🌈Earth Systems Science Unit 12 – Climate Change & Air Pollution Impacts

Key Concepts and Definitions

• Climate change refers to long-term shifts in global or regional climate patterns, primarily due to increased levels of atmospheric carbon dioxide produced by the use of fossil fuels
• Greenhouse gases (GHGs) trap heat in the atmosphere, leading to global warming (carbon dioxide, methane, nitrous oxide, water vapor)
• Global warming potential (GWP) measures the relative radiative effect of a given substance compared to carbon dioxide over a specified time period (usually 100 years)
• Radiative forcing quantifies the difference between solar irradiance (sunlight) absorbed by the Earth and energy radiated back to space
• Albedo is the measure of the reflectivity of a surface (snow and ice have high albedo, while oceans and forests have low albedo)
• Anthropogenic emissions originate from human activities (burning fossil fuels, deforestation, agriculture)
• Carbon cycle describes the exchange of carbon among the atmosphere, oceans, terrestrial biosphere, and geological deposits
  • Includes processes such as photosynthesis, respiration, decomposition, and weathering

Climate Change Basics

• Earth's climate has changed throughout history due to natural factors (variations in solar activity, volcanic eruptions, changes in Earth's orbit)
• However, the current warming trend is of particular significance because it is extremely likely (greater than 95% probability) to be the result of human activity since the mid-20th century
• The primary driver of climate change is the greenhouse effect, which occurs when GHGs trap heat in the atmosphere
• The concentration of atmospheric carbon dioxide has increased by more than 40% since pre-industrial times, primarily due to fossil fuel emissions and secondarily from net land use change emissions
• Global surface temperature has risen about 1.62°F (0.9°C) since the late 19th century, with most of the warming occurring in the past 35 years
• Oceans have absorbed much of this increased heat, leading to rising sea levels due to thermal expansion and melting land ice (glaciers and ice sheets)
• Climate change impacts various Earth systems (hydrosphere, cryosphere, biosphere) and can lead to more frequent and intense extreme weather events (heatwaves, droughts, hurricanes)

Major Air Pollutants

• Particulate matter (PM) consists of tiny particles of solid or liquid suspended in the air (dust, soot, smoke)
  • PM2.5 refers to fine inhalable particles with diameters 2.5 micrometers and smaller
  • PM10 includes inhalable particles with diameters 10 micrometers and smaller
• Sulfur dioxide (SO2) is a colorless, reactive gas produced by burning sulfur-containing fuels (coal, oil) and industrial processes (metal smelting)
• Nitrogen oxides (NOx) are highly reactive gases formed during combustion processes (vehicle emissions, power plants)
  • Include nitric oxide (NO) and nitrogen dioxide (NO2)
• Ground-level ozone (O3) is a secondary pollutant formed when NOx and volatile organic compounds (VOCs) react in the presence of sunlight
  • Ozone in the stratosphere is beneficial as it absorbs harmful ultraviolet (UV) radiation
• Carbon monoxide (CO) is a colorless, odorless gas produced by incomplete combustion of carbon-containing fuels (vehicle exhaust, industrial processes)
• Lead (Pb) is a toxic heavy metal that can be released into the air from industrial sources (metal processing) and leaded gasoline (now banned in many countries)
• Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids and can have short- and long-term adverse health effects (benzene, formaldehyde)

Sources of Emissions

• Transportation sector contributes significantly to air pollution and GHG emissions (cars, trucks, ships, airplanes)
  • Burning of fossil fuels in internal combustion engines releases CO2, NOx, PM, and VOCs
• Electricity generation from coal-fired power plants emits CO2, SO2, NOx, and PM
  • Natural gas power plants emit less CO2 and negligible amounts of SO2 and PM compared to coal
• Industrial processes (manufacturing, mining, oil and gas extraction) can release a variety of pollutants (PM, SO2, NOx, VOCs, heavy metals)
• Agricultural activities contribute to air pollution and GHG emissions (livestock farming, fertilizer use, rice cultivation)
  • Livestock farming releases methane (CH4) from enteric fermentation and manure management
  • Fertilizer application emits nitrous oxide (N2O) from microbial processes in the soil
• Waste management practices (landfills, wastewater treatment) can emit methane and other GHGs
• Residential and commercial buildings contribute to emissions through energy use for heating, cooling, and electricity consumption
• Deforestation and land use changes release stored carbon into the atmosphere and reduce carbon sequestration capacity

