Final answer:
The initial input of energy driving the global climate cycle comes from the Sun, with solar energy fueling processes like the hydrological cycle, wind generation, and photosynthesis. Greenhouse gases increase atmospheric temperature, leading to various climate feedbacks. Human activities significantly contribute to current climate changes by increasing greenhouse gas concentrations.
Step-by-step explanation:
The initial input of energy driving the global climate cycle is predominantly from the Sun, which deposits energy onto the Earth's surface at a rate of 240 W/m², averaged over the surface. Approximately 70% of this incoming solar energy is absorbed by the Earth's atmosphere and land, with the remainder being reflected back into space. Of the energy absorbed at the Earth's surface, about half goes into evaporating water, thereby powering the hydrological cycle, while smaller portions fuel wind generation, photosynthesis, and ocean currents. The input of energy from the Sun sets in motion a series of natural climate feedback mechanisms that regulate Earth's temperature and climate system.
Over time, the additional energy input from greenhouse gases has started to heat the Earth's environment to a higher average temperature, which leads to an increase in the radiation being emitted by the ground. Increased temperatures can also lead to positive feedback effects that raise the atmospheric concentrations of these gases and the absorption fraction, further impacting the global climate cycle. Additionally, human activities, such as the burning of fossil fuels and deforestation, play a crucial role in the current climate change by contributing to the accumulation of greenhouse gases in the atmosphere.