Misconceptions about global change (biology)
Talking about human-caused global environmental change
One of the most interesting things I learned last year, actually facilitated by an earlier post on substack and a resulting exchange with the authorGabe Popkin, was that the expression ‘global change’ is not widely known by the general public. This is in stark contrast to ‘climate change’, which everybody knows, because it is in the news. Same in German, ‘Klimawandel’ is known by everybody, but the Germany translation ‘Globaler Wandel’ is used infrequently and not generally known. If you speak a different language, maybe it’s the same for you (would like to hear, please let me know in the comments).
In my scientific ‘bubble’ in ecology, the term global change is ever-present and generally accepted. It is the title of textbooks and ‘Global Change Biology’ is a widely respected journal. So the realization that this term hasn’t made it to the public came as a surprise to me. What surprises me even more is that even among other natural scientists who don’t work exactly on global change, or among researchers in the social sciences that even work on climate change related topics, this term is also not clearly understood. That just became clear to me in the last days and weeks, when I was repeatedly in situations where it was evident that other people didn’t really know what I am talking about. There were three conversations or meetings just in the last bunch of days where this happened, and so it makes me think — in the absence of any real data this is just a gut feeling — that this issue is much more widespread than I thought.
Here are some misconceptions that I encountered (also over the years, not just recently):
The ‘global’ in global change does not mean that this phenomenon can only be studied at the level of the Earth. It is completely valid to do experiments at local scales or in the lab, even in a Petri dish. The global just means that this factor occurs planet-wide, not that it is everywhere, and not that it present everywhere to the same extent. That is not even the case for the poster child of climate change, warming. Warming is more intense in some parts of the planet (towards the poles) than in others. With drought it is the same, and even with carbon dioxide in the atmosphere, one of the probably best ‘mixed’ factors of global change, you can watch impressive movies online that show you that it’s not the same everywhere at all. So, the word ‘global’ just means that it is a planet wide issue, it doesn’t imply anything about the scale at which the phenomenon should and can be studied.
We mean human-caused global change. Even some textbooks don’t make this distinction clear (like Rosenblum’s very nice book ‘Global Change Biology’). But I think it is important to be clear on this point; we are not talking about geological time scale global change, but about changes that relate back to human activities. There is obviously nothing wrong with asking questions about geological time scales. It is just a real bummer, in my opinion, that these two things have the same name.
There is no canon of global change factors. Some of the factors are clear, like atmospheric N deposition, invasive plant species, elevated carbon dioxide in the atmosphere. But it gets complicated with chemical pollution. Is all of chemical pollution one factor, or is it several hundred thousand factors? Or is it a bunch of different factors depending on substance group, or mode of action? At what point does something become a global change factor? We argued in several papers that microplastic should be considered one, for example, but there are no hard criteria. I don’t think we need a board that decides on this, but some criteria would be good.
Which leads me to the last point: I looked for a definition everywhere. I only found one in a paper by Bernhardt et al. (one of the most important papers I read in the last years in terms of influencing my thinking). It has the three components: global occurrence, link to human activity, effect on biota. It sounds very reasonable to me. Can you find a paper or book where it is clearly defined like this? The paper above is from 2017, and someone must have thought about this before in terms of offering a definition. I would love to hear from you!! Most papers, chapters or reports I have seen define the term by enumeration of examples.
Climate change is not the same as global change. Climate change is a subset of global change.
I think these are the main points. Let me know what you think about this, and if you know a paper, book or book chapter that offers a definition of global change in the sense we talk about here, I would be very happy to hear from you.
It's interesting to note that about the same time as the IPPC was created to focus on climate change, another organization, the International Geosphere Biosphere Program was created to deal with global change, and as you point out , everyone knows the term climate change and no one knows the term global change. The IGBP was funded at 10% of the IPCC and disbanded for reasons ungiven in 2015. Since then climate change has engulfed and overshadowed all other environmental concerns in the public imagination. One question I have, is when did the term "global change" originate and by whom?
I'll push back a bit that Global Change must inherently include human driving forces (I would add a modifier to GC for those cases). I've been reading histories of Roman empire and medieval times and there are multiple cases where human migrations / differences in productivity are hypothesized to have been driven by (natural) changes in climate. "Geological" time scale connotes to me at least thousands if not millions of years, whereas natural forces have impacted plant and animal communities over a century or so and this has had a knock-on effect upon human societies.