Unpredictability as an aspect of global change?
Is this an overlooked aspect of human-caused global environmental change?
Are there more unpredictable events as a consequence of human activities, and does this contribute to the effects of global environmental change?
Much in nature follows a rather predictable course, such as the seasons, diurnal changes in conditions including temperature and light cues. But of course there are also many rather more stochastic features, such as rainfall patterns or disturbance.
Does human-caused global environmental change contribute to this unpredictability, thus posing additional challenges to organisms?
Climate change
Let’s look first at climate change. For this set of factors, I think the evidence is already relatively clear. Occurrence of temperature extremes (for example, heat stress events) would fit this category quite well. Also perhaps increased flooding and drought spells that increase in duration, severity or timing. Also larger and more frequent storms and more intense and frequent fires as a consequence of these climatic factors could be occurring, presenting challenges to organisms and communities. But what about other factors?
Other factors of global change
Invasive species arrival would certainly also be unpredictable events that resident species cannot really be prepared for. The invasive species can be plants, animals and microbes.
Chemical pollutants — including pesticides, microplastic, nanoparticles, consumer product chemicals, industrial products and many more — can also occur unexpectedly in terms of new products or new combinations arriving at certain places. This occurrence can be related to events, such as accidental spills or spill-over from sites of intentional application.
Why could this be important?
Dealing with a new event or environmental factor likely costs metabolic energy. Cells and organisms will by necessity have evolved to deal with fluctuations and changing conditions in the environment, since this is the reality. However, has the frequency of such events increased and their unpredictability (e.g., these things cannot be anticipated)? And does this therefore exert a new cost for organisms to deal with, adding to the already existing natural pressures?
This could be a part of the explanation for the experimental observation that an increasing number of factors has increasingly deleterious effects on biota and processes to which they contribute. In such experiments, where the number of factors is systematically varied, selecting factors from a pool by random draws, results are surprisingly insensitive to the identity and composition of factors, but rather a lot of the response can be explained by knowing just the number of factors at play. Of course, the comparison is only partially valid, since in these experiments the factors were all applied at the same time. But this could nevertheless offer a hint how effects with unpredictable factors could unfold.
Challenge: novel vs. unpredictable
I see the following main problem with this idea: how do we separate the occurrence of, say, a novel pollutant, which has toxic or other effects on biota, from the (un)predictability of its occurrence? In other words, does the fact that this occurred in an unpredictable way add to the challenge of organisms to deal with a new insult? How can this be tested empirically?
Is the fact that something is novel inextricably linked to this same thing also being unpredictable? If something is unpredictable, it can be novel (a novel pollutant) or not novel (fire, drought spells). Something can be not novel and predictable (seasonal change, diurnal patterns). But if something is novel, it cannot be predictable.
While that novel thing cannot be predictable, in the sense that organisms cannot anticipate it, organisms could still be well placed to deal with this new thing. Examples are cross-protection, where a novel agent can trigger already existing metabolic and defense responses (such as cellular efflux pumps). If some pollutant is novel, and its occurrence cannot be anticipated (it is an unpredictable event), its effects may still be dealt with using existing organismal machinery. Maybe in this case unpredictability might outweigh the ‘novelty’ in terms of the effect on that organism.
Can this idea be tested empirically? Where does this lead? Is ‘unpredictability’ worth pursuing as a feature of global change?
Any thoughts on this? please share in the comments!
Super piece Matthias! I'm always looking for some optimism on the ongoing global change crisis. I've always wanted to ask the question to climate scientists, such as physicists, ocean experts etc, could there be some kind of mechanism that would trigger a dampening or slow down of warming (for example)?
If we come back to biology, many times the study of "unnatural systems" is discouraged. For example, in plant pathology, if you put model pathogen X on model plant Y, but this association does not exist in nature, you get harsh criticism, which is partly deserved. Maybe the trick would be to base your plant-pathogen system on predictions of migration of either organisms?