COM203 — Man and the Environment: Lecture Note

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la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course code: COM 203 Course title: Man and the Environment Course credit load: 1 Unit Series 1: Climate Change • Part 1.1: The Climate System and Climate Change o Sub Part 1.1.1: Defining weather, climate, and the climate system o Sub Part 1.1.2: The greenhouse effect and global warming o Sub Part 1.1.3: Evidence and causes of contemporary climate change • Part 1.2: Consequences of Climate Change o Sub Part 1.2.1: Physical consequences: temperature, sea level, and extreme events o Sub Part 1.2.2: Ecological and agricultural consequences o Sub Part 1.2.3: Human health consequences of climate change • Part 1.3: Responses to Climate Change o Sub Part 1.3.1: Mitigation: reducing greenhouse gas emissions o Sub Part 1.3.2: Adaptation: adjusting to climate change impacts o Sub Part 1.3.3: Climate change, Nigeria, and global climate governance

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction Climate change is the defining environmental challenge of the twenty-first century, representing a fundamental alteration in the physical conditions that have underpinned human civilisation for the past ten thousand years; the global average surface temperature has risen by approximately 1.1 degrees Celsius above pre-industrial levels, driven primarily by human emissions of greenhouse gases from fossil fuel combustion, deforestation, and agriculture; this seemingly small change in average temperature is producing cascading consequences across every dimension of the Earth system, from the melting of polar ice sheets and the rising of sea levels to the intensification of extreme weather events, the disruption of agricultural systems, the spread of infectious diseases into new geographic ranges, and the displacement of millions of people from their homes. For students of Man and the Environment, climate change is not an abstract geophysical phenomenon but a profoundly human and social process: it is caused by human activities, its consequences are distributed unequally across populations (with the poorest and most vulnerable bearing the greatest burden despite contributing least to the problem), and its solutions require fundamental changes in human behaviour, technology, economics, and governance; this Series examines the science of climate change, its multiple consequences including its health impacts, and the range of responses available at individual, national, and global levels, with particular attention to the Nigerian context. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 explain the greenhouse effect, define climate change, and describe the scientific evidence for contemporary human-induced climate change, • SLO 1.2 describe the physical, ecological, agricultural, and human health consequences of climate change, and

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS • SLO 1.3 distinguish between mitigation and adaptation as responses to climate change and describe Nigeria involvement in global climate governance. 1.1 The Climate System and Climate Change 1.1.1 Defining weather, climate, and the climate system Weather refers to the short-term atmospheric conditions at a specific location at a particular time, including temperature, precipitation, wind speed and direction, humidity, and cloud cover; weather is inherently variable and changes from hour to hour and day to day; climate, by contrast, refers to the long-term average pattern of weather conditions in a region, typically measured over a thirty-year reference period and characterised by statistical summaries of temperature, precipitation, and other atmospheric variables; the distinction is fundamental: a single unusually hot day is a weather event, but a sustained increase in average summer temperatures over decades is a climate signal; the common confusion between weather and climate underlies much public misunderstanding of climate change, as people sometimes cite cold weather as evidence against global warming without recognising that local short-term weather variability is entirely consistent with long-term global warming trends. The climate system is the complex, interactive system consisting of five major components: the atmosphere (the gaseous envelope surrounding the Earth, which is the most rapidly responding component of the climate system and the medium through which most climate change signals propagate), the hydrosphere (all liquid water on and beneath the Earth surface, including oceans, lakes, rivers, and groundwater; the oceans cover 71 percent of the Earth surface and absorb approximately 90 percent of the excess heat generated by the enhanced greenhouse effect), the cryosphere (all frozen water including polar ice sheets, glaciers, sea ice, and permafrost, which plays a critical role in reflecting solar radiation and regulating global temperature through the ice-albedo feedback), the lithosphere (the solid Earth surface, including soils and rocks, which stores and releases carbon and influences climate through weathering and volcanic activity), and the biosphere (all living organisms, which influence climate through carbon storage in forests

