Final answer:
The article's main argument is that glaciers are receding worldwide due to global warming and climate change, which leads to significant environmental impacts. This is supported by examples of shrinking glaciers, temperature increases, and geological evidence.
Step-by-step explanation:
The main argument presented in part b of the article about glaciers is that global warming and climate change have led to the significant reduction of glacier sizes and mass worldwide. This phenomenon, referred to as glacier recession, is evidenced by the retreat of glaciers in various places, such as Glacier National Park in Montana and the volumetric ice loss in Greenland and Antarctica. The article highlights that glaciers provide critical seasonal water supplies and that their loss severely impacts local ecosystems.
Examples such as the McCarty Glacier in Alaska, which completely disappeared between 1909 and 2004, and the Grinnell Glacier, which saw a size reduction of 40 percent between 1966 and 2005, underpin the argument. These changes are linked to an increase in mean annual temperatures, such as the 1.33°C rise recorded in Glacier National Park since 1900. In addition, glacier retreat leaves a geological record of their former presence, as observed in the moraines and altered landscapes once covered by ice.