Lecture 10: Climate Change - Past Ice Ages

These flashcards cover key concepts related to climate change and ice ages as discussed in the lecture.

Combustion Pollution

Pollutants from direct discharges such as industry and cars, including CO, CO2, SO2, NO, NO2.

Photochemical Pollution

Pollution that requires sunlight for its formation, e.g. ozone.

Keeling Curve

Graph that shows the increase of atmospheric CO2 levels over time.

Greenhouse Effect

Process where certain gases trap heat from the sun, maintaining a livable climate.

Fossil Fuels

Natural substances formed from the remains of ancient organisms that release greenhouse gases when burned.

Ice Age

A period marked by significant cooling and the expansion of continental ice sheets.

Global Warming

An increase in average global atmospheric and sea-surface temperatures.

Global Cooling

A decrease in average global atmospheric and sea-surface temperatures.

Cenozoic Era

The current geological era, starting 65 million years ago, marked by significant cooling.

Latitude

The geographical coordinate that specifies the north-south position of a point on the Earth's surface.

Obliquity

The angle of tilt of the Earth's axis of rotation, influencing seasons.

Eccentricity

The measure of the deviation of the Earth's orbit from a perfect circle.

Milankovitch Cycles

Astronomical cycles that affect Earth's climate, including changes in eccentricity, obliquity, and precession.

Zone of Accumulation

The area where snow accumulation exceeds melting, leading to glacier formation.

Zone of Ablation

The area where melting exceeds accumulation, leading to glacier retreat.

Glacial Dynamics

The study of how glaciers move and reshape the landscape.

Greenhouse Gases

Gases in the atmosphere that trap heat, including CO2, CH4, and N2O.

Melting Ice

Process that contributes to rising sea levels due to climate change.

Glacial Retreat

The process of glaciers shrinking due to climate warming and increased melting.

U-Shaped Valley

A valley shaped like a U by the erosion of a glacier.

Glacial Striations

Scratches or gouges on bedrock caused by glacial movement.

Climate Classification

The Köppen-Geiger system, categorizing climates based on vegetation, temperature, and precipitation.

Average Global Temperature

The mean temperature of the Earth over a specified time period.

Oceans' Role in Climate

Oceans moderate climate by absorbing heat and influencing weather patterns.

Carbon Dioxide (CO2)

A greenhouse gas emitted through combustion of fossil fuels, contributing to global warming.

Methane (CH4)

A potent greenhouse gas with a significant impact on climate change.

Nitrous Oxide (N2O)

A greenhouse gas produced from agricultural and industrial activities.

Fluorinated Gases

Synthetic greenhouse gases that include hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

Water Vapour

The most abundant greenhouse gas, making up about 95% of the greenhouse gases in the atmosphere.

Solar Irradiance

The power per unit area received from the Sun.

Precipitation Variability

Fluctuations in rain and snowfall patterns that can alter climate norms.

Average Global Precipitation

The mean amount of rainfall across the globe over a specified time.

Seasons

Changes in climate corresponding to variations in solar energy received throughout the year.

Historical Climate Change

The study of how Earth's climate has changed over geological epochs.

Thermal Expansion

The increase in water volume that occurs as the temperature of the ocean rises.

Solar Cycle

Periodic changes in solar irradiance due to sunspot activity.

Carbon Footprint

The total greenhouse gas emissions caused directly and indirectly by an individual, organization, event, or product.

Absorption of Solar Energy

The process by which the Earth's surface takes in energy from the Sun, influencing local and global climates.

Glacier

A large accumulation of fallen snow that compresses into ice, flowing under its weight.

Climate Change Indicators

Observable signs that signify changes in the Earth's climate, such as rising temperatures and changing weather patterns.

Combustion Pollution

Pollution arising from the burning of fossil fuels and other combustible materials, often from sources like industrial facilities and vehicle exhaust. Key pollutants include carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), and various nitrogen oxides (NO_x like NO and NO2), which contribute to air quality degradation and climate change.

Photochemical Pollution

A type of air pollution formed when primary pollutants, such as nitrogen oxides (NO_x) and volatile organic compounds (VOCs), react in the atmosphere in the presence of sunlight. A prominent example is ground-level ozone, which can cause respiratory problems and damage vegetation.

Keeling Curve

A prominent graph that illustrates the continuous increase of atmospheric carbon dioxide (CO2) concentrations measured at Mauna Loa Observatory, Hawaii, since 1958. It provides compelling evidence for rising CO2 levels linked to human activities, particularly the burning of fossil fuels.

