is there any warning system for the first source mentioned above?
Yes, USGS has adopted such a system.
Volcano
The United States Geological Survey (USGS) has adopted a common system nationwide for characterizing the level of unrest and eruptive activity at volcanoes. 
what is rhodotus? Genus in the fungus family Physalacriaceae. is it edible? No where is it found? Eastern North America, northern Africa, Europe, and Asia. is it endangered in any way? Yes, critically endangered. what is the criteria for this status? Increase in levels of air pollution. which are the common contributors to this type of pollution? Gases, particulates, and biological molecules. what are the sources of the second one? Volcanoes, dust storms, and burning of fossil fuels in vehicles.
wiki:19579145
Volcano [SEP] Volcano warning schemes of the United States
The United States Geological Survey (USGS) has adopted a common system nationwide for characterizing the level of unrest and eruptive activity at volcanoes. The new volcano alert-level system classifies volcanoes now as being in a normal, advisory, watch or warning stage. Additionally, colors are used to denote the amount of ash produced.