9. Which of the following is used as evidence for global warming?

chemicals in estuaries (mouth of large river where the tide meets the stream)

global glacier mass

ocean masextinction

algal blooms in freshwater areas

global glacier mass

Explanation:

The shrink or reduction in the volume of the global glacier mass is one of the evidence of global warming.

By definition, global warming is the rise in global temperature associated with increase in the concentration of greenhouse gases such as carbon dioxide, methane, nitrogen, etc.

The gases naturally form a blanket layer over the earth's atmosphere and are responsible for preventing some of the sun's reflected radiation after reaching the earth from returning back to space. They absorb some of the radiations and warms up the planet in the process.

An increase in the concentration of these gases means that more radiation is absorbed from the sun, thus causing an increase in the amount to warming the earth gets. This increase in the amount of warming is what is termed global warming.

One known consequence of the increase in global temperature as a result of global warming is the melting of glacier mass. Glaciers are prone to melting with increase in temperature and the water derived from such melting are discharged into seas and oceans, causing a rise in their levels.