This scientist thinks so.
About a year and a half ago I attended an online conference hosted in Germany called Climate Landscapes. It was a gathering of professional, independent and citizen scientists, along with ordinary citizens like myself, looking at climate from the perspective of the land and what lives (or doesn’t live) on it. In the chat-room a paper was making the rounds with an evocative title: Ecology and Climate of the Earth—The Same Biogeophysical System. After the conference, I tracked down the paper, and seeing the lead author’s name, smiled. It was Dr. Roger A. Pielke Sr, a scientist I had begun an email dialog with three and a half years earlier, and who, from the paper’s title, seemed to have brought together in a single, bold statement the many strands I had observed in his thinking. I was curious to learn more. What exactly does he mean that climate and ecology are essentially the same thing? How should we picture that? What are the implications for climate science and policy? And how did he come to such an insight?
In terms of a biographic sketch, Dr. Pielke has made it easy for me, having written his own such account for the American Geophysical Union, entitled Following the Science. The account is written in the classic format of a scientific paper, replete with an Abstract, Plain Language Summary, Introduction and Conclusion. The Methods and Results sections are covered under Career Path. There’s even a list of references. Thus, the first insight: Roger A. Pielke Sr. is every bit the scientist.
He does give some hints into his personal nature, such as when, growing up in blue-collar Baltimore, manual labor took him to places where he saw the “ugly hyper-segregation” of his city. Working with tradesmen also showed him that expertise isn’t “limited to those with a PhD.” Later, under the mentorship of renowned meteorologist, Joanne Simpson, a pioneer in the field of tropical thunderstorms and the first US woman to get a PhD in meteorology, he heard the degrading language of some of his colleagues and was “sensitized to the difficulties that women have in entering science,” leading him to recruit women graduate students throughout his career. His greatest professional joy was mentoring his students, who were many. He ends his piece with links to each of their theses and dissertations.
It was an extremely productive career, during which he authored and coauthored over 400 papers, as well as the textbooks Mesoscale Meteorological Modeling and Human Impacts on Weather and Climate. He has been cited nearly fifty three thousand times, was once the State Meteorologist of Colorado as well as president of the National Association of State Climatologists. For their 2023 conference, the American Meteorological Society devoted a day-long symposium to his work.
Perhaps not surprisingly, he was also friends with and a colleague of Millan Millan, the late Spanish Meteorologist I have written about. In fact, Millan used models developed by Pielke for his work in the Mediterranean. And in a podcast I heard him describe Pielke’s book, Mesoscale Meteorological Modelling as a “classic,” saying in a tone of admiration, “Roger is one of the best.”
As to how he came to his insight, that climate and ecology are words for the same system, we find it early in his career, during his time with Joanna Simpson, who had an endowed professorship with the University of Virginia’s Department of Environmental Sciences. It was a large and internationally respected program, with noted researchers teaching on a wide range of subjects, and Pielke didn’t waste the opportunity to expand his horizons, sitting in on classes in ecology and hydrology and doing conservation research on the natural range of Red Spruce, even finding a fragment yet to be logged, of which he alerted the Nature Conservancy. It was in the midst of this cross-disciplinary ferment that it occurred to him that the people talking about ecology and the people talking about climate were talking about the same thing. It was an observation he apparently mused on for over fifty years before presenting it formally, in 2022, with two other scientists, Debra Peters of the USDA and Dev Niyogi, University of Texas. His early observation appears now as:
“When scientists focus on the physics of the Earth system, it has traditionally been called climate. In contrast, when scientists focus on the biological aspect of the Earth system, it is called ecology.”
To get a picture of what he means, we need to look at the climate a little differently than the standard view, which is temporal. That is, it describes climate as weather over long periods of time. For instance if you google “what is the climate?” you’ll find entries such as in Wikipedia defining the climate as the long-term weather pattern in a region, typically averaged over 30 years. Pielke recognizes this aspect of climate, that it involves systemic changes that are different than daily and seasonal shifts in weather. But the climate, he points out, is also made of things, many things really. One could say it’s the system that arises out the interaction of Earth’s innumerable things and processes, living and non-living.
For instance, if you change your questions from from “what is the climate” to “what is the climate system,” Wikipedia provides something very different: “Earth’s climate system is a complex system with five interacting components: the atmosphere (air), the hydrosphere (water), the cryosphere (ice and permafrost), the lithosphere (earth’s upper rocky layer) and the biosphere (living things.)”
