Laws focuses on another, rather frightening scenario: the Atlantic Meridional Overturning (AMOC), an ocean current system that distributes warm water from the southern tip of the Earth to the north. This has a major impact on the weather in North America and Europe, keeping these regions much warmer and wetter than they would be otherwise. The problem is that as Earth’s climate changes, the AMOC could break down in just a few decades. Several studies have looked at this possibility recently, including one published last year, which suggested that the collapse of the AMOC could begin as early as 2025, though that particular analysis suggested that it might not actually begin to break down until the end of the century.
Under such a scenario, average temperatures across Europe could fall by up to 8°C, and up to 3°C in North America, according to a 2022 analysis by the Organisation for Economic Cooperation and Development (OECD). That may not seem like a big deal, but it means the coldest days could get significantly colder.
“That would have a pretty big impact,” Laws stresses. “It would have an impact.” That means that some heat-pump installations designed for a minimum outside temperature of minus 10 degrees Celsius, for example, might no longer be enough. “You might need to think about bigger heat pumps,” Laws says. But if the AMOC really did break down, he adds, a country like the UK, where extreme cold is rare, would face bigger problems. Underground pipes freezing and snowstorms making roads impassable would be bigger problems.
AMOC collapse aside, it’s worth noting that winters are expected to get warmer in general due to climate change, but the coldest days in places like California will likely remain just as cold, says Duncan Callaway, professor of energy and resources at the University of California, Berkeley. “The heatwaves will be even more challenging,” he argues, highlighting the increased demand for cooling technologies. Air-to-air heat pumps differ from many competing technologies in that they can provide both heating and cooling.
While it’s difficult to predict exactly what shape climate change will take in the next few years, the broad trends are pretty clear, including expectations of greater variability and extreme weather. As power grids begin to rely more and more on renewable energy sources like solar and wind, this could have indirect effects on heat pumps.
For example, short periods of favorable weather can create surplus energy on the grid more frequently. Grid operators need to balance energy production and consumption to avoid blackouts, and heat pumps could actually be a useful tool here, says Joanna Mathews, an associate professor of electrical engineering and computer science at the University of Michigan. “If we had more heat pumps, we could do that job better,” she says, explaining that heat pumps could in principle be controlled remotely to use slightly more energy than usual, helping to balance the grid. Mathews and her colleagues recently launched a project to do this in about 100 homes in Texas, but the results have not yet been published.
Doing this on a large scale could help grid operators manage surplus electricity in future, and homeowners might be able to receive payments or discounts on their electricity bills as an incentive to take part in load-balancing efforts. Experiments of this kind, focusing on other household appliances such as washing machines and hot water tanks, have already been carried out on a large scale in the UK and other countries. One obstacle is that thermostat and heat pump technology is very diverse, each using different software, and the infrastructure to remotely control thousands of heat pumps has not yet been deployed, Matthew points out.
Climate change is unlikely to disable heat pumps, despite the effects of strong winds and extreme temperatures, Callaway argues. It’s more a matter of system design and contingencies. But Vangheli stresses that it’s worth thinking about climate change scenarios now. Having spare capacity and back-up technology in place could help ensure that decarbonized heating systems aren’t vulnerable.
