The IPCC Climate Change Report: Why It Matters to Everyone on the Planet

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• What Is the IPCC?
• IPCC Report History
• Special Report: Global Warming of 1.5 °C
• What Does the Report Conclude?
• What Actions Do We Need to Take?
• Can We Succeed?

You’d be forgiven for losing track of all the studies on climate change. There are a lot—each seemingly more dire than the last. But the latest report by one of the leading international authorities on the subject, the United Nations’ Intergovernmental Panel on Climate Change (IPCC), sounds an urgent warning that is worth heeding: We must cut emissions immediately to avoid the catastrophic effects of a changing climate.

The October report, Global Warming of 1.5 ℃, seeks to answer a pressing question: What would be the impact of a 1.5- degrees Celsius increase in global temperatures above preindustrial levels? At the Paris climate talks in 2015, nearly all countries committed to a target of keeping the temperature change to well below 2 degrees and to make efforts to prevent a change greater than 1.5 degrees. The IPCC’s special report answers the question of how important that seemingly small half-degree difference would be. And the conclusions are startling: A half degree more of warming would mean substantially more poverty, extreme heat, sea level rise, habitat loss, and drought. And we cannot prevent this unless we act immediately to cut emissions deeply. In fact, every tenth of a degree matters.

Here’s a look at this report’s findings—the starkest yet—and why it’s so critical that our leaders pay attention.

What Is the IPCC?

The IPCC is the leading international scientific authority on all things related to global warming. Established in 1988 as part of the United Nations Environment Programme, the panel aims to inform policymakers around the world on the risks of man-made climate change so they can take appropriate action. Currently 195 countries participate as members, determining the overall direction of the IPCC’s work.

At the time of the IPCC’s founding, many policymakers were just starting to grapple with a phenomenon known as the “greenhouse effect.” Thirty years later, most fifth-graders are familiar with the basic ideas behind our climate crisis: Global warming occurs when greenhouse gases, most notably carbon dioxide (CO₂), collect in the atmosphere. These pollutants, which can stick around for decades, prevent the sunlight and solar radiation that bounce off the earth’s surface from escaping back into space, instead trapping the heat and warming the planet.

Today the earth has already warmed an average of 1 degree Celsius above preindustrial levels. The climate crisis, once talked about in the future tense, has essentially arrived. If we continue business as usual (by remaining reliant on fossil fuels, for one thing), the best science says the world will warm as much as a catastrophic 3.7 degrees by the turn of the century. The IPCC, which wields significant scientific authority, is central to our effort to avoid this outcome, providing accurate analysis that global policymakers can use to take swift, effective action to fend off the worst.

The IPCC has a small staff to support its work, but the bulk of its manpower comes from the thousands of highly credentialed volunteer scientists from around the world who write, review, and provide commentary. The IPCC does not conduct its own science. Instead, it synthesizes the latest climate change research (thousands of published, peer-reviewed studies) into its own predictions and digestible reports, which come out roughly every six years. While the reports steer clear of being overly policy-prescriptive, they are intentionally “policy-relevant,” meaning their conclusions can easily be translated into real-world policy outcomes.

IPCC Report History

Though this might be the first time some people have heard about the IPCC, it is far from the first time the panel has sounded the alarm on climate change. The IPCC puts out regular comprehensive assessments, summarizing the most current research on our warming planet. Periodically it also issues special reports—on topics like climate adaptation, renewable energy, and most recently the consequences of 1.5 degrees of warming.

The IPCC’s warnings began in 1990 with its First Assessment Report, which successfully predicted the pace of global warming, even without the highly complex computer models of today. The Second Assessment, published in 1995, expressed greater certainty that climate change was largely caused by human activities. In 2001, the Third Assessment warned that the temperature increases would become worse than previously feared if we didn’t reduce our carbon emissions. Meanwhile, the world ramped up fossil fuel production.

By the time of its Fourth Assessment, in 2007, the IPCC was using words like unequivocal to describe the consensus that humans were the main cause of warming. And in the most recent regular report, in 2014, the Fifth Assessment, the panel dealt the world a hard truth: Greenhouse gas emissions were higher than ever, causing an unprecedented acceleration of climate change’s impacts.

