What if we’ve been looking at the climate, well, incompletely? What if there’s another side to climate change, one less concerned with what we put in the atmosphere than what we do to the land, a side which, despite four decades of climate education, has yet to be explained to us?
Scientifically speaking, there is. Scientists call it “land change,” a characteristically neutral term for the not-so-neutral ways humans alter landscapes, through things like logging, agriculture, road building and urban/suburban sprawl. By disturbing land this way, we disturb the land’s ability to hold and cycle water, and that affects climate, particularly on a local and regional level.
Though we tend to think of climate in terms of carbon, water is in fact the primary medium of Earth’s heat dynamics, perhaps not surprising on this 71% water planet. Water not only has the highest heat capacity around, it’s also a shapeshifter, continuously phase-changing between water, vapor and ice, absorbing and releasing heat at each juncture, elegantly distributing heat along the way.
Evaporation, the phase-change from water to vapor, is a cooling process. We’ve all felt it when we sweat. Plants essentially do the same thing when they respire, cooling themselves and their surroundings by releasing water vapor from under their leaves. Trees are the power lifters here, drawing upwards of 150 gallons per day through their roots and out through their leaves, giving an average tree the cooling power of two air conditioning units running all day.1
The vapor, with the heat held latent inside it as a chemical potential, rises until it is high and cold enough to condense back into clouds and rain, at which point the heat is released into the air again, only higher, some of which continues its journey out to space, the rest reentering the system elsewhere. It’s like a heat pump, soil to vegetation to cloud to rain and back to soil—hydrating, cooling and buffering climate along the way. If there’s an operator, it would be the landscape itself, or simply life.
But the land not only feeds clouds water vapor, it seeds them with the nuclei of future raindrops, sending up grains of biota like bacteria, pollen dust and terpenes. Those nuclei speed the formation of clouds, whose bright tops reflect sunlight for additional cooling.
Soil is key, as it collects and banks both water and carbon. Picture soil as a sponge, held together but full of tiny spaces. There are grains of sand, clay, and minerals within that matrix, but what binds them into a sponge is life, an astounding plethora of the invisible and nearly invisible: protists and bacteria, nematodes and soil mites, thousands of miles per square yard of fungal hyphae. It is their exudates and decaying bodies which not only glue the particles together, but hold them apart, making room for the water so crucial to all life.
Here we encounter feedback loops we like. The more carbon (life) in the soil, the more water it can hold. The more water it can hold, the more life (carbon) it can grow, bringing yet more carbon down to the soil, which can bank yet more water, and around it goes, literally swelling with life.
It follows as well that when we damage land, we reverse the cycle. Less life means less water, meaning less rain, meaning less vegetation and down it spirals to desert.
It doesn’t take long to realize the scale here. Consider all the land cleared over the centuries for agriculture alone. Add grazing, logging, mining, urbanization, suburban sprawl, roads, shopping malls. It’s estimated half the land surface of earth has been converted to human purpose.2 And now we must add “green infrastructure” to the list, with forests corridors cleared for transmission lines and deserts scraped for solar arrays.
If all this is news to you, you’re not alone. The climate movement has largely ignored land change, building its narrative almost exclusively around CO2 and green energy. Not all scientists are satisfied though with the approach. One in particular, Mediterranean-climate expert Millan Millan, remembers a time when science held both land change and greenhouse gasses in roughly equal measure as human causes of climate change. He has his own terminology for this more traditional view of climate, calling it two-legged—one leg for CO2 and the greenhouse effect, the other leg for land change and hydrological effects.
In 1991, the European Commission asked him to figure out why the afternoon storms in the western Mediterranean Basin were disappearing, and it was his understanding of land change that led him to the cause. “Land-use perturbations that accumulated over historical time and greatly accelerated in the last 30 years” had rendered the land incapable of supporting the region’s cloud regime. The storms were dying because the land was dying, and Millan’s work showed how.
Though published in the American Meteorological Association’s prestigious Journal of Climate,3 his findings proved, as Millan put it, “incommodious.” The CO2 oriented, global computer models that came to dominate climate science couldn’t see the fine grained, land-level processes Millan uncovered. Politicians, with their pet building projects and economic growth fixation, ran from them.
Millan often refers to a book called Inadvertent Climate Modification: Study of Man’s Impact on Climate, an early study published in 1971 by MIT and the Royal Swedish Academy of Sciences.4 The book is still available, and you can see the land leg there for yourself, it’s opening paragraph listing “climatic effect of manmade surface change” as a “major area” for consideration. Under the heading Man’s Activities Influencing Climate, there’s roughly equal treatment for subsections concerning both Atmospheric Contamination, and Land-Surface Alteration. Under Major Conclusions and Recommendations is an entire chapter written on the Climatic Effects of Man-Made Surface Change.
