Ed Davey, the energy secretary, has written a private letter to Michael Gove, the education secretary, urging him to rethink his plans to downgrade climate change in the new national curriculum.

Amid protests from environmentalists and some students, Gove has removed debate about climate change from the draft geography curriculum.

Davey, a Liberal Democrat, argues that inclusion of climate change in the geography curriculum would safeguard the very important role teachers can have in teaching children about climate change.

Gove is seeking to slim down the curriculum, but his critics claim the omission of climate change from key stage 3 geography is an attempt to downgrade its significance, and even its validity.

In a Guardian interview on Wednesday Nick Clegg revealed he was now spending more time trying to broker deals with the Conservatives on green issues than any other single issue in government.

In a sign that the status of climate change teaching in schools is set to become another coalition flashpoint, Davey writes: "While I understand that one of the main objectives of the curriculum is to make it more concise and that 'climate change' is included within the science section, it does not appear in the geography section."

He continues: "As you'll be aware, there has been a significant number of responses, both from academic experts and the public, calling for climate change to feature explicitly in the geography curriculum. I am writing to express my strong support for such a change.

"Specifically mentioning climate change alongside the existing reference to 'climate' will ensure clarity on this issue for schools without requiring any major drafting changes to the curriculum. In doing so we will demonstrate the coalition's willingness to respond to feedback. More importantly we will safeguard the very important role that teachers have in helping children understand the impacts of climate change, one of the most important global issues of this century."

Davey has asked for a meeting between the two department's officials to discuss his concerns.

So far more than 65,000 people have signed petitions urging the government to keep climate change in the national curriculum for England.

The Department for Education has insisted climate change is protected because of its presence in the draft science curriculum.

Campaigners have argued the issue is not about forcing students to believe in climate change, but allowing them to make an informed decision based on what they learn.

They have also argued it is not sufficient to learn about the scientific debate on climate change, but to understand its impact on people, the environment and their own lives.

Under the outgoing national curriculum schools teach seven to 11-year-olds about "managing the environment sustainably". The curriculum specifies that 11- to 14-year-olds should learn about issues such as "sustainable development and its impact on environmental interaction and climate change".

The draft curriculum for geography does not contain references to climate change but a section called "Earth science" in the chemistry syllabus says 11- to 14-year-olds should be taught about "the production of carbon dioxide by human activity and the impact on climate" and includes a section on "the efficacy of recycling".

Luciana Berger, the shadow climate change minister, said: "We have a responsibility to inform young people about global warming and the impact of climate change both here and across the world. Just this week, global carbon dioxide levels reached a record high. It's no surprise that Michael Gove is trying to airbrush climate change from the curriculum given this Tory-led government's disastrous green record."

In a response to the Davey letter, the Department for Education said: "It is not true that climate change has been removed from the new draft national curriculum. In fact, the curriculum will give pupils a deeper understanding of all climate issues and has been welcomed by the Royal Geographical Society – which has specifically praised its treatment of climate change.

"Climate change is mentioned in the science curriculum, and both climate and weather feature throughout the geography curriculum. Nowhere is this clearer than the science curriculum for 11- to 14-year-olds, which states that pupils should learn about the 'production of carbon dioxide by human activity and the impact on climate'.

"This is at least as extensive, and certainly more precise, than the current science curriculum for that age group, which says only that 'human activity and natural processes can lead to changes in the environment'."

Ministers published the proposed new curriculum in February, and the period for consultation has just ended.