Global warming and climate change

• The increased concentration of greenhouse gases like carbon dioxide and methane in the atmosphere leads to enhanced greenhouse effect, causing the planet to warm up.
• Global warming and Climate Change: Some gases in the atmosphere, called ‘greenhouse gases’, keep the Earth’s atmosphere warmer than it would be without these gases.
• The greenhouse effect is the natural process that allows the Earth to trap energy from the sun and is essential to life.
• The sun emits ultra violet (UV), visible and infra-red (IR) radiation (light).
• 30% of the light emitted by the sun is reflected back to space due to albedo (reflectivity of ice, snow, clouds and water).
• 22% of the light emitted by the sun is absorbed by the gases present in the stratosphere.
• 48% of the light emitted by the sun is absorbed by the Earth’s surface.
• 17% of the light emitted by the sun is re-radiated as IR radiation (lower in energy).
• Greenhouse gases absorb approximately 5% of this IR radiation, helping to trap the heat in the atmosphere.
• Greenhouse gases also re-release this IR radiation, helping to warm the Earth’s surface and troposphere (lower layer of atmosphere).
• Greenhouse gases are present in the Earth’s atmosphere and are present in higher concentrations closer to the Earth’s surface where the air is more dense.
• Greenhouse gases have polar bonds (uneven sharing of electrons due to a difference in electronegativity), however they do not need to be a polar molecule.
• The most concentrated greenhouse gases are water and carbon dioxide.
• Other contributors to greenhouse gases include nitrous oxide, methane, nitrogen trifluoride and ozone.
• For thousands of years the Earth has been in thermal balance, with the amount of thermal radiation entering the atmosphere equalling the amount being emitted.
• As concentrations of greenhouse gases increase due to anthropogenic influences, less thermal radiation is escaping, leading to an increase in average temperature.
• Anthropogenic increases in greenhouse gases disrupt the thermal balance of the atmosphere.
• Global warming and climate change are associated with consequences for the environment.
• Activities done by humans, such as industry and burning fossil fuels, have resulted in an increased concentration of carbon dioxide and other greenhouse gases.
• Different greenhouse gases have different atmospheric residence times, which is the length of time they exist in the atmosphere.
• Global warming potential is the ability of different greenhouse gases to absorb radiations as compared to CO2.
• Atmospheric carbon dioxide concentrations have been accurately and reliably recorded by the scientific community for over 50 years.
• Charles Keeling began measurements of CO2 concentration from Hawaii's Mauna Loa volcano observatory and south pole.
• Over the past 100 years, the average surface temperature in Australia has increased by 1.0°C.
• Global temperature rise is associated with impacts such as declining artic sea ice, shrinking ice sheets and retreating glaciers.
• The calcium carbonate shells of marine organisms will react with the ‘extra’ acid in the ocean, causing their shells to weaken: CaCO3(s) + 2H+ (aq) ® Ca 2+ (aq) + CO2(g) + H2O(l).
• Corals are negatively impacted by increasing CO2 levels and decreasing pH in seawater.
• Shelled animals, including mussels, clams, urchins and starfish, are going to have trouble building their shells in more acidic water, just like the corals.
• These photos show what happens to a pteropod’s shell when placed in sea water with pH and carbonate levels projected for the year 2100.
• An increase in the concentration of hydronium ions decreases the pH of the oceans.
• Ocean Acidification: Ocean acidification is caused by the ocean absorbing higher levels of carbon dioxide from the atmosphere.
• Many reactions exist in a pH dependent equilibrium.
• Full equation: CaCO3(aq) + H2SO4(aq) ↔ CO2(g) + H2O(l) + CaSO4(aq).
• As the pH decreases, the concentration of carbonate ions decreases.
• Climate and extreme weather events: Oceans around Australia have warmed, threatening ocean ecosystems like the Great Barrier Reef through coral bleaching and ocean acidification.
• The ionic product of water Kw is used to form the logarithmic pH scale.
• Carbonic acid: Carbonic acid is a fairly weak acid, and only partially ionises.
• Reactions of Acids and Carbonates: Acids react with metal carbonates and hydrogen carbonates to form water, carbon dioxide and a salt.
• The rates of dissolution of calcium carbonates also increase in acid, weakening their shell.
• Rising Sea levels: Rates of sea level rise to the north, west, and south-east of Australia have been higher than the global average.