The release of a report often coincides with—and helps shape—critical moments of international climate collaboration. The First Assessment Report supported the creation of the United Nations Framework Convention on Climate Change, which has become a foundation for coordinated political action. The Second Assessment provided key input to the 1997 Kyoto Protocol—a historic agreement that put binding emissions targets on developed countries for the first time. And more recently, the Fifth Assessment informed 2015’s Paris Agreement, a landmark global accord that was adopted by nearly every nation to address climate change and its negative impacts.

Yet despite three decades of warnings by the IPCC, world leaders have done far too little—and moved far too slowly—to stop climate change. In 2017 global carbon emissions hit an all-time high of 41 gigatonnes, after three years of plateauing, due to higher energy demand and a slowdown in investment in energy efficiency measures.

As the IPCC’s urgent new special report shows, the need for immediate action is clearer than ever. Already we are coping with the devastation wrought by a disrupted climate—from storms ravaging our coastline cities and towns to fires taking lives and destroying homes. This kind of damage will get worse if we do not start cutting emissions without delay. But the report also shows that every ton of emissions reduction matters.

Special Report: Global Warming of 1.5 °C

For years, a 2-degree rise in global temperature was the most widely cited threshold for avoiding climate catastrophe. Stay below it, some thought, and we could stave off the most existential threats posed by global warming. Go above it, and we would face war, famine, species extinctions, and disease—to name just some of the catastrophic impacts.

In 2015, when 195 nations made history by signing on to the Paris Agreement, they used this 2-degree marker as the basis for setting emissions reduction targets. The agreement’s stated aim is to keep temperature rise “well below” 2 degrees and to “pursue efforts” to limit it to 1.5 degrees.

But during the Paris negotiations, many countries—particularly island nations and others most vulnerable to rising seas—were concerned that 2 degrees of warming would be too dangerous. They argued that, instead, there should be a more ambitious target of no higher than 1.5 degrees. While some scientific findings already supported this idea, there wasn’t enough information to accurately predict the ramifications of that seemingly small half-degree. The IPCC was tasked with addressing that important question: Should we aim for 1.5 degrees instead? Would it even be possible? If so, what would it take?

What Does the Report Conclude?

Over the course of nearly three years, 91 authors from 40 countries drew from more than 6,000 scientific studies to create the Global Warming of 1.5 ℃ report. The report confirmed what those island countries, some already experiencing the impact of sea level rise, feared to be true: Every fraction of a degree of warming has grave consequences.

Limiting global warming to 1.5 degrees, rather than 2 degrees, “could reduce the number of people exposed to climate-related risks and susceptible to poverty by up to several hundred million by 2050,” the report states. That means hundreds of millions of people being able to avoid flooding, food scarcity, superstorms, deadly heat, and widespread disease. At 1.5 degrees, the number of people across the globe at risk of inadequate water supplies could be 50 percent lower than at 2 degrees, the report concludes.

Other species are also worse off with a 2-degree change. At that level of warming, coral reefs could nearly all be dead. Just half a degree cooler and the survival rate for reefs could be as high as 30 percent. Twice as many plant species—and three times as many insects, which are critical to our food supply—could lose at least half their habitat under a 2-degree versus a 1.5-degree rise. And the melting of Arctic ice—particularly concerning because of sea level rise and the positive feedback loop it would create by no longer reflecting the sun’s rays—would be far more drastic at 2 degrees. Summers warm enough to melt all of the Arctic’s ice would occur only once every 100 years at 1.5 degrees of warming. At 2 degrees, the ice would vanish every 10 summers.

Missing that 1.5-degree target—by failing to do enough or by doing it too slowly—would mean substantially more lives lost and ruined. It would mean more extinct species and more superstorms. It would mean fewer fish in the sea due to ocean acidification and fewer ecosystems capable of supporting biodiversity. It would mean more strain on economies and more people thrust into poverty. So it turns out that every half a degree of warming—or even a tenth of a degree—matters quite a bit.

What Actions Do We Need to Take?

In laying out what must happen to avoid climate catastrophe, the IPCC does not sugarcoat: Limiting warming to 1.5 degrees will require unprecedented changes to our global systems, at a scope—and especially at a pace—never before seen in human history. Indeed, the most alarming part of the report is the sheer speed at which the world needs to overhaul foundational elements of modern life, such as our energy, transportation, land use, and food systems.

