The variation of the Earth’s movements (orbital, tilt, and precession) and climate change

The Earth’s orbit and rotational axis change with time due to the gravitational interactions between the Sun, planets, moons, and asteroids of our solar system. These changes have considerable impact on the spatial and temporal distribution of solar radiation at the Earth’s surface and hence forces climate to change on timescales from 10 to 100, 000 of years. Using climate models and high-resolution climate proxy records, astronomical-forced climate changes can be studied in detail to constrain the physical processes (e.g., time lags and feedbacks in the climate system) behind Ice Ages, variations in monsoon strength, and the occurrence of extreme global warming (i.e., hyperthermal) events as presented in this chapter. In particular, the astronomical pacing of hyperthermal events during the highly elevated greenhouse conditions of the early Eocene, 56-48 Ma, shows that the Earth’s climate is also far from stable in a hothouse world, due to vital feedbacks in the carbon cycle, such as the release of methane clathrates. With the fast-rising CO₂ concentrations in the atmosphere, it is hence crucial to better constrain these feedback mechanisms and their impact on the Earth’s system and climate sensitivity by developing and testing a new-generation Earth system models and proxy records that can resolve the astronomical forcing of these hyperthermal events.