Sootless cities: if not for your health, think of the climate

There is much discussion about whether or not low emission zones (LEZs) have any effect on air quality. A report (in German) into the Berlin LEZ teaches us that keeping out the most polluting trucks, delivery vans and passenger vehicles leads to noticeable results. But Amsterdam decided to cancel its LEZ plans for passenger vehicles altogether. According to an article (Dutch) in Dutch newspaper Parool, research institute TNO predicted slight improvement of air quality in 2010, but hardly any effect anymore by the year 2015 because old cars are quickly replaced and drive little anyway.

A group of four German environmental and consumer associations, Naturschutzbund Deutschland (NABU), the Bund für Umwelt und Naturschutz Deutschland (BUND), Verkehrsclub Deutschland (VCD) and Deutsche Umwelthilfe (DUH), are pleased with the positive report into Berlin's LEZ, but call for more action. In March 2009 they started the Soot free for the climate! campaign. Instead of the health effects of LEZs, which of course they also deem important, they specifically address the climatic effects of locally diminishing black carbon – or soot particles. These particles result from fossil fuels and biomass.

Model
We asked Michael Müller-Görnert of Verkehrsclub Deutschland about the goal and strategy of the campaign and about the first results. “The goal is to push local governments to reduce diesel soot emissions quickly,” Michael says.

“We hold press conferences in several German cities. We've done Munich, Hamburg and today Berlin, and we will be in Stuttgart, Hannover, Cologne and Leipzig. We address specific issues for every city. All of these cities either have a low emission zone or are planning to begin one soon. Today, we highlighted the Berlin LEZ as a model for other cities. A report by the Senate Department for Health, Environment and Consumer Protection shows a 25 per cent reduction of diesel soot due to this zone alone. Mind you, the analysis has seperated the LEZ effects from other effects, like fleet renewal and weather conditions.”

Reflectivity
According to the campaign information black carbon, amongst other things “falls onto snow and ice and changes the overall reflectivity of those surfaces (albedo effect) and accelerates the onset of spring melt. (...) [S]oot emissions from Europe are carried by the prevailing wind currents of the northern hemisphere either over Siberia or directly to the Arctic and are deposited there." The warming potential of black carbon in the arctic region depends on where the emission takes place. Traffic is the major source of black carbon emissions between 40th and 50th northern latitude, which is the location of Central Europe.

Aren't people sceptical, thinking Europe is too far away from the Arctic to effect the reflectiv potential of arctic ice and snow? “We haven't had much critics,” Michael answers. “Most people have heard something about the climate effects of aerosols but are surprised when they learn more. Some aerosols, like sulphates, have a cooling effect, which used to counteract the heating effect of greenhouse gases like carbon dioxide. Due to better diesel quality with low sulphur content and to filter use in the industry, that effect has disappeared and the heating effect of black carbon has become apparent.”

Particle filters
Do not despair: effective diesel particle filters can reduce black carbon emissions by up to 99 per cent. But they are not commonly installed in cars, nor in lorries, busses, ships and construction machines. “We want to make people aware that they can buy effective filters,” Michael says. “We also address the national government to come with financial incentives and regulations for all diesel engines to be equipped with effective filters. And next year we want to take the campaign to the European level.”

The campaign concentrates on diesel emissions of the transportation sector, aiming for one hundred per cent reduction in the European Union by 2020. To achieve this, the associations say, German politics should set ambitious standards, designate local environmental zones and advance existing ones, and expand cycle traffic.

Not so good
To bring together scientists and politicians, the campaigning associations will be organising a workshop on June 19th in Berlin. The workshop is based, in part, on research done by Dr James E. Hansen from the NASA Goddard Institute for Space Studies. Michael explains the cooperation with US scientists: “In Germany we're not so good. There was less political interest in this issue so far and therefore less money for research. We have to raise this subject in the political debate in Germany.”

So there is a lot to be won from German politics. Unless, of course, the findings of Dutch research institute TNO for the Amsterdam LEZ are widely applicable.