Climate science

In brief: How much do volcanoes influence the climate?

  • 29 Aug 2014, 12:00
  • Roz Pidcock

Overnight, a volcano in Iceland called Bardabunga began erupting, triggering a flurry questions about the possible impacts for the UK and further afield.

In 2010, Eyjafjallajökull eruption in Iceland  disrupted global transport - shutting down air traffic across Europe for several days.

Volcanoes also have an effect on the climate. Throughout earth's history, volcanic eruptions have punctuated the temperature record. We take a quick look at the role of volcanic eruptions in climate - past, present and future.

A tiny contribution to global warming

Volcanic eruptions can affect climate in two main ways. First, they release the greenhouse gas carbon dioxide, contributing to warming of the atmosphere.

But the warming effect is  very small. Volcanic carbon dioxide emissions since 1750 are at least 100 times smaller than those from fossil fuel burning, according to the latest report from the Intergovernmental Panel on Climate Change (IPCC).

A two-year cooling effect

As well as carbon dioxide, volcanic eruptions also blast a cloud of ash, dust and sulphur dioxide into the stratosphere, which is quickly blown around the globe.

Sulphur dioxide combines with oxygen and water to form sulphuric acid "aerosols". These particles directly reflect sunlight and encourage clouds to form.

This cooling effect outweighs the warming contribution from carbon dioxide, causing an overall cooling that tends to lasts for about two years after a major eruption.

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Widespread methane leakage found on US Atlantic coast

  • 26 Aug 2014, 15:39
  • Robert McSweeney

New research has found evidence of methane leaking from under the sea floor on the Atlantic Coast of the US. Could this be the beginnings of a huge release of methane into our atmosphere? Scientists tell us probably not.

Seabed seeps

The research has identified hundreds of 'seeps' along the American Atlantic coast - places where gas bubbles out of the sea floor. This could be just the beginning, with perhaps "tens of thousands" more seeps to discover, the researchers say.

They also say it's likely the bubbling gases include methane - a powerful but short-lived greenhouse gas. Methane stored under the seabed is one of the largest reserves of methane on the planet - a companion article describes the overall size of the reservoir as "staggering".

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Pacific watch: Is El Niño finding its second wind?

  • 22 Aug 2014, 14:55
  • Roz Pidcock

Scientists around the world have been watching closely to see if an El Niño develops this year - a weather phenomenon in the Pacific that drives extreme weather worldwide.

After initially predicting with  90 per cent certainty we'd see an El Niño by the end of the year, forecasters began scaling back their predictions earlier this month.

But interest in the Pacific weather phenomenon shows no sign of waning. And after much talk of El Niño cooling off, there are hints it could be rebounding, say scientists.

El Niño watch

Every five years or so, a change in the winds causes a shift to warmer than normal ocean temperatures in the  equatorial Pacific Ocean - a phenomena known as El Niño.

Together, El Niño and its cooler counterpart La Niña are known as the El Niño Southern Oscillation (ENSO). Between them, they're responsible for most of the fluctuations in global temperature and rainfall we see from one year to the next.

Earlier this year, the ocean looked to be primed for an El Niño, with above average temperatures in the eastern Pacific lasting throughout March and May.

But last month, forecasters across the world began  dialling down their forecasts. The atmosphere had "largely failed to respond" to sea surface temperatures, scientists announced.

"Waiting for Godot"

This week, the US National Oceanic and Atmospheric Administration (NOAA)  dropped the odds of an El Niño developing in autumn or winter to 65 per cent, down from 80 per cent  earlier this month. As NOAA scientist, Michelle L'Heureux,  described recently:

"Waiting for El Niño is starting to feel like Waiting for Godot"

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