The legacy of Europe’s heat waves will be more air conditioning. That is a problem.

Climate change is making extreme heat the norm in a larger part of the world, increasing the need for adaptation. But in the case of AC, some experts are concerned about how to balance that need with the damage the solutions can cause.

According to a 2018 report by the International Energy Agency (IEA), global air conditioning sales more than tripled between 1990 and 2016. That growth is likely to continue, with global cooling energy consumption expected to triple again between now and 2050.

Warm countries such as India and Indonesia are responsible for much of the increasing AC adoption. According to the IEA, by 2050, about half of the growth in AC cooling capacity will come from just two countries, India and China. Incomes are rising there, giving people access to AC for the first time, says Enrica De Cian, an environmental economics researcher at Ca’ Foscari University in Venice, Italy.

But AC adoption is also increasing in relatively wealthier and cooler countries, including Europe, especially as urbanization and climate change are pushing up temperatures, De Cian says.

Yet many Europeans are hesitant to welcome air conditioners with open arms. “Of course, seeing AC as a solution to heat waves and climate change is a bit problematic because of the energy it uses,” said Daniel Osberghaus, an energy and climate economics researcher at the Leibniz Center for European Economic Research in Germany.

Today, refrigeration appliances such as ACs account for about 10% of global electricity consumption – and since most of the world’s electricity still comes from fossil fuels, that’s a significant portion of global emissions. Their massive energy consumption “gets them a bad reputation,” said Kevin Lane, an energy analyst at the IEA.

Refrigeration units, in particular, can challenge the grid, as they are all turned on around the same time, during the hottest parts of the day. This problem is evident in places like Texas, where summers are hot and air conditioners are rife. Texas grid operators regularly urge residents to reduce their AC usage during peak afternoon hours to avoid power outages.

More efficient alternatives to the window units that exist in many cities today, Lane says. Split units or heat pumps can act as both cooling and heating devices and may be more efficient than other options. Initial costs for heat pumps are still relatively high, although lifetime costs can compete with other options due to energy savings.