Story Guide
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[Target Audience: 10 years and older]
Quiz game!
Q1: What impact do increased levels of carbon dioxide in the air have on plants and soil?
Q2: Which is the first greenhouse gas that Professor Jackson thinks must be reduced?
Q3: About how long does methane remain in the atmosphere?
Answer
Q1: What impact do increased levels of carbon dioxide in the air have on plants and soil?
Answer: 2. Plant growth increases, but soil carbon can decrease.
When carbon dioxide in the air increases, plants grow faster and the amount of carbon dioxide they absorb increases. At the same time, however, soil microbes become more active, breaking down organic matter such as fallen leaves and releasing nutrients such as nitrogen and phosphorus that the plants need. Through the process of decomposition, part of the carbon containing organic matter returns to the air as carbon dioxide. Therefore, the amount of soil carbon can decrease.
Q2: Which is the first greenhouse gas that Professor Jackson thinks must be reduced?
Answer: 2. Methane
Viewed in the short run, methane is a greenhouse gas that has an approximately 90-fold greater impact than carbon dioxide does. Its atmospheric concentration has been rising rapidly, and it tends to cause photochemical smog as well as negative impacts on health. Therefore, Professor Jackson believes that reducing methane emissions is the first thing to do.
Q3: About how long does methane remain in the atmosphere?
Answer: 2. About 10 years
Although methane is a potent greenhouse gas, it remains in the atmosphere for about 10 years, a relatively short time compared to carbon dioxide. Therefore, reducing methane emissions has the potential to limit the average global temperature increase to 0.5 degrees C within a decade or two.
Important points!
When carbon dioxide in the atmosphere increases, plants grow well, but soil carbon can decrease.
In a short run, methane has a significantly greater impact on global warming than carbon dioxide does (about 90 times more in 20 years).
Methane emissions from natural sources account for only 1/3 of the Earth’s total emissions, and the remaining 2/3 arise from human activities.
Methane is relatively short-lived in the atmosphere, typically remaining about 10 years. Being short-lived means that if we reduce methane emissions, it is possible to reduce the average global temperature increase by as much as 0.5 degrees C within a decade or two.
More details
How do we find "invisible gases?"
Because methane is transparent, we cannot see it. Therefore, instead of trying to find ways of actually seeing methane directly, we use instruments to identify locations where concentrations are higher than they are in the surrounding areas. By doing this, we can locate the sources. Professor Jackson uses different instruments of various sizes to take measurements.
1) Mapping urban pipeline leaks by car (Mobile measurement)
By mounting a highly sensitive measuring device on a car, we can check the air while driving through an area. Methane has no odor, but concentrations can be detected using devices that measure infrared absorption, etc.
For example, when we detect a location with a higher methane concentration than in other areas, it is likely that methane is leaking from somewhere close by. In fact, by driving around in one city measuring methane concentrations, researchers found more than 3,000 spots at which leaks were strongly suspected. In other words, using cars specially fitted with measuring devices is a good way to find methane leakage in urban areas.
2) Finding significant sources of methane leakage using satellites (Satellite measurement)
Using a car to measure methane concentrations is a good way to find small-scale leakage in cities. However, this method, while effective, it limited in scope and is time-consuming. Taking advantage of satellite technology, researchers are able to measure methane concentrations on a global scale to detect large-scale leakage.
Satellites can observe broad areas, and estimate the distribution of infrared reflection and absorption, which allows us to identify areas of high methane concentration. This helps us to find:
▪Areas with high methane concentrations
▪Potential sources in or near areas with high methane concentrations
The greatest advantage of satellite observation is the ability to survey broader areas.
Professor Jackson also places a priority on validating the data received via satellite. Not only identifying locations, but also validating the accuracy of the data is an important part of these studies.
3) Directly capturing daily emissions (Indoor measurement)
Although outdoor surveys conducted using cars and satellites are effective in locating sources of methane emissions in both small and large areas, respectively, Professor Jackson focused on homes, where gas appliances such as cooking stoves and ovens can be a source of methane emissions.
There are two major types of methane emissions:
(1) Leaked methane
If there are gaps on gas appliances and pipes too small to be visible, gas may leak even when the appliances are not in use. This is gas leakage.
(2) Unburned methane
When using a gas stove, methane is burned and changed into carbon dioxide and other gases. However, methane may leak when an appliance is being turned on or off. This is called unburned methane.
Professor Jackson’s team measured the amount of methane that escapes from household gas appliances not only during use, but also when they are being turned on and off, and when they are not in use. The results showed that methane escapes from appliances when they are not in use.
Comparing three methods of obtaining data
| Car surveys | Find small leakage in areas by narrowing down potential locations (Detailed mapping) |
|---|---|
| Satellite surveys | Find relatively large sources of emissions on a global scale (Monitoring cameras) |
| Home surveys | Confirm emissions from homes (On-site validation) |
Professor Jackson combined different methods to detect methane. This shows that the presence and effect of methane is not an abstract concept, but a global issue that affects our lives.