YIJC [H2] ETB Impact of Climate Change (N) Part 1 (Vetted)

9744 H2 BIOLOGY LECTURE NOTES | JC 2 Impact of Climate Change on Animals & Plants 1 Extension Topic B: Impact of Climate Change on Animals and Plants Part 1 Learning Outcomes (a) identify and explain the human activities over the last few centuries that have contributed to climate change through accumulation of greenhouse gases (limited to CO2 and methane), including burning of fossil fuels linked to increasing energy usage, clearing of forests and food choices (increasing consumption of meat). (b) Explain the effects of climate change as a result of greenhouse gas emissions, including the melting of polar ice caps, rising sea levels, stress on fresh water supplies, heat waves and heavy rains, death of coral reefs, migration of fishes and insects and release of greenhouse gases in frozen organic matter. (c) explain how climate change affects plant distribution (vertical and latitude) and plant adaptations, including morphology and physiology. (d) discuss the consequences to the global food supply of increased environmental stress resulting from climate change, including the effects on plants and animals of increased temperature and more extreme weather conditions. Lecture Outline 1) Greenhouse Gases & the Greenhouse Effect 1.1 Human activities contributing to increase in greenhouse gas emissions 1.1.1 Combustion of Fossil Fuels (coal, natural gas and oil) 1.1.2 Industrial processes 1.1.3 Reduction in carbon sinks due to deforestation 1.1.4 Increased livestock production due to higher demand for meat and dairy 2) Effects of Climate Change as a result of Greenhouse Gas Emissions 2.1 Melting of Polar Ice Caps 2.2 Rising Sea Levels 2.3 Stress on Fresh Water Supplies 2.4 Heat Waves 2.5 Migration of Fishes and Insects 2.6 Release of Greenhouse HGs in frozen organic matter 3) Effects of Climate Change on Plants 3.1 Changes in Plant Distribution 3.2 Changes in Plant Adaptations 4) Effects of Climate Change on Global Food Supply

2 Learning Outcome (a): Identify and explain the human activities over the last few centuries that have contributed to climate change through accumulation of greenhouse gases (limited to CO2 and methane), including burning of fossil fuels linked to increasing energy usage, clearing of forests and food choices (increasing consumption of meat). 1 GREENHOUSE GASES & THE GREENHOUSE EFFECT A greenhouse gas (GHG) is a gas that both absorbs and emits radiation in the infrared range. When present in the Earth’s atmosphere, these gases trap radiation in the form of heat, leading to a warming process called the greenhouse effect. The greenhouse gases in the Earth’s atmosphere help keep the average temperature of the Earth at 15oC, whereas without the greenhouse effect, the average temperature would be a frosty -18oC. Fig. 1.0.1 Percentage share of greenhouse gases in the earth atmosphere

3 The greenhouse effect is a natural process by which heat radiated from Earth’s surface is trapped by greenhouse gases. With more greenhouse gases in the air, more heat is trapped in the Earth’s atmosphere, resulting in a warmer Earth. Fig. 1.0.2 Greenhouse effect leading to warming of Earth’s surface Global Warming Potential (GWP) is a measure of how much heat a substance can trap in the atmosphere over a period of 100 years, as compared to an equivalent amount of CO2. GWP is used to compare the global warming impact of different greenhouse gases. The larger the GWP, the greater the warming effect exerted by that gas compared to CO2 in the same time period. Fig. 1.0.3 Global Warming Potential of Greenhouse Gases While carbon dioxide is more abundant and longer-lived, methane is far more effective at trapping heat while it lasts. Over the first two decades after its release, methane is more than 80 times more potent than carbon dioxide in terms of warming the climate system.

4 1.1 Human activities contributing to increase in greenhouse gas emissions Greenhouse gas emissions due to human activities (e.g. industrialisation and development) have increased since the pre-industrial era, driven largely by population and economic growth . This has resulted in greenhouse gases reaching unprecedented levels in over the past centuries. Fig. 1.1 Trends in concentrations of greenhouse gases over the years The increase in greenhouse gas emissions is correlated with – and likely to be the main cause of – the increasing trend of Earth’s surface temperature over the past years. Fig. 1.2 Graphs of CO2 concentration and change in average temperature

5 There are many human activities which contribute to increased emission of greenhouse gases. Burning of fossil fuels for electricity, transportation and industry , as well as in agriculture, contribute to the bulk of greenhouse gas emissions. Fig. 1.3 Global Greenhouse gas emissions by sector for the year 2016 1.1.1 Combustion of Fossil Fuels (coal, natural gas and oil) • To generate electricity to power lighting, appliances, and heating in commercial and residential buildings • To power t ransportation e.g. road transport, aviation, shipping, rail and pipelines transporting fuel and commodities e.g. oil, gas, water or steam Note: Mining of fossil fuels e.g. coal mining releases methane (CH4) 1.1.2 Industrial processes • Production of mineral products e.g. cement for construction • Production of metals e.g. iron and steel • Production of chemicals e.g. ammonia for use in water purification

6 1.1.3 Reduction in carbon sinks due to deforestation • Trees convert CO2 in the air to O2 through the process of photosynthesis. The more trees, the less CO2 in the atmosphere and the more O2. • Some of the CO2 absorbed by plants is stored as organic matter throughout their lifetime. Soils can also store CO2, depending on how the soil is managed. This storage of carbon in plants and soils is called biological carbon sequestration . Since biological sequestration takes CO2 out of the atmosphere, it is also called a carbon “sink”. • Humans carry out deforestation t o provide land for agricultural expansion e.g. to grow crops, raising livestock or producing bio-fuels for export, as well as to provide timber for domestic fuel or charcoal . Deforestation contributes to increasing carbon dioxide emissions in two ways: o Burning or decomposition of wood releases carbon dioxide o Absence of trees to absorb carbon dioxide from the atmosphere Fig. 1.4 Carbon storage in Earth’s ecosystems 1.1.4 Increased livestock production due to higher demand for meat and dairy

7 • With economic development, industrial style agriculture replaced traditional small -scale farming. The increased efficiency of industrial agriculture has also led to reduced prices for many of our daily products. It helped to nourish large populations, and turned a food that was an occasional meal – meat – into an affordable, everyday product for many. • The growth in per capita meat consumption is strongly linked to increasing levels of income in many countries of the world. Fig. 1.5 Graph of per capita meat consumption vs per capita income • Coupled with global human population growth, global meat consumption also increased. Fig. 1.6 Global meat production increases over the years as global human population increases • Increase in populations of ruminants e.g. cows, goats and sheep.

8 o Ruminants produce methane as part of their normal digestive process and release methane through belching or as flatulence o Decomposition of animal manure under anaerobic conditions release methane o Increased production of feed resulted in an increase in consumption of energy supplied from burning of fossil fuels Fig. 1.7 Livestock-based methane emissions

9 Learning Outcome (b): Explain the effects of climate change as a result of greenhouse gas emi