HomeSpotlightIs land use change causing climate change?

Is land use change causing climate change?

Here is one global phenomenon that is not going to show any bias based on gender or economic/social status, location or age and is going to impact one and all the same way. Yes, climate change and global warming will impact all of us no matter where we live and how we live. Perhaps this is the pay back period where mother earth will be repaying us for all the atrocities committed by us all these centuries.

Land use changes causing havoc

One of the ways we have been destroying our nature which is eventually resulting in climate change is through various ways in which we use and change land cover. For example, by converting fields to urban areas or clearing forests, can affect every aspect of the water cycle. Land-use changes can alter precipitation patterns and how water is absorbed into the ground, flows into streams and rivers, or floods the land surface, as well as how moisture evaporates back into the air. Changes in any of these aspects of the interconnected water cycle can affect the entire cycle and the availability of freshwater resources.

Cause of carbon emissions

According to IPCC’s Sixth Assessment Report, Climate Change 2021: The Physical Science Basis, land-use change is currently responsible for about 15% of the emissions of carbon dioxide from human activities, leading to global warming, which in turn affects precipitation, evaporation, and plant transpiration. “In addition, higher atmospheric concentrations of carbon dioxide due to human activities can make plants more efficient at retaining water because the stomata do not need to open so widely. Improved land and water management (e.g., reforestation, sustainable irrigation) can also contribute to reducing climate change and adapting to some of its adverse consequences,” says the report.

Cause of urban flooding

Altering land use can modify the exchange of water between the atmosphere, soil and sub-surface. For instance, changes in land cover can affect the ability of soils to soak up surface water (infiltration). Now we all know why most of our cities experience floods after few hours of heavy rains. When soil loses its capacity to soak up water, precipitation that would normally infiltrate and contribute to groundwater reserves will instead overflow, increasing surface water (runoff) and the likelihood of flooding. For example, changing from vegetation to urban cover can cause water to flow rapidly over buildings, roads and driveways and into drains rather than soaking into the ground. Deforestation over wide areas can also directly reduce soil moisture, evaporation and rainfall locally but can also cause regional temperature changes that affect rainfall patterns.

TERI study confirms it

TERI which had conducted recently water sustainability assessment for Gurugram had found out that haphazard and uncontrolled growth in and around the city has had severe repercussions on local ecological systems; wetland and natural vegetation loss, and interruption of natural drainage channels. Gurugram has experienced continuous rapid depletion of water bodies due to alteration in the land topography to maximise real estate development in the city. Buildings have come up right upon low-lying places that once had johads (traditional name for ponds and lakes). TERI had also warned that rapid built up expansion in coming years could put an enormous pressure on land and water resources, which could further alter the resource availability and ecology of the area. Similar situation is seen in other major cities of the country too.

Ground water depletion

Further, its also true that extracting water from the ground and river systems for agriculture, industry and drinking water depletes ground water and can increase surface evaporation because water that was previously in the ground is now in direct contact with the atmosphere, being available for evaporation.

Changing land use can also alter how wet the soil is, influencing how quickly the ground heats up and cools down and the local water cycle. Drier soils evaporate less water into the air but heat up more in the day. This can lead to warmer, more buoyant plumes of air that can promote cloud development and precipitation if there is enough moisture in the air.

Changes in land use can also modify the amount of tiny aerosol particles in the air. For instance, industrial and domestic activities can contribute to aerosol emissions, as do natural environments such as forests or salt lakes. Aerosols cool down global temperature by blocking out sunlight but can also affect the formation of clouds and therefore the occurrence of precipitation.

Vegetation plays an important role in soaking up soil moisture and evaporating water into the air (transpiration) through tiny holes (stomata) that allow the plants to take in carbon dioxide. Some plants are better at retaining water than others, so changes in vegetation can affect how much water infiltrates into the ground, flows into streams and rivers, or is evaporated.

To conclude, there is abundant evidence that changes in land use and land cover alter the water cycle 50 globally, regionally and locally, by changing precipitation, evaporation, flooding, ground water, and the availability of fresh water for a variety of uses. Since all the components of the water cycle are connected (and linked to the carbon cycle), changes in land use trickle down to many other components of the water cycle and climate system.

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