Six major European oil companies are asking the United Nations to help impose carbon dioxide emission pricing in all countries. The oil giants said their request to the U.N. represents the best way they could contribute to reducing carbon emissions and fighting climate change.

The letter comes six months before U.N. member countries are due to meet in Paris to hammer out an international agreement to cut greenhouse gases and help nations cope with the effects of climate change.

“If governments act to price carbon, this discourages high carbon options and encourages the most efficient ways of reducing emissions widely, including reduced demand for the most carbon intensive fossil fuels, greater energy efficiency, the use of natural gas in place of coal, increased investment in carbon capture and storage, renewable energy, smart buildings and grids, off-grid access to energy, cleaner cars and new mobility business models and behaviors,” they wrote.

The letter was signed by representatives of the United Kingdom’s BG Group and BP, Italy’s Eni, the U.K.-Netherlands's Royal Dutch Shell, Norway’s Statoil and France’s Total.

They specifically asked for carbon pricing systems in the countries that do not have them and for them to be implemented in a way so the systems could eventually be integrated internationally.

The oil producers offered their help and expertise to the U.N. and any countries in implementing carbon pricing, which could include taxes on carbon emissions, cap-and-trade systems or other policies that charge companies to pollute.

While it could make oil production more expensive, carbon pricing could also encourage the production and use of natural gas, another major product for the oil companies.

“Pricing carbon obviously adds a cost to our production and our products — but carbon pricing policy frameworks will contribute to provide our businesses and their many stakeholders with a clear roadmap for future investment, a level playing field for all energy sources across geographies and a clear role in securing a more sustainable future,” they said.

Originally published by The Hill