1.of course, there are! environmental pollution, global warming,deforestation, etc.
2.it seems to me that the most serious problem is environmental pollution.people definately dont understand what can it be aftermaths.we will not survive , for example, without air, but at ate same time people persistently continue to pollute it by factories, petrol wastes , etc.
3.to save the Earth , firstly, start from yourself. stop to throw out the rubbish wherever you want, if it's possible, then try to use car less.
4 if i can do this, i would invent clean factories which cant hurt the atmosphere.