On 21 May, little over a year after the previous eruption, a second volcano in Iceland erupted.
As the Grímsvötn volcano in Iceland erupted, weather conditions meant that the volcanic ash plume started to head towards the UK. The Met Office had a key role in accurately predicting the spread of the ash and advising the relevant authorities.
In our role as a Volcanic Ash Advisory Centre (VAAC), we're responsible for monitoring and reporting the spread of volcanic ash over the UK, Iceland and the north-eastern part of the North Atlantic Ocean.
From 21 May onwards the Met Office London Volcanic Ash Advisory Centre (VAAC) continued to provide forecast guidance up to 24 hours ahead to support decision-making. This guidance was provided to the Civil Aviation Authority as the lead agency, , airports and airline operators in order to support their decisions on whether aircraft can fly safely.
Volcanic ash can have a major impact on aircraft, potentially causing engines to fail. The International Civil Aviation Organisation (ICAO) along with the CAA and aircraft manufacturers set safety thresholds for flying planes through volcanic ash. Our forecasts of ash plume trajectories are based on these thresholds.
During the Eyjafjjallajökull the UK Civil Aviation Authority (CAA) working with aircraft engine manufacturers and European transport ministers defined volcanic ash concentration safety thresholds levels for European and North Atlantic airspace. These thresholds supplemented the global ICAO standard of 'avoid all ash'. Responding to this new requirement the Met Office NAME model was used to produce supplementary volcanic ash concentration charts depicting concentration contours of 200 and 2000, and then latterly 4000 micrograms per cubic metre.
Our charts were largely used by respective European airspace authorities as the basis for informing their flight safety related decisions.
|21 May||Volcano erupts. Ash reported to be ejected to a height of almost 20 km. Met Office VAAC forecasts start to be issued.|
|22 May||Volcano continues to erupt. Met Office VAAC forecasts go live on the public area of our website. Flights in parts of Europe start to be affected.|
|23 May||Met Office forecasts that ash is likely to reach parts of northern and western Scotland overnight and 24 May. The research ship Discovery entered an area of thick volcanic ash between Scotland and Iceland with ash being deposited onboard.|
|25 May||Information received from the Icelandic Meteorological Office (IMO) indicated the GrÍmsvötn volcano was no longer emitting ash, and only minor steam plumes from the crater up to around 300 metres|
|29 May||IMO announces the volcano has 'paused'.|
The effect of volcanoes on our climate has led some to doubt the human impact on climate change. For example, it's been suggested that volcanoes put out more carbon dioxide (CO2) than human activity, but this is not the case.
In an average year, volcanoes put out an estimated 100-130 million tonnes of CO2 globally. Estimates suggest human activity puts out more than 200 times as much - about 26,000 million tonnes of CO2 per year, magnifying the greenhouse effect and causing our climate to change.
Last updated: 19 December 2011