Answer to Question 1
Humans are part of the natural world, and human populations are subject to processes such as birth and death. Even though the Millennium Ecosystem Assessment recognizes humans as an integral part of ecosystems, there are some differences between humans and other organisms that make our role in ecosystems different from that of others. One major reason humans are different from other populations is that we have a global population that acts like a whole unit. We are also unique in our ability to control our reproduction, use fire, store food for longer times, and adapt our environment with technology so we can live in more places. It is difficult to determine a carrying capacity for humans because we have the ability to increase our carrying capacity in the short term with technological advances. It is also difficult to determine at what standard of living to judge carrying capacity since there are so many lifestyle levels throughout the global population.
Answer to Question 2
The responses to this question will be very individual. Personal changes to lower an individual's contribution to climate change would include all aspects of energy and resource conservation. Taking shorter showers, taking showers instead of baths, and turning off water while brushing teeth and shaving save energy (water heating, pumping, and water and sewage treatment), turning off lights and other electrical equipment saves electricity (especially important if the energy source is coal), reducing the quantity of food wasted (less fuel needed for production, processing, transport, cooking, etc.), purchasing the most energy-efficient model when buying appliances, walking or riding a bicycle, carpooling, taking the bus or train, reducing air travel, considering if a purchase is even necessary (saves resources and energy in extraction, production, use, and disposal), living in a smaller house, and planting native plants (fewer pesticides and fertilizer, no water).
Interaction web of factors that might influence locust population size.
A simplified diagram of the Human Ear
Baby Gorilla versus Baby Human
Population Projections of the United States
Two ways of generating genetic variation in meiosis
Conventions commonly encountered in human pedigrees