Greenhouse Effect

The natural process by which certain gases in Earth's atmosphere, such as carbon dioxide (CO2), methane (CH4), and water vapor, trap some of the heat radiated from the Earth's surface. This process warms the planet and maintains temperatures suitable for life, but human-enhanced emissions are intensifying it.

Fossil Fuels

Combustible natural substances, including coal, oil, and natural gas, formed over millions of years from the anaerobic decomposition of ancient organic matter. When burned for energy, they release significant amounts of greenhouse gases, primarily carbon dioxide, contributing to global warming.

Ice Age

A prolonged geological period characterized by a significant reduction in global temperatures and the extensive expansion of continental ice sheets and glaciers across much of the Earth's surface. Earth has experienced multiple ice ages throughout its history, with alternating glacial and interglacial periods.

Global Warming

The long-term increase in Earth's average surface temperature, primarily due to the buildup of greenhouse gases in the atmosphere from human activities. This warming trend is a key aspect of broader climate change.

Global Cooling

A period characterized by a decrease in the Earth's average atmospheric and sea-surface temperatures, often associated with a decline in global temperatures over a sustained period, contrasting with trends of global warming.

Cenozoic Era

The current and most recent geological era, which began approximately 66 million years ago after the extinction of the non-avian dinosaurs. It is characterized by the diversification of mammals, birds, and flowering plants, and has experienced significant climatic shifts, including a general cooling trend and repeated glacial cycles.

Latitude

The geographical coordinate that indicates the north-south position of a point on the Earth's surface, measured in degrees from 0^ ext{o} at the Equator to 90^ ext{o} North or South at the poles. It plays a crucial role in determining climate zones due to varying solar radiation.

Obliquity

Also known as axial tilt, it refers to the angle that the Earth's rotational axis makes with its orbital plane around the Sun. This angle, currently about 23.5^ ext{o}, varies cyclically over tens of thousands of years, significantly influencing the intensity of the Earth's seasons.

Eccentricity

A measure of how much the Earth's elliptical orbit around the Sun deviates from a perfect circle. This value varies over cycles of approximately 100,000 years, affecting the total amount of solar radiation received by Earth, which in turn influences long-term climate patterns.

Milankovitch Cycles

Long-term astronomical cycles that describe changes in Earth's orbital parameters and axial tilt, which collectively influence the amount of solar radiation reaching different parts of the Earth. These cycles—including variations in eccentricity, obliquity, and precession—are believed to be a primary driver of natural climate variability and the timing of ice ages.

Zone of Accumulation

In glaciology, this is the upper part of a glacier or ice sheet where the annual snowfall and ice accumulation exceed the amount of ice lost through melting, sublimation, and calving. This surplus of ice contributes to the glacier's growth and movement.

Zone of Ablation

In glaciology, this is the lower part of a glacier or ice sheet where the annual loss of ice through melting, sublimation, and calving exceeds the amount of snow and ice accumulation. If this zone expands significantly, it can lead to glacial retreat.

Glacial Dynamics

The scientific study of the physical processes that govern the formation, movement, and erosion capabilities of glaciers. It encompasses aspects like ice flow mechanics, mass balance, and how glaciers carve out distinctive landforms such as U-shaped valleys and fjords.

Greenhouse Gases

Atmospheric gases that absorb and re-emit infrared radiation, effectively trapping heat within Earth's atmosphere. Key natural and anthropogenic greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and fluorinated gases, which are essential for maintaining a habitable temperature but, in excess, contribute to global warming.

Melting Ice

The process by which ice, particularly from glaciers and ice sheets, transforms into liquid water. This phenomenon, accelerated by global warming, significantly contributes to rising global sea levels and impacts ocean circulation patterns.

Glacial Retreat

The process where a glacier's terminus (or front) moves up-valley, indicating a reduction in the glacier's size and mass. It occurs when the rate of ice loss (ablation) exceeds the rate of ice accumulation, largely driven by rising global temperatures.

U-Shaped Valley

A distinctive valley landform characterized by a broad, flat floor and steep, straight sides, resembling the letter 'U'. These valleys are typically formed by the erosive action of glaciers (glacial scour) as they move through pre-existing river valleys.

Glacial Striations

Parallel scratches, grooves, or gouges inscribed on bedrock surfaces by the abrasive action of rocks and sediments embedded in the base of a moving glacier. They provide clear evidence of past glacial activity and indicate the direction of ice flow.

Climate Classification

A systematic method used to categorize and map Earth's climates, most notably the Köppen-Geiger system. This system classifies climates based on specific criteria such as average monthly and annual temperature and precipitation, often correlating with distinct vegetation types.

