When you turn on the AC, what's cooling you off is heating up the planet.
As temperatures rise, so do air conditioner sales, and what makes most of these 4 billion-plus machines cool indoor environments worldwide are HFCs (hydrofluorocarbons), gases with global warming potentials thousands of times greater than CO2.
HFCs started out as environmentally preferable alternatives to ozone-depleting CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons), now being phased out by the Montreal Protocol. Then scientists realized their true global warming potential. HFCs use is now increasing so rapidly that scientists warn that if not curtailed, greenhouse gas impacts of HFCs could undermine other efforts to curb global warming.
HFCs are so potent — atmospherically and politically — that the outcome of ongoing negotiations about their regulation could significantly affect both the rate of global warming and the course of international climate change legislation.
"Today, HFCs play a relatively small role in global warming, but the game will change if we address CO2 but do nothing about HFCs," says David Fahey, research physicist with NOAA's Earth System Research Laboratory and co-author of a study published in June by the Proceedings of the National Academy of Science that upended beliefs that the energy efficiency of HFCs would mitigate their inherent global warming potential.
Air conditioner sales have been growing by double-digit percentages throughout the Asia-Pacific region, where China recently surpassed the United States as the world's largest market. The 2008-2009 economic downturn notwithstanding, sales have also increased steadily in Eastern Europe, Latin America, Africa and the Middle East. Refrigerator and air-conditioned car sales have also been climbing in these regions. HFCs currently contribute only about 2% of greenhouse gasses, but if left unchecked, by 2050 HFCs could account for 9-19% of greenhouse gas impacts, the researchers found.
"The run-up in HFC use," observes Fahey, "is related to GDP growth."
Chemical manufacturers are working on a new generation of fluorine-based refrigeration compounds with lower global warming potentials to replace HFCs, but the greenhouse gas impacts of HFCs have prompted a number of major corporations — including Coca-Cola and Unilever — to begin adopting technologies that avoid any fluorine gases.
"Looking at our overall climate impact, what surprised us was that our refrigeration equipment was the biggest contribution to our carbon inventory," says Bryan Jacobs, director of energy and climate protection for Coca-Cola.
Wal-Mart made a similar discovery and has also begun to shift its commercial refrigeration to alternatives.
Billions of pounds of HFCs have been sold and emitted over the past decade. But the production figures typically reported by the consortium of the world's largest fluorocarbon producing companies, AFEAS, and often used to calculate environmental impacts, do not include production in Asia outside of Japan, despite the fact that all major producers have initiated joint ventures or similar arrangements to produce HFCs in China.
Adding to the overall HFC impacts are thousands of tons of HFC-23 — an HFC not included in the PNAS study — that have also been emitted over the past decade. HFC-23 is not produced commercially but is a manufacturing by-product of HCFC-22, one of the most widely used HCFCs, and it has a global warming potential about 12,000 times greater than CO2. It's been estimated that by 2015, HFC-23 emissions could reach the equivalent of 284 million metric tons of CO2 or 0.1 to 0.2 % of overall global warming impacts worldwide. Alone this may not be much, but given current greenhouse gas levels and their effects, policy-makers have begun to act.
In the United States, a "phase-down" that would reduce current HFC use 85% by 2033 is part of the House-passed America Clean Energy and Security (ACES) bill. HFCs are being restricted in the EU where they will be barred from new car air conditioning beginning in 2011. But the regulations with the potentially broadest impacts are being discussed internationally, between parties to the Montreal Protocol (the 1987 international treaty to curb ozone-depleting substances) and the Kyoto climate change agreement (United Nations Framework on Climate Change). What is decided in coming months could be precedent setting in terms of how developing countries agree to limit greenhouse gas emissions and how these treaties work going forward.
Yet as Greenpeace and companies involved with the "Refrigerants Naturally" effort — Coca-Cola, Unilever, PepsiCo, Ikea, McDonald's and Carlsberg — point out, non-HFC, non-fluorine gas technologies for air conditioning, refrigeration and insulation foam blowing exist and are already in use.
