Climate change occurs when changes in Earth’s climate system result in new weather patterns that last for at least a few decades, and maybe for millions of years. The climate system comprises five interacting parts, the atmosphere , hydrosphere , cryosphere , biosphere , and lithosphere .
The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth’s energy budget.When the incoming energy is greater than the outgoing energy, earth’s energy budget is positive and the climate system is warming.
As this energy moves through Earth’s climate system, it creates Earth’s weather and long-term averages of weather are called “climate”. Such changes can be the result of “internal variability”, when natural processes inherent to the various parts of the climate system alter Earth’s energy budget.Climate change can also result from “external forcing”, when events outside of the climate system’s five parts nonetheless produce changes within the system.
Human activities can also change earth’s climate, and are presently driving climate change through global warming. The first describes the average effect on a global scale, whilst the second describes how different geographical regions are affected differently.
Physical evidence of current climate change covers many independent lines of evidence, a few of which are temperature records, the disappearance of ice, and extreme weather events.
