Why is our world so blind to ways how landuse is changing our climate?

Global climate change is about greenhouse gases.

When nowadays we hear the word “Climate Change”, we mostly think about the impact of greenhouse gas emissions by humans that is shifting the global climate.  This is not surprising: Since the Kyoto Protocol negotiations started in 1997,  international efforts around climate change focused on “climate change due to anthropogenic greenhouse gas emissions”. Since then, scientists carefully separate out four effects that may shift our climate:

1. Natural climate variability, driven mostly by the Earth’s rotation and the meandering pressure fields that this creates, and overlaid by planetary oscillations like the El Nino/El Nina cycles. Even if this natural climate variability was our only concern, we would never be able to predict the weather – thanks to the “butterfly effect”.
2. Natural climate changes slowly shift average climate conditions, e.g. due to changes in solar radiation or the wobbles in the Earth’s rotation axis that trigger ice ages.
3. Global warming due to human greenhouse gas (GHG) emissions , and
4. Direct climate impacts of human actions (landuse, water management), e.g. heat island effects in cities or vegetation cooling via the terrestrial water cycle.

These four aspects of our climate – natural climate variability and change, global warming from human GHG emissions, and direct climate impacts from human actions, especially land use change – together determine our weather.

The United Nations once worked on the Kyoto Protocol, the first document that aspired political action to address global warming. From the earliest days, the Kyoto Protocol was intended to address global warming by reducing greenhouse gas concentrations in the atmosphere to “a level that would prevent dangerous anthropogenic interference with the climate system” (Article 2). The Protocol restricts itself to six greenhouse gases (Annex A): carbon dioxide (CO₂), Methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

Over time, the Kyoto Protocol also included landuse change, yet limited to how landuse impacted on greenhouse-gases. In increasing detail, the protocol accounted for sinks and sources of carbon dioxide and methane in our biosphere. Yet, these landuse-related aspects in the Kyoto protocol explicitly focus only on GHGs. The protocol  disregarded any climate effects of the biosphere and its interaction with the water cycle, transpiration cooling, and urban heat islands.  At that time, governments believed that these issues are national interests and should not be regulated by a UN body.

Subsequently, academic climate investigation carefully distinguished the four driving forces of the climate. I remember that, in my University years, any long-term climate station data  had to be “cleaned” from land use impacts on the data. If cities had grown around long-term climate stations, the urban heat island effect was partly responsible for a warming trend in the data! What does such data then tell us about global climate change, and the role of GHGs? Are we seeing global warming or just the increasing effect of the urban heat island? For decades, scientists learned how to prod apart global and local climate effects. Remember: there was still no final proof that the greenhouse gas effect even exists! So methods focused on finding the “global warming signal” in very chaotic weather data and next to significant direct climate impacts by humans.

In 2001, I learned how historic responsibility and financial liability intermingles at policy level. At the UN climate conference in Marrakesh, negotiators agreed that nations which suffer from climate change are entitled to compensation from the “big emitters”. Lawyers from these big emitters ensured that the damaged countries have “the burden of proof” – they must determine which percentage of the damage of a storm or flood was caused by human GHG emissions, and what percentage of the damage can be attributed to natural variability, natural change, or direct human climate change. Those of us with basic statistics knowledge will see that this proof is impossible – and in effect, this clause let rich emitter countries off the hook.

In 2003, the first conclusive evidence was presented that global warming is actually taking place, using monitoring data alone. The study by a Professor from Frankfurt, Germany, showed without any doubt that the earth is warming and that this warming is connected to greenhouse gases. As student doing my master thesis, I was invited to a high-level reception where leading climate scientists “celebrated” this evidence with Champaign — their climate concerns were not just their imagination but our shared reality. I remember this event as one of the strangest that I ever attended – it felt like getting seated in a roller coaster without a safety belt, and without knowing where it may take us. But at least we held a glass of Champaign!

Since then, ‘climate change’ has become almost a synonym with “greenhouse-gas driven global warming”.  The scientific mandate of IPCC was to support the Kyoto process with a solid academic consensus. Global warming from anthropogenic greenhouse gases has become the focus of academic investigation. Whereas the second impact of humans on climate, through changes of land use, the terrestrial water cycle, and the biosphere, were almost forgotten.

