4.4 Climate change Notes

Introduction

Climate change is a significant and complex issue that impacts various aspects of the environment and human society. This study note will delve into the topic of climate change, focusing on its effects on water, food, and energy supplies, as well as its broader impacts on ecosystems, human health, and vulnerable populations. We will also explore the feedback mechanisms and future projections associated with climate change.

Climate Change & the Water, Energy & Food Nexus

Impact on Water Supplies

Unpredictable Rainfall

Climate change leads to more erratic and unpredictable rainfall patterns, which can cause both floods and droughts. This unpredictability hampers water management efforts and affects the availability of freshwater.

Floods

Increased precipitation in some regions can lead to severe flooding. Floods can contaminate freshwater supplies with pollutants and sediments, reducing water quality.

Droughts

Conversely, other regions may experience prolonged droughts, reducing the availability of water for drinking, agriculture, and industry.

Rising Sea Levels

Rising sea levels, driven by the melting of ice sheets and glaciers, lead to saltwater intrusion into coastal freshwater aquifers, reducing the availability of potable water.

Melting Ice Sheets/Glaciers

The melting of glaciers and ice sheets has reduced freshwater storage by an estimated 3% since 1971. This loss is significant for regions that rely on glacial meltwater for their water supply.

Salinization of Groundwater

Saltwater intrusion due to sea-level rise is increasing salinization of groundwater at a rate of 10% annually, particularly in coastal areas.

Water Quality

Higher water temperatures, coupled with floods and droughts, can degrade water quality, making it unsuitable for consumption and agriculture.

Impact on Food Supply

Crops and Livestock

Increased temperatures and altered rainfall patterns affect crop yields and the availability of water for irrigation and livestock.

Declining Water Quality

Poor water quality can affect crop health and yields, while soil degradation and desertification reduce arable land.

Pests and Diseases

Warmer temperatures expand the geographic range of pests and diseases, further threatening crops and livestock.

Impact on Energy Supply

Biomass for Energy

Fewer trees and vegetation due to climate change mean less biomass for energy production, especially in regions where people rely on fuelwood for heating and cooking.

High-Income Countries

While high-income countries like the USA and Australia also face water shortages, they are less likely to experience severe impacts on food and energy security due to their ability to import resources.

Global Impacts

Changes to Ocean Circulation

Melting ice caps and glaciers increase the freshwater input into oceans, altering ocean circulation patterns. This can affect global climate systems and marine ecosystems.

Impacts in Cold Environments

Melting Permafrost

Approximately 40% of permafrost areas are at risk of degradation, which can release methane, a potent greenhouse gas, into the atmosphere.

Sea Ice Decline

The extent and thickness of Arctic sea ice have declined, threatening the traditional lifestyles of indigenous peoples and ice-dependent animals.

Present and Future Impacts

• Present Impacts: Increased rates of glacial retreat, sea level rise, and permafrost melting.
• Future Impacts: Positive feedback loops, such as methane release from permafrost, further sea level rise, and changes in migratory patterns of birds and animals.

Exposure & Vulnerability

Vulnerable Populations

Certain groups are more vulnerable to the effects of climate change due to factors like location, wealth, age, gender, and education. These include:

• Mothers and babies
• Infants and toddlers
• School-age and older children