Climate effects of non-compliant Volkswagen diesel cars

Abstract

On-road operations of Volkswagen light-duty diesel vehicles equipped with defeat devices cause emissions of NO x up to 40 times above emission standards. Higher on-road NO x emissions are a widespread problem not limited to Volkswagen vehicles, but the Volkswagen violations brought this issue under the spotlight. While several studies investigated the health impacts of high NO x emissions, the climatic impacts have not been quantified. Here we show that such diesel cars generate a larger warming on the time scale of several years but a smaller warming on the decadal time scale during actual on-road operations than in vehicle certification tests. The difference in longer-term warming levels, however, depends on underlying driving conditions. Furthermore, in the presence of defeat devices, the climatic advantage of 'clean diesel' cars over gasoline cars, in terms of global-mean temperature change, is in our view not necessarily the case.

The contagion effect of environmental violations: The case of Dieselgate in Germany

“…Employees had to worry about their jobs for the same reason (Müssgens & Peitsmeier, 2016). The government saw their environmental regulations disregarded as well as major public health and environmental damage as a result of the excess NO x emissions (Chossière et al, 2017; Dey, Caulfield, & Ghosh, 2018; Holland, Mansur, Muller, & Yates, 2016; Oldenkamp, van Zelm, & Huijbregts, 2016; Tanaka, Lund, Aamaas, & Berntsen, 2018). These consequences led stakeholders to penalize VW with calls for boycotts (customers), penalty fines (government), and other means of stakeholder activism with implications for the stock price.…”

Evaluating in-use vehicle emissions using air quality monitoring stations and on-road remote sensing systems

“…Real driving emissions (RDE) have attracted wide attention in recent years after the discovery of Volkswagen scandal which referred to the defeat devices installed on Volkswagen light-duty diesel vehicles that aimed to pass the certification tests in laboratory but emitted tens of times higher NOx emissions in real-world driving (Anenberg et al, 2017;Brand, 2016;Li et al, 2018;Oldenkamp et al, 2016;Schiermeier, 2015;Tanaka et al, 2018;Zachariadis, 2016). However, it should be noted the problem of higher RDE than laboratory test is not only limited to Volkswagen diesel NOx emissions, but also applies to other vehicle manufacturers (Schiermeier, 2015;Tanaka et al, 2018), fuel types (e.g. gasoline, hybrid and CNG powered vehicles) (Duarte et al, 2016;Huang et al, 2019b;Rašić et al, 2017) and emission species (e.g.…”

Short-lived Climate Forcers

“…At a global scale, land transportation has been estimated to be the dominant contributor to surface ozone concentrations in populated areas (Silva et al, 2016) and ozoneinduced vegetation damages (Section 6.4.4; Unger et al, 2020). Furthermore, it is now well established that real-world diesel NO x emissions rates are substantially higher, the so-called 'excess NO x ', in all regional markets than in laboratory tests, worsening air quality (Anenberg et al, 2017;Jonson et al, 2017;Chossière et al, 2018) and contributing to slightly larger warming on the scale of years and smaller warming at the decadal scale (Tanaka et al, 2018). Excess NO x emissions from key global diesel markets are estimated at 4.6 Tg yr -1 in 2015, with annual mean ozone and PM 2.5 increases of 1 ppb and 1µg m -3 across large regions of Europe, India and China (Anenberg et al, 2017).…”