That's the warning from some of the world's top scientists with the UN Intergovernmental Panel on Climate Change, who believe we only have 12 years to prevent those outcomes due to climate change.
A rise in global temperatures by another 0.5 degree Celsius would increase, deepen and spread the impacts wider, the scientists concluded.
The impact of 1.5 degrees Celsius warming is greater than what was anticipated earlier while the impacts at two degrees Celsius are "catastrophic" for the poor and for developing nations such as India, the Centre for Science and Environment (CSE) said.
The IPCC report is undeniably grim, but its authors state that the 1.5°C target can still be met if unprecedented, wide-ranging action is taken straight away.
That would require "unprecedented changes in all aspects of society", most especially within the energy industry.
He said the difference between a 1.5ºC rise and a 2ºC rise would have a particularly harsh effect on the mean temperature and rainfall in Southern Africa, which is a "hot spot because it is semi-arid and is water-stressed".
"Climate change is already affecting people, eco systems and livelihoods all around the world", he says.
The scientists said the report was meant to guide more than just governments, however, and that action by everyone - including individuals and businesses - would be required to hold the line on climate change.
Countries are already seeing an increase in extreme weather and rising sea levels as a result of the increase in average global temperatures of 1 degree above pre-industrial levels that has already occurred, the IPCC study said.
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If nothing is done, Earth can expect heat wave temperatures to rise by 3 degrees Celsius, more frequent or extreme droughts, an increase in deadly hurricanes and as much as 90 percent of coral reefs dying off - including the Great Barrier Reef in Australia, according to the report.
Some of the actions that would be required to limit global warming to 1.5 degrees Celsius are already underway around the world.
Global net emissions of carbon dioxide would need to fall by 45% from 2010 levels by 2030 and reach "net zero" around 2050 in order to keep the warming around 1.5 degrees C.
The IPCC report incorporates recent research suggesting that the amount of carbon that humanity can emit while limiting warming to 1.5 °C might be larger than previously thought.
"This report gives policymakers and practitioners the information they need to make decisions that tackle climate change while considering local context and people's needs", she said.
These are just a few examples taken from a depressingly long list of climate change threats that would be made significantly more risky if the temperature were to rise by 2°C or beyond by the end of the century. Even with the promises countries have made as part of the Paris Agreement to cut the greenhouse gas emissions that cause global warming, the world is set to breach the 1.5C threshold by around 2040.
"Limiting global warming to 1.5°C compared with 2°C would reduce challenging impacts on ecosystems, human health and well-being, making it easier to achieve the United Nations Sustainable Development Goals (SDGs)", Co-Chair of IPCC Working Group III Priyardarshi Shukla said, referring to the 17 Goals adopted by UN Member States three years ago to protect the planet and ensure that all people enjoy peace and prosperity by 2030.
The global temperature is now 1°C warmer than pre-industrial levels. The sea level will still rise, and there always be more extreme weather events and natural disasters, but these won't be as extreme as the worst case scenario we're now headed for.
In the United Kingdom, where existing legal targets require 80pc cuts in emissions by 2050, the government is under pressure to strengthen action on climate change.