Coca-Cola, for example, has begun using a carbon-dioxide based technology in its cold-drink chillers, a shift the company says has helped spur additional energy conservation measures. Internationally, Coke has deployed nearly 40,000 such units and in 2009 began introducing them in the U.S. Coca-Cola and other "Refrigerants Naturally" companies say these chillers are more energy-efficient than their HFC predecessors.
Unilever has over 400,00 such ice cream coolers in use in Asia, Europe and Latin America, and last fall, Ben & Jerry's received EPA permission to launch a pilot program for these freezers in U.S. ice cream shops.
While not yet available in the U.S., in Europe, Latin America and Asia, some 40% of all home appliance refrigerators now use hydrocarbon refrigerants: a small isobutene/propane gas canister that lasts the working lifetime of the fridge.
First promoted in Germany in the 1990s through a Greenpeace effort called "Greenfreeze," proponents say this cost-competitive technology offers the most energy efficient refrigeration. The fluorine-chemical industry claims the same for their products. These hydrocarbon refrigerators are made by major appliance manufacturers including Bosch, Miele, Panasonic, and Whirpool. GE plans to introduce such fridges in the U.S. in 2010.
Meanwhile, chemical companies are developing new fluorine-based refrigerants. The first will be launched to meet the EU's 2011 ban on HFCs in mobile air conditioning.
Ian Shankland of Honeywell describes one such compound as a drop-in substitute that will contribute minimally to greenhouse gas build-up. Called HFO-1234yf — DuPont and others are marketing comparable products — this non-ozone depleting gas has global warming potential (GWP) of 4. Its predecessor, HFC 134a, has a GWP of about 1400.
DuPont spokesperson Daniel Turner says this new refrigerant's global warming potential is comparable to that of the hydrocarbon gas in the technology "Greenfreeze" is promoting but is less flammable. "Greenfreeze" advocates counter that for practical purposes, the flammability is a non-issue.
The association of fluorine compound producers, called the Alliance for Responsible Atmospheric Protection, supports the phase-down of HFCs now articulated in the ACES bill. Environmental advocates note, however, that this process is not a phase-out and would allow HFC use to continue for decades.
The Montreal Protocol, now signed by nearly 200 countries, began to phase-out consumption and production of CFCs and other ozone-depleting substances. Its provisions have now reduced global consumption of CFCs by over 95%. But in the wake of this phase-out, use of HCFCs – promoted as an environmentally preferable transitional alternative – has increased rapidly, growing, for example, by about 20% annually in developing countries.
The Montreal Protocol has since been amended to speed HCFC phase-out. But Montreal's efforts to promote use of non-ozone depleting substances includes millions of dollars in World Bank and UN funding to support HFC production in countries, including China and India — this despite HFCs' extreme warming potential. What Fahey and colleagues show, and what now concerns treaty negotiators, is that if HFCs fill the gap left by the HCFC phase-out – and the acquisition of HFC cooling and refrigeration appliances continues to climb — by 2050, HFCs' global warming impacts will wipe out the climate benefits now achieved by the Montreal treaty.
"We've built an infrastructure for the climate we've had, not the climate we have," comments Kert Davies, research director at Greenpeace U.S.
Parties to the Montreal Protocol meet next in November. Meanwhile, the vulnerable island nations of Mauritius and Micronesia have proposed adding aggressive restrictions on HFCs to the Montreal treaty, making them the first developing nations willing to agree to binding limits on greenhouse gas emissions. The U.S., Canada, Mexico, and Europe have responded with their own proposals – thereby expanding potential international agreement on greenhouse gas reductions outside of Kyoto or what may follow in Copenhagen.
"We can't do HFCs instead of CO2," says Samuel Labudde, U.S. director for climate policy at the non-profit Environmental Investigation Agency. But he says of HFCs, "We're never going to find another low-hanging fruit of comparable magnitude for drawing down greenhouse gas emissions."