Christoph Domenig

Around 75% of global anthropogenic greenhouse gas emissions are related to energy use in industry, buildings and transportation. In comparison, the 18.4% attributable to agriculture, forestry and land use seem meagre . In spite of this fact, it is nevertheless of utmost importance to concentrate our efforts on re-evaluating the way we allocate and cultivate the land on our planet.  Improving land use will not only help mitigate climate change but have many positive spillovers such as improved health and food security, decreased energy use and increased resilience against climate change.

 Conflicting land use and unsustainable practices

We can see that forests and agricultural land make up most of the habitable area on our planet (Figure 1). Their importance extends far beyond their size because plants and soils are the most important natural carbon sources and sinks next to our oceans.

Increasing the supply of agricultural land to feed a growing population has caused aggressive deforestation releasing a third of anthropogenic carbon emissions since 1850 (OECD 2017) and causing massive biodiversity loss. As a consequence of climate change the amount of extreme weather events have increased, which could reduce the earth’s natural carbon sequestration capacities and exacerbate global warming, e.g. increased CO2 release through wildfires and rainforest producing less biomass due to reduced rainfall (Kaushik et al. 2020). These alarming signals call for action, but what can be done?

Figure 1: Global Distribution of Land taken from Ritchie et al. (2020)

Existing land for forestry and agriculture can me managed in a more sustainable way by ensuring an adequate supply of timber and food without water depletion, loss of biodiversity and neglecting the local population. Increasing carbon sequestration in agricultural soil by no-till farming, crop rotation and cover cropping  would have great additional benefits such as increasing yields while at the same time improving soil health and making our food supply more resilient to climate change (Pimentel et al., 2005).

In addition to making our agricultural and forestry practices more sustainable, one could reduce food waste and change to more plant-based diets to free up some of the 77% of agricultural land used for livestock cultivation. This could in turn be used for reforestation, increased crop production to accommodate vegan diets or to install renewable energy sources. Especially in countries where available land is sparse there are conflicting uses between climate mitigation and food production (Van de Ven et al. 2017, Levin et al. 2019). If one opts for planting trees it is still not as easy as it sounds because we need to make sure that the benefit of additional carbon capture is not offset by the increased radiative absorption due to trees’ darker color in comparison to the ground. This is one of the reasons, in addition to higher biodiversity, why tropical regions are generally preferable  to snowy areas for reforestation and afforestation (Bala et. al 2007). Furthermore, we need to make sure that these reforested areas are protected to not reverse their uptake of CO2 in couple of decades. Instead of achieving this by so called “fortress conservation” we should promote social justice by including the local indigenous peoples that depend on these lands and are champions at conservation and biodiversity management (Tauli-Corpuz et al. 2018).

 Urban and Built-up land- the top 1%

Our efforts to reallocate land should not end with crops and forests. Even though built-up land only accounts for 1% of the total habitable land on earth it causes major ecological impacts. Around 55% of the world population lives in urban areas, consumes 75% of final energy and is responsible for 70% of the emissions caused by burning fossil fuels (Ranalder et al. 2021, Galina 2016). In order to tackle these emissions, there is no way around decarbonizing transport, buildings and energy, but if we reshape how we use the area in our cities we can strongly support these efforts. By changing zoning  from suburban single-family homes too more dense forms of housing we will benefit on multiple dimensions. First of all, we will consume less building materials per person causing less construction-related CO2 emissions. Secondly, we will reduce heating requirements for houses and can offer low carbon district heating services. Furthermore, more densely populated areas will increase modes of transportation such as walking or public transportation, reducing emissions, improving health and freeing up extra space from parking lots and roads. This space could be used to plant more trees to reduce local heat islands, help with stormwater runoff and improve air quality. Finally, by creating denser housing areas people living in informal settlements in areas more prone to wildfires or flooding could be relocated to less vulnerable areas (Boland et al. 2021) All of these measures synergize with decarbonization efforts while increasing resilience to climate change but will require the support of local governments to transform zoning and land use regulations.

Conclusion

We will require a complete reevaluation of the way we cultivate and develop our land across all levels of urbanization. The management of agriculture and forestry land in rural areas as well built-up land in cities will need to switch to sustainable practices in the future. This will not only have positive impacts for climate change but also improve local resilience and entail additional co-benefits such as improved health and food security. The power to make these changes lies with local governments who are responsible for designing and implementing laws that concern zoning, public transportation and local energy strategies. Therefore, local planners must consider competing land use interests in their social cost-benefit analyses  before deciding how to allocate land in an efficient and equitable way as these decisions will have a lasting impact on generations to come.

References:

Kaushik, A., Graham, J., Dorheim, K., Kramer, R., Wang, J., & Byrne, B. (2020). The Future of the Carbon Cycle in a Changing Climate.

Boland, B., Charchenko, E., Knupfer, S., & Sahdev, S. (2021).How cities can adapt to climate change. Mc Kinsey Sustainability Report.

Churkina, G. (2016). The Role of Urbanization in the Global Carbon Cycle. Frontiers in Ecology and Evolution, Volume 3.

Pimentel, D., Hepperly, P., Hanson, J., Douds, D., & Seidel, R. (2005). Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems. BioScience, Volume 55, Issue 7, Pages 573–582.

Van de Ven, D., González-Eguino, M. & Arto, I. (2017). Transitions Pathways and Risk Analysis for Climate Change Mitigation and Adaptation Strategies Land-Use Impacts from Renewable Energy Policies.

Bala, G., Caldeira, K., Wickett, M., Phillips, T.J., Lobell, D.B., Delire, C., & Mirin, A. (2007). Combined climate and carbon-cycle effects of large-scale deforestation. PNAS, pp. 6550-6555.

Ritchie, H., Roser, M., & Rosado, P. (2020). CO₂ and Greenhouse Gas Emissions. Published online at OurWorldInData.org.

Levin, K., & Parsons, S. (2019). 7 Things to Know About the IPCC’s Special Report on Climate Change and Land.

OECD (2017). The Governance of Land Use: Policy Highlights.

Ranalder, L., Brommer, M., Busch, H., Couture, T., Gibb, D., Guerra, F., Hansen, T., Nana, J., Reddy, Y., Sawin, J., Seyboth, K. & Sverrisson, F. (2021). Renewables in Cities – 2021 Global Status Report.

Tauli-Corpuz, V., Alcorn, J., & Molnar, A. (2018). Cornered by Protected Areas:Replacing ‘Fortress’ Conservation with Rights-based Approaches Helps Bring Justice for Indigenous Peoples and Local Communities, Reduces Conflict, and Enables Cost-effective Conservation and Climate Action.