Glossary of Climate Change - I

I

• Ice age - a period of long-term reduction in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and alpine glaciers.
• Ice core - a core sample from the accumulation of snow and ice over many years that have re-crystallized and have trapped air bubbles from previous time periods.
• Insolation - amount of solar radiation reaching the surface of the Earth.
• Invasive Species - introduced species that adversely affect the habitats and bioregions they invade economically, environmentally, and/or ecologically.
• Irradiance - amount of electromagnetic radiation reaching a surface, measured in watts per square meter.
• Instrumental temperature record - shows the fluctuations of the temperature of the atmosphere and the oceans as measured by temperature sensors. The longest-running quasi-global record starts in 1850.
• Interdecadal Pacific Oscillation (IPO) - a cycle of 15–30 years between warm or cool waters in the north and south Pacific.