It’s the same climate, but a very different viewpoint. Now, google “what is the planet’s ecology?” and Wikipedia gives you this “By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere.” Do you see? In a description of the planet’s ecology are the the same “interacting components” as seen in the planet’s climate system. Rather than two separate things, they are two aspects of a common thing, which Pielke refers to as the Earth system.
Even mammals and insects figure in to climate, says Pielke, noting that “the slaughter of millions of bison on the Great Plains of the USA in the late 1800s altered the short grass prairie from what it had been and, thus, likely changed surface flux exchanges with the atmosphere.” By “surface flux exchanges” he means movements of moisture, heat and gasses between the land surface and atmosphere. These exchanges are hard to picture because they’re invisible, but they are nonetheless fundamental to climate.
It is the land’s surface, after all, that determines the fate of the solar radiation that reaches it. If the surface is man-made or unvegetated the radiation simply enters the ground to be reradiated out as long-wave radiation, which greenhouse gasses are able to absorb, with resultant heating of the atmosphere. Yet if it lands on vegetation something much different happens. Some of course is used for photosynthesis, but only about 1%. The majority powers what can be thought of as a living heat and water pump. It takes heat to evaporate liquid water to water vapor, and living landscapes send huge amounts of water vapor to cloud level through transpiration Thus, they’re also sending up heat, where upon condensation of the vapor back to liquid, the heat is released. Clever trick. Water is cycled, heat is removed. Plant and ecosystem maintain stasis in a moderated environment. All powered by the sun and run by living things.
It can also be as simple as the roughening effect vegetation gives to the land surface. To illustrate the point he references Mars. There, he says, “dust storms are a major factor in its climate, and they propagate across the planet in a few weeks because there is no vegetation to limit their spread. Mars is a physical system only. That is, there is no need to consider biology to predict the spread of dust storms. However, understanding dust storms on Earth intimately involves biology and other land surface properties.”
We don’t have to go to Mars though to see these principles at work. We can go to the Florida Everglades. In the later part of the twentieth century drought often gripped south Florida. In addition, an unexpected freeze in 1997 decimated the citrus crop, resulting in massive economic loss. Industrial farms had long been migrating south to escape such freezes, yet the freezes seemed to be following them. Pielke wondered whether historic and recent land change played a role, land changes which had all but transformed the landscape, as the following figure shows:
Though changes in “land” may not be the best way to think about it. Much of that land, sweeping southwest then southeast through the center of the peninsula, was covered in water most of the year, beginning with the Kissimmee River floodplain, a wide, wet-prairie marsh draining into lake Okeechobee. From there it continued as a wide sheet of water sliding over a natural dam at the lake’s southern edge and flowing across saw grasses marshes, sloughs and bogs—what we know as the Everglades, or the river of grass. Notice the light lavender section just below the lake, “Saw Grasses/Other Marshes.” Here’s what that kind of land change looks like:
To drain and develop such land is like draining an inland sea, a change indeed. But how to uncover the link between that change and climate? On this question, Pielke had an advantage. He knew the Everglades well, having conducted studies there early in his career during his association with Joanne Simpson. For his PhD dissertation he developed a three dimension model of Florida’s weather behavior that could be used for cloud-seeding experiments being conducted at the time (which he now argues against.) That model continued to develop over the years, eventually becoming the Regional Atmospheric Modeling System, used worldwide, such as by the government of Brazil. It also provided the perfect tool for testing his hypothesis.
What would happen, he and his associates wondered, if they ran the model for relatively recent summer periods where the broader meteorological conditions are known and recorded, but reverted the land cover to pre-1900 conditions. Would the change in land cover produce different results in the models? It did, fairly dramatically. For instance, in the once-much-wetter center of the peninsula, daytime highs increased as much as 4C after the land change. Meanwhile, average precipitation decreased by 10 – 12%.
The warming makes intuitive sense. They dryer and less-vegetated land will generate less evaporative and transpirative cooling. But why less rain? That has to do with air currents. Notice in the top left image that surrounding the wet interior were pine forests, which grew on higher, drier land. The morning sun would heat up these strips of land, causing the air to rise above them, to which the cooler ocean air would rush in, creating a sea breeze. A similar phenomenon would also happen inland, with the cooler air over the marshes rushing outward toward the heated margins. Land breeze and sea breeze would converge into a moist, rising “convective convergence,” ideal for precipitation. But the land change, by diminishing the land breeze, diminished precipitation.
The next question was, if the draining of marshes and spread of agricultural/urban development had warmed and dried the region, how was it affecting the increasing frequency of winter freezes? On this question the results were even more dramatic. Since water has a higher heat-holding capacity than dry land, the bogs and marshes were able to hold daytime heat like a hot water bottle through the night, buffering the depth and length of winter freezes. Draining them for agriculture also drained that temperature-buffering capacity, It appeared that the freezes were not so much following the agricultural development, but being pulled down by it.
