They do, however, offer a radical vision which could achieve a 72% drop in emissions by 2030 - a figure that is 83% lower than the current UK average. The solution involves combining a car-free London with high levels of active transport (for example walking and cycling) and realistic but challenging energy-efficient improvements.
Their findings will be released today at a press event taking place at LSHTM to launch the Lancet Series on Energy and Health, which looks at access to electricity and energy poverty, transport, agriculture, nuclear and renewable power, and a range of other energy issues, and the effect each has on health. The Series calls for action to be taken at personal, national and global level to address these issues.
Land transport emissions in London have remained stable since 1990 and are now responsible for about 14% of total emissions. Although cycling is gaining popularity, with an 83% increase in the capital since 2000, more than seven out of ten (72%) car journeys in London cover a distance shorter than 8 kilometres.
There is evidence of substantial negative health effects from motorised transport in London5. Replacing car trips with active transport such as walking or cycling would lower emissions and offer greater health gains than other options. In 2003, only 32% of men and 26% of women in London achieved minimum activity recommendations5.
Calculations show that a car-free inner London scenario equates to a 49% reduction in emissions7. Because most London car trips are within outer London, changes in inner London boroughs alone were not found to be sufficient to meet the GLA emissions target. The car-free inner and outer London model was found to bring about a 72% reduction in emissions, with active transport making up 53% of all trips. Given the lower starting point, this means 83% lower emissions than the UK average for 2000.
The authors highlight the many benefits, in terms of public health and safety, that the adoption of the car-free scenario would achieve. Not only would the former car users benefit in terms of improved health as a result of greater physical activity, but as active transport in the form of walking or cycling increased, more people would be willing and able to comfortably walk or cycle longer distances.
They also point to the strong link between pedestrian injury and deprivation, with rates in the most deprived London areas over twice those in the least deprived. In London, as in virtually all locations, walking is the main transport mode of the poor. With fewer cars, people would be exposed to less traffic danger. Although pedestrians and cyclists are exposed to greater risk than car drivers, previous studies have shown that as the number of pedestrians and cyclists increase, so the danger per km walked or cycled falls.
James Woodcock, who led a team of researchers at the London School of Hygiene & Tropical medicine, comments: 'Only the car-free greater London scenario is close to achieving the emission reductions required by 2030. Even then we need to reduce carbon fuel use on our public transport. Car-free streets could transform the quality of our urban environment, while improving health. Although London has made small improvements, achieving a car-free city would require a dramatic move in favour of walking and cycling'.
A separate paper uses London travel data to identify four archetypal car using groups in London: Claire, a 10 year old girl; Lucy, a 40 year old mother; Tom, a 50 year old man living and working in outer London; and Derek, a 78 year old man. It calculates the increases in physical activity and energy expenditure that would result if they transferred their car journeys to walking, cycling and public transport, with occasional trips by taxi.
By doing so, they would expend an average of 139,300 kJ of energy a year, equivalent to an average of 4.5 kg of fat. Lucy would reduce her risk of breast cancer by 25% and increase her life expectancy by between 1 and 2 years, while Tom would enjoy a 20-40% reduction in the risk of premature mortality and around a 30% reduction in risk of type 2 diabetes.