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS and vegetation, water cycling through transpiration, and the production and absorption of greenhouse gases). Fill in the blank: The climate system has five major components: the atmosphere, the ________ (all liquid water on and beneath the Earth surface including the oceans), the cryosphere, the lithosphere, and the biosphere. 1.1.2 The greenhouse effect and global warming The greenhouse effect is the natural process by which certain gases in the Earth atmosphere trap outgoing infrared radiation (heat) from the Earth surface and re-radiate it back toward the surface, maintaining the planet at a temperature warm enough to support life; without the natural greenhouse effect, the Earth average surface temperature would be approximately minus 18 degrees Celsius rather than the current plus 15 degrees Celsius; the principal natural greenhouse gases are water vapour (the most abundant and powerful, responsible for approximately half of the natural greenhouse effect), carbon dioxide (CO2, released by respiration and decomposition), methane (CH4, produced by wetlands, termites, and other natural sources), and nitrous oxide (N2O, released from soils and oceans). The enhanced or anthropogenic greenhouse effect refers to the intensification of the natural greenhouse effect caused by human activities that have substantially increased the atmospheric concentration of greenhouse gases; since the beginning of the industrial revolution around 1750, the atmospheric concentration of carbon dioxide has increased from approximately 280 parts per million (ppm) to over 420 ppm, the highest level in at least 800,000 years; this increase is due primarily to the combustion of fossil fuels (coal, oil, and natural gas, which together account for approximately 75 percent of global greenhouse gas emissions), deforestation (which releases the carbon stored in forest biomass and reduces the capacity of forests to absorb CO2), and agricultural practices including livestock production (which produces large quantities of methane from enteric fermentation and manure management) and rice cultivation (which produces methane from flooded paddies).

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Fill in the blank: Without the natural greenhouse effect, the Earth average surface temperature would be approximately minus 18 degrees Celsius; with it, the average temperature is approximately plus ________ degrees Celsius, warm enough to support life as we know it. 1.1.3 Evidence and causes of contemporary climate change The scientific evidence for contemporary human-induced climate change is overwhelming and draws from multiple independent lines of inquiry: direct measurements of atmospheric CO2 concentrations at the Mauna Loa Observatory in Hawaii (the Keeling Curve) show an unbroken rising trend from 315 ppm in 1958 to over 420 ppm today; global surface temperature records maintained by multiple independent research groups (NASA, NOAA, the UK Met Office, and others) show a warming trend of approximately 1.1 degrees Celsius above pre-industrial levels, with the ten warmest years on record all occurring since 2010; satellite measurements show that Arctic sea ice extent has declined by approximately 13 percent per decade since records began in 1979; global sea level has risen by approximately 20 centimetres since 1900, with the rate of rise accelerating; and ice core records from Greenland and Antarctica reveal the direct correlation between greenhouse gas concentrations and global temperature over the past 800,000 years. Attribution science, the field that determines the extent to which specific climate events or trends can be attributed to human activities versus natural variability, has advanced substantially in recent decades; the Intergovernmental Panel on Climate Change (IPCC), the scientific body established by the United Nations to assess the state of climate science, concluded in its Sixth Assessment Report (2021) that it is unequivocal that human influence has warmed the atmosphere, ocean, and land, and that widespread and rapid changes in the atmosphere, ocean, cryosphere, and biosphere have occurred; the major natural factors that influence climate (solar variability and volcanic activity) cannot explain the observed warming trend, which is consistent only with the addition of greenhouse gases from human activities; 97 percent or more of actively publishing climate scientists agree that contemporary climate change is primarily human-caused. Fill in the blank: The Intergovernmental Panel on ________ Change (IPCC), established by the United Nations, concluded in its 2021 Sixth Assessment Report that it is unequivocal that human influence has warmed the atmosphere, ocean, and land.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.1:

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