Climate scientists have been studying the effect of a global temperature rise of 3.6 degrees Fahrenheit (2 degrees Celsius) over preindustrial levels and have determined that is the maximum possible warming before sea level rise, drought, and other climate-change effects become catastrophic.
Overall, the authors say that current greenhouse gas emissions must be reduced by 45 percent from 2010 levels by 2030.
Carbon emissions need to reach "net zero" by 2050 and almost halve from 2010 levels by 2030.
Henri Waisman, a senior researcher at Paris-based think tank IDDRI and one of 91 report authors, said the report's aim was to set out the types of transformation required as clearly as possible to inform discussions at United Nations climate talks and beyond.
How much more urgent can it get?" and "Science pronounces its verdict: "World to be doomed at 2°C, less risky at 1.5°C" and "A major new climate report slams the door on wishful thinking".
'It was given to me and I want to look at who drew it, which group drew it, ' Trump told reporters at the White House on Tuesday, as he left for an Iowa campaign rally.
If emissions can't be cut to a sufficient degree, researchers will need to devise effective methods of removing Carbon dioxide from the air, such as devoting land to growing trees and biofuel crops, Erik Solheim, executive director of the UN Environment Program, tells The Washington Post.
The report suggests that coral reefs would decline by 70-90 percent with global warming of 1.5°C, whereas virtually all ( 99 percent) would be lost with 2ºC.
Individuals and civic groups have a big role to play in pushing governments to tackle climate threats, and are stepping up pressure as recognition of the danger grows, she said.
Limiting global warming to 1.5C will cost the world $2.4 trillion every year for the next two decades, the United Nations report warns.
"The next few years are probably the most important in our history", said Debra Roberts, an IPCC co-chair.
To curb the trend, governments will have to spearhead "rapid and unprecedented societal transformation", including major reductions in their carbon emissions.
It furthers the Paris Agreement of 2015, where and aim of limiting global temperature rises to "well below" 2C was set. Climate change is moving faster than we are....
The report further revealed that global warming has already had an effect in regions across the world.
"Even at a little over 1.0°C warming, India is being battered by the worst climate extremes - it is clear that the situation at 1.5°C is going to worsen".
The lower target would also reduce species loss and extinction and the impact on terrestrial, freshwater and coastal ecosystems, the report said. We can't find any historical analogies for it.
Joyashree Roy, a professor of economics at Jadavpur University and a co-author of the IPCC report, says: "We have found that the burden of global warming will fall disproportionately on the poor who are not responsible for the problem if we don't meet (the) 1.5 degrees target".
"Many parts of the world will see mean temperature increases that, in time, will be higher than 1.5°C, including the South West of Western Australia", Dr Kala said.
"There are some areas we are making progress quickly enough that they are compatible with 1.5C, the example of renewables is one, where we've seen costs falling and deployment across the world".