Human activities, especially large-scale agriculture and forestry, have significantly altered the Earth's surface, the composition of the atmosphere, and consequently the climate. These activities continue to alter the Earth's energy balance through changes in greenhouse gas fluxes and changes in the albedo of the Earth's surface. For example, between 2007 and 2016, agriculture, forestry and other land use contributed 23 % of the total anthropogenic radiative forcing caused by greenhouse gases.

Historical deforestation of a particular ecoregion in the Upper Midwest of the United States caused net global warming (1626 ± 44 µWm-²). This effect was mainly due to 76 % by reducing carbon stocks in ecosystems, but also 84 % by reducing the soil methane sink and 115 % by increasing soil nitrous oxide emissions. The increase in albedo associated with deforestation, due to more reflective agricultural vegetation and the absence of trees that previously covered the snow, offset 24 % of this warming caused by greenhouse gases.

Given this impact of land use on the global climate, it is proposed to adopt sustainable land use practices as nature-based climate solutions (NBCS)These solutions have the potential to remove carbon dioxide from the atmosphere, making them a key tool for reversing the effects of climate change.

Study examined the climate impacts of eight different NBCSs in the US Upper Midwest. These solutions included three types of conservation agriculture (no-tillage, reduced-input, organic), three types of perennial crops/forestry (alfalfa, poplar plantation, pine plantation), and two types of ecosystem restoration (early and mid-successional). The reference condition was conventional agriculture (corn-soybean-winter wheat).

The radiative forcing of NBCS over 100 years was largely influenced by changes in carbon stocks in ecosystems. Conservation agriculture resulted in soil carbon sequestration ranging from 4.5 to 7.1 Mg C ha⁻¹ during the first ~25 years. At perennial crops/forestry Both soil carbon sequestration (8.1 to 10.6 Mg C ha⁻¹) and carbon accumulation in woody biomass (0.0 to 48.7 Mg C ha⁻¹) contributed to the negative radiative forcing. Ecosystem restoration also relied on increases in soil and woody biomass carbon. The natural forest regeneration scenario (middle succession stage) was able to store the largest amount of carbon in woody biomass (70.4 ± 1.6 Mg C ha⁻¹).

Another important factor was albedo of the Earth's surfaceConventional and conservation agriculture, as well as alfalfa, had the highest outgoing shortwave radiation at the top of the atmosphere. Forest plantations and ecosystem restoration scenarios had lower outgoing shortwave radiation due to darker vegetation and taller growth that prevented reflection from snow in winter. Nitrous oxide emissions from soil were another component, with some conservation agriculture scenarios having surprisingly higher emissions than conventional agriculture, while forest and early successional scenarios had the lowest emissions. Sink soil methane had the least impact, with intact forest (late successional stage) having a strong sink that was significantly weakened after conversion to agricultural land; only pine plantation and mid-successional stage restored most of this capacity.

By summarizing all components of radiation exposure, it was found that various NBCS bring clear trade-offs for climate, nature, and society. Conservation agriculture provided the least climate mitigation (-39 to -76 ± 31 µWm⁻²). Perennial crop plantations provided greater mitigation (-147 to -881 ± 44 µWm⁻²). Scenario early stage of succession (with regular burning) led to net global warming (69 ± 31 µWm⁻²) due to albedo effects and methane emissions from combustion, which offset carbon sequestration. The biggest climate mitigation provided a natural forest regeneration scenario (middle stage of succession) with -1555 ± 44 µWm⁻².

When making land use decisions, it is important to consider these climate mitigation potentials along with other factors such as the provision of food, fiber, and habitat for plants and animalsWhile conservation agriculture provides little habitat for native species, perennial crops and forestry provide limited habitat, and ecosystem restoration and natural forest regeneration scenarios support more diverse communities. Integrating NBCS into existing agricultural landscapes could be a significant step toward offsetting the climate debt from past deforestation in the region. Spring

A study published in the journal nature.com