The 159-page submission said that displacing imported liquified nature gas (LNG) from the United States with gas from the Jackdaw field would save the equivalent of four million tonnes of CO2 equivalent.
It says that could result in around 20% more emissions from imports compared with gas produced domestically.
Those "losses" would principally come from eliminating the need to liquify, transport and then regasify the imported product.
It also said the climate effects would be "minor" because the UK has a "well-regulated industry, with targets and commitments that are aligned with the expectations of the Paris Agreement", a legally binding commitment to limit global warming to between 1.5 and 2C.
Last year, the Court of Session in Edinburgh ruled that both Jackdaw and Rosebank had been unlawfully approved, because the government failed to take into account the climate impact of burning extracted oil and gas from the fields.
The legal case had been brought by environmental groups Uplift and Greenpeace.
In his judgement, Lord Ericht required a more detailed climate assessment and fresh approval from the UK government before production could begin.