Eight years later, in 1979, we see land change again in the proceedings of the World Meteorological Organization’s first World Climate Congress. From the conference’s keynote address: “We now change the radiative processes of the atmosphere and perhaps its circulation by emission of the products of our industrial and agricultural society. We now change the boundary processes between earth and atmosphere by our use of the land.” The first of 28 scientific papers, under a discussion of “the impacts that are of the most relevance to the subject of climate,” places “the transformation of the land surface of the planet by forest clearance, the ploughing up of the steppes and great plains, land reclamation, etc” at the top of the list. And in a section titled, Human Activities that Affect Climate, the author literally breaks the subjects into two parts. “The subject of this paper is clearly of very wide scope and accordingly presented in two main parts as follows: Part I…covers the main human impacts on climate, excluding mankind’s interference in the atmospheric carbon dioxide (C02) balance; and Part II…deals comprehensively with those aspects of climatic change which are related to the carbon dioxide balance.”
But there was a problem. The living, water-mediated processes of land change were too complex and variable to be put in the global computer models, while CO2, well mixed in the atmosphere, was relatively easy to model. Not only that, CO2 was the novel threat, its atmospheric concentrations easily measured, and rising fast, which caught the attention of the US office of Science and Technology Policy under the Carter administration. In 1978 it made a formal request of the National Research Council to look into the matter, and an Ad Hoc Study Group of scientists was put together, led by Jules Charney, the mathematician behind the computer modelling that revolutionized modern weather prediction.
They gathered in Woods Hole, Massachusetts and began reviewing the modelling on CO2, assessing weak spots, somewhat averaging the findings. The result was a slim, 22-page report called Carbon Dioxide and Climate: A Scientific Assessment.5 Unlike the WMO report, which though comprehensive at 700 pages long, offered no definitive statement on CO2, this report provided the closest thing yet to a firm prediction. If CO2 concentrations double, it said, global temps will increase 3 degrees centigrade.
It was a bombshell. Petroleum interests immediately attacked it, environmentalists lined up to defend it and a kind of social feedback loop developed. The more CO2 was denied as a cause of climate change, the more it was championed by its defenders, cementing in place the sense that carbon gasses were the sole matter of climate change.
Did Charney and his associates intend to portray CO2 as the only cause of climate change? Likely not. They point out in their Summary and Conclusions, “we have limited our considerations to the direct climatic effects of steadily rising concentrations of CO2.” They likely understood there’s a land change aspect to climate change, but until it was mathematically translatable, it was placed aside as “all other things being equal.”
You can imagine where this left the WMO and the other international organizations. The Americans had come out with a strong statement on CO2, while they were far from such consensus, still sorting through various uncertainties, often related to land change. What to do?
A series of international workshops were held in Villach, Austria, to work such complications out. The solution was to split the two legs, with two organizations created roughly side by side. One we’re all familiar with: the Intergovernmental Panel on Climate Change, or IPCC. The other you’ve likely never heard of: the International Geosphere-Biosphere Program, or IGBP. That’s where the land leg, with all it’s complex, watery, difficult-to-model process, seems to have been filed, but in the context of different language. Rather than dealing with “climate change,” this group was responsible for something called “global change,” for which it received one tenth the funding of the IPCC.
Thus, the CO2 leg, championed by the IPCC, strode into the climate spotlight, while the land change leg, under the IGBP, remained in shadow for further research, where it was largely ignored. In 2015 the IGBP was closed and turned into a private organization called Future Earth.
Of course, the research continued anyways, and now it is common to see the term “biophysical” used, which is basically the two legs contracted into a single word: bio (land and water process,) physical (atmospheric chemistry and the greenhouse effect.) It seems the land change leg is coming forward again. For instance, at the University of Washington there is a research group called the Ecoclimate Lab, looking specifically at “how plants and climate interact with one another.”
Unfortunately, the IPCC’s most recent report, published in August 2021, devoted less than four pages out of three thousand eight hundred and fifty to land change. Nonetheless, the next report will likely include land and water processes as the science is moving that way. But at the IPCC’s typical rotation of six years, that’s still five years off. We shouldn’t have to wait that long. Nor should we require the permission of computer models to treat land change as a human cause of climate change. Though we might want to ask why land change has remained publicly unexplained for so long.
Just to be clear, nothing here contradicts the CO2 leg of climate. Nor does it allow us to continue saturating the atmosphere with carbon gasses. It just puts it in a different context, the context of life, where CO2 is food, and the living land is the true green infrastructure of climate.
The Lakota say Mni Wconi, “Water is Life.” Something in that insight appears in climate as well, over and over. We could say, “because water is life, there is climate.” That would be one way to put. It may not be “the science.” It certainly isn’t the politics or the economics. But it may well be the Law.
Make carbon life again.
- 1971, Inadvertent Climate Modification: Study of Man’s Impact on Climate, MIT.