The document discusses several factors that influence global temperature change: 1) Increased greenhouse gas emissions like carbon dioxide trap heat and have warmed the planet about 1 degree Celsius over the past century. 2) Sulfate aerosols from burning fossil fuels once had a cooling effect but regulations have reduced their impact. 3) The urban heat island effect makes cities several degrees warmer than surrounding rural areas due to lack of vegetation and heat-absorbing structures. 4) Thawing permafrost releases methane, a powerful greenhouse gas, which could further accelerate global warming through a feedback loop.