Glaciers, Climate Change, and Energy Resources Overview

Glacier

A large mass of ice that forms on land from the compaction and recrystallization of snow and moves slowly over land.

Conditions for glacier formation

A cold climate, sufficient snowfall, and preservation of snow year-round so it accumulates over time.

Snow, firn, and ice relationship

Snow compacts into firn (a granular type of snow) as it becomes denser under pressure. Firn then compacts further and recrystallizes into glacial ice.

Alpine glaciers

Glaciers that occur in mountainous regions and flow down valleys.

Continental glaciers

Vast glaciers (ice sheets) that cover large land areas.

Numerosity of glaciers

Alpine glaciers are more numerous today than continental glaciers.

Locations of continental glaciers

Continental glaciers exist today in Antarctica and Greenland.

Rigid zone of a glacier

The upper part of a glacier that is brittle.

Plastic zone of a glacier

The lower part of a glacier that flows ductilely due to pressure.

Depth boundary of glacier zones

The boundary between the rigid and plastic zones is usually at a depth of ~60 m (200 ft).

Zone of accumulation

The area where snow accumulates and turns into ice.

Zone of ablation

The area where ice melts or sublimates.

Glacier movement

Glaciers move via plastic flow within the ice and basal sliding at the base where meltwater acts as a lubricant.

V-shaped valleys

Valleys formed by rivers.

U-shaped valleys

Valleys carved by glaciers, which widen and deepen the valley.

Cirque

A bowl-shaped depression at the head of a glacier.

Arête

A sharp ridge between cirques.

Horn

A sharp mountain peak formed by erosion of several cirques.

Glacial striations

Scratches on bedrock from glacier movement.

Glacial till

Unsorted sediment deposited directly by a glacier.

Lateral moraine

Debris along the sides of a glacier.

Medial moraine

Formed where two glaciers meet, combining lateral moraines.

Terminal moraine

Debris deposited at the glacier's furthest advance.

Glacial period

A cold period with expanded ice sheets.

Interglacial period

A warmer period when ice sheets retreat.

Climate change and glaciers

Climate change influences glacier size and sea levels; warming causes ice melt and sea level rise.

Milankovitch cycles

Cyclical variations in Earth's orbit and axial tilt that influence solar radiation distribution, helping trigger Ice Ages.

Dune

A mound of sand formed by wind.

Dune movement

Dunes move via saltation, as sand is lifted and deposited downwind.

Desert definition

Deserts receive less than 25 cm (10 in) of rain/year.

Desert formation

Natural formation occurs due to subtropical highs, rain shadows, and distance from moisture sources.

Desertification

Land degradation turning semi-arid areas into deserts, worsened by human activity.

Rain shadow

A dry region on the leeward side of a mountain range where moist air loses water on the windward side.

Deserts at 30° latitude

At 30° N/S, descending dry air creates arid zones.

Rain shadow

Dry region on the leeward side of a mountain range where moist air loses water on the windward side.

Weather

Short-term atmospheric conditions (hours to weeks).

Climate

The long-term average of weather patterns in an area.

Greenhouse effect

The process by which atmospheric gases trap heat. Solar radiation reaches Earth, is absorbed, and re-emitted as infrared radiation, which greenhouse gases absorb and re-radiate.

Major greenhouse gases

Carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), water vapor (H₂O), and ozone (O₃).

Most abundant greenhouse gases

CO₂ and water vapor are the most abundant.

Greenhouse gases and global warming

These gases trap more heat as their concentrations increase, enhancing the natural greenhouse effect and raising Earth's average temperature.

Charles Keeling and the Keeling Curve

Keeling began measuring CO₂ at Mauna Loa Observatory in 1958, documenting rising atmospheric CO₂.

Annual fluctuations in CO₂

Due to seasonal changes in plant photosynthesis.

CO₂ levels since the Industrial Revolution

CO₂ levels have increased from ~280 ppm to over 415 ppm.

Global surface temperature rise

Global surface temperature has risen approximately 1.1°C.

Loss of Arctic sea ice

Ice reflects sunlight (high albedo). Loss of sea ice reduces albedo, increasing heat absorption and accelerating warming.

Permafrost

Permafrost is permanently frozen ground.

Thawing permafrost

Its thaw releases trapped methane, a potent greenhouse gas, further accelerating warming.

Oceans and climate regulation

Oceans absorb CO₂ and heat, acting as reservoirs.

