Coral reefs would decline by a further 70 to 90 per cent under global warming of 1.5 degrees and "virtually all" would be lost with 2 degrees. By 2100, global sea level rise would be 10 centimetres lower under the 1.5 degree scenario, reducing the risks for 10 million people. Loading Replay Replay video Play video Play video The "likelihood of an Arctic Ocean free of sea ice in summer" would be once per century rather than once per decade. Human activities have already caused about 1 degree of global warming and the impacts on humans and the environment has already been felt through more extreme weather, rising sea levels and melting polar ice caps. Warming would reach 1.5 degrees as early as 2030 if it continues at the current rate, the report found.

The IPCC releases reports regularly, but the latest version, released on Monday, was billed as one of its most controversial in recent years and called for swift, unprecedented cuts to greenhouse gas emissions. Jim Skea, co-chairman of the IPCC's "working group three" said limiting warming to 1.5 degrees was "possible within the laws of chemistry and physics but doing so would require unprecedented changes". Loading "Working group two" co-chairwoman Debra Roberts said the report was intended to give policy makers around the world information to make decisions on tackling climate change while considering local context and needs. "The next few years are probably the most important in our history," she said.

The findings put pressure on governments around the world to prioritise efforts to decarbonise their economies. This includes the Morrison government, which is riven by internal tensions over climate change policy and has been condemned for inaction by supporters of the Paris climate agreement. Australia has vowed to reduce greenhouse emissions, based on 2005 levels, by 26 per cent by 2030. The government has indicated it will not increase that target despite it being incompatible with the Paris accord's efforts to keep global warming well below 2 degrees. Asked whether he could imagine any scenario where coal was phased out in Australia within 30 years, Energy Minister Angus Taylor said: "The key here is not to focus on an industry, it's to focus on the outcome. "It's the outcomes that matter and reaching Paris is part of that outcome," he told Sky News on Monday. "We also know Australia is around 1 per cent of global emissions so the critical thing here is other countries, whether it's China or India ... the developing world is where there's a great deal of growth in emissions and it's going to be crucial that they of course contribute over time."

Mr Taylor repeated his previous position that the government's focus was on reducing power prices. Energy and power prices The summary for policymakers, released on Monday, warns that, if the limit of 1.5 degrees is to be met, coal use for electricity must be "reduced to close to 0 per cent" by 2050. Some fossil fuel and nuclear generation could occur alongside carbon capture and storage technology. This would mean gas – a major export industry for Australia - would comprise about 8 per cent of global electricity generation, down from current levels of about 23 per cent. Renewables would make up 70-85 per cent of electricity in 2050 if warming is kept below 1.5 degrees.

"While acknowledging the challenges, and differences between the options and national circumstances, political, economic, social and technical feasibility of solar energy, wind energy and electricity storage technologies have substantially improved over the past few years," the report said. "These improvements signal a potential system transition in electricity generation." A source close to the talks said Australian officials sought to remove references to phasing out coal from the final version of the document when government negotiators joined scientists and diplomats from around the world in South Korea over the past week. Loading Replay Replay video Play video Play video Fairfax Media was told Australia joined Japan, South Korea, Poland and Estonia in calling for the change, but the group later abandoned the push.

However a spokeswoman for Environment Minister Melissa Price said the claim was "untrue". Australia is the world's largest coal exporter, and the findings of the report are at odds with the Coalition government’s insistence that coal will play an essential role in the nation’s economic future. The government is without a policy to reduce carbon emissions from the electricity sector following the dumping of the National Energy Guarantee, and has strongly backed a proposal by Indian mining giant Adani to build what would be Australia’s largest coal mine in regional Queensland. Labor has voiced concerns over the mine, but its position has shifted several times and it has not committed to cancelling Adani's approvals if it wins office. Prime Minister Scott Morrison has indicated his government would not increase Australia’s target under the Paris accord, despite it being incompatible with the accord's efforts to keep global warming to well below 2 degrees.

Labor has pledged to cut 2005-level emissions across the economy by 45 per cent by 2030. Launching a new action plan on Sunday ahead of the federal election, leader Bill Shorten reiterated the party's goal for 50 per cent renewables in the energy mix also by 2030. "If you don’t care about doing the right thing by the environment, then you actually have no right to be the government of Australia," he said. Decarbonising across the economy The report found that global net human-caused carbon emissions must fall by about 45 per cent from 2010 levels by 2030 and reach net zero by 2050, to stay below 1.5 degrees warming. Carbon emissions from industry must be reduced by 75 to 90 per cent by 2050, compared with 2010 levels.

Urban planning would undergo substantial change and transport systems would be drastically decarbonised. Around the world, millions of square kilometres of agricultural land - larger than Australia - now used for food and feed crops would have to be converted into forests and energy crops, which are used to make bio-fuels. Limiting global warming to 1.5 degrees would also require methods to remove carbon dioxide from the atmosphere. These include reforestation, land restoration and direct air carbon capture and storage – options at vastly different stages of maturity and with varying costs, potential and risks. The Great Barrier Reef has already undergone severe damage due to back-to-back bleaching events caused by climate change. Credit:Dean Miller/GBR Legacy Coral reefs in peril

The Great Barrier Reef has already undergone severe damage due to back-to-back bleaching events caused by climate change. This adds to other pressures such as poor water quality from agricultural sediment and nutrient runoff. World-leading coral reef expert Terry Hughes told Fairfax Media that despite the grim predictions “there is certainly hope ... if we get our act together in time”. “There is a narrowing window of opportunity to really knuckle down and achieve 1.5 degrees,” he said. “If we delay action on reducing greenhouse gases for another decade or two we will sail past 1.5 degrees and probably pass 2 degrees, so there is no time to lose.” Natural systems under pressure

Keeping below the 1.5 degrees limit, compared with 2 degrees or more, would avoid a number of climate change effects, the report said. The risk of drought and heavy rain events, including tropical cyclones, was found to be higher at 2 degrees than 1.5 degrees, as were impacts on biodiversity and ecosystems, including species extinction. The report confirmed the grave risks that sea level rises pose to coastal communities around the world, including Australia’s Pacific neighbours. Increasing warming will amplify the exposure of small islands and low-lying coastal areas to saltwater intrusion, flooding and infrastructure damage. Human security threatened The report found that climate-related risks to health, livelihoods, food security, water supply and economic growth would increase with global warming of 1.5 degrees and worsen further under the 2-degrees scenario.