"A major theme in the early years of the sharing economy was that these new services were more environmentally beneficial than existing businesses, in part because they were using ‘idle resources’; Airbnb claimed it would reduce new hotel construction. Ride-sharing apps like Uber and Lyft were expected by many to reduce car ownership, increase the number of passengers per ride, and reduce carbon emissions. However, it has been difficult to assess these claims because the companies will not provide their data to independent researchers. But there are strong reasons to believe that platforms are increasing, rather than reducing environmental impacts, and especially climate emissions. The evidence is hiding in plain sight: lower prices lead to more demand. In the lodging sector, cheap accommodation increases miles travelled and trips taken. Furthermore, Airbnb enables hosts to rent out their homes when they travel, so that lodging is essentially free. (We also find some hosts travel specifically to rent, to take advantage of price arbitrage – they can rent out their homes at a higher rate than the places they stay at.) Similarly, in the US ride-hailing apps appear to be taking people away from lower-carbon modes of transport. A recent study based on survey data finds that had there been no transportation app, 49–61% of ride-hailing trips would have either not been made at all, or been taken via walking, biking or transit (Clewlow and Mishra 2017). Furthermore, this study finds that there is no reduction in car ownership as a result of ride-hailing."