The following are answers to the questions posed on the ECU's Climate Fest Quiz Walk in May 2016.
What is the greenhouse effect caused by?
- Greenhouse gases in the lower atmosphere absorbing solar radiation
- Greenhouse gases in the lower atmosphere absorbing radiation from the Earth's surface, and preventing much of it escaping into space
- Too much heat in the atmosphere
- Too much sunshine reaching Earth
b) Greenhouse gases in the lower atmosphere absorbing radiation from the Earth's surface, and preventing much of it escaping into space. The greenhouse effect simply describes the fundamental role our atmosphere plays in sustaining life on Earth. Energy from the sun in the form of sunlight passes through our atmosphere and warms the surface of the Earth which then emits the energy back into the atmosphere in the form of infrared radiation. Greenhouse gases, which make up only about one per cent of the atmosphere, absorb and re-emit some of this heat, preventing much of it leaving the Earth's atmosphere. This keeps the blue planet at a comfy temperature to sustain life.
But over time, climate scientists argue, our atmosphere has accumulated more greenhouse gases, in particular carbon dioxide, methane, nitrous oxide and fluorocarbons. This increased concentration of atmospheric gases traps more heat close to the Earth's surface in the lower atmosphere and increases the average global temperature. This process, called the 'enhanced greenhouse effect', is fundamental to global warming.
The IPCC assesses with very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming. Computer climate models estimate that the average global temperature will rise by a further 1.8oC to 4.0oC by the year 2100.
Which of these natural events affect the climate?
- Thawing permafrost
- The path of the Earth around the sun
- Volcanic eruptions
- All of the above
d) All of the above. Peat bogs (wetland that accumulates peat- a deposit of dead plant material) play an important role in maintaining climate. Permafrost in the Northern Hemisphere is an important carbon sink but when it thaws exposing peat bogs, captured carbon and methane is released into the atmosphere. The greenhouse gases released from peat bogs can amplify climate change.
Changes in the Earth's orbit around the sun can also affect the climate. These changes, as well as changes in the tilt of the Earth on its axis, are part of what are known as Milankovitch cycles, which are linked to the timing of ice ages.
Volcanic eruptions have been known to greatly affect global temperatures in the past — the 1815 eruption of Tambora caused 'The year without a summer' in 1816 — ash, rock and sulphur particles in the atmosphere increased cloud cover and reflectivity (albedo), causing widespread global cooling.
Which of these greenhouse gases has the highest ability to retain heat in the atmosphere?
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
- HFCs and PFCs
d) HFCs and PFCs have the highest ability to retain heat in the atmosphere. They have a global warming potential (GWP) of 12-14800 (depending on the exact chemical) times that of carbon dioxide.
Hydrofluorocarbons are used as refrigerants, aerosol propellants, solvents, and fire retardants. The major emissions source of these compounds is their use as refrigerants--for example, in air conditioning systems in both vehicles and buildings. These chemicals were developed as a replacement for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) because they do not deplete the stratospheric ozone layer. Chlorofluorocarbons and HCFCs are being phased out under an international agreement, called the Montreal Protocol. Unfortunately, HFCs are potent greenhouse gases with long atmospheric lifetimes and high GWPs, and they are released into the atmosphere through leaks, servicing, and disposal of equipment in which they are used.
Perfluorocarbons are compounds produced as a by-product of various industrial processes associated with aluminum production and the manufacturing of semiconductors. Like HFCs, PFCs generally have long atmospheric lifetimes and high GWPs.
In what order are these greenhouse gases most abundant in the atmosphere, going from most to least abundant? Carbon dioxide (CO2), Methane (CH4), Ozone (O3), HFCs and PFCs, Water vapour (H2O)
- H2O, CO2, PFC's/HFC's, O3 and CH4
- CO2, H2O, CH4, PFC's/HFC's and O3
- H2O, CO2, CH4, O3, and PFC's/HFC's
- CO2, H2O, CH4, O3, and PFC's/HFC's
c) H2O, CO2, CH4, O3, and PFC's/HFC's
Water vapour is the most abundant greenhouse gas in the atmosphere. As the Earth's atmosphere warms, more water evaporates from oceans and ground sources, which in turn heats up the atmosphere further and continues the cycle. The amount of water vapour varies depending on weather all around the world.
Carbon dioxide (CO2) is the next most abundant gas, followed by methane, ozone and last PFC's/HFC's.
So if carbon dioxide isn't the most abundant gas, why are climate change scientists so concerned about carbon dioxide? While methane actually has a much stronger warming effect than carbon dioxide, carbon dioxide so much more abundant that it is responsible for over 60% of the enhanced greenhouse effect. It can also stay in the atmosphere a lot longer than methane, with a lifetime of up to 200 years as opposed to methane's 12 years. Burning of fossil fuels is releasing carbon into the atmosphere at a faster rate than it can be absorbed. Since we started burning fossil fuels we have increased the concentration of carbon dioxide with 43% in just about 260 years.
(400 ppm (concentration 2015)- 280 ppm (concentration in preindustrial times)) → 43%
280 ppm (concentration in preindustrial times)
Another concern with the greenhouse gases CFCs, HFCs and PFCs is that they are ozone depleting. Although the ozone layer is a greenhouse gas, it is essential for all life on earth because it protects us from harmful UV rays from the sun. It is therefore imperative that we protect the ozone layer. This has been acknowledged by the Montreal Protocol, an international agreement to protect the ozone layer. More than 160 nations have ratified this agreement on decreasing and eliminating ozone depleting substances.
