Which gas is known to have the highest GWP?

The correct choice for the gas with the highest Global Warming Potential (GWP) is indeed HFC-23. GWP is a measure of how much heat a greenhouse gas traps in the atmosphere over a specific time period, typically 100 years, relative to carbon dioxide (CO2), which has a GWP of 1.

HFC-23, or trifluoromethane, has a GWP of approximately 14,800. This number indicates that it is significantly more effective at trapping heat in the atmosphere compared to CO2. HFC-134a, while also a greenhouse gas with a GWP of about 1,430, is much lower than HFC-23.

Carbon dioxide and methane (CH4) also have lower GWPs, with methane around 28-36 times more effective at warming the atmosphere than CO2 over a century but still far less than HFC-23. Therefore, HFC-23 is distinguished as having the highest GWP among the options, emphasizing its pronounced impact on climate change despite its lower concentration in the atmosphere compared to CO2 and CH4.