1. Understanding Earth’s energy balance is essential to understanding the issue of global warming. For example, the solar energy striking Earth’s surface averages 168 watts per square meter (W/m2), but the energy leaving Earth’s surface averages 390 W/m2. Why isn’t the Earth cooling?
Due to the greenhouse effect, the atmosphere will absorb and re-radiate energy back to Earth’s surface.
Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate energy in all direction.
Most of this re-radiation will fall back on Earth’s surface and thus contribute to warming the Earth’s surface. This is how we achieve Earth’s energy balance and hence Earth will not cool down.
2. “The winter has lowered my concerns about global warming…”. Do you think the statement made by the cartoon is justified? Explain.
No, this statement is not justified. The cartoon shows that people are ignorant and unaware of global warming. It does not mean that the earth is getting colder just because there are winter days. Global warming has led to extreme weather changes. Some parts of the world are experiencing snowing repeatedly, while other parts are very warm. For instance, certain parts are experiencing droughts, heatwaves, fire and floods. Thus there will still be snow in certain parts of the globe, but the average climate is getting warmer. Hence the global surface temperature is generally increasing and global warming must be a concern.
3. One of the first radar devices developed during World War II used microwave radiation of a specific wave range that triggers the rotation of water molecules. Why was the design not successful?
As the war dragged on, American military scientists tried to find ways of producing more powerful microwaves. Led by Dr. Charles Townes, these researchers found that microwave radiation does not work very well for radar because the waves are too easily absorbed by water vapor in the air; and as the beam travels farther more of it gets absorbed, so it gets too weak to do any good. But in a way, these experiments had not failed. They had made Townes very interested in learning more about microwaves, research that would eventually lead to the laser.
4. Now that you have studied air quality (Unit 1), stratospheric ozone depletion (Unit 2), and global warming (Unit 3), which do you believe poses the most serious problem in the short run? In the long run?
We believe that in the short run, air quality would pose to be the most serious problem. This is because changes in air quality have widespread effects and most of them are immediate. An example would be the haze that affected Singapore, Malaysia and Indonesia. The drop in air quality due to the haze could be seen instantly with the appearance of fogs. Not only that, everyone’s health was affected as they breathed in the polluted air. It was reported that there was a higher incidence of people visiting the doctors for respiratory problems and eye irritation during the haze period. On top of being a health hazard, the haze also affected the transportation industry especially so in Indonesia as flights are disrupted due to poor visibility. This would also affect other industries such as tourism and even business. Hence, as seen from how extensive and immediate the effects of the haze could be, air quality would likely pose to be the most serious problem in the short run.
As for the long run, we believe that air quality, ozone depletion and global warming would all pose to be a serious problem.
- This is because common pollutants such as CO2, SO2, Nitrogen oxides, CH4 and halogenated organics have health consequences like asthma, cancer and liver, kidney and central nervous system damage if humans constantly breathe the pollutants. Acid rain may also occur from NOx and SOx.
- Ozone depletion will increase UV exposure and may cause skin cancer.
- The common pollutants can also absorb IR radiation and thus trap heat as a greenhouse gas. This will then raise the Earth’s temperature causing global warming. Global warming have serious consequences such as extreme weather, rising sea levels and mass extinction.
All of these consequences are not reversible and can only be slowed down if companies producing large amounts of the pollutants view sustainability as a business strategy. Most of the pollutants are caused by humans activities as such change depends on us.