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The Anthropogenic Greenhouse Effect. Lesson 3 . History in a Tree Trunk. Recording growth is one way to document change. The growth of a tree is documented in the widths of its rings. . One tree ring is formed every year, during the summer when the tree grows.

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history in a tree trunk
History in a Tree Trunk
  • Recording growth is one way to document change. The growth of a tree is documented in the widths of its rings.
  • One tree ring is formed every year, during the summer when the tree grows.
  • Thicker rings mean the tree grew in better conditions; enough precipitation and appropriate temperatures.
  • Thin rings mean poorer conditions: drought, or higher or lower temperatures than usual.
history in a tree trunk1
History in a Tree Trunk
  • By comparing the rings, scientists can determine the weather conditions over the life of the tree. Since some trees live for hundreds of years, the rings provide long-term climate data.
greenhouse gases
Greenhouse Gases
  • The natural greenhouse effect is due mainly to the presence in our atmosphere of water vapour, with other naturally occurring greenhouse gases, such as carbon dioxide, methane, and nitrous oxide, also playing a role. However, these gases are also produced by human activities, such as industry, electricity generation, transportation, and agriculture.
  • The four main greenhouse gases are water vapour, carbon dioxide, methane, and nitrous oxide.
greenhouse gases1
Greenhouse Gases
  • Persistence is the length of time the gas remains in the atmosphere.
  • Gases that persist longer can absorb thermal energy over a longer period of time. Persistence of carbon dioxide is not defined because it depends on the amount emitted and carbon dioxide has a variety of sinks (places of storage).
  • Oceans, Forests
greenhouse gases3
Greenhouse Gases
  • Others
    • CFC’s – chlorofluorocarbons
    • HCFC’s – hydrochlorofluorocarbons
    • HFC’s - hydrofluorocarbons
history of greenhouse gas research
History of Greenhouse Gas Research
  • The discovery that different gases absorbed infrared radiation differently dates back to the work of the Irish scientist John Tyndall in 1861.
  • Climatologists discovered that a good source of data was in the continental glacier in Greenland, a glacier that had been there for hundreds of thousands of years.
greenland ice core project grip
Greenland Ice Core Project (GRIP)
  • Each year’s snowfall is recorded as a distinct layer. From 1989 to 1992, a 3029-m-long ice core was drilled vertically and removed from the continental glacier.

At its deepest, the ice layer is thought to be 200 000 years old, while the ice layer at the surface was formed the previous winter. The pieces of the ice core were dated, labelled, and stored frozen.

greenland ice core project grip1
Greenland Ice Core Project (GRIP)
  • Ancient ice can be studied, air at the time of freezing is trapped in the ice can be analyzed for CO2 concentrations. CO2 remained stable for 10,000 years at 280 ppm, then around 1750 (Industrial Revolution) CO2 began to rise rapidly to its current state of 385 ppm.
slide11

Ancient ice can be studied, air at the time of freezing is trapped in the ice can be analyzed for CO2 concentrations.

CO2 remained stable for 10,000 years at 280 ppm, then around 1750 (Industrial Revolution) CO2 began to rise rapidly to its current state of 385 ppm.

greenhouse gas concentrations
Greenhouse Gas Concentrations
  • During the Industrial Revolution, the focus shifted rapidly to coal-fired steam engines and the mass production of goods. Human society became more and more dependent on the consumption of fossil fuels.

Increased greenhouse gas concentrations mean that less thermal energy is released back into space, and as a result, the average temperature at Earth’s surface increases.

greenhouse gas concentrations1
Greenhouse Gas Concentrations
  • The additional greenhouse gas emissions are causing the anthropogenic greenhouse effect, which is the enhancement of the natural greenhouse effect due to human activities.
sources of greenhouse gases
Sources of Greenhouse Gases
  • The most significant greenhouse gas is carbon dioxide. Any process that releases carbon dioxide to the atmosphere is called a carbon source. Example: Burning fossil fuels and the cellular respiration.
sources of greenhouse gases1
Sources of Greenhouse Gases
  • Fossil fuels - coal, oil, and natural gas — formed underground from the remains of once-living organisms.

