The Earth's Atmosphere Flashcards
(19 cards)
The proportion of gases in the atmosphere:
- 78% Nitrogen
- 21% Oxygen
- small quantities of other gases (noble gases, carbon dioxide and water vapour)
What was the Earth’s early atmosphere like?
- For the first billion years, highly active volcanoes populated the surface
- The volcanoes frequently erupted, releasing lots of carbon dioxide
- Scientists think carbon dioixide dominated the early atmosphere, like Mars or venus
Later Existence: - The volcanoes also released:
nitrogen (which slowly built up in the atmosphere)
and water vapour (which condensed to form oceans) - the oceans removed carbon dioxide
Photosynthetic organisms:
- algae was the first photosynthetic organism to evolve 2.7 billion years ago
- over the next billion years, photosynthesising plants began to evolve, which led to an ever-increasing rate of oxygen accumulating in the atmosphere
What happened when the concentration of oxygen increased?
more complex life forms evolved, such as animals
3 factors causing atmospheric carbon dioxide to decrease:
- photosynthesis - carbon dioxide is a reactant in this process, so plants and algae removed carbon dioxide
- oceans - carbon dioxide dissolved in the oceans. Some of it reacted with seawater to give carbonate precipitates.
- marine animals - they evolved and used carbonate from the oceans to build their shells and skeletons
The greenhouse effect process:
1) The sun emits short wavelength infrared radiation that enters the atmosphere and travels towards the Earth’s surface
2) The Earth absorbs some of this radiation, but long wavelength radiation is reflected back into the atmosphere
3) Greenhouse gases can’t absorb the frequency of radiation emitted by the sun, but can absorb longer wavelength reflected radiation
4) The gases then re-radiate this energy in all directions, including back towards Earth
5) This increases the temperature at the Earth’s surface
Human activties that increase greenhouse gases:
- Agriculture - farm animals release methane during digestion
- Burning fossil fuels - releases carbon dioxide
- Landfill sites - number and size of landfills are increasing, meaning more waste is decomposing, which releases methane
- Deforestation - fewer trees means less photosynthesis so less carbon dioxide is being removed
What is the scientific consensus about greenhouse gases?
- increased greenhouse gas emissions caused by human activity will lead to global climate change
- consensus is based on peer-reviewed evidence
Sources of misinformation regarding climate change:
- Biased opinions published in the media
- Overly simplistic models
What are the severe consequences of climate change?
- Melting of polar ice caps - causes sea levels to rise, leading to floodingand erosion of coastal regions. Some species are losing their habitats (polar bears)
- Meteorological events - the frequency of these extreme events (e.g. storms, heatwaves, droughts) could increase
- Changes in water availability - affect species distributions
- Changes in precipitation - regions could receive much more or less (flooding, droughts)
- Food shortages - hinders a region’s ability to produce food
What is a carbon footprint?
a measure of the total amount of greenhouse gases emitted
How can we minimise carbon footprints?
- individuals - maximising efficiency of energy use, minimising waste, using renewable energy sources
- governments - imposing: emission- based taxes, emission caps, emission licenses up to a certain cap
- capture carbon before it’s released into the atmosphere and store it deep underground
- compensate emissions by planting trees, which remove carbon dioxide with photosynthesis
- use carbon-neutral products - which don’t change the atmospheric carbon dioxide concentration
Barriers to reducing carbon footprint:
- political factors - countries have different opinions about the right course of action, which causes uncertainty - meaning no decisions get made
- social factors - people in developed countries might not want to change their lifestyle, or aren’t educated
- economic factors - many countries think making changes will restrict their economic development
- scientific factors - scientists don’t agree on the causes and consequences, preventing scientific advances
Barriers to reducing carbon footprint:
- political factors - countries have different opinions about the right course of action, which causes uncertainty - meaning no decisions get made
- social factors - people in developed countries might not want to change their lifestyle, or aren’t educated
- economic factors - many countries think making changes will restrict their economic development
- scientific factors - scientists don’t agree on the causes and consequences, preventing scientific advances
Common atmospheric pollutants from fossil fuels:
- internal combustion engines in cars - when fossil fuels are burned in a confined space, the high temperatures can cause nitrogen and oxygen to react, leading to formation of toxic nitrogen oxides
- sulfur is an impurity in all fossil fuels and produces the toxic gas sulfur dioxide when burnt
- incomplete combustion happens when fuels are burned in insufficient oxygen, producing carbon monoxide and particulates
What are the negative effects of sulfur dioxide?
- inhaling can cause respiratory problems
- sulfur dioxide can react with water to form sulfuric acid - a major component of acid rain which can cause weathering of buildings, and insects + plants to die
What are the negative effects of particulates?
- inhaling can cause respiratory problems
- particulates reflect incoming radiation back into space, causing global dimming (decreases the level of sunlight available for photosynthesis)
What are the negative effects of carbon monoxide?
- binds to haemoglobin in the blood. This restricts the blood’s ability to transport oxygen around the body
- it is odourless and colourless, making it difficult to detect
- carbon monoxide poisoning can lead to fainting, comas or even death
What are the negative effects of nitrogen oxides?
- inhaling can cause respiratory problems
- nitrogen oxides can react with water to form nitric acid (a major component of acid rain)