As you can see, the intermixing of ecology and climate has direct, on-the-ground implications, but Pielke and his associates were also concerned about the implications for science. For if it’s assumed that the components of ecology and climate are intimately coupled, as they appear to be, then those “components cannot be viewed separately if an accurate understanding and predictions of the coupled system are to be achieved.”
And yet, viewed separately they are. As I’ve written and Pielke points out, The IPCC’s climate assessments declare a Physical Science Basis in their assessments, leaving unanswered the question of what happens with the biological side of climate. Is it recognized? Do the models reflect biological and related hydrological processes. Does the IPCC include land change in their assessments?
It’s a hard question to answer. They kind of do and kind of don’t, a situation to which Pielke is trying to bring some clarity.
Let’s begin with the physical science basis. What is it? A 1979 report of the World Meteorological Organization’s first World Climate Congress gives us some clues. In a chapter entitled The Physical Basis of Climate, it writes: “Like all other phenomena in nature, the climate and its changes are presumably governed by physical laws, and the discernment of those laws is the goal of modern climate research.” It goes on to say: “This represents the most rational approach to the problem, and the possibilities of scientific climate prediction and control rest directly upon our understanding of the physical processes involved.”
But is the climate system governed by physical laws? It’s quite an assertion. A physician presented with a patient’s symptoms won’t get far if he or she tries to reduce the patient’s biological condition to physical data to be run through mathematical equations for a diagnosis. The Earth system is infinitely more complex. Can we expect the climate system of a living planet to be fully comprehended the same way?
It’s a mechanical perspective that harkens back to a Newtonian clockwork vision of the universe, and is in many ways considered antiquated. How ironic that such a musty assumption imbues some of the most sophisticated computer modelling ever undertaken. It’s as if the sophistication of our technology has raced ahead while the sophistication of our thinking has not.
Along with this assumption of a physically run climate system, there seems to come another assumption: that climate exists outside of the system and from there governs it. “There is still a general assumption by many that the physical components of the Earth system…drive the ecological components,” Pielke writes. It’s not that those physical processes, such as the physical warming of the atmosphere by greenhouse gasses, don’t exist. They do, and all biological process involve physics in one way or another. But it’s a two way street. Ecology also drives climate and that introduces a whole new dynamic into the picture. “In the real world,” he says “there is no “physical” climate system on Earth. There is only a physical component of the Earth system.” If you want to see a climate run by physics alone, you’ll have to go to Mars.
Note also Gates’ conclusion, “the possibilities of scientific climate prediction and control rest directly upon our understanding of the physical processes involved.” Here we see the purpose of the physical science basis, to give us a means of mathematical prediction. Reasonable enough, and important. But, given the ecological complexity of the climate system, should it be our only means of prediction? One can predict with basic certainty that if you clearcut a forest it will immediately got hotter and drier in that place, and that will effect the local and therefore regional, and ultimately global climate. One can also predict that if the forest is converted to industrial monocrop the soils will degrade and desiccate and the plantation, lacking biological complexity and hydrologic function, will become susceptible to disease and fire. One can further predict that after such a fire, the unprotected ground will be susceptible to erosive rains, losing vital soil, such that come summer it will be even more susceptible to drought, while at the same contributing to it.
Very little of this activity, however, is represented in the models. And it really wasn’t meant to be. The initial models were designed specifically for one ingredient of the climate system, CO2, and the originating question was simple: what would happen if you doubled CO2 concentrations in the atmosphere? It’s an important question, and numerical models provide a useful tool for getting at an answer. Pielke, who not only builds models but has written books on them, understands as well as anyone how “practically powerful” such tools are. But knowing them as well as he does, he also sees their limitations.
Have we confused the tool with it’s subject? Have we taken a legitimate means of predicting one factor of the climate system, CO2, and thrown it around the entire system? Rather than a tool, the physical science basis seems to have become more like a gate, through which one must pass in order to see the climate “properly.”
As for the IPCC, it kind of does and kind of doesn’t recognize the biological aspect of climate. On the one hand, it has to. The land/atmosphere relationship is long-accepted science. On the other hand, such biological processes are generally too complex to be reduced to global-scale modelling. The IPCC, though recognizing them, generally treats them as a mitigating factor in what is presented as a physical, CO2 run climate.
