Where was the $UN$ Climate Change Conference held in $2012$?

Which of the following is not an effect of global warming?

Assertion : The concentration of methane in the atmosphere has more than doubled in the last $250$ years.
Reason : Wetlands and rice fields are the major sources of methane.

World Environment Day is celebrated on

$A$ lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this:
$1.$ Lots of urea and phosphate fertilizer were used in the crops in the vicinity.
$2.$ The area was sprayed with $DDT$ by an aircraft.
$3.$ The lake water turned green and stinky.
$4.$ Phytoplankton populations in the lake declined initially,thereby greatly reducing photosynthesis.
Which two of the above were the main causes of fish mortality in the lake?

At the beginning of the twentieth century,forests covered about ........... of the land area of India. (in $\%$)