Yes. fossil fuels differ from other fuels in that, when we burn them we are burning carbon that has been sequestered from the atmosphere for millions of years. This adds 'new' carbon dioxide that increases the total atmospheric level of greenhouse gases.
Yes, it's very real!
The industries threatened by global warming are spending tens of millions of dollars on disinformation campaigns to make us believe that man is not causing the climate to warm up. Science historian Naomi Oreskes has done an excellent job of documenting the fact that there has been a continuous scientific consensus in anthropogenic global warming (man is causing the climate to heat up) since 1979. The American Geophysical Union recently did a survey of scientists on this topic. They found that 97% of climate scientists who are actively doing research on the climate all believe that man is causing global warming. Global warming is very, very real.
A closely related phenomenon could end up killing us all. Recent research has shown that 3 of the five mass extinctions in earth's history has been caused when the oceans have gone anoxic (oxygen deprived) and hydrogen sulfide producing anaerobic bacteria has released hydrogen sulfide into the atmosphere killing most forms of plant and animal life. These events have happened when the C02 concentration in the atmosphere reached about 1000 ppm. We are currently at 400 ppm and this is increasing by 3.5 ppm per year -- and the rate of increase in increasing.
well, the ozone layer being depleted does not cool off the atmosphere. Quite the opposite actually. The ozone layer protects the earth from harmful radiation from the sun. Radiation such as UV radiation that contributes to: sunburns, skin cancer, and heating of the atmosphere and ground. Carbon Dioxide CO2 does heat the atmosphere like you said due to it's greenhouse effect. This effect occurs when radiated heat from earth tries to escape into space, but is stopped and reflected back by a barrier of CO2 (similar to what happens in a greenhouse with the glass being like CO2). So your answer is NO. Those two effects cannot cancel each other out.
in the jungle