7.1 Factors Influencing Climate Change

Introduction to Climate and Weather:

• Weather refers to the condition of the atmosphere in a specific place at a specific time, including factors like wind, temperature, and moisture.

• Climate is the average conditions of the atmosphere over a period of several years across a large region.

Climate and Weather impact on regions:

• Canada experience distinct weather patterns throughout the seasons, with hot summers and cold winters.

• Near the equator, like Ecuador and Indonesia, have a different climate, characterized by wet and dry seasons rather than cold winters.

• Ecuador and Indonesia experience tropical climates with minimal temperature variation throughout the year, focusing on wet and dry cycles.

• The average temperature in Canada can differ drastically from that of equatorial nations due to Earth's curvature and the angle of solar rays.

• Thousands of years ago, thick ice sheets covered most of Canada and a significant part of the United States, indicating a much colder climate.

• In 1988, the Intergovernmental Panel on Climate Change (IPCC) was established to investigate climate change evidence and advise governments globally about its effects on their citizens.

Solar Energy’s Role in Climate:

• Energy from the Sun is the single most important factor that affects climate on Earth.

• Solar energy travels through space as light and heat, influencing the temperature of air, water, and land.

• Variations in solar activity can change the amount of solar energy, which in turn can lead to climate changes.

Changes in Solar Activity:

• The sun may appear unchanging, but the amount of radiation it produces varies

• A more regular solar cycle occurs approximately every 11 years

Earth’s Movements and Climate:

• Earth rotates once every 24 hours around its axis, causing day and night.

• Earth makes a year-long journey around the Sun. This orbit affects sunlight distribution, resulting in seasonal changes as Earth moves through its path.

• Earth's axis is tilted at about 23.5° from perpendicular to the orbital plane.

Eccentricity and Its Climate Impact:

• Earth's orbit fluctuates slightly over a cycle of about 100,000 years due to the gravitational attraction of other planets, changing from nearly circular to elliptical.

• When Earth's orbit is more elliptical, the planet receives much more solar radiation when it is nearest the Sun than when it is farthest.

Tilt and Seasonal Temperature Differences:

• he angle of Earth's tilt on its axis changes by approximately 2.4° over a period of about 41,000 years. 

• The greater the tilt is, the greater the temperature differences are between summer and winter. 

• Currently, Earth is tilted at about 23.44°, or roughly halfway between its extremes, and the angle is slowly decreasing.

Wobble and Climate Variation:

• The wobble of Earth, also known as precession, refers to the change in the direction of the axis of rotation.

•  This wobble affects the amount and intensity of solar energy received by the northern and southern hemispheres at different times of the year.

Latitude’s Impact on Climate:

• The climate in Ecuador is hotter than in Canada due to the curved shape of the Earth and the different angles at which the Sun's rays strike the planet's surface.

• At the equator, sunlight strikes the surface perpendicularly, resulting in higher energy absorption compared to areas further from the equator.

• At latitude 45° south, the Sun's rays hit at an angle, spreading the energy over a larger area, which decreases the energy absorbed per square meter.

• At the poles, sunlight is spread over an even larger area, leading to significantly less solar energy absorption, resulting in colder temperatures.

Atmosphere’s Role in Climate:

• The atmosphere extends from Earth's surface up to about 560 km into space, composed mainly of nitrogen (N2) and oxygen (O2), along with water vapor (H2O) and trace gases.

• The atmosphere absorbs thermal energy from the Sun and thermal energy emitted by Earth's surface, a process known as the greenhouse effect.

GreenHouse Effect in Climate:

• The greenhouse effect is a natural part of Earth's climate system, helping to keep temperature fluctuations within a certain range.

• Without the greenhouse effect, most solar energy would radiate back into space, causing Earth's average temperature to drop by about 34°C.

• This process is essential for maintaining the climate and supporting life on the planet.

Hydrosphere and Climate:

• The top 2.3 metres of the world's oceans holds as much heat as all of the planet's air, influencing climatic conditions significantly.

• Oceans cover about two thirds of Earth's surface, acting as a "heat reservoir" that buffers temperature changes in the atmosphere.

• Water has a large specific heat capacity, requiring a large quantity of energy to raise its temperature compared to land, causing ocean temperatures to change slowly.

Albedo Effect:

• Ice and snow reflect solar radiation due to their light color, a phenomenon known as the albedo effect.

• The fraction of energy reflected by a surface is known as albedo; light-coloured surfaces reflect more energy than dark surfaces.

• fresh snow can reflect as much as 80 to 90 percent of the solar energy that strikes it.

• the ocean surface reflects only about 7 percent of solar energy, leading to greater heat absorption.

Tectonic Plates and Climate:

• Earth's outer layer is composed of massive pieces of solid rock known as tectonic plates.

• Earth has about 12 major plates that move at a rate of a few centimetres each year, carrying the continents with them. 

• The changing distribution of land and water affects patterns of air and water circulation and the transfer of thermal energy around the world. The formation of mountain chains also affects the pattern of wind and precipitation around the globe.

Volcanic Activity and Climate:

• Volcanic eruptions affect climate by releasing ash and aerosols into the atmosphere, which reflect solar radiation and contribute to cooling effects.

•  the 1815 eruption of Tambora in the Philippines resulted in the "Year Without a Summer," demonstrating how volcanic activity can influence global temperatures.

• some volcanic eruptions release greenhouse gases, which can contribute to warming over time.

Human Influence on Climate:

•  the burning of fossil fuels—such as coal, oil, and natural gas—has been a major source of energy for humans.

• For example, The Industrial Revolution, which began in the late 1700s demanded fossil fuels. As fossil fuel usage has expanded, the concentration of greenhouse gases in the atmosphere has increased, impacting natural processes that produce the greenhouse effect.

• trains, automobiles, ships, factories, aircraft, and home furnaces, all contributing to atmospheric pollution due to burning fossil fuels.