The year 1816 is called the Year Without a Summer because of extreme weather changes that made global temperatures drop by 0.4–0.7 °C (0.7–1 °F). In Europe, summer temperatures that year were the coldest recorded between 1766 and 2000, leading to failed crops and serious food shortages across the Northern Hemisphere. Scientists believe this unusual cold was mainly caused by a volcanic winter after the huge eruption of Mount Tambora in the Dutch East Indies (now Indonesia) in April 1815.
Radiative forcing, also called climate forcing, is a way to measure changes in the balance of energy moving through a planet’s atmosphere. Factors like the amounts of greenhouse gases and aerosols in the air, changes in how much sunlight is reflected by Earth’s surface (called albedo), and changes in the sun’s energy reaching Earth all affect this energy balance. In technical terms, radiative forcing is the change in the net amount of energy (measured in watts per square meter) moving into and out of Earth’s atmosphere due to changes in climate drivers.
The Maunder Minimum, also called the “prolonged sunspot minimum,” was a time from about 1645 to 1715 when sunspots became very rare. Between 1672 and 1699, during this period, scientists observed fewer than 50 sunspots. This is much lower than the typical 40,000 to 50,000 sunspots seen in modern times over a similar length of time.
The Little Ice Age (LIA) was a time when temperatures in certain areas, especially near the North Atlantic, were cooler than usual. It was not a global ice age that covered the entire planet. The term “Little Ice Age” was first used in scientific writing by François E.
The Medieval Warm Period (MWP), also called the Medieval Climate Optimum or the Medieval Climatic Anomaly, was a time of warmer temperatures in the North Atlantic region. This period lasted from about 950 CE to about 1250 CE. Evidence from nature shows that the warmest times happened at different times in different places.
The Holocene Climate Optimum (HCO) was a warm period during the first half of the Holocene epoch, occurring roughly between 9,500 and 5,500 years before the present. The warmest part of this period happened around 8,000 years before the present. This time has also been called by other names, such as Altithermal, Climatic Optimum, Holocene Megathermal, Holocene Optimum, Holocene Thermal Maximum, Holocene global thermal maximum, Hypsithermal, and Mid-Holocene Warm Period.
The Pleistocene is a time period that lasted from about 2.58 million to 11,700 years ago. It is known as the Ice Age because it was Earth’s most recent time of repeated ice cover. Before 2009, scientists believed the Pleistocene started 1.806 million years ago, but this was changed by the International Union of Geological Sciences.
The Cretaceous period lasted from about 143.1 to 66 million years ago. It is the third and final period of the Mesozoic Era and the longest geological period in the entire Phanerozoic. The name comes from the Latin word creta, meaning “chalk,” which was common in deposits from the later part of the period.
The Paleocene–Eocene thermal maximum (PETM), also called “Eocene thermal maximum 1 (ETM1)” and previously known as the “Initial Eocene” or “Late Paleocene thermal maximum,” was a short period in Earth’s history marked by a global temperature increase of 5–8 °C (9–14 °F) and a large release of carbon into the ocean and atmosphere. This event began exactly at the boundary between the Paleocene and Eocene geological time periods. Scientists are still unsure of the exact age and length of the PETM, but it is believed to have occurred about 55.8 million years ago and lasted approximately 200,000 years.
Deep time is the idea of geological time that covers billions of years, much longer than human experiences. It helps explain how Earth formed, how life developed, and the slow processes that change the planet. This concept was first created as a scientific idea in the 18th century and became more well-known in the 20th century through writers like John McPhee.