Carbon dioxide emissions need to fall about 45 percent from 2010 levels by 2030 and to "net zero" - so no more is being put into the atmosphere than is being removed by measures such as planting trees - by 2050, while other greenhouse gases will also need to decline steeply.
The 2015 Paris Agreement sets a goal to cap the increase in the global average temperature to below 2 degrees above pre-industrial levels. But even though the world has already warmed by 1 °C, humanity has 10-30 more years than scientists previously thought in which to kick its carbon habit.
However, limiting global warming global warming to 1.5 C would require "rapid, far-reaching and unprecedented changes in all aspects of society". "Consequently, limiting global warming to 1.5°C is projected to reduce risks to marine biodiversity, fisheries, and ecosystems, and their functions and services to humans, as illustrated by recent changes to Arctic sea ice and warm water coral reef ecosystems".
The planet will begin to see the effects of climate change sooner ー and more broadly ー than experts originally thought, according to a landmark report by a United Nations commission of dozens of climate scientists released Monday.
Keeping the Earth's temperature rise to 1.5 degrees Celsius means making rapid, unprecedented changes in the way people use energy to eat, travel and live or we risk even more extreme weather and loss of species, a United Nations report said on Monday. The report also examines pathways available to limit warming to 1.5 °C, what it would take to achieve them and what the consequences could be.
Temperatures during summer heatwaves, such as those just experienced across Europe this summer, can be expected to increase by 3 degrees C says the report. He says that researchers will provide a more comprehensive look at the numbers in the next full climate assessment, which is scheduled to be released in 2021.
Adding another 0.5 degrees on top of that - the looser global goal - essentially means a different and more challenging Earth for people and species, said another of the report's lead authors, Ove Hoegh-Guldberg, director of the Global Change Institute at the University of Queensland, Australia.
"Every extra bit of warming matters, especially since warming of 1.5 C or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems", said Hans-Otto Pörtner, Co-Chair of IPCC Working Group II.
The world is now warming up at about 0.2 C each decade, and has already warmed by more than 1 C compared to the mid-19th century.
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Governments invited the IPCC to prepare the report in 2015 when they adopted the Paris Agreement to combat climate change.
Coal consumption by Indian thermal generators needs to be cut by two thirds within 2030 and to nearly zero by 2050 if India has to limit temperature rise to 1.5 degrees said Greenpeace India in a statement.
Before the Paris Agreement was inked in 2015, almost a decade of scientific research rested on the assumption that 2C was the guardrail for a climate-safe world.
There is some good news. "But doing so would require unprecedented changes".
In order stop climate change from reaching risky levels, it is necessary to reduce worldwide emissions whilst at the same time removing Carbon dioxide out of the atmosphere. In any case these are also the countries responsible for much of the emissions in the atmosphere.
The technology to do this is in the early stages of development and many researchers say it could be hard to develop it for use on a global scale.
The report also urges individuals to act, such as by reducing consumption of meat and dairy products, driving electric vehicles or taking public transport and demanding and buying low-carbon products. "Our countries are not near where they need to be on achieving the kinds of emission reduction that we need if we want to actually successfully fix the planet and reverse the changes that we've already made".
"Unfortunately, the Trump administration has become a rogue outlier in its shortsighted attempt to prop up the dirty fossil fuel industries of the past".