Final answer:
The word 'uncomfortable' is used to present heat waves as a problem, and evidence of high death tolls from past heat waves is provided to support this idea.
Step-by-step explanation:
The author uses the word uncomfortable in the first sentence to present heat waves as a problem. To support this idea, the author includes evidence of high mortality rates associated with heat waves, mentioning significant events where heat waves have caused numerous deaths. These include the 2003 heat wave in Europe that resulted in about 50,000 deaths and the 1995 heat wave in Chicago that led to more than 600 deaths. The author further emphasizes that heat waves cause more deaths annually in the United States than several other natural disasters combined, such as hurricanes, tornadoes, floods, and earthquakes.