Soot causes twice as much global warming as previously thought

Cutting 'black carbon' emissions could help to cool the planet, according to scientists

Soot created by the incomplete burning of fossil fuels and organic matter is the second most important man-made substance behind global warming and reducing its emission into the atmosphere could buy valuable time in tackling climate change, a major study has found.

New estimates of how much soot, or “black carbon” as it is known by scientists, is released into the atmosphere show that it causes about twice as much warming as previously believed. Cutting emissions could help to cool the planet, scientists said.

Black carbon, which is released from diesel engines, coal-fired power stations and wood-burning stoves, has a warming effect of 1.1 Watts per square metre, which is about two thirds the warming effect of carbon dioxide, the principle man-made greenhouse gas.

The new study found that soot emissions globally are substantially larger than previously estimated. It found that black carbon is a significant cause of the rapid warming seen in northerly regions of America, Canada and northern Europe and Asia and its effects extend further south, inducing changes in rainfall patterns of the Asian monsoon.

Reducing soot emissions with filters or more efficient forms of combustion could lower global temperatures over the coming couple of decades and would create a breathing space for the more difficult long-term task of reducing carbon dioxide emissions, scientists said.

“There are exciting opportunities to cool climate by cutting soot emissions, but it is not straightforward. Reducing emissions from diesel engines and domestic wood and coal fires is a no-brainer, as there are tandem health and climate benefits,” said Professor Piers Forster of Leeds University, a co-author of the new report.

“If we did everything we could to reduce these emissions, we could buy ourselves up to half a degree [Celsius] less warming, or a couple of decades of respite,” Professor Forster said.

However, the incomplete combustion of fossil fuels and organic matter produces other substances, such as sulphate aerosols, that have an opposite effect by cutting out incoming sunlight and cooling the climate, the scientists warned.

“Mitigation is a complex issue because soot is typically emitted with other particles and gases that probably cool the climate.  For instance, organic matter in the atmosphere produced by open vegetation burning likely has a cooling effect. Therefore the net effect of eliminating that source might not give us the desired cooling,” he said.

“One great candidate is soot from diesel engines. It may also be possible to look at wood and coal burning in some kinds of industry and in small household burners.  In these cases, soot makes up a large fraction of their emissions, so removing these sources would likely cool the climate,” Professor Forster added.

The four-year study into soot, published in the Journal of Geophysical Research-Atmosphere, involved hundreds of scientists from around the world and was carried out under the auspices of the International Geosphere-Biosphere Programme based in Stockholm and the International Global Atmospheric Chemistry Project.

“This study confirms and goes beyond other research that suggested black carbon has a strong warming effect on climate, just ahead of methane,” said David Fahey of the US National Oceanic and Atmospheric Administration.

Unlike carbon dioxide, which lingers in the atmosphere for many decades, black carbon is soon washed out of the air and so cutting emissions will have an almost immediate effect on reducing global temperatures, said Tami Bond of the University of Illinois.

“Mitigating black carbon is good for curbing short-term climate change, but to really solve the long-term climate problem, carbon dioxide emissions must also be reduced,” Dr Bond said.

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksA celebration of British elections
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Senior Digital Marketing Consultant

£28000 - £45000 per annum: Recruitment Genius: A Senior Digital Marketing Cons...

Recruitment Genius: Assistant Stores Keeper

£16640 - £18500 per annum: Recruitment Genius: An Assistant Stores Keeper is r...

Recruitment Genius: Claims Administrator

£16000 - £18500 per annum: Recruitment Genius: This is an excellent opportunit...

Recruitment Genius: Software Developer - C# / ASP.NET / SQL

£17000 - £30000 per annum: Recruitment Genius: Developer required to join a bu...

Day In a Page

Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power
Rare and exclusive video shows the horrific price paid by activists for challenging the rule of jihadist extremists in Syria

The price to be paid for challenging the rule of extremists

A revolution now 'consuming its own children'
Welcome to the world of Megagames

Welcome to the world of Megagames

300 players take part in Watch the Skies! board game in London
'Nymphomaniac' actress reveals what it was really like to star in one of the most explicit films ever

Charlotte Gainsbourg on 'Nymphomaniac'

Starring in one of the most explicit films ever
Robert Fisk in Abu Dhabi: The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers

Robert Fisk in Abu Dhabi

The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers
Vince Cable interview: Charging fees for employment tribunals was 'a very bad move'

Vince Cable exclusive interview

Charging fees for employment tribunals was 'a very bad move'
Iwan Rheon interview: Game of Thrones star returns to his Welsh roots to record debut album

Iwan Rheon is returning to his Welsh roots

Rheon is best known for his role as the Bastard of Bolton. It's gruelling playing a sadistic torturer, he tells Craig McLean, but it hasn't stopped him recording an album of Welsh psychedelia
Russell Brand's interview with Ed Miliband has got everyone talking about The Trews

Everyone is talking about The Trews

Russell Brand's 'true news' videos attract millions of viewers. But today's 'Milibrand' interview introduced his resolutely amateurish style to a whole new crowd
Morne Hardenberg interview: Cameraman for BBC's upcoming show Shark on filming the ocean's most dangerous predator

It's time for my close-up

Meet the man who films great whites for a living