MEVE 011: Unit 11 – Mountain and Hill Ecosystems

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 UNIT 11: MOUNTAIN AND HILL ECOSYSTEMS

11.1 Introduction

Mountain and hill ecosystems are unique ecological zones that are highly sensitive to climate variability. They play a critical role in regulating regional and global climate, providing freshwater through glaciers, and supporting rich biodiversity. The Himalayas, Western Ghats, and other hilly regions in India, for instance, serve as both climate regulators and lifelines for river systems. However, these ecosystems are increasingly threatened by rising temperatures, glacier retreat, erratic snowfall, cloudbursts, and biodiversity loss.

11.2 Objectives

After studying this unit, learners will be able to:

·         Understand glacier formation and types.

·         Recognize the link between climate change and glacier melting.

·         Explain the causes and impacts of glacier retreat.

·         Describe cloudburst and glacial lake outburst floods (GLOFs).

·         Analyze the impact of climate change on mountain biodiversity and agriculture.

·         Understand the concepts of timberline and snowline in mountain ecology.

11.3 Glaciers and Their Formation

Glaciers are massive, slow-moving rivers of ice formed from accumulated snow over centuries. They are significant freshwater reservoirs, feeding rivers and sustaining ecosystems downstream.

11.3.1 Components of a Glacier

·         Accumulation zone: Where snow accumulates and compresses into ice.

·         Ablation zone: Where melting, sublimation, or calving causes ice loss.

·         Crevasses: Deep cracks on the glacier surface.

·         Moraine: Rock debris deposited by moving glaciers.

11.3.2 Types of Glaciers

·         Valley Glaciers: Found in mountain valleys (e.g., Gangotri Glacier).

·         Continental Glaciers: Ice sheets that cover vast areas (e.g., Antarctica).

·         Cirque Glaciers: Small glaciers that form in mountain hollows.

11.3.3 Glaciers in the Himalayas

The Himalayas host over 9,500 glaciers, including Gangotri, Siachen, and Zemu. These glaciers are the sources of major Indian rivers like the Ganga, Yamuna, and Brahmaputra.

11.3.4 Ice Ages

Ice ages are long periods of global cooling during which ice sheets expanded significantly. The last Ice Age ended about 11,700 years ago, marking the start of the Holocene.

11.4 Glacier Melting

11.4.1 Glacier Retreat

Glacier retreat is the process of shrinking glacier size due to higher temperatures and reduced snowfall. Many Himalayan glaciers have receded by hundreds of meters over recent decades.

11.4.2 Climate Change and Glacier Melting

Increased global warming has accelerated glacier melting. Rising atmospheric CO₂ levels, black carbon deposits, and heatwaves are major contributors.

11.4.3 Melting of Himalayan Glaciers

Reports show that Himalayan glaciers are melting faster than ever. For example, the Gangotri glacier has retreated over 1.5 kilometers in the last 70 years. This poses risks to water security and biodiversity.

11.4.4 Impact on River Systems

Glaciers act as natural water tanks. Their melting leads to initial surge in river flows, followed by long-term water scarcity. Rivers like Ganga and Indus depend heavily on Himalayan glacial melt.

11.4.5 Impact on Agriculture

Erratic snowfall patterns and reduced water flow disrupt traditional cropping cycles. Mountain farming communities are experiencing delayed planting, poor yields, and food insecurity.

11.5 Cloudburst and Flash Floods

Climate change has increased the frequency of intense, localized rainfall events, known as cloudbursts. These cause flash floods, landslides, and significant loss of life and infrastructure.

11.5.1 Glacial Lake Outburst Floods (GLOFs)

As glaciers melt, they form unstable glacial lakes. GLOFs occur when these lakes suddenly breach, releasing massive water volumes. The Kedarnath disaster (2013) is a recent example of such an event.

11.5.2 Impacts of Cloudbursts and Flash Floods

·         Infrastructure destruction (roads, bridges, homes)

·         Loss of lives and livestock

·         Disruption of livelihoods

·         Soil erosion and landslides

·         Long-term ecological damage

11.6 Biodiversity and Ecosystem Services

Mountain ecosystems host a rich variety of flora and fauna, many of which are endemic and adapted to specific altitudes.

11.6.1 Impacts of Climate Change on Biodiversity

·         Species migration to higher altitudes

·         Habitat fragmentation

·         Loss of pollinators and medicinal plants

·         Decline in snow leopards, red pandas, and mountain goats

11.6.2 Barriers in Migration

Steep slopes, habitat fragmentation, and human settlements act as barriers to species movement, reducing survival and reproduction opportunities.

11.6.3 Extinction of Species

Some species cannot migrate or adapt fast enough and face extinction. For example, certain alpine plants are disappearing as snowlines shift upward.

11.7 Timberline and Snow Line

·         Timberline: The altitude above which trees cannot grow. With warming, timberlines are shifting upward, altering ecosystems.

·         Snow Line: The lowest elevation at which snow remains year-round. Rising snowlines indicate climate warming and reduce freshwater storage.

11.8 Let Us Sum Up

Mountain and hill ecosystems are highly fragile yet essential components of Earth’s biosphere. Glacial retreat, flash floods, and biodiversity loss are all symptoms of climate change in these regions. Protecting these ecosystems requires sustainable tourism, scientific monitoring, afforestation, and local community involvement. These regions not only preserve natural beauty and biodiversity but also sustain the water needs of millions of people across the Indian subcontinent.

 

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