Here's why:

* Natural causes of climate change are long-term processes that have been happening for millions of years, often on a much larger scale than human-induced changes. These include:

* Volcanic eruptions: Release gases and ash into the atmosphere, affecting solar radiation and cooling the Earth.

* Solar variations: Changes in the sun's energy output can influence Earth's temperature over long periods.

* Earth's orbital variations: Subtle changes in Earth's orbit around the sun can alter the amount of solar radiation received, impacting ice ages and warm periods.

* Plate tectonics: The movement of continents can change ocean currents and alter climate patterns over millions of years.

* Human activity, on the other hand, is a relatively recent phenomenon that has dramatically accelerated climate change. This includes:

* Greenhouse gas emissions: Burning fossil fuels releases carbon dioxide, methane, and other greenhouse gases into the atmosphere, trapping heat and warming the planet.

* Deforestation: Removing forests reduces the Earth's ability to absorb carbon dioxide, further exacerbating climate change.

* Other human activities: Industrial processes, agriculture, and transportation all contribute to greenhouse gas emissions and other climate-altering factors.

Therefore, human activity is the only option that is not a natural cause of climatic change.