Non-greenhouse gas impacts on our climate

Urban heat islands can warm entire cities by 10-15°C today. Today, such urban warming is about ten times as strong as the greenhouse effect is projected for the year 2050.

How relevant are these “non-greenhouse gas” impacts of humans on our local climate? Is it relevant compared to global warming? The answer is: it depends  on your local context.  Your local context determines how strong global warming impacts you, and your local context determines how resilient your region is to landscape-driven changes to your climate [Mahmood et al., 2014, Pielke et al., 2016].

The greenhouse effect is not the only pathway how our climate is changing – there are a myriad of other climate factors that too many people ignore today, in particular:

• River runoff is partly tied to rainfall and snow melt, and partly to the water retention within a watershed. Forest soil absorbs water and release it slowly into the groundwater; if the surface is covered by asphalt and degraded agricultural soil then water runs off rapidly at the surface. Drainage and wetlands are other buffers that slow down water runoff. Together, landscape management determines whether a region stays hydrated and moist, or whether water drains in a flash flood and the region then dries out. This has impacts on wildfire risk, irrigation requirements of crops, the biosphere at large, and even rainfall formation.
• Vegetation triggers cloud formation and rainfall. Above forests, plants “create” clouds by exuding organic particles where micro droplets then form. Also, plants transpire water vapour that is required for condensation. Two islands that have exactly the same mountains and are in view of each other, one with intact forest and one that is deforested, may have totally different rainfall readings – just because of this vegetation effect.
• Heat islands originate where surfaces have low moisture and high heat absorption. The best-known heat islands are our cities – everyone can sense the urban heat island effect when driving from the countryside into town. But the same effect exists in rural areas: if a beaver wetland is drained, or if a field is fallow, it is easy to observe changes in temperature (it’s much hotter), updrafts, cloud patterns, and wind patterns.

All of these changes to our local climate are triggered by changes of our land use. Birds and glider plane pilots know that well and use local updrafts above fallow fields.  Changes happen at all scales:

• when you walk from the hot asphalt of your street into the cooler air in your garden, when you move from a forest into a fallow field,
• when a landscape is turned from natural vegetation into annual crop fields such that cloud formation and wind patterns shift;
• when entire regions desertify because of poor grazing management. Or
• when the biosphere of an entire continent was changed, as happened in Australia when British colonizers discontinued 50,000 years of aboriginal land management and settlers brought British agricultural practices into a brittle landscape [1],[2],[3],[4],[5],[6].

Human land use management can dramatically change landscapes. Deforestation can turn humid tropical rain forests with very small day-night temperature changes into barely vegetated drylands with huge temperature daily changes.  Poor grazing management can turn lush grasslands into sand deserts. Soil degradation from intensive agriculture has already shifted the terrestrial water cycle globally and dried out large patches of land [Levia et al., 2020].

Limitations of the global greenhouse lens on climate change

When comparing model resolution with the physical scale of some climate effects (Figure 1), the limitations of climate models for representing local effects become apparent.  Global climate models were designed to prove and analyze the impacts of global warning due to greenhouse gases. With horizontal resolution around 150 – 300 km , these global models are unable to resolve many of the landscape climate effects that are relevant locally. Fine-scale features such as mountains, coastlines, lakes, irrigation, land use, and urban heat islands can substantially influence a region’s climate dynamics [7]).  Global climate models still have some usefulness for assessing large-scale changes. For example, they can demonstrate vast deforestation impacts on the global climate, which has indeed the same magnitude as GHG-driven warming (e.g. [8], [9],[10]).

But global models cannot resolve transpiration cooling of vegetation, water vapour and cloud formation around vegetation, local rainfall intensity and frequency, updrafts and changes of wind patters, storms, and extreme events [11]. These physical processes are driven by those human land use practices that we can influence locally – but our climate models, and our academic climate methods, are unable to assess these effects. As a result, the scientific literature is mostly silent about these landuse-driven aspects of climate change – driven by human impacts on the terrestrial water cycle, vegetation cover, and soil health.

