Peer Reviewed Annotated Sources

Daily, Grechen C., and Paul R. Ehrlich. "Population, Sustainability, and Earth's Carrying Capacity: A framework for estimating population sizes and lifestyles that could be sustained without undermining future generations." Population, Sustainability, and Earth's Carrying Capacity:. Web. http://dieoff.org/page112.htm

The population is growing at an annual rate of 1.7%, which will approximately add up to 93 million people this year.
In this paper they define carrying capacity as the maximal population size of a given species that an area can support without reducing its ability to support the same species in the future. Specifically, it is "a measure of the amount of renewable resources in the environment in units of the number of organisms these resources can support". "Carrying capacity is a function of characteristics of both the area and the organism. For humans, the matter is complicated by two factors: substantial individual differences in types and quantities of resources consumed and rapid cultural (including technological) evolution of the types and quantities of resources supplying each unit of consumption. Thus, carrying capacity varies markedly with culture and level of economic development."

McDougall, Rosamund. "Climate Change & Population." Optimum Population Trust. 3 Oct. 2009. Web. http://www.optimumpopulation.org/opt.more.climate.html 24 Feb. 2010.

In the end of 2007 there was still little doubt that the world's 6.8 billion people are under serious threat from global warming and that urgent action must be taken. "There is now both scientific and political consensus that greenhouse gases trapped in the Earth’s atmosphere are due largely to human activities, and that "deep emissions cuts" must take place within as little as a decade to curb warming of our atmosphere, land and sea. If this is not done, further rises in the Earth’s temperature caused by the greenhouse effect may cause dangerous and irreversible climate change." Global surface temperature averaged 14 degrees Celsius in the 20th century. The rate of increase tripled in the last 25 years, faster each time.
population affects because we are overpopulating and instead of more of us becoming aware & helpful to the environment we all remain ignorant, letting ourselves get fooled by people who try to cover this up.
"According to the UN population projections revised in 2006: "A fertility path half a child below the medium would lead to a population of 7.8 billion by mid-century." If the world's mothers reduce the number of children they have accordingly, there could be 1.4 billion fewer climate changers in 2050 - equivalent to the whole population of China."
Humans cause the problem we have to be part of the solution as well.