Study: Volcanoes helped offset global warming

2014-02-24 14:30

(Shutterstock)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

kalahari.com

Paris - Volcanoes spewing Sun-reflecting particles into the atmosphere have partly offset the effects of Man's carbon emissions over a 15-year period that has become a global-warming battleground, researchers said on Sunday.

A so-called hiatus in warming since 1998 has pitched climate sceptics against mainstream scientists.

While temperatures have risen relentlessly, 13 of the l4 warmest years on record occurred since the start of the century they tracked far below the increase in man-made greenhouse gases.

This gap between the expected and actual temperatures has been cited by sceptics as proof that human-induced global warming is either a green scare or bad science.

But a study in the Journal Nature Geoscience said volcanic eruptions helped explain the apparent warming slowdown.

Researchers using satellite data found a link between surface temperatures and the impact from nearly 20 volcanic eruptions since 2000.

Blockbuster eruptions

Sulphuric droplets disgorged by the volcanoes reflected sunlight and slightly cool the lower atmosphere, they said.

The effect of these "aerosols" accounted for as much as 15% of the gap between expected and measured temperatures between 1998 and 2012, according to the team's figures.

"The 'warming hiatus' since 1998 has a number of different causes", study co-author Ben Santer of the Lawrence Livermore National Laboratory in California told reporters by email.

"The cooling caused by early 21st century volcanic eruptions is one of the causes."

Other explanations for the "hiatus" have been a bigger-than-expected take-up of atmospheric heat by the ocean, or a decline in solar activity.

Blockbuster eruptions, notably that of Mount Pinatubo in the Philippines in 1991, were known to have discernible cooling effects on Earth's surface.

But volcanoes have not featured in the "hiatus" debate mainly because there had been no major eruptions since the mooted pause began in 1998, only smaller ones whose impact is harder to measure.

This is a gap, as it left computer models of climate change incomplete, the new study suggested.

Other causes

"Better observations of eruption-specific properties of volcanic aerosols are needed, as well as improved representation of these in climate model simulations", it said.

Global warming sceptics have pointed to the "hiatus" as proof of flaws in models used to predict warming and thus play a key role in driving policies to tackle climate change.

They contend that these models exaggerate the heat-trapping effect from carbon dioxide (CO2) emitted by fossil fuel burning.

Santer said the new findings "do not support" such an argument.

"We've been lucky that a natural cooling influence [an uptick in 21st century volcanic activity] has partly counteracted human-caused warming", he said.

"We do not know how volcanic activity will evolve over the coming decades, and thus we do not know how long our luck will continue".

Experts generally agree that Earth is on track for greatly exceeding the maximum 2°C of warming targeted in UN climate negotiations.

Last year the level of carbon dioxide (CO2) in the atmosphere crossed a threshold of 400 parts per million (ppm) a level never experienced by humans.

CO2 concentrations are rising at two or three ppm per year, driven especially by the burning of coal in emerging economies.

Commenting on the study, Piers Forster, a professor of climate change at the University of Leeds, said it confirmed that volcanoes contributed to the slowdown, but could not be the only cause.

Read more on:    un  |  france  |  climate change  |  volcanoes
NEXT ON NEWS24X
SHARE:

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
15 comments
Add your comment
Comment 0 characters remaining
 

Inside News24

 
/News

Jobs in Cape Town [change area]

Property [change area]

Travel - Look, Book, Go!

Magical Massinga

Spend 5 nights at the gorgeous Massinga Beach Lodge in Mozambique and only pay for 4 from R13 220 per person sharing. Includes return flights, accommodation, transfers and romantic turndown. Book now!

Kalahari.com - shop online today

Camping gear!

We’ve got all your camping must have’s right here at mind blowing low prices. Check them out now!

Herbex – buy 3 & get 1 free!

Fat burn packs, appetite control chewies, stretch mark cream and more. Offer valid while stocks last. Shop now.

30% off Jinger Jack handbags

Spice up your wardrobe and save 30% on stylish Jinger Jack handbags. Offer valid while stocks last. Shop now!

Buy 3 books & pay for 2

The cheapest of the 3 books will be free. Offer valid while stocks last. T&Cs apply. Shop now!

Deal of the week!

Hisense 40” Full HD LED Television now R3999. Offer valid while stocks last. Buy now!

OLX Free Classifieds [change area]

Samsung Galaxy s4

Mobile, Cell Phones in South Africa, Western Cape, Cape Town. Date October 24

Best bargain in big bay

Real Estate, Houses - Apartments for Sale in South Africa, Western Cape, Cape Town. Date October 25

VW Golf 6, 1.6 Trendline (Excellent condition)

Vehicles, Cars in South Africa, Western Cape, Cape Town. Date October 25

Horoscopes
Aquarius
Aquarius

Today is a good day to network and share your ideas and thoughts with your colleagues and friends. Information overload is...read more

There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.








Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.