Volcanic Winter
Volcanic winter is a quite similar with nuclear winter in the way that winter is caused by ash. A volcanic winter means a reduction in global temperatures caused by volcanic ash and droplets of sulfuric acid obscuring the Sun and raising Earth's albedo after a large particularly explosive volcanic eruption. Long-term cooling effects are primarily dependent upon injection of sulfide compounds in aerosol form into the upper atmosphere(stratosphere) the highest, least active level of the lower atmosphere where little precipitation occurs, thus requiring a long time to wash the aerosols out of the region.
One of the effect on life is population bottleneck. The causes of this effect is attributed to volcanic winters by some researchers. According to anthropologist Stanley Ambrose, such events diminish populations to "levels low enough for evolutionary changes, which occur much faster in small populations, to produce rapid population differentiation". With the Toba bottleneck, many species show massive effects of narrowing of the gene pool, and it is believed Toba nearly exterminated humankind.
The effects of volcanic eruptions on recent winters are modest in scale, but historically have been significant. For example, some researcher in Korea National Disaster Management Institute assert that if the Mt. Baekdu's volcano erupted, it will occur natural climate cooling effect due to volcanic ash. Also, most recently real case, the 1991 explosion of Mount Pinatubo, a stratovolcano in the Philippines, cooled global temperatures for about 2–3 years. In 1883, the explosion of Krakatoa created volcanic winter-like conditions. The four years following the explosion were unusually cold, and the winter of 1887-1888 included powerful blizzards. Record snowfalls were recorded worldwide.
One of the effect on life is population bottleneck. The causes of this effect is attributed to volcanic winters by some researchers. According to anthropologist Stanley Ambrose, such events diminish populations to "levels low enough for evolutionary changes, which occur much faster in small populations, to produce rapid population differentiation". With the Toba bottleneck, many species show massive effects of narrowing of the gene pool, and it is believed Toba nearly exterminated humankind.
The effects of volcanic eruptions on recent winters are modest in scale, but historically have been significant. For example, some researcher in Korea National Disaster Management Institute assert that if the Mt. Baekdu's volcano erupted, it will occur natural climate cooling effect due to volcanic ash. Also, most recently real case, the 1991 explosion of Mount Pinatubo, a stratovolcano in the Philippines, cooled global temperatures for about 2–3 years. In 1883, the explosion of Krakatoa created volcanic winter-like conditions. The four years following the explosion were unusually cold, and the winter of 1887-1888 included powerful blizzards. Record snowfalls were recorded worldwide.
Case Study: Krakatoa Volcano Eruption
- Aafter Krakatoa and other late 19th century volcanoes
The volcanoes increase the amount of aerosols in the stratosphere, which leads to increased short-wave scatter. Due to the increased availability of short-wave radiation, stratospheric ozone absorb more radiation and heat up the equatorial stratosphere as shown in fig (a)
. This change in the meridional temperature gradient in the stratosphere means by geostrophic balance that there will be anomalous westerlies in the northern hemisphere, which leads to a positive AO(Arctic Oscillation)/NAO(North Atlantic Oscillation). The positive AO/NAO normally only persists for two winters following the eruption. Pressure anomalies lead to temperature anomalies over the North Atlantic, shown for years 5-6 in fig 2a. 950hPa winds are overlaid in the same plot and show how southerly winds bring warmth and northerly winds (especially in Barents Sea) bring cold. Associated with these temperature anomalies are sea-ice anomalies. There is increased ice-cover in Barents Sea and reduced ice cover in the Norwegian Sea (not shown).
. This change in the meridional temperature gradient in the stratosphere means by geostrophic balance that there will be anomalous westerlies in the northern hemisphere, which leads to a positive AO(Arctic Oscillation)/NAO(North Atlantic Oscillation). The positive AO/NAO normally only persists for two winters following the eruption. Pressure anomalies lead to temperature anomalies over the North Atlantic, shown for years 5-6 in fig 2a. 950hPa winds are overlaid in the same plot and show how southerly winds bring warmth and northerly winds (especially in Barents Sea) bring cold. Associated with these temperature anomalies are sea-ice anomalies. There is increased ice-cover in Barents Sea and reduced ice cover in the Norwegian Sea (not shown).