Global Warming | Agriculture Optional Notes for UPSC PDF Download

Global Warming – Impacts

Melting of the ice caps refers to?

The melting of polar ice caps and glaciers will result in a rise in sea levels.

• Thermal Expansion: Additionally, the expansion of seawater due to increasing temperatures contributes to the rising sea levels.
• Agricultural Consequences: This phenomenon will lead to the submersion of productive coastal farmlands, and the infiltration of salty water will negatively impact the adjacent land. It will also render groundwater in these areas ineffective.
• Urban Areas: Major cities located along the coastlines will become submerged under the sea.
• Climate Extremes: The country will face disastrous outcomes, including flooding in the Himalayas and Ganga plains during the wet season, as well as severe droughts during the dry season.
• Arable Land Changes: Simultaneously, the quantity of farmable land in high-latitude regions is expected to grow due to the melting of snow and the reduction of frozen areas. However, the availability of arable land along the coastlines will decrease due to rising sea levels and saltwater inundation.

Extreme Climatic Events

• The heightened probability of severe occurrences like heatwaves, floods, hurricanes, and similar events will nullify any economic benefits. 
• Alterations in precipitation trends, as exemplified by the 2015 Chennai floods and the 2018 Kerala floods, will have a profound effect on agriculture.

Environmental Degradation

• The abnormal behavior of glaciers, leading to a decrease in hydroelectric power generation, will result in a greater dependence on fossil fuels. 
• The loss of habitat causing the extensive extinction of animal populations will contribute to the growing numbers of species classified as 'threatened' or 'extinct.'

What are the Rising Health-Related Issues?

• Emerging health concerns include heightened strain on the healthcare industry due to the proliferation of diseases, such as malaria, in tropical regions. 
• The more frequent and intense occurrence of heatwaves and other extreme weather events is projected to raise mortality rates. 
• Additionally, challenges related to water scarcity during droughts and the pollution of freshwater sources during floods threaten sanitation and contribute to the higher incidence of illnesses like cholera and diarrhea.

How Biodiversity Loss occurred?

Biodiversity decline has occurred through various means:

• The decrease in plankton caused by rising sea levels will negatively affect the marine ecosystem's food chain.
• Extensive coral reef bleaching, known as the "ocean rainforests," will lead to a significant reduction in marine biodiversity.
• Escalating temperatures will demand increased fertilizer usage to meet production targets, resulting in higher greenhouse gas emissions, ammonia release, and elevated crop production expenses.
• Increasing temperatures will exert a more pronounced influence on the physical, chemical, and biological characteristics of freshwater lakes and rivers, posing a significant threat to numerous individual freshwater species.

No Food Security

• Crops are affected by climate change through changes in factors like irrigation, sunlight exposure, and the prevalence of pests.
• There's a likelihood of increased variability in agricultural production due to the rising frequency of droughts, floods, storms, and cyclones.
• While crop yields in moderate climates may see improvements from modest warming (an increase of 1 to 3°C in average temperature), crops in tropical regions are expected to suffer.
• Nevertheless, the advantages in temperate regions might be outweighed by the natural disasters caused by global warming.
• Rising sea levels will worsen water resource limitations in coastal areas due to the increased salinity of groundwater supplies.

Degradation of Carbon Sinks

• Carbon storage in high-latitude forests surpasses that of tropical rainforests.
• Taiga and tundra regions hold one-third of the world's soil-based carbon.
• The thawing of permafrost, driven by global warming, results in the release of carbon in the form of carbon dioxide and methane.
• While the tundra used to absorb carbon in the 1970s, it now emits carbon due to global warming, creating a feedback loop that exacerbates global warming.

Sea Level Change

Sea level change refers to the long-term variations in the average sea level.

Processes Influencing Sea Level Changes

• Eustatic variations occur when the quantity of seawater undergoes alterations due to factors such as global warming and the melting of ice sheets (leading to rising sea levels) or during ice ages (causing a decrease in sea levels), as well as shifts in the volume of mid-oceanic ridges.
• Tectonic alterations are the result of changes in land elevation.
  • Isostatic adjustments happen due to the addition or removal of a load. During ice ages, the landmass depresses under the weight of glacial ice, but it rises as the ice melts.
  • Epeirogenic movement is triggered by the extensive tilting of continents, where one part may rise while another part sinks, creating the illusion of sea level changes.
  • Orogenic movement, which involves the formation of towering mountain ranges, leads to an apparent reduction in sea level.

Importance of understanding Sea Level Changes

It provides key evidence regarding climate change in the past. It helps in estimating the rates of tectonic upliftment in the past geological periods.

• To determine whether coastal areas are suitable for industrial and agricultural development.
• To protect low-lying countries by building coastal dykes and embankments.
• Only when we are aware of the areas that will likely be affected by future sea level rise can we map the areas that will likely experience storm surges and intermittent flooding.
• It becomes possible to build tidal power generation facilities in suitable locations by identifying the areas that may soon be submerged.

