New climate response model calculates impact of road traffic fast

News - 06 December 2018 - Communication

Vanessa Rieger created a model which assesses the impact and the contribution of road traffic emission scenarios on O3 and CH4 concentration and the subsequent climate effect.  She will defend her PhD thesis at TU Delft on Friday 7 December.


Emissions of road traffic crucially influence our climate. The vehicle fleet emits not only carbon dioxide, but also nitrogen oxides (NOx), volatile organic compounds (VOCs) and carbon monoxide (CO). The latter species lead to a production of ozone (O3) and a reduction of methane (CH4) in the troposphere. ‘Several studies have already quantified the impact of road traffic emissions on climate. But climate simulations with complex chemistry climate models are still computationally expensive, hampering the assessment of many road traffic emission scenarios. An efficient method for quantifying the climate impact and contribution of mitigation options is required’, says researcher Vanessa Rieger.


Rieger therefore created a unique chemistry-climate response model called TransClim (Modelling the effect of surface Transportation on Climate) which assesses the impact and the contribution of road traffic emission scenarios on O3 and CH4 concentration as well as their subsequent climate effect.

‘Comparing the results delivered by TransClim with simulations of the complex global chemistry climate model EMAC, reveals very low deviations. TransClim reproduces the results calculated by EMAC very well. TransClim thus offers a new method to quickly assess the climate impact and the contribution of mitigation strategies for road traffic in a sufficiently accurate manner. As TransClim simulates about 6,000 times faster than a complex chemistry climate model, it enables to quickly quantify the effect of many emission scenarios in different regions.’


TransClim made it possible to assess the climate effect of three prospective mitigation options of German road traffic. The future emission scenario including the strictest environmental regulations and emission controls leads to the strongest decrease of O3 and CH4 radiative forcing. ‘Secondly, two scenarios have been constructed describing the cases that European vehicles use fuel blends containing a low and a high proportion of biofuels. Simulations with TransClim reveal that fuels with a low content of biofuels mainly reduce CH4, while fuels with a high content of biofuels reduce tropospheric O3.’

More information

7 December 2018, 09.30 - 11.00, Aula, TU Delft

PhD Defence Vanessa Rieger ‘A new method to assess the climate effect of mitigation strategies for road traffic. The fast chemistry- climate response model TransClim

Contact info:

Science Information Officer TU Delft Roy Meijer,, +31 15 2781751