The world could hit two degrees Celsius of warming – the point at which many scientists believe climate change will become dangerous – as early as 2050, a group of leading experts has warned.
In a report called The Truth About Climate Change, they said many people seemed to think of global warming as “abstract, distant and even controversial”.
But the planet is now heating up “much faster” than anticipated, said Professor Sir Robert Watson, a former chair of the Intergovernmental Panel on Climate Change and one of the authors of the report.
If their analysis is correct, it means the majority of people alive today will experience what it is like to live on a dangerously overheated planet.
At the Paris Climate Summit last year, world leaders agreed to try to limit global warming to as close to 1.5C above pre-industrial levels as possible – amid concerns the 2C target may not be safe enough.
But in the same year the level of warming reached 1C after an astonishing 0.15C rise in just three years.
Droughts, floods, wildfires and storms are all set to increase as the world warms, threatening crops and causing the extinction of species.
The new report warned the 1.5C target had “almost certainly already been missed”.
Even if all the pledges to cut emissions made by countries at Paris are fulfilled, the average temperature is set to reach that level in the early 2030s and then 2C by 2050, they said.
Professor Watson, a chemist who has worked for Nasa, the World Bank, the US president and now at the renowned Tyndall Centre for Climate Change Research in Norwich, said: “Climate change is happening now and much faster than anticipated.
“While the Paris Agreement on Climate Change is an important step in the right direction, what is needed is a doubling or tripling of efforts.
“Without additional efforts by all major emitters, the 2C target could be reached even sooner.”
The report said an extra 0.4 to 0.5C of warming was expected to take place because of greenhouse gases that have already been emitted due to the slow response of the ocean and atmosphere.
The report said that full implementation of the pledges made at Paris would require wealthy countries to give a total of $100bn a year – as promised at the summit – to poor countries to help them transition to a zero-carbon economy.
“About 80 per cent of the pledges are subject to the condition that financial and technological support is available from developed countries,” Professor Watson said.
“These conditions may not be met, which means that these pledges may not be realized.”
The UK has already indicated its share of this total will come from the foreign aid budget, meaning poor countries will actually not get any more cash than they do at present.
The report suggested there was little chance the world would not see 2C of warming at some point.
“The main concern is not when the 2C target will be exceeded, but the impacts of climate change resulting from such an increase in global temperature,” it said.
“Weather-related events due to climate change have doubled in number since 1990.
“An increase in global average temperature of 2C within the next couple of decades implies an additional doubling in the number of these events.
“As the number of weather-related events due to climate change continues to rise, their impact on water resources, food production, human health, services and infrastructure in urban and rural areas, among other sectors, will be more frequent and intense.
“Some of the impacts of climate change may be beneficial, while most will not, negatively impacting lives and livelihoods everywhere.”
But there was “still time to slow down the current path towards the 2C target”, the report stressed.
The experts called for drastic changes to the way the world produces and uses energy with a switch to electric cars among steps that should be taken quickly.
They also said carbon capture-and-storage (CCS) of emissions from fossil fuel power stations and industrial plants could be part of the solution if the system could be made to work.
Deforestation should be reduced and more trees – which absorb carbon from the atmosphere as they grow – should be planted.
But humanity should also take steps to deal with the “unavoidable” adverse effects of climate change that are already in the pipeline.
Professor James McCarthy, an oceanographer at Harvard University and one of the report’s authors, said: “Climate change is already causing harm. Although implementation of the Paris Agreement will slow the rate of change, we will still need widespread adaptation to reduce its risks.
“It is important that appropriate adaptation measures be planned and implemented with sensitivity to specific regional context.”
Mark Lynas, in his award-winning book Six Degrees: Our Future on a Hotter Planet, laid out just what will happen as the world’s average temperature increases.
He described the report’s findings as “extremely worrying”.
“If we hit 2C by 2050 then we will be well on the way to a really terrifying 3C-plus scenario by the end of the century,” Mr Lynas said.
“The world’s ice-caps will be in full-scale meltdown, and large areas of what are now breadbaskets could become deserts, threatening serious global food shortages.
“We would likely lose all the tropical coral reefs, combined with a devastating mass extinction of plants and animals more widely.
“And we would be condemning our children and grandchildren to multi-metre sea level rise, and the eventual evacuation of major coastal cities.”