Projections of future climate change vary widely. What is the primary source of uncertainty for how much Earth's climate will warm by the end of the century

i believe that if you say you can, you cant and if you say you can't your right. i believe i can do anything i set my mind to. i've applied this with my everyday life. it me get motivated to do stuff.for example, i apply this to do school. if i believe i can finish a whole class in a couple of week's i will be motivated to do the class until i finish it, and if i believe i can't, i will get distracted and do other stuff besides doing my work. it changed me by believing i can accomplish anything i set my mind to.

question

which are human systems?

the amazon rain forest

the appalachian trail

the george washington bridge

the himalayas

the hoover dam

the north american free trade agreement