Environmental Impacts

• Climate change leads to rising sea levels due to thermal expansion of oceans and melting of land ice (glaciers, ice sheets)
  • Threatens coastal communities and infrastructure, increases risk of flooding and erosion
• Warmer temperatures alter precipitation patterns, leading to more frequent and intense droughts in some regions and heavy rainfall and flooding in others
• Ocean acidification occurs as oceans absorb excess atmospheric CO2, lowering the pH of seawater
  • Negatively impacts marine ecosystems, particularly shell-forming organisms (corals, mollusks)
• Biodiversity loss and ecosystem degradation result from changing climate patterns, habitat loss, and species migration
  • Some species may adapt or shift their ranges, while others face increased risk of extinction
• Air pollution can lead to acid rain when SO2 and NOx react with water and oxygen in the atmosphere
  • Acid rain damages forests, crops, and aquatic ecosystems, and accelerates the deterioration of buildings and monuments
• Ground-level ozone and PM can harm vegetation by reducing photosynthesis and growth rates
  • Ozone damage to crops can lead to reduced agricultural yields
• Deposition of nitrogen and sulfur compounds from air pollution can lead to eutrophication of water bodies
  • Excess nutrients stimulate algal blooms, depleting oxygen levels and creating "dead zones" in aquatic ecosystems

Human Health Effects

• Air pollution exposure is linked to respiratory diseases (asthma, chronic obstructive pulmonary disease)
  • PM and ozone can irritate the airways, aggravate existing conditions, and reduce lung function
• Cardiovascular diseases (heart attacks, strokes) are associated with long-term exposure to PM and other pollutants
  • PM can enter the bloodstream and cause inflammation, increasing the risk of blood clots and atherosclerosis
• Certain air pollutants (PM, ozone, NO2) can exacerbate allergies and increase the risk of respiratory infections
• Exposure to air pollution during pregnancy has been linked to adverse birth outcomes (low birth weight, preterm delivery)
• Long-term exposure to air pollution may contribute to the development of neurodegenerative diseases (Alzheimer's, Parkinson's)
• Climate change can impact human health through various pathways (heat stress, vector-borne diseases, food and water insecurity)
  • Warmer temperatures can lead to heat-related illnesses (heat exhaustion, heat stroke) and increase the risk of cardiovascular and respiratory mortality
  • Changing climate patterns can alter the distribution and transmission of vector-borne diseases (malaria, dengue fever)

Measurement and Monitoring

• Air quality monitoring networks measure concentrations of criteria pollutants (PM, SO2, NO2, O3, CO, Pb)
  • Data is used to assess compliance with air quality standards and inform public health advisories
• Satellite remote sensing provides global coverage of air pollutants and GHG concentrations
  • Instruments measure backscattered solar radiation or thermal infrared emission to derive atmospheric composition
• Ground-based monitoring stations directly measure pollutant concentrations using various techniques (chemiluminescence, UV photometry, beta attenuation)
• Atmospheric dispersion models simulate the transport, transformation, and deposition of pollutants based on emissions data and meteorological conditions
• Greenhouse gas inventories estimate anthropogenic emissions by sector and source category
  • Follow standardized methodologies developed by the Intergovernmental Panel on Climate Change (IPCC)
• Climate models project future changes in temperature, precipitation, and other variables based on different emission scenarios and assumptions about socioeconomic development
• Health impact assessments estimate the burden of disease attributable to air pollution exposure using epidemiological studies and exposure-response functions

Mitigation Strategies and Policies

• Transitioning to clean energy sources (renewable energy, nuclear power) can reduce GHG emissions from the electricity sector
  • Renewable energy sources include solar, wind, hydro, geothermal, and biomass
• Improving energy efficiency in buildings, industry, and transportation can reduce energy demand and associated emissions
  • Includes measures such as building insulation, energy-efficient appliances, and fuel-efficient vehicles
• Implementing carbon pricing mechanisms (carbon taxes, cap-and-trade systems) can create economic incentives to reduce emissions
  • Puts a price on carbon emissions, encouraging companies and individuals to adopt low-carbon technologies and practices
• Promoting sustainable transportation (public transit, electric vehicles, active transport) can reduce emissions from the transportation sector
• Adopting sustainable land management practices (reforestation, afforestation, reduced deforestation) can enhance carbon sequestration and reduce emissions from land use change
• Implementing air quality regulations and standards can limit emissions of criteria pollutants from industrial sources and vehicles
  • Includes emission control technologies (scrubbers, catalytic converters) and fuel quality standards
• Encouraging sustainable consumption and production patterns can reduce the environmental footprint of goods and services
  • Includes measures such as eco-labeling, extended producer responsibility, and circular economy principles
• Enhancing public awareness and education can promote individual actions to reduce emissions and support climate-friendly policies