In the past, human activities   61   (have) little effect on global warming, but now

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.

61. had       62. from       63. called       64. has increased/has been increasing  65.attitudes 

66. while       67. cooler     68. which     69. Actually          70. to reduce