As spring temperatures in the UK inched above
20C in recent weeks, air conditioners in offices across the country
will have rumbled into life after a silent winter.
But while these machines cool our buildings and
cars, they could be having an increasing warming effect on the
planet, a new study says.
Air conditioners and fridges contain potent
greenhouse gases known as hydrofluorocarbons (HFCs). The new
research shows global emissions of HFCs have risen by more than
half between 2007 and 2012.
And as temperatures and incomes rise during this
century, air conditioning use is set to grow rapidly in warm
countries around the world, a second study finds.
Potent greenhouse gases
In 1987, countries around the world signed
Montreal Protocol, an agreement to phase out use
of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons
Scientists had found the gases were depleting
layer, the atmospheric shield that filters the
Sun's harmful ultraviolet radiation from reaching the Earth's
CFCs and HCFCs were used as refrigerants in air
conditioning units and fridges, propellants in aerosol sprays, and
fire suppressants in extinguishers.
HFCs to take their place. HFCs don't damage
the ozone layer, but as with their predecessors, they are potent
greenhouse gases - as much as several
thousand times stronger at absorbing heat than
Now a new study, published in Proceedings
of the National Academy of Sciences, finds their
emissions have risen rapidly in just five years.
Researchers estimated the abundance of the five
most common HFCs from two global datasets: the Advanced Global
Atmospheric Gases Experiment (AGAGE) and
Japan's National Institute Environmental Studies (NIES
The data showed a dramatic rise in HFC emissions
from 303 to 463 million tonnes of carbon dioxide equivalent between
2007 and 2012. This equates to an increase of 33 million tonnes per
year, similar to the
annual fossil fuel carbon emissions of New
Zealand, the researchers say.
You can see this increase as the blue line in
the graph below. The researchers also divided the results between
developed countries (Annex I, green line) and developing countries
(Non-Annex I, red line).
Combined emissions of five HFCs from 2007 to 2012 for the
world (blue line), developed countries only (green) and developing
countries only (red line). Dotted and dashed black lines show
emissions reported to the UNFCCC (for developed countries only).
Grey, orange and purple lines show estimates from other studies.
Source: Lunt et al. (2015)