Pinatubo – a case study

15th June, 1991 – September, 1991 Produced a plume that rose 34km, well into the stratosphere Released 20,000,000 tonnes of sulphur dioxide Ejected more material into the stratosphere than any volcano since Krakatau in 1883 Coincided with a typhoon, causing lahars of ash and rain. Also pyroclastic flows 847 people killed directly by the eruption 10% reduction in the amount of sunlight reaching the Earth’s surface

The distribution of sulphate aerosol in the stratosphere The distribution of sulphate aerosol in the stratosphere. The y axis shows latitude, and the x axis time – so you can see how the aerosol spread away from the equator and then slowly decayed. Source: Gao, Robock, Ammann, Volcanic Forcing of Climate over the Past 1500 years: an Improved Ice Core-Based Index for Climate Models, 2008

Source: Volcanoes and their effect on climate , David Viner and Phil Jones, Climatic Research Unit The global temperature impact of Pinatubo (f, bottom) compared to other recent eruptions which have had an impact on the climate. Month 0 is when the volcano erupted. The temperature is the temperature anomaly – ie how different the temperature is from the long term average (or climate). The northern summers of 1992 and 1993 were the coolest of the period from 1986 to the present.

Can you find evidence of Pinatubo’s eruption? Go to the Met Office website http://www.metoffice.gov.uk/public/weather/climate-historic/#?tab=climateHistoric Choose a location Copy the data into Excel What can you say about the impact of Pinatubo’s eruption on the weather? Depending on the ability level of the group, teachers may like to direct the students to only look at one variable (eg Tmax), and only a specified period (e.g. 1980-2009). More able students could calculate the climate (30 year average) for the period and subtract that from the data, to give anomalies.