The number of electric cars on the roads around the world rose to 2 million in 2016, following a year of strong growth in 2015, according to the latest edition of the International Energy Agency’s Global EV Outlook.

China remained the largest market in 2016, accounting for more than 40% of the electric cars sold in the world. With more than 200 million electric two-wheelers and more than 300,000 electric buses, China is by far the global leader in the electrification of transport. China, the US and Europe made up the three main markets, totalling over 90% of all EVs sold around the world.

Electric car deployment in some markets is swift. In Norway, electric cars had a 29% market share last year, the highest globally, followed by the Netherlands with 6.4%, and Sweden with 3.4%. The electric car market is set to transition from early deployment to mass market adoption over the next decade or so. Between 9 and 20 million electric car could be deployed by 2020, and between 40 and 70 million by 2025, according to estimates based on recent statement from carmakers.

Still, electric vehicles only made up 0.2% of total passenger light-duty vehicles in circulation in 2016. They have a long way to go before reaching numbers capable of making a significant contribution to greenhouse gas emission reduction targets. In order to limit temperature increases to below 2°C by the end of the century, the number of electric cars will need to reach 600 million by 2040, according to IEA’s Energy Technology Perspectives. Strong policy support will be necessary to keep EVs on track.

Cities are taking leadership roles in encouraging EV adoption, often because of concerns about air quality. Major urban centres often achieve higher EV market shares compared to national averages. A third of global EV sales took place in 14 cities in 2015.

Paris, for instance, has mandated that any electric car is allowed to re-charge at the re-charge stations of its car-sharing program, called Autolib. Amsterdam has a unique strategy of offering the installation of charging points on public parking spaces to people who make a request, ensuring that charging infrastructure is installed where it’s actually needed. London for its part encourages EV adoption by waiving its congestion charge.

The analysis shows that fleet procurement is an important means of encouraging early EV uptake. Fleet operators, both public and private, can contribute significantly to the deployment of EVs, first from demand signals that they send to the market, and second thanks to their broader role as amplifiers in promoting and facilitating the uptake of EVs by their staff and customers.

In that respect, four major US cities – Los Angeles, Seattle, San Francisco and Portland – are leading a partnership of over 30 cities to mass-purchase EVs for their public fleets including police cruisers, street sweepers and trash haulers. The group is currently seeking to purchase over 110,000 EVs, a significant number when compared to the 160,000 total EVs sold in the United States in 2016.

The report offers a comprehensive collection of national-level data on EV deployment based on primary data collected from member governments of the Electric Vehicle Initiative (EVI). The EVI is a multi-government policy forum established in 2009 under the Clean Energy Ministerial (CEM), dedicated to accelerating the deployment of EVs worldwide.

EVI members will also launch the EV30@30 campaign during the Eighth CEM Meeting on June 8 in Beijing. The campaign will set a collective aspirational goal for all EVI members of a 30% market share for electric vehicles in the total of all passenger cars, light commercial vehicles, buses and trucks by 2030. The campaign will also raise support for accelerated deployment of charging infrastructure, commitments on fleet procurement, and exchange and replication of best practices for the promotion of EVs in cities.

Clear and ambitious policy support is vital to keeping the growth of EVs on track with IEA low-carbon scenarios, to improve urban air quality, and diversify transport energy sources. Despite impressive improvements in costs and energy density over the past decade, battery packs are still expensive, driving up retail prices. Financial incentives for EV adoption and taxes on fossil fuels will continue to be important in the current phase of EV technology deployment to initiate and reinforce a positive feedback loop that, through increasing sales, production scale-ups and technology learning, will further support cost reductions for batteries and other components.