Welcome to Physics Forums, ambzrose!
It is believed that much of the increase in CO2 concentrations in the atmosphere is a result of human activity (e.g., burning of fossil fuels, burning of forests, etc.). Of course, there are natural sources of CO2 as well and if you bring this question to the Earth Sciences subforum, you'll be sure to get a spirited debate on the subject.
The thinning of the ozone layer means that more ultraviolet radiation (from sunlight) can reach the ground. UV light is damaging to many organisms (for example, skin cancer in humans). Again, lots more details can be provided once we move this topic to the Earth Sciences forum.
Life, generally speaking, will surely adapt to such new conditions. The big question is how the new conditions will suit us and other species. Little change? Decline in quality of life? Major mass extinctions? Some moderate benefits as well as drawbacks?
The mainstream consensus sees it causing significant drawbacks/problems, but there's a broad range of predictions.