An international team of scientists from the Beijing Institute of Technology, the University of Birmingham, the International Institute for Applied Systems Analysis in Austria, Aalborg University and the University of Groningen has presented a major study on an unexpected climate impact of widespread air-conditioning use. This technology, which helps people handle increasing heat, is itself becoming a contributor to global warming.
The researchers ran a simulation of global development to 2050 under five scenarios, from a stringent climate policy to a scenario with a high dependence on fossil fuels. The calculations took into account income growth, urbanization, climate change, demand for air conditioning, energy consumption and the resulting impacts on global temperature.
The chief conclusion of the study was that demand for air conditioning is going to grow at a fast rate. Even in the medium scenario, global demand for air conditioning by mid-century will increase by about 25% compared to 2010. Growth will be even stronger in the more extreme scenarios. During their study, the scientists took into account not only temperature but also air humidity and population distribution, as genuine demand for air conditioning arises in areas where people live.
The researchers estimate that by 2050, the number of air-conditioning units operating worldwide could reach some 2.3 billion, exceeding 3 billion in the adverse scenario. Power consumption will increase accordingly. In the baseline scenario, air-conditioning units will use about 4,000–5,000 TWh per year, or up to 12,000 TWh with high emissions. This is comparable to a significant share of today’s global power output.
Climate stress stems from two main sources. The first source is CO₂ emissions from coal-, oil- and gas-fired power generation. The second is refrigerant leaks from air-conditioning units. Many of these gases exert a very strong greenhouse effect. According to the researchers’ calculations, it is refrigerants that could become the main source of emissions in the A/C sector by mid-century.
Air-conditioning use between 2010 and 2050 could produce emissions of about 113 billion tons of CO₂-equivalent in the medium scenario and up to 180 billion tons in case of high reliance on fossil fuels. This would contribute up to 0.07°C to global warming by 2050. While this figure may not seem large at first glance, it is comparable to several years of the current warming rate, making it considerably more difficult to achieve the 1.5–2°C targets.
The conclusion regarding the causes of this increase is quite illustrative. It indicates that the decisive role is played not by the warming itself but by rising incomes. It stands to reason that welfare improvement, expanding living space and urbanization are becoming the main drivers of the growth in the number of air-conditioning units and rising power consumption. The additional impact of climate change itself is proven to be relatively small.
The study also draws attention to global inequality. The world’s hottest regions often remain poor and have limited access to air conditioning. If incomes in these regions rise to the level of developed countries, the number of air-conditioning units will increase by hundreds of millions, and emissions will further exacerbate the warming. This leads to a difficult choice between protecting people from heat and improving their quality of life or curbing the growth of climate stress.
The study’s authors believe that the only solution is a transition to low-carbon energy, more efficient technologies and safe refrigerants.
