Desert Greening Reduces Land Surface Temperature by 4°C

Deserts cover about one-third of the Earth's land surface, but they are not barren wastelands. They are home to diverse flora and fauna, and they play important roles in the global climate and water cycle.

However, deserts are also facing serious threats from human activities, such as overgrazing, deforestation, mining, and urbanization.

These activities can lead to desertification, which is the degradation of land in arid and semi-arid regions.

Desertification can have negative impacts on the environment, such as reducing soil quality, biodiversity, and carbon storage, and increasing dust storms, erosion, and droughts.

How desert greening can affect the global climate and water cycle

(Photo : Mario Tama/Getty Images)

Desert greening is the process of transforming arid and semi-arid lands into more productive and sustainable ecosystems.

It can be achieved by various methods, such as planting trees, restoring soil fertility, harvesting rainwater, and using renewable energy sources.

Desert greening has many potential benefits, such as improving food security, biodiversity, livelihoods, and carbon sequestration.

However, it also has some unintended consequences, such as altering the regional and global climate and water cycle.

Researchers from the University of California, Irvine, and the University of Exeter have developed a new framework to measure the impact of desert greening on the Earth system.

They used satellite data, climate models, and hydrological models to quantify the changes in land surface properties, atmospheric circulation, precipitation, and river runoff caused by desert greening.

They applied their framework to three regions: the Sahara, the Arabian Peninsula, and the Australian Outback.

Desert greening can increase rainfall and vegetation in some regions, but reduce them in others

The researchers found that desert greening can have different effects on the climate and water cycle depending on the location, extent, and type of greening.

For example, greening the Sahara can increase the rainfall and vegetation in the region, as well as in the neighboring Sahel and Mediterranean.

This is because the increased vegetation can enhance the surface roughness, evapotranspiration, and moisture convergence, which can trigger more convection and precipitation.

However, greening the Arabian Peninsula can reduce the rainfall and vegetation in the region, as well as in the Horn of Africa and India.

This is because the increased vegetation can reduce the surface albedo, which can weaken the land-sea thermal contrast and the monsoon circulation, which can reduce moisture transport and precipitation.

Similarly, greening the Australian Outback can decrease the rainfall and vegetation in the region, as well as in Southeast Asia and the Pacific Islands.

This is because the increased vegetation can reduce the surface temperature gradient, which can alter the Walker circulation and the El Niño-Southern Oscillation, which can affect the rainfall patterns.

Also Read: Dryland Ecosystems Drivers of Global Carbon Cycle

Desert greening can affect the global water cycle and carbon cycle

The researchers also found that desert greening can have significant impacts on the global water cycle and carbon cycle.

They estimated that greening the Sahara can increase the global terrestrial evapotranspiration by 7.5%, the global terrestrial precipitation by 1.7%, and the global terrestrial net primary productivity by 12.4%.

On the other hand, greening the Arabian Peninsula can decrease the global terrestrial evapotranspiration by 1.8%, the global terrestrial precipitation by 0.6%, and the global terrestrial net primary productivity by 2.4%.

Likewise, greening the Australian Outback can reduce the global terrestrial evapotranspiration by 1.4%, the global terrestrial precipitation by 0.4%, and the global terrestrial net primary productivity by 1.9%.

These changes can have important implications for the global carbon budget, water resources, and ecosystem services.

Desert greening requires careful planning and monitoring

The researchers concluded that desert greening is not a simple solution to combat desertification and climate change, but a complex intervention that can have diverse and far-reaching consequences.

They suggested that desert greening projects should be carefully planned and monitored, taking into account the local and global effects, the trade-offs and synergies, and the uncertainties and risks.

They also recommended that desert greening should be integrated with other adaptation and mitigation strategies, such as reducing greenhouse gas emissions, enhancing water efficiency, and promoting sustainable development.

They hoped that their framework could provide a useful tool for assessing the impact of desert greening and informing decision-making.

Related article: Africa's 'Great Green Wall' May Have Profound Effects on Climate Change