Figure 1, taken from (⁷)

Efforts are ongoing to understand global climate at local scale:

• Regional climate models are being developed with horizontal resolutions between 1km and 50km. These models use several types of architecture: some are physically based dynamic models, others use statistical downscaling methods that generate high-resolution predictions, and others combine both approaches.  Today, four regional models exist for downscaling the impact of global GHG-driven warming on in the Great Lakes area [⁸].
• Integrated human-earth system modeling assess the feedback between human actions and the earth climate [12]. For example, a recent analysis shows that landuse changes in the United States have influenced rainfall intensity to a much larger degree than generally expected [13].

Until today, regional climate impacts from landuse and land cover change remain poorly understood and lack general model consensus [¹³]. When investigating the feedback between the water cycle, land use change, and the regional climate,  a combination of regional climate models, hydrological catchment models and landuse data may be required [14]).

Why are we talking so little about these non-GHG human impacts on our climate?

In the positivist paradigm of natural sciences, only proven facts count. Conflicts arise whenever sensitive people can perceive certain aspects of reality that our scientific methods fail to prove. This becomes apparent in numerous examples : Our gut’s impact on our emotional state is known for millennia and traditional healers used diets accordingly. Chinese medicine is based on energy meridians , which Western medicine shunned until recently – now Western science has “discovered” and proven their power. Many indigenous agricultural systems actively nourished mycorrhizal soil fungi that are essential for plant nutrition. In Western agricultural sciences, mycorrhiza were “discovered” about one decade ago and remain a “regenerative” secret. Landuse-driven climate change, as described above, is yet another example that is just too complex for our assessment models – so scientists ignore its relevance. Again and again, Western science only recognizes and supports those processes that its reductionist methods can demonstrate with high levels of certainty. Whenever these methods fail, science is in denial of central aspects of our lived reality, and scientists filter these out of their perception.

Unfortunately, this blindness of our academic apparatus directly translates into our social and political decision making. We don’t have good strategies to manage “complexity” – systems categorized by large uncertainty that evade our scientific methods.  Yet, mycorrhizal fungi and viruses and local climate feedbacks are as real ten years before Western science “discovered” them, as they are after their discovery.  They are as relevant to our ecosystems, our plants, our own health. Many traditional cultures have developed cultural antenna for these “inexplicable yet reproducible” phenomena. Many cultures were entirely dependent on such phenomena for their survival! But in our science-centric world, we live in denial of the things that we don’t understand.

I am not arguing against any field of science, not even the most reductionist one. Science is valid within its boundaries. Many political forces are anti-science, which means they dispute clear causal connections that we could prove with our scientific methods. I have no understanding or patience for anti-science movements – flat earthers, anti-vaxxers, or climate change deniers. But as a society, we have to acknowledge that there’s truth beyond our current scientific method.

Until today, mainstream sciences are still incapable of defining such basic concepts as “health”, “a good diet”, “life”, or “happiness”. Our sciences can suggest checklists of factors that contribute to these “beyond-science concepts”, but these checklists are neither conclusive nor definitive. Still, we all understand these concepts intuitively. Indigenous cultures have built empires on this intuitive understanding. We also recognize the need for contextualization – these concepts may mean different things to different people.

“Healthy, climate-resilient landscapes” also fall into this category of concepts that are “beyond our scientific method”. We need to learn how to foster such landscapes, with our action, our policy framework, our regulations. But at this point in time, the climate change debate seems solely focused on greenhouse gas emissions – building on three decades of scientific advancement in global climate models. We seem to totally ignore how we interact with our climate through landscape management, how biodiversity plays a fundamental role for sustaining a livable climate. Instead, we advocate for policies that trade off known CO2 benefits against unknown feedbacks of our water cycle. We mostly ignore the massive impact of industrial agriculture on our climate, as its pathway is the elimination of biodiversity and the disruption of the terrestrial water cycle [Levia et al., 2020] rather than a greenhouse gas effect.

I increasingly start to believe that the future of humankind, of our planet, depends on our ability to move beyond the reductionist lens of science. Not in an “anti-science” way that legitimizes whatever opinion. But in a thoughtful way that accepts the limitations of Western science and explores ways how we can manage our world in the face of deep uncertainty.

