The Arctic, for example, is likely to be several degrees warmer, increasing ice melt and sea level rise.
"Every bit of warming matters, especially since warming of 1.5C or higher increases the risk associated with long-lasting or irreversible changes such as the loss of some ecosystems", co-chair of the IPCC Working Group II Hans-Otto Portner said.
"We've told you the scientific facts, the evidence, the costs; it is up to the governments now to decide what to do with it", says Jim Ski, a co-chair of this panel, who calls on the globe's governments to come together to fight climate change.
Limiting global warming to 1.5 °C would require rapid, far- reaching and unprecedented changes in all aspects of society, the IPCC said in a new assessment. It compares the impact of global warming of 1.5C and 2C.
A critical step is to ensure human-caused emissions of carbon dioxide (CO2) will fall by about 45 percent from 2010 levels by 2030, reaching "net zero" around 2050.
Economies would have to shift away rapidly from burning coal, oil and gas and invest heavily in renewable energy.
The report also enlists ways to slow down the warming process and limit the rise to 1.5 degree Celsius by 2100 - well below the 2 degree Celsius rise which is the intended goal of the Paris Agreement on climate change.
Allowing the global temperature to temporarily exceed or "overshoot" 1.5ºC would mean a greater reliance on techniques that remove Carbon dioxide from the air to return global temperature to below 1.5°C by 2100.
One of the lead authors, Murdoch University climate scientist Jatin Kala, said even if global warming was kept to 1.5C there could still be "dire consequences" for WA's South West, such as altered growing seasons in the Wheatbelt and wine regions such as the Swan Valley.
The report is seen as the main scientific guide for government policymakers on how to implement the 2015 Paris Agreement, which aims to limit the rise in global average temperatures to "well below" 2C above pre-industrial levels, while seeking to tighten the goal to 1.5C.
"1.5 degrees is the new 2 degrees", Jennifer Morgan, executive director of Greenpeace International, told The Washington Post after attending the finalisation of the IPCC report in Incheon, the Republic of Korea. "But it will require unprecedented and collective climate action in all areas".
The report compares the impacts of warming at 1.5°C against 2°C across the planet - from ecosystems on land and in oceans to the health and well being of people - and finds universal benefits in the lower target, such as 0.1 meter less sea level rise that could mean 10 million less people were exposed to related risks.
The report calls for immediate and radical action by all global governments, saying the required actions are affordable and feasible but require ambition and dedication.
Four scenarios are modeled in the report that reflect different strategies governments could take to deliver "no or low overshoot" of the 1.5°C target.
If we fail to meet this objective and global temperatures rise by even a mere half a degree Celsius more to 2°C (3.6°F), the effects on our planet are expected to be devastating.
"Large quantities of current gas plants will need to be retired early, while those under construction or in planning stages must be reconsidered immediately as they are not compatible with the 1.5-degree future", Chen said.
In the Indian subcontinent, the IPCC report specifically mentions Kolkata and Karachi among cities that could face an increased threat of heat waves. This would require all countries to enhance their existing emission reduction targets under the agreement for the period starting 2020. 'While it's technically possible, it's extremely improbable, absent a real sea change in the way we evaluate risk.
Theoretically, technologies that suck carbon out of the air and allow us to bury it underground could help - and will be needed.