He points to a passage in the IPCC’s most recent assessment, from Climate Change 2021: The Physical Science Basis. “There is abundant evidence that changes in land use and land cover alter the water cycle globally, regionally and locally, by changing precipitation, evaporation, flooding, ground water, and the availability of fresh water for a variety of uses. Since all the components of the water cycle are connected (and linked to the carbon cycle), changes in land use trickle down to many other components of the water cycle and climate system.”
Note how water cycles are viewed in terms of their links to the carbon cycle, as if that were the main avenue of their effect on climate, missing the more direct effects of evapotranspirative cooling and moderation. Consider also the language, how “changes in land use trickle down…to the climate system.” (Emphasis mine.) That doesn’t really make sense. When landscapes are altered, the effect is immediate and direct. The land changes in the Everglades, for instance, didn’t trickle down through the carbon cycle. They directly affected soil and atmospheric moisture, cloud development, and temperatures, both highs and lows.
Such statements amount to what Pielke describes as “implicit” recognition of the ecological dynamics of climate, but he calls for an “explicit” understanding, for a formal recognition of ecological damage as a first order driver of climate, not an implied trickle-down effect related to the carbon cycle.
There is much at stake, as the 2021 IPBES (Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services) report grimly enumerates. 75% of Earth’s land surface has been significantly altered. 85% of wetlands are gone. Between 2010 and 2015, over 123,000 square miles of primary forest were lost. The report also bluntly states that for terrestrial ecosystems “land change has had the largest relative negative impact on Nature since 1970.” Pielke cites a New York Times article on the report, entitled Our Response to Climate Change Is Missing Something Big, Scientists Say. It concludes “the world needs to treat warming and biodiversity loss as two parts of the same problem” Such a convergence would be much more likely, says Pielke, with the “explicit recognition that climate and ecology study the same system.”
The risks extend to humans as well. Most of the climate changes currently immiserating people around the world, especially in the developing world, have direct connections to land change. This is especially true in dry climates, where natural, healthy land cover is so crucial for holding moisture, cooling the atmosphere and moderating drought/flood cycles. If we continue to treat climate-change as purely the result of globalized average warming from C02 emissions, we deprive millions of people the understanding they need to improve their own lived conditions.
It’s why in his paper Pielke advocates a “vulnerability” approach to assessing climate risk. Every locale has it’s own climatic situation and it’s own land-change reality. It’s critical that people assess their particular, placed-based vulnerabilities, along with what resources they have in their landscapes to improve their situation. Switching to renewables may eventually help the carbon balance in the atmosphere, but it will do little in the short term for people where they live in ways they can feel.
Pointing such things out, despite doing so in the most scientifically cautious of ways, has not made the path easy for Pielke and scientists like him. There seems to have grown an institutional suspicion of perspectives that don’t fit a strictly physical, CO2-driven interpretation of climate, and Pielke is not alone in his frustrations with such an approach. “Many of us feel marginalized,” he wrote me once. But a growing community of people are uniting around a broader vision of climate, one more inclusive and ecological, less constrained by the physical ocular of numerical models. One that sees ecosystems as more than helpless victims of a CO2-run climate, but as active regulators of a biophysical climate and our greatest ally in restoring the climate to its natural condition.
For myself, one of the most convincing things about the ecology/climate overlay has been my own trajectory in studying it. Simply put, I started out with climate and ended up in ecology. Now I see relationships everywhere, the world more alive because of them. The atmosphere, rather than a distant, inanimate layer of gasses, has come to feel more like an extension of Earth itself, not floating mechanically over it, but dynamically upheld by it. The sky I once stood under I now stand inside of. Land and atmosphere have become woven into a single living system.
It’s hard to overstate the effect this has had on me. It is science, but the implications verge on the poetic and spiritual. The more I divine the interweave of life and climate, the more awe I feel at the life around me. And this leaves me wondering what is possible for others. What might grow in the human psyche if such understanding were to exist at large? And why doesn’t it? Why at this very late date do we still keep such a distance from the living beings and relationships around us?
As we’ve seen, Pielke is all science. He leaves such questions to poets like me, focusing on the science itself, not only on what it is, but how it’s done and what it says. “Effective communication for public outreach, to advance scientific understanding, and to develop policy and make decisions have been hampered when it is assumed that climate is an external forcing function outside ecological systems,” he writes. It may not be a popular idea, and certainly complicates an already carefully laid out narrative. It reminds me of an exchange between Lynn Margulis, the microbiologist who pioneered the theory of symbiotic evolution, and Richard Dawkins, who took exception to the theory’s contradictions of Neo-Darwinian theory. In a recording he can be heard asking her, in effect, why she would want to trouble such a well worked-out system.
She laughed, answering, “because it’s there.”
