The world's leading climate change scientists are warning that if global temperatures go up by 1.5 degrees, there'll be unprecedented levels of flooding, drought, wildfires and food shortages affecting billions of people.
When the target was put into the Paris Agreement, relatively little was known about the climate risks that would be avoided in a 1.5C warmer world compared with a 2C warmer world, or about the action needed to limit temperature rises to that level.
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.
If every country fulfills the pledges it made for the Paris agreement in 2015, the world may still warm 2.6 to 3.2 degrees C by the end of the century, by some estimates. They have "medium confidence" that there will be more extreme storms in areas such as high-elevation regions, eastern Asia and eastern North America. The risk of such severe weather would be even greater in a 2 °C world. In the Paris accord, 197 countries agreed to the goal of holding global temperatures "well below" 2°C above pre-industrial levels and to pursue efforts to limit it to 1.5°C.
The report warned that half a degree increase in global warming temperature is a big deal and can have catastrophic consequences which will be there for people to see in their current lifetimes. The word "or" does not work in relation to the ambition of 1.5º warming. The likelihood of an Arctic Ocean free of sea ice in summer would be once per century with global warming of 1.5°C, compared with at least once per decade with 2°C. Coral reefs would decline by a still unsustainable 70 percent to 90 percent instead of being virtually wiped out under the higher target. Starting in 1994, a central aim of the UN's climate change efforts (the Framework Convention on Climate Change, or UNFCCC) was to stabilise greenhouse gas concentrations at a level that would "prevent risky anthropogenic interference with the climate system".
"We've all got to play our part". "We need to halve greenhouse gas emissions globally by 2030 and cut coal use by two-thirds by the same date". "We also need more effective harmonised regulatory processes to facilitate significant growth in nuclear capacity and an effective safety paradigm where the health, environmental and safety benefits of nuclear are better understood and valued by society". 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.
A second pathway emphasises the need for changing our consumption patterns - eating less meat, travelling less, giving up cars, etc. - along with an overhaul of agricultural and land-use practices, including the protection of forests.
The report is set to lay out four scenarios that could result in Earth's average surface temperature stabilising at 1.5°C. Thus there is consistency between the Paris and IPCC assessments.
A summary of the Special Report on Global Warming is available here.
Australian professor Ove Hoegh-Guldberg of the University of Queensland says: "The report strongly concludes that climate change is already affecting people, ecosystems and livelihood all around the world and that is beyond reasonable doubt that humans are responsible". "We have a lot of the solutions available to us today", she says.
In the meantime, the newer and larger carbon budget could send the wrong message to policymakers, says Oliver Geden, a social scientist and visiting fellow at the Max Planck Institute for Meteorology in Hamburg, Germany.
In the Indian subcontinent, the IPCC report specifically mentions Kolkata and Karachi among cities that could face an increased threat of heat waves. "It's always five minutes to midnight, and that is highly problematic", he says.
"The United States is quite constructive, though I don't think they want that said out loud", said on delegate who asked not to be named.
This article is reproduced with permission and was first published on October 8, 2018.