What greenhouse gas was not present in the atmosphere in pre-industrial times (before the 1750's)?
- Carbon dioxide
- Nitrous oxide
a) Trichlorofluoromethane is a type of CFC (Chlorofluorocarbon), which is the predecessor of HCF's and PFC's. Fluorocarbons were not present in the atmosphere before the 1750's. Today trichlorofluoromethane is present in the atmosphere at 242 to 244 parts per trillion (ppt).
Since the industrial revolution concentrations of pre-existing greenhouse gases such as carbon dioxide, methane and nitrous oxide have also risen significantly. For example, in 1750, the average concentration of carbon dioxide was 280 parts per million (ppm), in 2015 it was 400 ppm.
Why is planting of trees/ preserving forests one of the ways to deal with climate change?
- Trees emit natural chemicals called terpenes that break down greenhouse gases
- Trees produce oxygen and thus decrease all the other concentrations of greenhouse gases
- The trees absorb carbon dioxide as they grow and therefore decrease some of the carbon dioxide in the air
- All of the above
c) All living beings on earths are carbon based. Plants photosynthesize and take up carbon dioxide from the air and produce oxygen that we breathe. As the plants, particularly trees, grow they bind more and more carbon dioxide from the air in their stems, branches and leaves. Land use is therefore an important matter relating to climate change. Humans have cleared a lot of forested land, which has an impact because less trees are now able to absorb the carbon dioxide that is emitted from various sources. If we replant bare areas with trees we are actually decreasing carbon dioxide emission levels.
About one half of the forests that covered the Earth are gone. Each year, another 16 million hectares disappear. The World Resources Institute estimates that only about 22% of the world's (old growth) original forest cover remains "intact" - most of this is in three large areas: the Canadian and Alaskan boreal forest, the boreal forest of Russia, and the tropical forest of the northwestern Amazon Basin and the Guyana Shield (Guyana, Suriname, Venezuela, Columbia, etc.)
Which of these countries has the highest per capita carbon dioxide emissions?
- United States
- Saudi Arabia
b) Australia. The bulk of greenhouse gas emissions arise from the countries at the centre of global economic activity. As political entities, the largest emitters are China, the United States and the European Union, which between them are responsible for more than 40 per cent of global emissions.
But on a per capita basis, Australians lead the world when it comes to carbon dioxide emissions from activities excluding land use or forestry (forestry-related emissions are subject to large uncertainties in many of the main emitting countries), according to the Garnaut Climate Change Review.
Each year, every Australian emits 26 tonnes of carbon dioxide. Per capita, Americans emit 24.5 tonnes, Saudi Arabians emit 16.5 tonnes and the Chinese emit 5 tonnes.
Which of the following activities contributes the most to carbon emissions globally?
- Energy supply
d) Energy supply. According to the IPCC energy supply contributes over a quarter (25.9%) of carbon emissions followed by industry (19.4%), forestry (17.4 %), agriculture (13.5%), transport (13.1%), residential and commercial buildings (7.9%), waste and wastewater (2.8%).
In research published in Nature scientists claim we have a good chance of stabilizing global warming below 2oC if the world's total carbon dioxide emissions from 2000 to 2050 don't exceed 1 ,000 billion tonnes. How much carbon dioxide did the human race emit between 2000 and 2006?
- 94 billion tonnes
- 234 billion tonnes
- 446 billion tonnes
- 820 billion tonnes
b) Globally we added 234 billion tonnes of carbon dioxide into the atmosphere between 2000 and 2006. In other words, we've already emitted close to one quarter of our fifty year 'allocation' in less than a decade. If carbon dioxide emissions remain at this high level, we'll have exceeded the sub 2oC target before 2030.
What can you as individual do to decrease GHG?
- Choose to buy local foods and products instead of imported such and minimize your shopping of clothes, electronics etc.
- Show your support for developing and adopting Dominica's environmental laws
- Minimize your plastic and Styrofoam consumption
- All of the above
d) All of the above. When you choose to buy local foods and products instead of imported you are “saving” emissions because the imported products and foods are often imported from far away and both the production and transportation are emission sources of greenhouse gases. Another upside to choosing local is that you boost your country's economy, which is a gain to all citizens in the end.
Plastic and Styrofoam are made from oil and oil is a fossil fuel. Fossil fuel is pressurized carbon that has been tucked away into the depths of the earth for millions of years and would not have been released unless man did not drill and pump it up from the earth. Oil and its refined products (such as gasoline and plastics) are not only a source of carbon dioxide- they are also cancerous, making it a danger for human and environmental health.
Showing your support and action for making sustainable choices is very important because it shows the decision makers that are responsible for making policies, strategies, plans and legislation, that the citizens prioritize a sustainable development. You can show your support by living in a sustainable way: reducing your use of products, chemicals and so on that are harmful to the environment, raising your voice in forums concerning environmental issues, for example articles in online newspapers, calling in to radio shows to show your environmental concerns, joining ecological and sustainable movements, educating yourself within these areas as well as informing others, choosing ecological unsprayed foods before foods that have been grown or produced with pesticides, limiting your consumption of products not really needed and much, much more. By making these conscious choices you are showing that you are aware that we need to use our resources better than we have been doing and that it is a priority for you.