Average Global Temperature

The calculated mean temperature of the Earth's surface and lower atmosphere over a given period, typically averaged annually or over longer timescales. It is a key indicator of climate change, reflecting worldwide warming or cooling trends.

Oceans' Role in Climate

Oceans play a critical and multifaceted role in regulating Earth's climate by absorbing vast amounts of heat and carbon dioxide from the atmosphere, distributing warmth through ocean currents, and influencing global weather patterns, including precipitation and storm formation.

Carbon Dioxide (CO2)

A naturally occurring greenhouse gas that is a vital component of Earth's atmosphere. Anthropogenic emissions, primarily from the burning of fossil fuels, deforestation, and industrial processes, have significantly increased its concentration, making it the leading contributor to human-induced global warming.

Methane (CH4)

A powerful greenhouse gas, far more potent than carbon dioxide over a shorter timescale, released from natural sources like wetlands and anthropogenic activities such as agriculture (livestock, rice paddies), fossil fuel extraction, and landfills. It has a significant, albeit shorter-lived, impact on climate warming.

Nitrous Oxide (N2O)

A potent greenhouse gas and ozone-depleting substance. It is naturally produced in soils and oceans and emitted by various human activities, including agricultural fertilization, industrial processes, and the combustion of fossil fuels and solid waste.

Fluorinated Gases

A group of synthetic, powerful greenhouse gases, including hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF_6). These gases are emitted from a variety of industrial applications, have extremely high global warming potentials, and can persist in the atmosphere for thousands of years.

Water Vapour

Gaseous water in the atmosphere (H2O), which is the most abundant and naturally occurring greenhouse gas on Earth, accounting for roughly 95\% of the natural greenhouse effect. Its concentration in the atmosphere is closely linked to temperature; warmer air holds more water vapor, leading to a positive feedback loop that intensifies warming.

Solar Irradiance

The power emitted by the Sun that is received per unit area at a given distance from the Sun, typically measured at the top of Earth's atmosphere (Total Solar Irradiance). Variations in solar irradiance, usually small, can influence Earth's climate over different timescales.

Precipitation Variability

Refers to the natural and anthropogenic-driven fluctuations in the amount, intensity, and timing of rainfall and snowfall over different regions and time periods. Changes in precipitation variability can significantly impact water resources, agriculture, and ecosystem health, often leading to more frequent droughts or floods.

Average Global Precipitation

The mean amount of liquid and solid precipitation (rain, snow, hail, etc.) that falls across the Earth's surface over a specific time period, typically averaged annually. It is a critical component of the global water cycle and a key indicator for climate patterns.

Seasons

Divisions of the year, each with its own characteristic weather patterns, light, and ecological conditions. Seasons are caused by the Earth's axial tilt (obliquity) as it orbits the Sun, which results in variations in the intensity and duration of solar radiation received at different latitudes throughout the year.

Historical Climate Change

The scientific study of how Earth's climate has naturally varied over geological timescales, ranging from millions to billions of years. This field uses proxy data (e.g., ice cores, tree rings, sediment layers) to reconstruct past climates and understand natural drivers of climate shifts, providing context for current anthropogenic climate change.

Thermal Expansion

The fundamental physical property where the volume of a substance increases as its temperature rises. In the context of climate change, the thermal expansion of seawater as oceans warm is a major contributor to global sea-level rise, independent of melting ice.

Solar Cycle

A periodic 11-year cycle of waxing and waning solar activity, characterized by changes in the number of sunspots, solar flares, and coronal mass ejections. These cycles cause slight variations in solar irradiance, which can have minor, short-term influences on Earth's climate.

Carbon Footprint

The total amount of greenhouse gases (including carbon dioxide and methane) emitted directly and indirectly into the atmosphere by an individual, organization, event, or product, usually expressed in equivalent tons of carbon dioxide (CO2_e). It quantifies the impact of human activities on climate change.

Absorption of Solar Energy

The process by which the Earth's surface, atmosphere, and oceans absorb incoming solar radiation. This absorbed energy is converted into heat, driving atmospheric and oceanic circulation, influencing temperature, weather patterns, and ultimately shaping local and global climates.

Glacier

A persistent body of dense ice that is constantly moving under its own weight; it forms from the accumulation of snow that compacts and recrystallizes over time. Glaciers are significant agents of erosion and deposition, and their dynamics are sensitive indicators of climate change.

Climate Change Indicators

Observable physical, biological, and societal signs that directly or indirectly reveal changes in Earth's climate system. These indicators include rising global temperatures, increasing atmospheric greenhouse gas concentrations, ocean warming, sea-level rise, melting glaciers and ice sheets, changes in precipitation patterns, and shifts in species distribution.