Climate change occurs over long, medium, and short terms. Long term climate cycles, like variations in Earth's orbit and axial tilt that occur over tens of thousands of years, influence how much sunlight reaches Earth. Medium term changes over hundreds of years may be linked to solar output variations from sunspot activity levels. Short term volcanic eruptions can temporarily block sunlight with ash particles, lowering temperatures for months or years, like the 1815 Tambora eruption caused a "year without a summer" and famine.