Global sea level experiences both short-term and long-term changes

Short Term: Short-term variations occur within a year and are typically in the range of 5-6 cm, often influenced by factors such as:

• Marine water density, which is influenced by temperature and salinity. Colder and saltier water results in higher density and lower sea levels.
• Atmospheric pressure, with low pressure causing local sea level increases, as seen in storm surges.
• Ocean currents, particularly fast-moving ones, causing sea level variations along their curved paths.
• Ice formation and seasonal changes, which can lead to sea level drops as water gets trapped in polar ice caps.
• Wind-driven water piling up along windward coasts due to air masses pushing water toward the shore.

In the 20th century, short-term sea level rise occurred due to:

• Thermal expansion of ocean water resulting from anthropogenic global warming, contributing to a 10-15 cm increase in sea level over the past century.
• Partial melting of Antarctica's ice sheets (about 3% of the world's total ice mass).
• The melting of approximately 15% of Greenland's ice cap.
• Other glaciers around the world, which collectively contributed about 48% of the global sea level rise.

Long Term
Long-term changes in sea level of more than 100 meters can only occur if major ice sheets melt or if there are significant alterations in the volume of the world's mid-oceanic ridge.

A decline in sea level has several consequences

• Coral reefs can die when the sea level falls because the areas where they typically grow, like continental shelves, become exposed to the air. However, in these areas where the old coral reefs perish, new coral reefs tend to form along their edges.
• The reduction in sea level leads to increased aridity in regions with shallow continental shelves because there is less surface runoff, negatively affecting the land's moisture.
• In temperate and high-latitude regions, a drop in sea level causes ice caps and glacial tongues to extend outward onto the continental shelves.

Impact of possible rise in sea level

The potential rise in sea levels due to further increases in atmospheric temperature could have significant and dire consequences:

• Low-lying coastal regions with dense populations, which constitute a substantial portion of inhabited land, would be inundated, leading to the submergence of even small islands.
• The estimated one billion people living on Earth would be directly affected by rising sea levels.
• Coastal infrastructure like ports and industrial facilities could experience severe damage.
• About one-third of the world's croplands, including fertile coastal plains and deltas, might be submerged, causing a significant agricultural impact.
• Accelerated coastal erosion could result in the degradation and destruction of beaches, coastal dunes, and bars, leaving a large portion of coastal land vulnerable to direct sea wave impacts.
• Groundwater resources in coastal areas would be at risk of salinization due to the intrusion of marine water.
• The destruction of reefs, coral atolls, and deltas would harm ecosystems, although new coral reefs might develop on the periphery of the affected areas.
• The mouths of river drainage basins would be submerged, necessitating adjustments to the river's long profiles and potentially causing a rise in their levels.

Recent sea level rises have had the most significant impact on islands, with the Carteret Islands in the Pacific Ocean and the Tuvalu Islands in the South Pacific being notable examples. The United Nations Environment Programme (UNEP) established the "Oceans and Coastal Areas Programme Activity Centre" in 1987 to investigate sea level rise and assess the nations most vulnerable to submersion.

• Efforts to combat climate change by reducing carbon emissions from burning coal are essential:
• Coal is a major source of electricity generation worldwide, and it will continue to be dominant for years. The burning of coal releases major greenhouse gases, including CO2 and CO (carbon monoxide), as well as harmful pollutants like nitrogen oxides and sulphur oxides.
• Clean coal technology employs various methods to mitigate environmental impacts and reduce emissions. Some techniques involve purifying coal before combustion.
• Coal washing, for example, removes undesirable minerals by mixing crushed coal with a liquid, allowing impurities to separate and settle.
• Other systems control the burning process to minimize emissions of sulphur dioxide, nitrogen oxides, and particulates.
• Electrostatic precipitators capture particulates by charging them with an electrical field and collecting them on plates.
• Gasification offers an alternative to traditional coal burning, where coal is reacted with steam and pressurized air or oxygen to create syngas, which is then cleaned and used to generate electricity in a gas turbine.
• Wet scrubbers, or flue gas desulfurization systems, remove sulphur dioxide, a leading cause of acid rain, by spraying flue gas with a mixture of limestone and water.
• Low-NOx burners minimize nitrogen oxide production, a contributor to ground-level ozone, by controlling oxygen levels and manipulating the combustion process.

Carbon capture and storage

• Carbon capture and storage (CCS) is a process that captures and hides carbon dioxide (CO₂) emissions from stationary sources, such as power plants.
• The process consists of three main steps:
  • Capture: Flue-gas separation is used to extract CO₂ and condense it into a concentrated CO₂ stream.
  • Containment: The collected CO₂ is then stored in secure containers to prevent its release back into the atmosphere.
  • Storage: There are two storage options - geological and oceanic. The CO₂ is stored and kept hidden, with the intention of retaining it for hundreds of years until peak emissions subside.
• Given the increasing levels of atmospheric carbon, there is a growing focus on the potential of soil, plants, and trees to temporarily store the carbon emitted from burning fossil fuels.
• The Kyoto Protocol, a key international agreement aimed at combatting global warming, supports the idea of reducing carbon dioxide emissions from fossil fuels while also allowing trees and soil to absorb and store carbon dioxide as a valid strategy.