Query: However, volcanoes have had very little impact on the last 40 years of global warming.

Relevant passages:
Ice age <=SEP=> An ice age is a period of long-term reduction in the temperature of Earth 's surface and atmosphere , resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers . Within a long-term ice age , individual pulses of cold climate are termed `` glacial periods '' ( or alternatively `` glacials '' or `` glaciations '' or colloquially as `` ice age '' ) , and intermittent warm periods are called `` interglacials '' . In the terminology of glaciology , ice age implies the presence of extensive ice sheets in both northern and southern hemispheres . By this definition , we are in an interglacial period -- the Holocene -- of the ice age . The ice age began 2.6 million years ago at the start of the Pleistocene epoch , because the Greenland , Arctic , and Antarctic ice sheets still exist .

Climate change (general concept) <=SEP=> Climate variability includes all the variations in the climate that last longer than individual weather events, whereas the term climate change only refers to those variations that persist for a longer period of time, typically decades or more. In the time since the industrial revolution the climate has increasingly been affected by human activities that are causing global warming and climate change.The climate system receives nearly all of its energy from the sun. The climate system also radiates energy to outer space. The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth\'s energy budget. When the incoming energy is greater than the outgoing energy, earth\'s energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling.\nThe energy moving through Earth\'s climate system finds expression in weather, varying on geographic scales and time. Long-term averages and variability of weather in a region constitute the region\'s climate. Such changes can be the result of "internal variability", when natural processes inherent to the various parts of the climate system alter the distribution of energy. Examples include variability in ocean basins such as the Pacific decadal oscillation and Atlantic multidecadal oscillation. Climate variability can also result from external forcing, when events outside of the climate system\'s components nonetheless produce changes within the system. Examples include changes in solar output and volcanism.\nClimate variability has consequences for sea level changes, plant life, and mass extinctions; it also affects human societies.

Younger Dryas <=SEP=> The Younger Dryas is a geological period from c. 12,900 to c. 11,700 calendar years ago ( BP ) . It is named after an indicator genus , the alpine-tundra wildflower Dryas octopetala . Leaves of Dryas octopetala are occasionally abundant in the Late Glacial , often minerogenic-rich , like the lake sediments of Scandinavian lakes . The Younger Dryas saw a sharp decline in temperature over most of the northern hemisphere , at the end of the Pleistocene epoch , immediately before the current warmer Holocene . It was the most recent and longest of several interruptions to the gradual warming of the Earth 's climate since the severe Last Glacial Maximum , c. 27,000 to 24,000 calendar years BP . The change was relatively sudden , taking place in decades , and resulted in a decline of 2 to 6 degrees Celsius , advances of glaciers and drier conditions , over much of the temperate northern hemisphere . It is thought to have been caused by a decline in the strength of the Atlantic meridional overturning circulation , which transports warm water from the equator towards the North Pole , and which in turn is thought to have been caused by an influx of fresh cold water from North America into the Atlantic . The Younger Dryas was a period of climatic change , but the effects were complex and variable . In the southern hemisphere , and some areas of the north such as southeastern North America , there was a slight warming .   The presence of a distinct cold period at the end of the Late Glacial interval has been known for a long time . Paleobotanical and lithostratigraphic studies of Swedish and Danish bog and lake sites , e.g. the Allerød clay pit in Denmark , first recognized and described the Younger Dryas .   The Younger Dryas is the youngest and longest of three stadials that resulted from typically abrupt climatic changes that took place over the last 16,000 calendar years . Within the Blytt-Sernander classification of north European climatic phases , the prefix ` Younger ' refers to the recognition that this original ` Dryas ' period was preceded by a warmer stage , the Allerød oscillation , which in turn was preceded by the Older Dryas around 14,000 calendar years BP . This is not securely dated , and estimates vary by 400 years , but it is generally accepted that it lasted around 200 years . In northern Scotland the glaciers were thicker and more extensive than during the Younger Dryas . The Older Dryas , in turn , is preceded by another warmer stage , the Bølling oscillation that separates it from a third and even older stadial . This stadial is often , but not always , known as the Oldest Dryas . The Oldest Dryas occurred approximately 1,770 calendar years before the Younger Dryas and lasted about 400 calendar years . According to the GISP2 ice core from Greenland , the Oldest Dryas occurred between about 15,070 and 14,670 calendar years BP .   In Ireland , the Younger Dryas has also been known as the Nahanagan Stadial , while in Great Britain it has been called the Loch Lomond Stadial . In the Greenland Summit ice core chronology , the Younger Dryas corresponds to Greenland Stadial 1 ( GS-1 ) . The preceding Allerød warm period ( interstadial ) is subdivided into three events : Greenland Interstadial-1c to 1a ( GI-1c to GI-1a ) .

Huaynaputina <=SEP=> Huaynaputina ( -LSB- wainapuˈtina -RSB- , Pronounced : -LSB- waɪnəpʊˈtiːnə -RSB- ; from young volcano , meaning `` Young Volcano '' ) is a stratovolcano in a volcanic upland in southern Peru . The volcano does not have an identifiable mountain profile , but instead is a large volcanic crater . It has produced high-potassium andesite and dacite . On 19 February 1600 , it exploded catastrophically ( Volcanic Explosivity Index -LSB- VEI -RSB- 6 ) , in the largest volcanic explosion in South America in historic times . The eruption continued with a series of events into March . An account of the event was included in Fray Antonio Vázquez de Espinosa 's Compendio y Descripción de las Indias , which was translated into English as Compendium and description of the West Indies in 1942 .