Latest IPCC Report Describes the Impact of 1.5-Degree Warming

It's not pretty, it's happening now, and we have run out of time.

Flooding in Germany
Climate change in action in Germany.

Thomas Lohnes / Getty Images

A new report just released by the Intergovernmental Panel on Climate Change (IPCC)—the AR6 Working Group II report—looks at the impact of global warming of 1.5 degrees Celsius (2.7 degrees Fahrenheit) and it is pretty dire. But not nearly as bad as it will be if we let temperatures rise by 2 degrees C. And as Stephanie Roe of the World Wildlife Fund notes, sitting at 1.1 degrees C isn't exactly a picnic.

"We’re already seeing enormous harm and damage to our cities, economy, human health, food and water security, and natural ecosystems. Climate impacts, like extreme weather events, sea-level rise, and species extinctions are projected to get worse with additional warming, and some risks are irreversible beyond 1.5° C."

United Nations Secretary-General António Guterres said in the press conference: "With fact upon fact, this report reveals how people and the planet are getting clobbered by climate change." He notes "the abdication of leadership is criminal" and that big polluters "are guilty of arson." He calls the report an “atlas of human suffering and a damning indictment of failed climate leadership.”

The 2015 Paris agreement aimed to keep the temperature rise below 2 degrees C, and a subsequent 2018 report said that 1.5 degrees C should be the target. This was controversial. Some (like Ted Nordhaus of the Breakthrough Institute) have claimed the IPCC "had moved the goalposts" and that the numbers were arbitrary. In a sense they are: They are targets based on calculations and degrees of probability and the temperatures are rounded numbers. Many also say it is too late to keep warming below 1.5 degrees C, which would require us to reduce carbon dioxide (CO2) and equivalent emissions by 45% between now and 2030. This is probably true, but what this report does is show what the implications of this will be. As the report notes,

"The scientific evidence is unequivocal: Climate change is a threat to human well-being and the health of the planet. Any further delay in concerted global action on adaptation and mitigation will miss a brief and rapidly closing window of opportunity to secure a livable and sustainable future for all."
what happens as it gets warmer


As the graphic shows, everything gets worse as it gets warmer, and there is a lot more high-risk purple up there at 2 degrees C. The report states:

"Climate models project robust differences in regional climate characteristics between present-day and global warming of 1.5°C, and between 1.5°C and 2°C. These differences include increases in: mean temperature in most land and ocean regions (high confidence), hot extremes in most inhabited regions (high confidence), heavy precipitation in several regions (medium confidence), and the probability of drought and precipitation deficits in some regions (medium confidence)."

This report differs from earlier ones in that, instead of estimating impacts of what is to come, it lists events that have already occurred, the heat waves, the flooding, the storms, and more. As Katherine Hayhoe, chief scientist of the Nature Conservancy states:

“Loss of biodiversity, stresses on agricultural productivity, human health risks – the themes highlighted by WGII are not new. We’ve been tracking most of them for years now. What is emerging is the indisputable evidence for how climate change is acting to compound and conjoin these challenges at a rate humankind is currently struggling to keep pace with, and how these impacts often hit the most vulnerable first."
global temperature change


The report is 3,700 pages long and very detailed, but a quick dive into the chapter on mitigation pathways indicates the direction we have to take.

"Warming will not be limited to 1.5°C or 2°C unless transformations in a number of areas achieve the required greenhouse gas emissions reductions. Emissions would need to decline rapidly across all of society’s main sectors, including buildings, industry, transport, energy, and agriculture, forestry and other land use. Actions that can reduce emissions include, for example, phasing out coal in the energy sector, increasing the amount of energy produced from renewable sources, electrifying transport, and reducing the ‘carbon footprint’ of the food we consume."

That's the supply side or the production side; there is also what we call the consumption side, or that the report calls the demand side:

"A different type of action can reduce how much energy human society uses, while still ensuring increasing levels of development and well-being. Known as ‘demand-side’ actions, this category includes improving energy efficiency in buildings and reducing consumption of energy- and greenhouse-gas intensive products through behavioral and lifestyle changes, for example."

Report co-author Ed Carr is more straightforward, and is quoted by Reuters saying we need "transformational changes... everything from our food to our energy to transportation, but also our politics and our society."

The key takeaways from the report:

  • Climate change is real and it is here, having already caused “substantial damages and increasingly irreversible losses, in terrestrial, freshwater and coastal and open ocean marine ecosystems”.
  • Goodbye Miami: "Increasing warming amplifies the exposure of small islands, low-lying coastal areas and deltas to the risks associated with sea level rise for many human and ecological systems, including increased saltwater intrusion, flooding and damage to infrastructure."
  • Goodbye diversity: "Of 105,000 species studied, 6% of insects, 8% of plants and 4% of vertebrates are projected to lose over half of their climatically determined geographic range for global warming of 1.5°C, compared with 18% of insects, 16% of plants and 8% of vertebrates for global warming of 2°C."
  • Goodbye ecosystems and the coral reefs: "Global warming of 1.5°C is projected to shift the ranges of many marine species to higher latitudes as well as increase the amount of damage to many ecosystems. It is also expected to drive the loss of coastal resources and reduce the productivity of fisheries and aquaculture (especially at low latitudes)."
  • It affects all of us: "Climate-related risks to health, livelihoods, food security, water supply, human security, and economic growth are projected to increase with global warming of 1.5°C and increase further with 2°C."
  • We need to make major changes: "Pathways limiting global warming to 1.5°C with no or limited overshoot would require rapid and far-reaching transitions in energy, land, urban and infrastructure (including transport and buildings), and industrial systems."
  • We need to stop building highways and leaky buildings: "The urban and infrastructure system transition consistent with limiting global warming to 1.5°C with no or limited overshoot would imply, for example, changes in land and urban planning practices, as well as deeper emissions reductions in transport and buildings compared to pathways that limit global warming below 2°C"
  • We need to work together: International cooperation can provide an enabling environment for this to be achieved in all countries and for all people, in the context of sustainable development. International cooperation is a critical enabler for developing countries and vulnerable regions."

As noted previously, it's pretty dire. But it's not impossible—and holding the temperature rise to 1.5 degrees C is not yet totally out of reach. And the time to start getting serious about it is right now.

View Article Sources
  1. "Special Report: Global Warming of 1.5˚C," Intergovernmental Panel on Climate Change. February 2022.

  2. "UNEP: 1.5C climate target 'slipping out of reach'," CarbonBrief.