The correct matches are:
1. Greenhouse gases - Trapping of heat on Earth
The greenhouse gases, especially the CO2 and the methane, have properties that enable them to trap the heat in the atmosphere. So the more there is from these gases in the atmosphere, the bigger the temperature will be on the Earth.
2. Chemicals released in river - Unsafe drinking water
The chemicals that are released in the rivers result in polluted waters that are unsafe for usage, especially not for drinking. Because of the releasing of chemicals thousands of rivers have been led to a state where their waters can not be used for drinking, and considering the limited amount of freshwater, that is very alarming.
3. Excess usage of land for agriculture - Fragmentation of forests
In order to be made more land available for agriculture, the forests are cleared. During that the process, the forests are totally destroyed, and the process is constantly going on, which is why more than half of the forests in the world have already been destroyed, and probably the percentage will increase as things are going.
