How land use affects climate change

Tue 31 Jan 2017


The interaction between people and land is as old as human evolution. When early hunter-gatherers started to settle down in the Neolithic transition and practise agriculture, they began to change their relationship with land in a major way. Starting with the Holocene, approximately 11,500 years ago, many plants were domesticated for agriculture. These and the associated social and technological changes led to dense human settlements that then paved the way for the formation of early cities. As is evident, even now human interventions transform land, water and local ecologies, and in doing so deeply affect the availability of resources. Over the past half-century or so, it has become clear that these changes have so profoundly modified the earth that a geological transformation to the Anthropocene is now firmly in place.

Land use change lock-in

Land-use change takes place through human activity in several ways. For example, in Indonesia, about 500 sq km of forest area are cleared each year, much of which is replaced with oil palm plantations. Another pattern of changing land use is seen in expanding cities. In many countries, including India, cities are expanding well beyond their formal limits, either along inter-city corridors or in other directions. Various forces shape these patterns of urbanisation, transforming land use from agriculture and forests into industry, residential and commercial buildings and associated infrastructure, and horticulture. Often the contested spaces of peri-urban areas (outside city limits but not quite part of the rural hinterland) become sites from which groundwater is pumped and transported to the city, where new industrial zones are developed, where urban waste is dumped, and where vegetables and other high-value crops are grown for nearby urban centres.

These land-use changes are alarming for climate change because they tell us how deeply locked into semi-permanence they can be, just by proliferating at a rapid pace. Cars are replaced on average every decade or so and new breakthrough vehicle technology may spread and change the fleet in one to two decades. Coal power plants may be replaced every four to five decades. However, cities and urban ‘tissue’ last over 500 years. Urbanising areas grow and expand in different ways, parts of them planned, with other portions of informality containing infrastructure, homes, slums and industries, waterbodies and marshlands.

In India, there are multiple patterns of urban and peri-urban growth resulting in different consequences for each region. For example, whether infrastructure is able to guarantee some degree of equity of access to services in cities varies depending on both history and geography. The suburban trains and excellent network of BEST (Brihanmumbai Electric Supply and Transport Undertaking) buses, for instance, defined Mumbai early on in its growth. But in some cities such as Hyderabad and Bengaluru, expansion and infrastructure development took place primarily outside the core areas with the view to establishing and supporting public sector companies such as HMT, Bharat Electronics Limited, and the Defence Research and Development Organisation, and later Information Technology companies. They also serviced an auto-led transport network and associated land-use change. In fact, Chennai, quite intentionally, set up industrial hubs for automotive and parts suppliers. Gurugram, south of Delhi, is a privatised Mecca for several kinds of industries and has developed into a financial and industrial hub. Similarly, the peri-urban areas of many other cities — New Town in Kolkata, Navi Mumbai, and so on — have each had their own version of sprawl, or vast planned or unplanned spaces, that have together extended a large footprint across India.

Implications

The specific patterns of urban growth of a city and its periphery have implications for poverty, food, water, health, jobs and access to services. A city can, therefore, based on its pattern of growth and expansion, lead to particular lifestyles and circumscribe a quality of life for its many residents.

Interventions like converting agricultural land for housing or industry, filling up ponds and building housing complexes on lake beds, etc. impact ecosystem services and climate adaptation. These especially affect the poor who are largely reliant on ecosystems for their livelihoods. Keeping water in the ground, in tanks and waterbodies is regarded as a precaution for dry spells or irregularity in precipitation. These measures can improve resilience towards the possible effects of climate change.

According to some scientists, unlike carbon dioxide, the greenhouse gas whose effects last for hundreds of years, land cover and land management generate drivers in climate systems that influence local and regional weather patterns. This is largely due to changes in aerosols, carbon, nitrogen and other gases along with the moisture in the air, heat and light. The urban heat island effect is understood readily, but this also affects peri-urban regions of expansion.

This subject clearly requires more research to provide guidance to policymakers. But we already know that protecting waterbodies, conserving groundwater, reducing our ecological footprint and living in more compact communities are good ways to address both climate change mitigation and adaptation, which are about reducing greenhouse gases and preparing to live in a warmer world.

Sujatha Byravan is Principal Research Scientist at the Center for Study of Science, Technology and Policy, Bengaluru.

[source:TheHindu]

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