In the 728-page document, the United Nations organization detailed how Earth's weather, health and ecosystems would be in better shape if the world's leaders could somehow limit future human-caused warming to just 0.9 degrees Fahrenheit (a half degree Celsius) from now, instead of the globally agreed-upon goal of 1.8 degrees F (1 degree C). We need to make to make major changes in transportation, buildings, industry, and how we use land.
Matthew Spencer, Oxfam's director of campaigns and policy said: 'Climate change has set our planet on fire, millions of people are already feeling the impacts, and the IPCC is clear that things could get much worse without immediate action.
The Intergovernmental Panel on Climate Change, meeting in South Korea, issued a report with 91 authors and editors from 40 countries declaring that there's now a 12-year window to make "far-reaching and unprecedented changes" to avert dramatic effects of global warming.
Measures would have to include reducing man-made carbon emissions by 45 per cent by 2030 from 2010 levels, and reaching "net zero" emissions by 2050, the report said. The Arctic, which would be ice-free about once per century at 1.5 degrees of temperature rise, would be ice-free once per decade at 2 degrees.
Professor Corinne Le Quere, from the University of East Anglia, said: "For the United Kingdom, this means a rapid switch to renewable energy and electric cars, insulating our homes, planting trees, where possible walking or cycling and eating well - more plants and less meat - and developing an industry to capture carbon and store it underground". Even at 1.5°C, the report says there is "high confidence" that coral reefs will further decline by 70 to 90 percent.
The world must invest US$2.4 trillion in clean energy every year through 2035 and cut the use of coal-fired power to nearly nothing by 2050 to slow the quickest pace of climate change since the end of the last ice age, according to scientists convened by the United Nations.
One of them, who didn't want to be identified, told The Hindu that the report gave a more comprehensive assessment of the differences in a 1.5C world and 2C world and quantified the carbon dioxide that would need to be removed from the atmosphere to achieve this.
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Limiting warming to "well below" 1.5 degrees hotter than pre-industrial levels was the promise made by governments all over the world at the Paris climate talks in 2015.
If governments fail to ramp up their ambition to reduce heat-trapping emissions over the next two years, they will have consciously abandoned the 1.5 degree goal, he added. "Climate activists have been calling for decades for leaders to show responsibility and take urgent action, but we have barely scratched the surface of what needs to be done".
Negative impacts of climate change occur on a continuum, and defining a point at which climate change becomes risky is hard and contentious.
"Temperature rise to date has already resulted in profound alterations to human and natural systems, bringing increases in some types of extreme weather, droughts, floods, sea level rise and biodiversity loss, and causing unprecedented risks to vulnerable persons and populations", it says.
The review of thousands of scientific papers also said the spread of disease and economic damage and harm to yields of crops will be less severe at 1.5C than 2C, as will the extinction of species. This would require all countries to enhance their existing emission reduction targets under the agreement for the period starting 2020. The agency removed its section on climate change from its website past year for an "update" that has yet to materialize.
Theoretically, technologies that suck carbon out of the air and allow us to bury it underground could help - and will be needed.