The lowermost layer of earth’s atmosphere (called the lower troposphere) ranges from ground level to about five miles (8 km) high. Satellite data correlated and adjusted by the National Space Science and Technology Center at the University of Alabama Huntsville shows that the average temperature of the lower troposphere increased by about 1.0F (0.6C) between the 1980s and the most-recent decade from 2015 to 2024. This increase is greater than the range of measurement uncertainty. For context, a temperature analysis of a glacier in Greenland found that it was about 22F colder during the last ice age than it is now. Some studies suggest the earth is warmer now than it was 1,000 years ago, while others indicate the opposite. Over the longer-term, a college textbook explains that “Earth’s climate has fluctuated substantially - from temperatures that were much warmer than those of the modern climate to much colder temperatures,” and such shifts often occurred “in far less than 100 years.”