More than $70\%$ of the world's freshwater is contained in $............$.

The periodic change in temperature in the Pacific Ocean is known as .............

$A$: $El$ $Nino$ is a climatic change which causes deleterious environmental changes.
$R$: Increased tropospheric ozone due to $El$ $Nino$ causes a shift of climatic regions.

The pesticide used as a preventive measure in buildings is

Select the appropriate option regarding the natural aging of a lake.

Human activities interfere with the carbon cycle. List any two such activities.