therefore, that 1998 was the warmest year and that warming has paused.
This means that the evidence doesn’t tell us whether the earth’s warming paused. “The evidence” is in many places. It shows many things. So what is happening? We decide what we want to believe and what we find more trustworthy.
Science Does Not Pick and Choose What Evidence is Best, but People Do
Which evidence is best: thermometer readings or satellite readings? That’s like asking what car is best: a Prius or a Land Rover? Each person has their own subjective interpretations, their own preferences. A person may prefer a Prius due to its exceptional mileage. A person with a family of five may prefer the Land Rover due to its seating capacity.
Neither is wrong. The evidence is just that – evidence. It is up to each person to view the evidence and make their own conclusions based upon their own readings. Many argue the supremacy of a certain data set over another. This is fine. It’s acceptable. If a person prefers the truly global coverage of RSS data, then that is fine. The error comes in ignoring contrary evidence. The error is suggesting that contrary evidence does not exist.
Scientists Are People, Too
Science is not an all-powerful truth. Science does not tell us we must cut emissions. Nature does not care whether sea level rises ten meters in the next century. Nature is not sentient. Nature does not seek to punish. Nature does not ask us to lower our carbon footprint.
People, however, will say that if we want to slow the rise of sea level, cutting carbon emissions is a good way to do it. Science would never say that a method is “good.” Science makes no judgments. Scientists give us ideas of what CAN happen. Policy makers balance that input with input from others. Science doesn’t say what the objective balance should be.
Trial lawyers know this. Trial lawyers know what evidence is. Trial lawyers know what argument is. Trial lawyers understand that the evidence says what it says and hopefully the jury will agree with the interpretation they try to implant.
Nevertheless, trial lawyers spend a lot of time picking juries. Because they know that people have subjective biases and judgments. And they seek to get the right personality into the jury and exclude those who may view the evidence differently.
Does the evidence show that a person should be put to death? Or does the evidence show that there should be mercy? I’d bet that in every case, the evidence shows both. And neither side will be objectively wrong in making the decision they make.
Does the evidence show that the earth is heating more quickly than 100 years ago? It depends on what evidence you are looking at.
What will the earth be like in 100 years? Ask Google Maps..