Query: ‘While volcanic eruptions are natural events, it was the timing of these that had such a noticeable effect on the trend.

Relevant passages:
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.

1257 Samalas eruption <=SEP=> The 1257 Samalas eruption was a major volcanic eruption of the Samalas volcano , next to Mount Rinjani on the island of Lombok , Indonesia . It left a large caldera next to Rinjani volcano , the lake Segara Anak . This volcanic eruption reached a volcanic explosivity index of 7 , making it one of the largest eruptions of the Holocene . The occurrence of this eruption was originally deduced from ice core information revealing a spike in sulfate deposition around the year 1257 ; in 2013 the source of this eruption at Samalas was definitively proven as a result of historical records from that time .   This eruption proceeded during four distinct phases , alternately creating eruption columns reaching up for tens of kilometres and pyroclastic flows that buried large parts of Lombok , destroying human habitations including the city of Pamatan . Ash from the eruption fell as far as Java . The volume of the deposits left exceeds 10 km3 . Later activity from the volcano created additional volcanic centres in the caldera , including the present day active Barujari cone .   The eruption was witnessed by humans on Lombok , who recorded its effects on text written on palm leaves . The aerosols injected by the volcano into the atmosphere reduced the solar radiation reaching the surface of the Earth , triggering a volcanic winter and cooling lasting for several years . It is possible that the 1257 Samalas eruption helped trigger the Little Ice Age .

Volcano <=SEP=> A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from a magma chamber below the surface .   Earth 's volcanoes occur because its crust is broken into 17 major , rigid tectonic plates that float on a hotter , softer layer in its mantle . Therefore , on Earth , volcanoes are generally found where tectonic plates are diverging or converging , and most are found underwater . For example , a mid-oceanic ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates pulling apart ; the Pacific Ring of Fire has volcanoes caused by convergent tectonic plates coming together . Volcanoes can also form where there is stretching and thinning of the crust 's , e.g. , in the East African Rift and the Wells Gray-Clearwater volcanic field and Rio Grande Rift in North America . This type of volcanism falls under the umbrella of `` plate hypothesis '' volcanism . Volcanism away from plate boundaries has also been explained as mantle plumes . These so-called `` hotspots '' , for example Hawaii , are postulated to arise from upwelling diapirs with magma from the core -- mantle boundary , 3,000 km deep in the Earth . Volcanoes are usually not created where two tectonic plates slide past one another .   Erupting volcanoes can pose many hazards , not only in the immediate vicinity of the eruption . One such hazard is that volcanic ash can be a threat to aircraft , in particular those with jet engines where ash particles can be melted by the high operating temperature ; the melted particles then adhere to the turbine blades and alter their shape , disrupting the operation of the turbine . Large eruptions can affect temperature as ash and droplets of sulfuric acid obscure the sun and cool the Earth 's lower atmosphere ( or troposphere ) ; however , they also absorb heat radiated up from the Earth , thereby warming the upper atmosphere ( or stratosphere ) . Historically , so-called volcanic winters have caused catastrophic famines .

Volcanism <=SEP=> Volcanism is the phenomenon of eruption of molten rock ( magma ) onto the surface of the Earth or a solid-surface planet or moon , where lava , pyroclastics and volcanic gases erupt through a break in the surface called a vent . It includes all phenomena resulting from and causing magma within the crust or mantle of the body , to rise through the crust and form volcanic rocks on the surface .