Historically,
1.earth's climate has been stable since the atmosphere was formed
2.earth's climates have changed and a likely to change in the future
3.earth's climate was stable all along until in the last century
4.earth's climates have a very predictable cycle

The correct answer is - 2. Earth's climates have changed and are likely to change in the future.

From what is known for the geologic past of the Earth, our planet's climate has been changing numerous times. The climate on the planet has varied from being predominantly wet tropical climate, to having ice ages, having multiple different climate types at the same time... The reasons for the changes in the Earth's climate are numerous, with the Sun's radiation, tectonic movements and activities, volcanic activity, outside influences like asteroid and meteorite collisions, the vegetation, and all of them have managed to create a very colorful climate history of the planet. This trend of climate change should continue in the future as well, as all of the aforementioned factors are still influencing the climate and on top of that the humans have become a factor in the climate change too.