Lecture 13: Climate Change

Weather

Atmospheric conditions at a certain place and time, including temperature, pressure, humidity, and wind.

Climate

The average weather or statistical description of mean and variability of relevant quantities over a long period.

Climate Change

Change in climate state identified by changes in mean and variability of its properties over an extended period.

Oxygen Explosion

Period when cyanobacteria evolved, dramatically increasing O2 levels in the atmosphere.

Paleocene - Eocene Thermal Maximum

A significant warming of 5-8° that occurred over 20,000 years, likely due to carbon release.

Plate Tectonics

The movement of Earth's continents and ocean floors affecting ocean currents and climate.

Volcanism

Volcanic activity that injects ash and gases into the atmosphere, which can influence climate.

Solar Output

Variations in the Sun's energy output that can affect Earth's climate over time.

El Niño

A natural ocean cycle causing shifts in sea surface temperatures and global weather patterns.

La Niña

The counterpart to El Niño, affecting global weather patterns through ocean temperature shifts.

Thermohaline Circulation

The global ocean conveyor belt that distributes heat around the planet.

Milankovitch Cycles

Cycles related to Earth's orbit, tilt, and wobbling that contribute to predictable climate changes.

Eccentricity

The variation in the shape of Earth's orbit around the sun, affecting solar radiation received.

Axial Tilt

The inclination of Earth's axis that influences seasons and climate variability.

Precession

The wobbling of Earth’s axis that affects the orientation of the Earth relative to the Sun.

Greenhouse Gases (GHGs)

Gases in the atmosphere that trap heat, contributing to warming of the Earth.

Volcanism and CO2

The relationship between volcanic activity and levels of atmospheric carbon dioxide.

Anthropogenic GHG Emissions

Human-caused emissions of greenhouse gases that have increased since the Industrial Revolution.

Carbon Dioxide (CO₂)

A greenhouse gas released from burning fossil fuels for energy.

Methane (CH₄)

A greenhouse gas emitted from agriculture and fossil fuel extraction.

Nitrous Oxide (N₂O)

A greenhouse gas produced by agricultural practices and industrial activities.

Fluorinated Gases

Synthetic greenhouse gases used in refrigerants and industrial applications.

30-year average (World Meteorological Organization)

A standard time frame used to determine climate averages.

Oxygen levels dramatically increased

Result of the evolution of cyanobacteria during the Oxygen Explosion.

Sudden release of carbon

Potential cause for the warming during the Paleocene - Eocene Thermal Maximum.

Movement of Earth's continents

What plate tectonics refers to in the context of climate change.

Gases like sulfur dioxide

Particles injected by volcanism that can block sunlight.

Solar cycles

Variations in sunspot activity affecting solar radiation.

Sea surface temperatures

Factors influenced by natural ocean cycles like El Niño and La Niña.

Changes in thermohaline circulation

These can lead to regional or global climate shifts over time.

Tilt angle effect on summer/winter

A greater tilt leads to more pronounced seasonal differences in climate.

Hypothesis of axial tilt reduction

Suggests a warmer winter promotes greater snowfall accumulation.

Earth's tilt fluctuation

Varies between 21.5° and 24.5° every approximately 41,000 years.

Precession effect on solstices

Influences the timing of northern hemisphere solstices with Earth's orbit.

Heat absorption by GHGs

Process by which greenhouse gases prevent heat from escaping into space.

Supercontinents and volcanism

Supercontinents stabilizing lead to a decrease in volcanism and atmospheric CO2.

Sources of Methane

Including livestock agriculture, fossil fuel extraction, and landfills.

Sources of Nitrous Oxide

Includes fertilizers used in agriculture and certain waste processes.

Timing of climate changes

Influenced by the combined effects of multiple natural and anthropogenic factors.

Fossil fuel emissions

Major contributor to the increase in atmospheric carbon dioxide levels.

Importance of ocean currents

Critical for distributing heat and influencing climate around the globe.

Cyanobacteria's role

Pivotal in increasing atmospheric oxygen during early Earth history.

Historical climate records

Key to understanding past climate changes and predicting future shifts.

Variability in weather patterns

Essential aspect of defining climate over long periods.

Natural greenhouse gas effects

Result from both natural processes and human activities on climate.