According to an internal government document obtained by the BBC, the government appears to be breaking its landmark $11.6 billion commitment to funding for the environment and developing nations.
According to the document, the government has consistently underspent and is currently having difficulty meeting its 2026 target.
To catch up, it continues, about 83% of the overall foreign aid budget would need to be redirected toward climate.
The government has stated that it is still committed to keeping its word.
A government spokesperson said, "The government remains committed to spending £11.6bn on international climate finance and we are delivering on that pledge.
The former prime minister Boris Johnson committed in 2019 to spending at least £11.6bn on the UK's international climate finance (ICF), which provides assistance to vulnerable countries to address the causes of climate change, between 2021–2022.
However, the internal briefing paper cautions that "subsequent turbulence" — referring to economic shocks like the Covid pandemic — means the government is falling behind.
Since then, total international aid spending has decreased from 0 point 7 percent of GDP to 0 point 5 percent.
A "reorientation" of the budget on a scale that has "not previously been achieved" is necessary for the government to spend 83 percent of the total foreign aid budget on climate in order to meet the ICF target by 2026.
Additionally, according to civil servants, doing so would leave no money for projects "specifically targeted at helping women and girls" or other priorities.
It comes after Rishi Sunak's government was led by Tory peer Lord Zac Goldsmith, who resigned last week in protest of what he called the prime minister's "apathy" toward climate change.
The now-former minister accused the government in his scathing resignation letter of reneging on important environmental commitments, including spending £11 point 6 billion of UK aid on climate and the environment and giving up its position as a global leader.
In fact, the final year of expenditure falls after the next general election and will therefore be the problem for the next government, not this one, he said in his letter, "so the only reason the government has not had to come clean on the broken promise.".
Lord Goldsmith, according to Mr. Sunak, resigned after being asked to apologize for remarks he made regarding the Privileges Committee investigation into Boris Johnson's behavior and whether he purposefully misled the House of Commons while prime minister.
Lord Goldsmith, however, refuted this and stated that his resignation had been a "long time coming.".
The International Climate Fund (ICF) is a term used to describe UK aid provided to help vulnerable nations deal with the causes of climate change, such as preventing deforestation and reducing carbon emissions, as well as preparing for its effects.
It fits into the global pledge to spend $100 billion annually on climate finance for developing nations.