WARSAW—It's crazy to pay people to burn more fossil fuels if one is concerned about man-made global warming.

At the 19th Conference of the Parties (COP-19) of the U.N.'s Framework Convention on Climate Change (UNFCCC), one of the better ideas for lowering the emissions of greenhouse gases is to eliminate consumer and producer fossil fuel consumption subsidies. The International Energy Agency estimates that consumption subsidies amounted to $544 billion in 2012. Ending subsidies would encourage consumers and producers to cut back fossil fuel use, which in turn would reduce carbon dioxide emissions. And would save taxpayers a great deal of money.

On Thursday, the United Nations Environment Program (UNEP) held a session on reducing nitrous oxide emissions. Nitrous oxide is a long-lived gas that has a global warming potential of 310, meaning one molecule traps over 310 times more heat than a molecule of carbon dioxide. The amount of nitrous oxide put into the atmosphere is equivalent to about 3 gigatons of carbon dioxide, which approximates the emissions of half of the world's entire vehicle fleet. In addition, nitrous oxide depletes the stratospheric ozone layer that shields the earth's surface from damaging ultraviolet light. So preventing nitrous oxide emissions is a twofer—cutting it lowers the temperature and protects the ozone layer.

Nitrous oxide exists naturally in the atmosphere, but, as a result of human activities, its concentration has increased by 20 percent over pre-industrial levels, making it the third most important greenhouse gas after carbon dioxide and methane. The new UNEP report, Drawing Down N2O, outlines several ways to cut emissions.

Two-thirds of human emissions come from agricultural activities, e.g., using nitrogen fertilizer or livestock waste management. It is not an exaggeration to say that the invention of a process to synthesize nitrogen fertilizer made the modern world possible, as fertilizers boost crop yields as much as 50 percent. Nitrogen fertilizer that isn't taken up by plants boosts input costs to farmers. However, farmers have to make tradeoffs between a number of different costs for fuel, equipment, seed, labor, fertilizer, and so forth in order to make a profit, and managing nitrogen fertilizer is usually not at the top of the list for improving the bottom line.

That being said, if it's economic and ecological madness to subsidize the burning of fossil fuels, it's just as barmy to subsidize agriculture in the amount of $300 billion annually. The World Bank reported in 2012 that fertilizer subsidies in India amounted to 2 percent of that country's GDP. Agricultural subsidies clearly encourage farmers to overuse fertilizer, which in turn produces nitrous oxide emissions that harm the ozone layer and raise global temperature. The UNEP report notes that research and development can help improve nitrogen use efficiency. As it happens, private seed growers have already developed crop plants that use half of the nitrogen of conventional plants.

Another UNEP report reckons that, in order to remain on a path that keeps the average increase in global temperatures below 2 degrees centigrade of the pre-industrial level, the world must close a "gap" in what countries have pledged to cut under the UNFCCC by an additional 8 to 12 gigatons of greenhouse gases by 2020. The UNEP nitrous oxide report estimates that by 2020 it should be possible to cut those emissions corresponding to about 0.8 gigatons of carbon dioxide. Such a reduction would represent about 8 percent of the cuts needed to close the emissions gap and it would also help protect the ozone layer.

Finally, cutting back on the emissions of hydrofluorocarbons (HFCs) as refrigerants would help lower projected future increases in the mean global temperature. HFCs were introduced in the 1990s to replace chlorofluorocarbon (CFC) refrigerants whose emissions were damaging the ozone layer. Under the Montreal Protocol in 1987 countries began a phase-out of CFCs, a project I agreed with, as explained in my book Eco-Scam: The False Prophets of Ecological Apocalypse. CFCs were also powerful greenhouse gases and eliminating them avoided emissions equivalent to 8 gigatons of carbon dioxide per year between 1990 and 2010. With respect to keeping the mean global temperature down, the effects of cuts in CFC emissions are calculated to have been four times greater than the carbon dioxide reductions achieved under the UNFCCC's Kyoto Protocol.

While the HFCs that replaced CFCs do not harm the ozone layer, they do have very high global warming potentials. For example, a molecule of HFC 134a, which is often used in home refrigerators and car air conditioners, has a global warming potential that is 3400 times greater than a molecule of carbon dioxide. HFCs already represent about one percent of global greenhouse gas emissions. The United States, Canada, and Mexico have been pushing to phase-out HFCs under the Montreal Protocol, which would lead to a 2.2 gigaton reduction of carbon dioxide emissions in 2020, with cuts eventually amounting to the equivalent of 100 gigatons of carbon dioxide by 2050.

Ironically, carbon dioxide is a cost-effective replacement for HFCs in large-scale refrigeration in grocery stores and warehouses. Amusingly, environmentalist proponents of using carbon dioxide as a coolant coyly refer to it as "natural" refrigerant. In other applications, Dupont and Honeywell have developed a new refrigerant, hydrofluoroolefin (HFO-1234yf), which is a near drop-in replacement for HFC refrigerants in automobile air conditioners. The new HFO refrigerant has a global warming potential of less than one. Of course, transitioning away from HFCs will not be costless, but if man-made global warming turns out to be a problem, reducing their emissions would likely be less costly than cutting the equivalent of carbon dioxide emissions.

Next: The Warsaw climate change conference wraps up. The diplomatic teams are negotiating face-saving texts in the back rooms while various environment ministers take their turns at the podium in the half empty plenary hall to deliver five minutes of platitudes on the importance of what they are doing. Meanwhile, poor country envoys have walked out of the negotiations over charging rich countries climate change loss and damage and activist groups self-styled as "civil society" staged a "massive" walk out of the conference yesterday. My final dispatch will detail what has been agreed to by the remaining diplomats.