Warnings about the dangers of global warming are being watered down in the final version of a key climate report for a major international meeting next month, according to reviewers who have studied earlier versions of the report and its summary.

They say scientists working on the final draft of the summary are censoring their own warnings and “pulling their punches” to make policy recommendations seem more palatable to countries – such as the US, Saudi Arabia and Australia – that are reluctant to cut fossil-fuel emissions, a key cause of global warming. “Downplaying the worst impacts of climate change has led the scientific authors to omit crucial information from the summary for policymakers,” said one reviewer, Bob Ward, policy director at the Grantham Research Institute on Climate Change and the Environment.

“However, if governments do not recognise the full scale and urgency of the risks, they may underestimate how critical it is to meet the goal of the Paris agreement on climate change. And that could have very serious knock-on effects in the battle to limit the impact of global warming.”

The Special Report on Global Warming of 1.5C and its summary for policymakers were commissioned by governments following the UN meeting in Paris in 2015, when it was agreed to act to limit increases in global average temperature to less than 2C above pre-industrial levels and to try keep that increase nearer to 1.5C.

The report – to be presented at a meeting in Korea in early October – will make clear that allowing temperatures to rise by 2C will have devastating consequences, including rising sea levels, spreading deserts, loss of natural habitats and species, dwindling ice-caps and increases in the number of devastating storms.

However, it is the report’s summary for policymakers that is causing concern. This is the document politicians will use as a key climate guide when making changes to legislation. Reviewers of earlier drafts say it is being altered to make the dangers of climate change seem less alarming. As a result, they say,, policymakers could seriously underestimate the risks of global warming. Cuts made to the final draft of the summary include:

• Any mention that temperature rises of above 1.5C could lead to increased migrations and conflict;

• All discussion of the danger of the Gulf Stream being disrupted by cold water flowing from the Arctic where more and more sea-ice is melting;

• Warnings about the dangers that 1.5–2C temperature rises could trigger irreversible loss of the Greenland ice sheet and raise sea levels by 1–2 metres over the next two centuries.

Other cuts from the summary include the sentence: “Poverty and disadvantage have increased with recent warming (about 1C) and are expected to increase in many populations as average global temperatures increase from 1C to 1.5C and beyond.”

The original summary also stated “at 2C warming, there is a potential for significant population displacement concentrated in the tropics”. Again this is not mentioned in the report for policymakers. “The scientists who produce reports like these try to summarise the latest knowledge, but they have a reputation for being conservative about the worst risks of climate change,” Ward said. “This time they have outdone themselves in pulling their punches, however.”

An IPCC spokesman said member governments would work to ensure the summary for policymakers was consistent with the findings in the main report. “They may change the wording of text there to clarify, remove material from the summary for policymakers, or bring material from the main report that was not there at the start of the session. Any text in the summary for policymakers … is based on the assessment in the main report. Even if it is removed from the summary for policymakers, the finding it is based on remains in the main report.”