Final answer:
The Little Ice Age was a cooler climate period in the Northern Hemisphere lasting from the 14th to the 19th century, succeeding the warmer Medieval Warm Period. Earth's history also includes glacial cycles and the IGY which contributed to the space race. The seasons occur due to Earth's 23.5° tilt, which results in varying sunlight exposure during its orbit around the Sun.
Step-by-step explanation:
Throughout Earth's history, climate patterns have shifted due to natural causes affecting the Northern Hemisphere. Notably, during a period called the Little Ice Age which spanned from the fourteenth century to approximately 1850, temperatures were cooler than the centuries before and after. This period followed the Medieval Warm Period that began in the tenth century.
Our planet has also experienced repeated glacial cycles with continental glaciers extending as far south as 40° latitude in the Northern Hemisphere during ice ages. The most recent glaciation period occurred eighteen thousand to one million years ago, profoundly impacting sea levels and landscape.
Another significant event impacting our understanding of Earth's geophysics was the International Geophysical Year (IGY) which took place between 1957 and 1958. During IGY, numerous scientific studies were coordinated globally, including research on high altitudes and the launch of the first Earth-orbiting satellite which marked the beginning of the space race.
Our seasons are caused by Earth's tilt, with the axis tilted by 23.5°. As Earth orbits the Sun, different hemispheres lean towards or away from the Sun at various times of the year, resulting in summer and winter seasons. Due to this tilt, the Northern Hemisphere experiences summer when it leans into the Sun in June and winter when it leans away in December.
In the distant future, due to the axial precession, the orientation of Earth's axis will be such that in the current position of the Northern Hemisphere's winter, there would be summer instead. This gradual shift happens as Earth's axis moves around a cone over a 26,000-year cycle.