Climate change is causing greater impacts than expected at lower temperatures than anticipated, disrupting natural systems and affecting the lives of billions of people around the world, according to the latest report from the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
The new report found that droughts and heat waves are killing off trees and corals; sea level rise is forcing people in vulnerable areas to leave their homes; and extreme conditions may be increasing the likelihood of violent conflict. If warming is not halted soon, and it continues, as many as half the species living on land could become extinct, malnutrition in parts of the world will likely become widespread, and extreme weather events will become increasingly common.
The poor, the very young and very old, ethnic minorities, and Indigenous peoples are at most risk. And while measures to limit the impact of climate change do exist, the only truly meaningful step is to reduce greenhouse gas emissions as soon as possible.
According to Kelly Levin of the Bezos Earth Fund, a foundation that funds efforts to combat climate change, the report “shows clearly how much we need to change course, because delayed action risks triggering impacts that are so catastrophic that our world slowly becomes unrecognizable.”
The report, Climate Change 2022: Impacts, Adaptation and Vulnerability, was published on Monday after approval from 195 governments. It runs 3,675 pages. Here are its major findings.
Many climate change impacts are worse than thought
To date, greenhouse gas emissions have resulted in a mean global temperature increase just shy of 1.1 degrees Celsius (about 2 degrees Fahrenheit). According to Camille Parmesan of the University of Plymouth’s Marine Institute, who was co-author of the report’s 35-page “Summary for Policymakers,” “one of the most striking conclusions of our report is that we’re seeing adverse impacts that are much more widespread and much more negative than expected” at that level of temperature increase.
Of particular concern, she adds, is that this relatively small amount of warming has been enough to begin melting permafrost, drying out peatlands, and damaging forests through insect pest outbreaks and wildfires.
The report also finds that climate change is already impacting agriculture, forestry, fisheries, and aquaculture, including in North America. “Across North America, climate change has reduced agricultural productivity since 1961,” says Rachel Bezner-Kerr of the Cornell College of Agriculture and Life Sciences, who was also a co-author of the official summary.
What’s more, scientists can increasingly link extreme weather events directly to climate change. In fact, argues Michael Mann, director of the Earth System Science Center at Pennsylvania State University and author of The New Climate War: The Fight to Take Back Our Planet, current models continue to “underestimate the impact that climate change is already having on persistent weather extremes and underpredict the worsening of these impacts with additional warming.”
The report concludes that increased heat waves, droughts, and floods “are already exceeding plants’ and animals’ tolerance thresholds, driving mass mortalities in species such as trees and corals. These weather extremes are occurring simultaneously, causing cascading impacts that are increasingly difficult to manage.”
The need for action is urgent
The recognition that climate impacts are already being felt increases the urgency of limiting further warming. On land, up to 14 percent of species will likely face “very high risk of extinction” at global warming levels of 1.5°C (2.7°F), says the report; that figure increases to as much as 18 percent at 2°C (3.6°F), and all the way up to 48 percent at 5°C (9°F). (If the world’s nations keep their current promises to reduce emissions, a recent analysis found, warming will be kept under 2.5ºC.)
At 2°C or higher of warming, human food security risks due to climate change will be more severe, leading to nutrient deficiencies and malnutrition, particularly in Sub-Saharan Africa, South Asia, Central and South America, and small island states. Furthermore, as temperatures continue to climb, climate change impacts and risks are likely to become “increasingly complex and more difficult to manage,” with multiple hazards—from droughts and wildfires to sea-level rise and floods—occurring simultaneously.
It is for that reason that the goal of the Paris Agreement is to limit warming to “well below 2 degrees, and preferably 1.5 degrees” of warming. However, even many of the countries committed to 1.5°C are expecting the average global temperature to rise above that level first before dropping, a process known as overshoot. With severe impacts being felt now, such an approach may be dangerous.
“Because of all these changes already being put into motion, we are concluding that with overshoot … we have an increased risk of irreversible impacts, such as species extinctions, and also that some of these processes that we’re already seeing take place, will be increasingly difficult to reverse,” says Parmesan.
“I would argue we have to try to limit warming to 1.5°C with as little overshoot as possible, ideally zero overshoot,” says Mann. “But what we need to do is actually pretty straightforward: We need to ramp carbon emissions down as rapidly as possible.”
Climate change affects some more than others
“Climate change affects us all, but it doesn’t affect us all equally,” explains Katharine Hayhoe, chief scientist for The Nature Conservancy. “Those already living below the poverty line, the very young and very old, ethnic minorities and Indigenous peoples: these are populations disproportionately affected by climate impacts. And in many cases, they’re also the ones who have done the least to contribute to the problem. That’s why climate change is profoundly unfair.”
The report points out that vulnerability to climate change is higher in locations and among populations that have less resilience to extreme change: for example, those affected by poverty and violent conflict. While there is little evidence so far that climate change directly causes conflict, it may increase the risk of it by exacerbating social, economic, and environmental problems. From 2010 to 2020, human deaths from floods, droughts, and storms were 15 times higher in highly vulnerable regions, compared to regions with very low vulnerability. Flood and drought-related food insecurity and malnutrition have increased in Africa and Central and South America.
Climate and weather extremes are increasingly driving displacement of populations in some regions; small island states threatened by rising seas are disproportionately affected. The loss of ecosystem services has especially severe effects on those who rely directly on them to meet basic needs, including Indigenous peoples.
We can adapt; nature is key
As temperatures increase, humans need to adapt. One of the report’s key findings, says Parmesan, is that such adaptation “is more reliant on natural ecosystems than we’d seen in prior reports. There is more evidence now of that dependency.”
Flood risk along rivers can be reduced by restoring wetlands and other natural habitats in flood plains, or by returning rivers to their natural courses. Conserving mangroves protects shorelines from storms and erosion. By reducing overfishing, marine protected areas provide resilience against climate change. Cities can be cooled by parks and ponds and by greening streets and rooftops. Farmers can increase both their climate resilience and their yields by improving soil health.
Adaptation that focuses on the maintenance of natural systems also helps avoid “maladaptation,” the report says. Irrigating fields with groundwater can provide immediate relief from drought, for example—but if droughts become more frequent or long-lasting, the water table may ultimately disappear. Similarly, sea walls might protect coastal areas in the short term, but their construction can destroy coastal ecosystems such as coral reefs, which themselves contribute to coastal protection.
“The worst possible maladaptation,” Mann argues, would be “to put too many marbles in the adaptation bag and not enough in the mitigation bag”—in other words, to adapt to the impacts of climate change without taking adequate steps to eliminate the greenhouse gas emissions that cause it. In a sense, he continues, “the report is a summary of what we already know: Dangerous climate change is now upon us, and it is simply a matter of how bad we’re willing to let it get.”
About the IPCC reports
The report covers 3,675 pages, detailing the impact of climate change on continental and polar regions, terrestrial and marine ecosystems, food, and health. It also explores the intersection of global warming and poverty and examines pathways to development that are as resilient as possible to climate change and its impacts. It is prefaced by a 35-page “Summary for Policymakers” which, says Field, “is painstakingly approved, sentence by sentence, by consensus.”
That process means that IPCC reports are sometimes criticized for being watered down, but Field argues that it gives the report a strength that individual studies cannot match, in that “every country in the world agrees that every sentence in the summary for policymakers is an accurate description of the underlying technical literature.”
Editor's Note: The IPCC's report comprises 3,675 pages.