Transport is one of the major sources of greenhouse gas emissions. However, little has been done in terms of climate protection, especially in road traffic. Scientists have now examined which measures are most likely to bring about progress in reducing CO2 emissions in the future. They come to the conclusion that a combination of higher fuel prices and incentives for clean cars is most effective.
In order to counteract the progressing climate change, greenhouse gas emissions must be reduced in many sectors. But although the transport sector is responsible for around a quarter of Germany's greenhouse gas emissions, little has happened on the roads so far. But to become carbon neutral by 2050 at the latest, according to the International Energy Agency (IEA), global emissions from the transport sector, which stood at 8.5 gigatonnes of CO2 in 2019, must fall below one gigatonne per year.
The station wagon does it
While there is often still disagreement in this country about the most effective measures to save CO2 in road traffic, there are already some countries that can show a successful reduction in their CO2 emissions in this sector with a stable economic situation. A team led by Nicolas Koch from the Mercator Research Institute on Global Commons and Climate Change (MCC) in Berlin is now examining how this came about and what recommendations and opportunities can be derived from it for future transport policy. Unlike previous studies, in which mostly individual measures were evaluated in isolation for their effectiveness, Koch and his colleagues chose a new approach that takes into account the interaction of different measures. Because in political reality bundles of measures are usually established, which can influence each other in their effect.
For their study, the researchers therefore specifically looked for packages of measures that actually show an effect in terms of CO2 savings in road traffic. To do this, they looked at road traffic emissions from 1995 to 2018 in 15 EU countries and compared them with economic output and population. Using machine learning, they then looked for so-called "emission dips" that are not a result of economic conditions and could be due to climate protection measures. An artificial intelligence then breaks down what proportion of individual or several interacting climate policy measures in the respective country were decisive for the reduction in emissions.
High prices are a deterrent
The results show the most promising combinations of political measures and highlight one intervention in particular: "Over a period of 24 years in 15 EU countries, we only found ten examples of successful climate policy in road traffic," reports Koch. "All ten cases are linked to at least one measure that has increased the running costs of driving - usually through higher fuel prices through CO₂ pricing, sometimes through energy taxes or tolls." So the higher prices meant that people no longer, or at least less often, chose the car as a means of transport, since there were cheaper alternatives such as buses or trains.
Another important point that the study identified as an effective CO2 reduction measure is to encourage the use of clean cars. According to Koch, in almost all of the ten countries with successful climate policies, the government has provided incentives to buy zero-emission or lower-emission vehicles. The federal states achieved this either through vehicle taxes based on CO₂ emissions or through grants. In combination with higher fuel prices, for example in Luxembourg, this measure led to an effective reduction in road traffic emissions of 26 percent from 2015. But this mix of political measures also had an effect in Finland with 17 percent, Ireland with 13 percent and Sweden with eleven percent.
model for climate policy
For the future, the research team recommends increasing CO2 pricing in road traffic combined with a system that provides subsidies for e-cars and vehicle tax rates for combustion vehicles. "In principle, the leverage effect of such a package of measures is strong enough to achieve the goal of climate neutrality proclaimed by the EU in this problem area by the middle of the century," predicts Koch. “The instruments are there – now we need the political will to apply them consistently, across the board and over the long term.”
Source: Mercator Research Institute on Global Commons and Climate Change; Specialist article: Nature Energy, doi: 10.1038/s41560-022-01095-6