Topic 6: Atmosphere and Climate Change

What is the atmosphere

• it forms the boundary between Earth and space.

• It is the outer limit of the biosphere

• its composition and processes support life on Earth.

Differential heating

• (of the atmosphere) creates the tricellular model of atmospheric circulation that redistributes the heat from the equator to the poles.

• this reduces heat at the equator and warms the poles

GHGs and aerosols

absorb and re-emit some of the infrared (long-wave) radiation emitted from the Earth’s surface, preventing it from being radiated out into space.

enhanced greenhouse effect

the accumulation of GHGs by human activity leading to global warming

climate

typical conditions that result from physical processes in the atmosphere.

What has caused atmospheric carbon levels to rise significantly

Anthropogenic carbon dioxide emissions. (Since about the start of the Industrial Revolution)

What can we examine to prove rising CO₂ causes global warming

Analysis of:

• Ice cores (trapping ancient air bubbles, recording seasonal snowfall layers)

• Tree rings (the wider the ring the warmer the environment was that year)

• and deposited sediments (analysis of chemical isotopes, and layer composition)

What affect does climate change have on local ecosystems

• coral bleaching

• desertification

What affect does climate change have on the global ecosystem

• sea level rises

• changes to ocean circulation

To avoid the risk of catastrophic climate change

global action is required, rather than measures adopted only by certain states.

What does it mean to ‘Decarbonise’ the economy

reducing or ending the use of energy sources that result in CO2 emissions and their replacement with renewable energy sources.

What are the 3 main categories of mitigation strategies

• reducing the process of global warming (making household changes)

• reducing production of GHGs (carbon taxes, food choice changes)

• removing CO₂ from the atmosphere (carbon sinks, rewilding)

What are the 2 main categories of adaptation strategies

• Structural Adaptation (flood defenses, desalination plants)

• Non-structural changes (land zoning, planting drought resistant stuff)

UV radiation

• short wavelengths

• higher frequencies

• 3 types (UVA, UVB, UVC)

• pose a danger to life

Stratospheric ozone absorbs

• all UVC radiation and most UVB

what effects does UV radiation have

• reduces photosynthesis in phytoplankton

• causes mutations and cancer

• sunburn, premature aging and cataracts

why has the concentration of ozone stayed constant

due to a steady state of equilibrium between the concurrent processes of ozone formation and

destruction.

Ozone-depleting substances (ODSs)

destroy ozone molecules, augmenting the natural ozone breakdown process.

Ozone depletion allows

increasing amounts of UVB radiation to reach the Earth’s surface, which impacts ecosystems and human health.

The Montreal Protocol

is an international treaty that regulates the production, trade and use of chlorofluorocarbons (CFCs) and other ODSs.

The atmosphere is mainly

• Nitrogen (78%) and Oxygen (21%)

• However it also contains traces of CO₂ , water vapour, and argon

CO₂ in the atmosphere

is essential for maintaining the greenhouse effect and photosynthesis

Water Vapour in the atmosphere

is essential for photosynthesis, weather patterns and the formation of clouds and precipitation

How are gases in the air moved around

• wind (changes in air pressure)

• convection (warm air rises)

• diffusion

• Turbulence (irregular air flow caused by obstacles like buildings)

2 key layers for living in the atmosphere

troposphere and stratosphere

Troposphere

• where the weather occurs

• the lowest layer at a max 10km above the earth’s surface

stratosphere

• above the troposphere (10-50km above sea level)

• contains the ozone layer