As a carbon source, very little CO2 and CH4 is released. When it is burned, large amounts of CO2 and N2O are produced.

For every litter of gasoline burned, 2.3kg of CO2 is produced.

increasing greenhouse gas emissions
Increasing Greenhouse Gas Emissions
  • Forests play an important role in removing carbon dioxide from the air through the process of photosynthesis. Photosynthesis is a carbon sink

Any process that takes carbon dioxide from the atmosphere and stores it. Example: As the ocean warms CO2 stored in the cold water is released in the air.

increasing greenhouse gas emissions1
Increasing Greenhouse Gas Emissions
  • Deforestation has decreased the size of Earth’s Carbon sink. The amount of CO2 being added to the atmosphere is more than carbon sinks can remove, there is a net increase in atmospheric CO2.
    • CO2 has increased by 38% in the last 200 years.
quick facts
Quick Facts
  • Human activity accounts for approximately 2% of CO2 production
  • Since 1750, CO2 has increased by 30%, CH4 by 151% and N2O by 171 %
effectiveness of greenhouse gases
Effectiveness of Greenhouse Gases
  • Methane is twenty times more effective at trapping heat than CO2.
  • N2O is 300 times more effective at trapping heat than CO2.
  • CFC’s are several thousand times more effective at trapping heat than CO2
greenhouse gases global warming and climate change
Greenhouse Gases, Global Warming, and Climate Change
  • Climate scientists have concluded that the increased emissions of greenhouse gases by human activity have influenced the global climate.

The anthropogenic greenhouse effect is a change in Earth’s net radiation budget caused by the increase in human-generated greenhouse gases.

greenhouse gases global warming and climate change1
Greenhouse Gases, Global Warming, and Climate Change
  • Temperatures from 1880 to 2008 indicate that the 8 warmest years have all occurred since 1998.
  • The warming trend is known as globalwarming,

The observed increase in Earth’s average annual temperature.

greenhouse gases global warming and climate change2
Greenhouse Gases, Global Warming, and Climate Change
  • Global warming is leading to climatechange,
    • The significant long-term change in expected climate patterns.
slide26

Climate change means that more than just temperature is changing; so are the number and severity of storms, the strength of winds, and the amounts of precipitation, contributing to both floods and droughts. In general, the world is experiencing more extreme conditions

a global problem
A Global Problem
  • An important international organization that has noted the change is the Intergovernmental Panel on Climate Change (IPCC), a group of the world’s leading climate scientists from many countries brought together by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP).
a global problem1
A Global Problem
  • The IPCC has linked global warming to the increase in the amount of greenhouse gases in the atmosphere.
  • If we continue living like we are now, global warming will happen even faster.
human activities contribute to climate change
Human Activities Contribute to Climate Change
  • Both natural processes and human activities can affect carbon sources, carbon sinks, and the anthropogenic greenhouse effect.
  • Example: Forest fires remove the forest carbon sink and add carbon to the air.
human activities contribute to climate change1
Human Activities Contribute to Climate Change
  • The generation of electricity, transportation and industry also produces large amounts of CO2, but lifestyle also contributes to the greenhouse gas.

We live in a disposable society where everything is thrown out. Landfills compress the garbage; bacteria break down the garbage and produce methane gas. By reducing consumption we can help to reduce our carbon footprint.

questions
Questions
  • 1. What do thicker tree rings mean? K (1)
  • 2. Name three greenhouse gases and give one human activity that produces each one. K (2)
  • 3. Where do scientists find the gas samples to analyze in ancient ice? K (1)
  • 4. Define “carbon source” and “carbon sink.”Give two examples of each. C (2)
  • 5. Define the term “anthropogenic greenhouse effect.” Why is it important to distinguish it from the term “natural greenhouse effect”? C (2)
  • 6. List three human activities that contribute to climate change. K (1)