AGW: The Utility of Separating Human and Natural Climate Change in Public Discourse

John asked the question last week “what is AGW?” in the context of my throwing in acronyms to posts without explaining them.  This post is my rather-long answer to why I sometimes use the term to indicate the human-caused part of climate change (anthropogenic global warming).  I also don’t use it sometimes, I’m sure inconsistently and confusingly, because some windmills are too big for even me to tilt at (!). In this post I’ll talk about the terminology, and in the next post I’ll follow it through a recent real-world series of events.

But first I need to introduce the concept of the Climate Hydra.  It’s the mix of conscious decisions by a variety of actors that lead to how climate change is framed and portrayed by scientific communities, the media, and politicians.

But let’s start with the globally validated clump of experts.  Here’s how the IPPC SREX defines climate change:

Climate change
A change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.

Note that this definition  involves both human and natural causes and isn’t just about greenhouse gases (GHGs) but also about land use changes, which we know something about, at least for forests.

However, as commonly used, it can mean only the human-caused part.

Weird, huh? “Climate change” has become a shorthand for only a part of climate change.  And the natural part kind of disappears from view. You know, natural parts like glaciation, El Niño and La Niña, and so on.   It would be a bit like defining “forest regeneration” as natural and planted, and then only talking about planted.  You would miss the bigger picture.

I don’t know why this is, and I’m not assuming any bad intentions from anyone.  It could be just a natural part of the Hydra ecosystem. My current hypothesis is that it’s too hard for journalists to explain every time, and it’s definitely too hard to keep up with the details of attribution studies for specific parameters and places, so it has just fallen by the wayside.  Using AGW (albeit inconsistently) is my own way of saying “natural variation exists also.”

How do scientists determine the proportion of each?  I’ll explain that in a later post.  I’m sure it won’t surprise you that it is both complicated and contested. You’d think that there would be a great deal more written about it since it is so key to building trust.

Again, I don’t know how much variation in what aspects of climate, where and for what time periods, is natural and how much is human-caused.  But I don’t think it’s all human-caused. So let’s take a relatively simple example of something that we are all familiar with, and that has become a poster-child for the Climate Hydra: wildfire.

There have been changes in temperature and weather patterns and drought through time, but also fire suppression, more human-caused ignitions, and large-scale fires where we didn’t have the resources to put them out when they were small, so they grew big.  And different suppression strategies, and more people living and recreating (in California, but not so much in Kansas).  And grass fires are different from forest fires, and so on.. Just understanding ignition sources and how they’ve changed over time would be huge. How can you tease apart the impacts of all these different factors? And what are we trying to model for.. acres burned? Bad environmental consequences? Bad social-economic-health consequences?

What if we agreed…”bad” fire impacts are influenced by :

a) weather

b) fuels

c) ignitions (human and weather)

d)  suppression resource availability, strategy and tactics

e)  human-caused climate change (of course these would affect weather (sooner) possibly ignitions (by lightning) and ultimately fuels)

f)  natural variation climate change (think of El Nino and La Nina and longer term changes) (like human-caused, these affect weather sooner, and then will circle back to changing a b and c.)

g) luck (other fires at the same time; weather luck, convenient stopping points, resource availability and so on), or what we scientists call “stochastic factors”.

Maybe you can think of others.  And we can do a simple model.. would we still have bad fire impacts without e?  Of course, so it’s a factor- but one of many. And there were bad fire impacts (at least large fires) in our country before human-caused climate change started, so that fits.

When someone says “the average temperature in my county in July has gone up 6 degrees in the last 20 years due to climate change” it makes it sound as though we know all of that was due to human-caused climate change.  What IPCC does with this is that it calls the difference “detection” of change (any cause)  versus “attribution” which is usually done with models with and without human influences on climate (usually GHG’s and land use).

In conversations, I sometimes hear “how can people observe this difference (warmer temperatures, drought) and “deny” climate change?”  Well, they may not be “denying” climate change at all.  They may be saying “I don’t know how much is due to humans and how much is due to natural variation.” Or for something more complicated than a temperature measurement, like wildfires, they might be thinking “there are factors a to g and I don’t know how important each one is. I do know if we stopped producing GHGs today (highly unlikely), we would still have problematic wildfires.” Or they might simply distrust attribution models. Or their Grandma may have told stories about droughts in the 1930’s that seemed worse than today.  Rather than call someone a denier, we might get further by engaging in these conversations.

One of the essential missing links in climate discourse is an honest acknowledgement of all the related uncertainties. It seems like the Climate Hydra has us stuck on “if we acknowledge them, people won’t want to do anything.”  But others (and I) feel “if you’re not honest about uncertainties, people won’t trust you, even you are certain.” So this climate action strategy may be shooting itself in the proverbial foot.

9 thoughts on “AGW: The Utility of Separating Human and Natural Climate Change in Public Discourse”

  1. Bravo! We’ll put as it relates to a/the hydra; most climate “hawks” have already lost their credibility with me over the very fact (they assert) they are right and I am wrong. No one really knows how much is anthropogenic, and until we figure that one out we are just “rearranging the scatter”

    Looking forward to more discussion on this important topic!

    • Hi Jim: I will gladly join in on this issue in a few days, but I am curious why you use a pseudonym. This is an interesting topic, but I’m always more interested in discussions with known people — or at least anonymous people with reasonable purposes, such as employment concerns or warrants.

