Firstly, let's compare production process between paper bags and plastic bags.
Plastic bags is made from a by-products of oil refining which only contain 4% of total world oil amount. There are various steps to turn plastic into final products. To make bags, machines heat polyethylene to nearly 200 Celsius to extrude, and then go to printing process with ink, cutting, sealing then packaging. Apart from fuel burning, heavy machinery, used in the acquisition of oil, the entire process of plastic bags just uses electricity.
Whereas, look at the process of making paper bags. It starts with selected trees found, marked and felled. Then road from forest to paper factory need to be built to transport, move timber to manufacturing location. This creates huge impact on the forests natural habitat including plants as well as creatures. Once timbers reach mill, it take 3 years for proper drying before they can be used. Then it will be put under tremendous heat and pressure. After this process, they are "digested" with a limestone and sulphurous acid for eight hours. This team and moisture come from this will expel into outside atmosphere. Then, pulp will be washed and bleached with tons of clear water. So, briefly, the whole process of making paper will take a huge amount of wood, electricity, water, fuel and even emission of harmful exhaust which worse for environmental rather than producing plastic.
Secondly, look at where plastic and paper will go after used and compare its impact on environment.
Paper bags after used it can be thrown away or recycle. If it goes to the land, it will be easily decayed. Otherwise, it will go to recycle process which contains various steps. In recycling process of paper, it will need using many different chemicals, such as sodium hydroxide, hydrogen peroxide, and sodium silicate to bleach, clean contaminants, and water to remove ink...
There are also 2 ways for plastic bags after used. One is going to landfill and the other is recycling. Once plastic go to landfill, it is said to take hundreds of years to degrade totally, however, actually only 3% of overall plastic bags all over world are really plastic. Moreover, plastic bags actually very thin with 0.008mm to 0.03mm, therefore the big volumes in landfill is not huge as people think (about 18%) Furthermore, it is said that plastic is used only for 1 time because of its cheap price and convenience; actually people tend to reuse plastic bags because of its durability, tough, strength. Especially high class products such as rigid handle bags, soft loop handle bags, die cut bags, etc with beautiful printing images is mainly reused times and times. Therefore, compare with paper bags, plastic bags have longer life service and less bad impacts to environment. Besides, plastic bags now has been improved with alternative material made from starch called biodegradable plastic bags which can be totally degrade within 3 months or 6months with the same characteristics as normal plastic.
Protecting environment is each person' responsibility, therefore, let's be rational to make better choice when you want to use bags. People normally can not omit products which bring them convenience, so let's choose what is best for you as well as for environment.