In the past, human activities 61 (have) little effect on global warming, but now they have caused the rise of the earth temperature. All scientists agree that the increase in the temperature results 62 the burning of fossil fuels. One of some byproducts 63 (call) greenhouse gases is carbon dioxide which can trap more heat energy in the atmosphere.
Over the last 100 years, the temperature of the earth 64 (increase). The 65 (attitude) towards this rise are completely different. Some are positive 66 others are negative. Those who are positive think that without the greenhouse gases the earth would be 67 (cool) than it is, 68 would not be suitable to live on. Others think the rise of the earth temperature may cause severe storms, floods, droughts and so on.
69 (actual), green house gases will continue to build up in the atmosphere. Luckily, we human beings are doing what we can 70 (reduce) green house gases. More importantly, individuals can make a difference.