Tomizuka (2015) introduces the concept of radioactive forcing, which is the size of greenhouse gases contributing to global warming index. In turn, this enhances understanding of the impact of each greenhouse gas to the global warming concept. The researcher reports that from 1750 to 2011, the concentration of each of the three greenhouse gases (carbon dioxide, methane, and nitrous oxide) has increased significantly in the atmosphere, as depicted in Table 2 below (Tomizuka, 2015).
Table 2: Increase in GHGs over the years.
Greenhouse gas
Concentration (PPMV)
Radioactive forcing
Global warming potential

2011
2017
Average (Wm-2)
20 years
100 years

Carbon dioxide
278
390.5
1.82
1
1

Methane
0.722
1.803
0.48
84
28

Nitrous oxide
0.270
0.324
0.17
264
268

Figure 2 further emphasizes the important finding that, in addition to industrial and commercial processes, residential and commercial activities were also reported to contribute to at least 11% of the greenhouse gas emissions. Different researchers have also reported similar findings, observing that the residential sector (cities and urban centers) is supposed to account for at least 78% of greenhouse gas emissions (Lin et al., 2013). The researchers add that household activities are identified as the main drivers of energy use and related emission of GHGs (Lin et al., 2013). In particular, Hong and Howarth (2016) reveal that domestic heating applications, such as hot water systems, are the main sources of carbon dioxide and methane gas emissions considering the residentials’ contribution. Household emission of GHGs also originates from our daily activities such as burning gasoline as we drive, using electricity which originates from coal, oil, or natural gas (IPEA). The emissions consist mainly of CO2, which is about 80% of the total household emission and methane and nitrous, which each constitute (6%) of residential GHG emissions.