Let’s face it, there’s a lot of “climate science” out there that’s absolute rubbish.

Whichever side of the debate you’re on. Whether you believe global warming is a political hoax or that all skeptics are funded by Exxon. No matter what your opinions are, chances are that you’ve seen or read claims that you dismiss as outlandish.

Type “climate change” into Google. Within seconds you can find statements that the Earth is warming or that its temperatue is stable (or cooling since 1998!). You can find “proof” that the warming is caused by the sun, volcanoes, flaws in the temperature data, or fossil fuel burning. You can read that the Hockey Stick graph is broadly accurate, or that it was manipulated by the IPCC to agree with a predetermined conclusion.

Whatever you read about climate change, chances are that there’s another source saying the opposite thing. It’s not like we’re all climatologists who can see straight through misinformation. So how do you possibly sort out what to believe?

When people ask me this question, I invariably respond with, “Assess the credibility.”

The “climate change analysis” you read could be from a national academy of science, or from a blogger. It could be from an atmospheric physicist or a economist. It could be from a scientific journal or a political think-tank. If we calculate credibility to be “expertise + objectivity”, it’s obvious that some sources merit more weight than others.

I’ve put together a climate change credibility spectrum, inspired by Greg Craven from the Manpollo Project. This is a basic way to assess credibility and assign weight to a source. Keep in mind that this is only a guideline. The sources in the middle, especially, could be shuffled around based on the situation. The spectrum is also only used for scientific statements, such as “the Arctic is losing sea ice”. Matters of policy, such as “cap-and-trade is our best bet”, are much more a personal opinion.  

• At the bottom of the spectrum we have the individual. This is someone with no formal education in the field of climate science. Bloggers generally fall into this category, which is why I plan to refrain from creating my own “expert analysis” of data on this blog.
• Above that we have the professional. This is someone who is not a scientist, but is in an occupation that requires them to keep up to date with science. High school teachers are a good example, as well as politicians or CEOs.
• Then we have the non-publishing scientist. Someone with a scientific background, but who is not currently publishing peer-reviewed literature, does not necessarily follow methods which are accepted by the scientific community. They have a good knowledge of science, but lack the “peer-reviewed” credential.
• Above that is the publishing scientist in any area, such as medicine, physics, or chemistry. Even if they do not study climate change, they have the basic scientific background to understand it, as well as the “peer-reviewed” check on their scientific methods.
• The publishing Earth scientist specializes in areas closer to climate science, such as geography, geology, or environmental science. They have a more in-depth knowledge of the way the biogeochemical systems of the Earth work.
• The publishing climatologist (or atmospheric physicist/radiative physicist/any other area that’s so relevant to climatology that we can basically classify it as climatology) is the best you can get in terms of the individual professional. They understand more about climate change, and have more widely approved methods, than any other scientist.
• Above the individuals come groups. Universities are generally quite up-to-date in their scientific knowledge, as they are training scientists-to-be, and have a large number of scientific professors behind their statements.
• Peer-reviewed scientific articles are often written by more than one scientist, and have undergone an extensive review process. These articles minimize bias or misconceptions as much as science possibly can.
• Finally, professional scientific organizations employ thousands of publishing scientists, have massive reputations to uphold, and often publish their own peer-reviewed journals. Their statements carry more weight than any others.

This isn’t to say that the NAS is infallible, or that the blogger is always wrong. The credibility spectrum is simply a tool used to decide how much weight to give a statement.

So go do some reading. Do some searching and reading and watching. See what individuals, professionals, groups and scientific bodies are saying about climate change. Assess their credentials. Decide who you’re going to believe.