    • I recommend two books by anthropologist Brian Fagan: The Great Warming: Climate Change and the Rise and Fall of Civilizations, and The Little Ice Age: How Climate Made History 1300-1850. Fagan, who is by no means a climate change denier, offers a look at climate change — mostly natural — before 1850, the end of the Little Ice Age and the year often cited as the beginning of anthropogenic climate change. Fascinating books!

      FWIW, my forestry students are shocked when they learn that the mighty Columbia and Willamette Rivers used to freeze over enough that cars could drive and planes could land on the ice, as recently as the 1930s.

    • Jim, I’m thinking of writing a book on this for “regular people” (mostly the people I run into at church). I had a major wake-up call on the gap between my associates there and I when I mentioned cap and trade and they didn’t know what it was. So it seems like there’s a huge gap. And the gap becomes filled with (humankind is bad) breast-beating or stone-casting (oil and gas people are bad) or both, coupled with despair. Which is one way of looking at the world, but not the only way.

      And my only goal is not to convince anyone of anything, but to show them how people can have different views without necessarily being ignorant or morally bad. One of my favorite bosses at the Forest Service was Tom Mills, and when I would brief him I would say “my goal is not to convince you of different views (than yours) on this issue; but, if at the end of the meeting, you understand that there are different views, and to some degree why people hold them- that would be a success for me.”

  2. One graphic showing how recent natural drivers have remained steady while human causes have accelerated is here (EPA):,also%20affect%20the%20earth's%20climate.

    I don’t think there are very many scientific views that would tell us the human component of climate change is small to the point of not worth doing something about now (especially since it is the only one we could do anything about). Or maybe I’m missing your point.

    (I also think you would find human causes operating behind all of the factors you listed, including “natural” forces like El Nino that have been modified by climate change.)

  3. I have only co-moderated two blogs ever — this one, several years ago, and “Global Warming Realists” the past ten-plus years or so. The latter blog includes several scientists and meteorologists with expert opinions on this topic. Most are based in the Pacific Northwest, but we also have contributors from England and Australia and occasionally another country or two. I think a book for general readers on this topic is a great idea, and there are people in GWR who would likely be glad to review — just so long as they weren’t termed “deniers.” Probably the best term for scientists who do not accept AGW is “skeptics.” Or “realists.”

    My thought is that the climate fears of GHG as outlined by the IPCC is SNAFU, LOL. (That was a PDQ effort, but I think I did it OK.) Basically, I agree with the outline, except there is no current way to measure the effect of human uses of fossil fuel on the weather. For reasons you give, plus volcanoes, water vapor, albedo (including human-related), and a few other factors. That means the 10-year impacts of “climate change” may be having an effect on wildfires — as apparently took place during the 1930s — but it is the weather that is the factor, not climate. Changing or no — climate is just an average. Therefore, I’d suggest combining e) and f) and renaming the combo as “weather” or maybe “weather seasons.” Had a great conversation with Doug MacCleery, retired USFS historian, on this topic a few days ago and we agreed that the bottom line was weather-related “fire seasons” were changing with the climate, too — in some places — with huge regional differences between California, Arizona, and western Oregon regarding this factor.

  4. I couldn’t agree more with you Sharon that being honest about the gray in topics helps build trust. I did that locally on the Rio Grande NF/SLV Field Office through a variety of avenues that were able to skirt WO/RO/SO (State Office) censoring. I knew it was working when at the end of a very contentious public meeting I facilitated about a proposed wildcat drilling permit people came up to me and said some variation of, “I don’t like what you are telling us but I believe you are telling the truth.” Also, in my environmental education work with the RGNF, I put together a multi-grade fire curriculum on fire ranging from Smokey Bear for young concrete learners to understanding fire history and ecology for older students. I never used “good” and “bad” in my lessons except with the young concrete learners. Did it work? Anecdotally, I can tell you that while a river of smoke from the West Fork Fire streamed over the San Luis Valley a young adult who had been through some of my classes came up to me and said, “This looks really bad, but I know that this is what sometimes happens in forests and everything will be okay.”

    I wanted to tell you the above to validate what I perceived to be one of the main themes of your post. Including the known and unknown of AGW in every news story is challenging, but I notice that there is often a disclaimer in stories saying something along the lines of “it is difficult to pin any one event on AGW.” The great thing about electronic media is stories often include links for further information, but I would guess most people don’t click on those links. Per wildfire and climate change, I have seen several stories that have focused on the combination of factors that drive wildfires, but there are, of course, many that do not. On the one hand we had a President who said CA needed to “rake their forests” and on the other we had groups blaming everything on AGW. This kind of polarization seems to be common place in all sorts of topics in the media. Conservative media covers one side, liberal media another and some aim for the middle. So the question is how to effectively put out the grey information around the impacts of AGW in this time of rampant biased media and disinformation/misinformation.

    • Mike, I just read something today about climate information campaigns.. exceedingly well-funded and sophisticated..
      And I also thought that somehow the very smoothness made me suspicious. I don’t know if it’s a psychic thing or just some factor psychologists haven’t discovered yet.
      I know when I hear one of these stories, I know that someone is tugging at my heartstrings.. but I want to know also “who” and “to what end?”
      The fact is that many folks with megabucks don’t want to be nuanced. They appear not to be interested in informing as much as activating in a desired direction.
      So all I think we can is try our best to write and find the best pieces and put them out there to the best of our abilities.

      Or as the Universe tells me, “you do production, I’m in charge of dissemination.”


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