A little bit like managing a marriage, or raising a child. We manage uncertain living systems all the time. Even if it is an art rather than a science!

How can I learn more?

• Walter Jehne educates about direct human climate impacts (e.g. here).
• John Liu talks about large-scale ecosystem regeneration for healing our climate (e.g. here)
• Zach Weiss offers an excellent video on ecosystem regeneration through water restoration (here).
• Kiss The Ground educates about soil health and also has an excellent movie (link).
• Didi Pershouse educates about soil health & watershed functions (here).
• Allan Savory summarizes the role of regenerative grazing in our fight against desertification (here).
• Diana Rogers’ movie “Sacred Cow” and its companion book explain the role of integrated animal-crop agriculture (link).

References

[1] Hallam S. The biggest estate on earth: how Aborigines made Australia. Australian Aboriginal Studies. 2011 Sep 22;2011(2):123-7.

[2] Melissa Nursey-Bray, R. Palmer, T. F. Smith & P. Rist (2019) Old ways for new days: Australian Indigenous peoples and climate change, Local Environment, 24:5, 473-486, DOI: 10.1080/13549839.2019.1590325

[3] https://theconversation.com/the-biggest-estate-on-earth-how-aborigines-made-australia-3787

[4] https://www.natureaustralia.org.au/what-we-do/our-insights/perspectives/human-impact-nature-australia/

[5] https://www.smithsonianmag.com/smart-news/australian-stories-capture-10000-year-old-climate-history-180954030/

[6] https://news.mongabay.com/2016/04/rekindling-australias-aboriginal-past-to-fight-climate-change-commentary/

[7] Gutowski WJ, Ullrich PA, Hall A, Leung LR, O’Brien TA, Patricola CM, Arritt RW, Bukovsky MS, Calvin KV, Feng Z, Jones AD. The ongoing need for high-resolution regional climate models: Process understanding and stakeholder information. Bulletin of the American Meteorological Society. 2020 May 1;101(5):E664-83.

[8] Davin EL, de Noblet-Ducoudré N. Climatic impact of global-scale deforestation: Radiative versus nonradiative processes. Journal of Climate. 2010 Jan 1;23(1):97-112.

[9] Lawrence D, Vandecar K. Effects of tropical deforestation on climate and agriculture. Nature climate change. 2015 Jan;5(1):27-36.

[10] Strandberg G, Kjellström E. Climate impacts from afforestation and deforestation in Europe. Earth Interactions. 2019 Feb;23(1):1-27.

[11] Delaney, F. and Milner, G. 2019. The State of Climate Modeling in the Great Lakes Basin – A Synthesis in Support of a Workshop held on June 27, 2019 in Ann Arbor, MI. Toronto, Canada.

[12] Calvin K, Bond-Lamberty B. Integrated human-earth system modeling—state of the science and future directions. Environmental Research Letters. 2018 Jun 11;13(6):063006.

[13] Devanand, Anjana, et al. “Land Use and Land Cover Change Strongly Modulates Land‐Atmosphere Coupling and Warm‐Season Precipitation Over the Central United States in CESM2‐VR.” Journal of Advances in Modeling Earth Systems 12.9 (2020): e2019MS001925.

[14] Sun Q, Lu C, Guo H, Yan L, He X, Qin T, Wu C, Luan Q, Zhang B, Li Z. Study on Hydrologic Effects of Land Use Change Using a Distributed Hydrologic Model in the Dynamic Land Use Mode. Water. 2021 Jan;13(4):447.

[Mahmood 2014] Mahmood R, Pielke Sr RA, Hubbard KG, Niyogi D, Dirmeyer PA, McAlpine C, Carleton AM, Hale R, Gameda S, Beltrán‐Przekurat A, Baker B. Land cover changes and their biogeophysical effects on climate. International Journal of Climatology. 2014 Mar;34(4):929-53.

[Pielke 2016]  Pielke RA, Mahmood R, McAlpine C. Land’s complex role in climate change. Phys. Today. 2016 Nov 1;69(11):40