Thermohaline circulation

Driven by temperature and salinity differences, it circulates water globally.

Disruption of thermohaline circulation

Can shift regional climates dramatically.

Coastal upwelling

Coastal winds push surface water away, allowing nutrient-rich deep water to rise.

El Niño

Disrupts coastal upwelling by weakening trade winds, collapsing upwelling, and altering weather patterns.

CO₂ and ocean acidity

More CO₂ lowers ocean pH.

Impact of lower ocean pH

Harms limestone-based reefs and marine organisms like plankton by dissolving calcium carbonate.

Oxygen isotope ratios (¹⁸O / ¹⁶O)

Ice cores contain ¹⁶O-rich water during cold periods (more ¹⁸O in oceans).

Ice-core record span

Some cores date back over 800,000 years, providing climate history.

Albedo

Albedo is reflectivity; ice has high albedo, oceans/forests low.

Positive feedback in climate

Warming melts ice → lower albedo → more warming.

Negative feedback in climate

Warming increases clouds → more reflection → cooling.

Regolith

Loose, unconsolidated rock and mineral fragments.

Soil

Regolith that has been altered by organic matter, water, and biological activity.

Mechanical weathering

Breaks rocks into smaller pieces without changing chemical composition (e.g., frost wedging).

Chemical weathering

Alters the chemical composition (e.g., oxidation, dissolution).

Weathering

The breakdown of rock in place; erosion involves the movement of that material by wind, water, or ice.

O horizon

Organic material.

A horizon (topsoil)

Mix of organic material and minerals, leached of some substances.

B horizon (subsoil)

Zone of accumulation of leached materials.

Leaching

The removal of dissolved materials by water percolating through the soil.

Loam

A soil with roughly equal parts sand, silt, and clay—ideal for agriculture because of its balance of drainage and nutrient retention.

Pedalfer

Forms in humid climates; rich in aluminum and iron oxides, leached of calcium.

Pedocal

Forms in arid regions; rich in calcium carbonate and less leached.

Lateritic soil

Found in tropical regions with heavy rainfall, highly leached and rich in iron and aluminum oxides.

Mineral resource

A concentration of naturally occurring material useful to humans.

Mineral reserve

The known portion of a resource that is economically recoverable with current technology.

Ore

A rock or sediment containing a valuable mineral that can be mined for profit.

Concentration factor

Ratio of the element's average crustal abundance to its concentration in the deposit.

U.S. predominant mineral resources

Large amounts of industrial minerals like sand, gravel, and crushed stone.

Iron

The most abundant ore among metals.

Igneous rocks

Ore deposits may form in volcanic arcs, mid-ocean ridges, or at subduction zones where magmas concentrate metals.

Pegmatites

Very coarse-grained igneous rocks that may contain rare minerals like beryl or tourmaline.

Kimberlites

Volcanic pipes that often contain diamonds.

Hydrothermal deposits

Formed when hot, mineral-rich fluids precipitate metals in veins or fractures.

Banded iron deposits

Ancient sedimentary layers of iron-rich minerals; formed when oxygen began accumulating in Earth's atmosphere.

Evaporite deposits

Form from evaporation of saline water in enclosed basins.

Placer deposits

Form when heavy minerals are concentrated by moving water (e.g., in rivers).

Iron and aluminum

The two most heavily consumed U.S. metals.

Economically significant nonmetallic minerals

Includes salt, phosphate rock, gypsum, and clay.

Ways to avoid resource shortages

Recycling, substitution, improved efficiency, exploration, and conservation.

Are minerals renewable?

No. Minerals form over geologic time scales and are thus nonrenewable.

Environmental/health issues of underground mining

Subsidence, toxic gas exposure, explosions, and black lung disease.

Two surface mining types

Open-pit mining and strip mining.

Hazards of surface mining

Habitat destruction, acid mine drainage, erosion.

Spoil banks

Piles of waste rock.

Tailings

Waste from ore processing.

Heap-leaching

Uses chemicals (often cyanide) to extract metals from ore piles.

Mining and pollution

Mining creates dust, acid mine drainage, and waste.

Smelting concerns

Smelting releases sulfur dioxide, leading to acid rain and air pollution.

Examples of fossil fuels

Coal, oil (petroleum), and natural gas.

Characteristics of fossil fuels

Called fossil fuels because they form from ancient organic matter and are composed mainly of carbon and hydrogen.