Limiting warming to no more than 1.5 degrees requires decreasing carbon pollution by 45 percent from 2010 levels by 2030, the report concludes. That’s a little over a decade from now. The world would need to reach net zero emissions by 2050.

There are multiple ways to reduce emissions, the report points out, most notably by decreasing the use of fossil fuels and ramping up renewables. But many of the scenarios considered by the IPCC also rely on “negative emissions technologies,” which remove carbon pollution from the atmosphere and store it, sparing our planet from further warming. Some of these methods are relatively straightforward—such as capturing more carbon in forests and soil—but others aren’t quite as simple.

One controversial negative emissions technology is bioenergy coupled with carbon capture and storage (BECCS), which the IPCC includes in several possible scenarios. BECCS involves growing plants to naturally absorb carbon dioxide, burning them to generate power, and then capturing the resulting emissions and storing them deep underground. Unfortunately, studies indicate that massive use of BECCS could be untenable and exact too high an ecological cost. It would require a huge amount of land—as much as half the area of the United States—to grow plants that could trap enough carbon, crowding out ecosystems and leaving less room for food production. And it’s never been tested to scale.

The IPCC report ultimately offers four mitigation scenarios—four ways to limit global warming—all with trade-offs. The differences among the four pathways hinge largely on how quickly we can move away from fossil fuels. There is no scenario in which our fossil fuel use can continue unabated if we are to meet the 1.5-degree goal; coal power will have to be essentially eliminated by mid-century. And all scenarios are more ambitious than what would be achieved by the existing Paris Agreement targets.

Scenario 1

This route provides the best shot at limiting warming to 1.5 degrees and requires moving away from fossil fuels very quickly. Coal, the worst carbon polluter, must decrease as a share of primary energy by 78 percent from 2010 levels by 2030, and 97 percent by 2050. Gas and oil use must decrease by 25 and 37 percent, respectively, by 2030, and 74 and 87 percent, respectively, by 2050. This option builds on the current momentum of renewables—their growing affordability and effectiveness—and thus doesn’t have to rely on BECCS. It does require additional offsetting, but only by growing more forests and enhancing soil carbon.

Scenario 2

Relative to the first scenario, the other three options provide a longer runway (though not very long) to move away from fossil fuels, and some consider this more politically practical. But these options are far from practical overall, since they require a heavier reliance on carbon-offset methods. The second pathway involves a longer use of fossil fuels and a decrease in overall energy demand. But the scenario requires some use of BECCS to avoid missing the 1.5-degree goal.

Scenario 3

Described as a middle-of-the-road scenario by the IPCC, the third option allows social and technological trends to follow historical patterns—meaning energy demand and consumption stay high—while drastically reducing fossil fuel. But under this scenario, the world is relying heavily on negative emissions technologies, including unreliable BECCS.

Scenario 4

This pathway in particular would put a high burden on BECCS to reduce emissions, which is risky because it counts on a long-shot technological save. It could also divert focus from transitioning out of fossil fuels.

None of the four options would allow for continued long-term investment in fossil fuel infrastructure. The IPCC is clear that policymakers should abandon proposals for things like new pipelines, coal industry bailouts, or leases for offshore drilling. The panel also sees a rapid ramping up of renewable energy—in particular solar and wind—which it considers both technically possible and economically feasible. In 2017, global investment in clean energy soared to its second-highest level in history, but that trend will need to accelerate rapidly.

Can We Succeed?

Nobody said it would be easy. To the contrary, even optimists agree that limiting global warming will be a major challenge. It will require political shifts that may seem unfathomable, especially in light of the Trump administration’s continued support of fossil fuels.

Indeed, even if every country hits the emissions reduction target that it committed to on the basis of the Paris accord—and many countries are not on track—the world would still see somewhere between 2.6 and 3.2 degrees of warming by the end of the century. These targets, or “nationally determined contributions” (NDCs), are simply not strong enough to meet the 2-degree goal—much less to rein in warming to 1.5 degrees. But as the IPCC makes clear, doing everything we can to reach the 1.5-degree limit will help prevent deadly consequences for millions around the world—particularly those living in developing countries and nations vulnerable to political instability.

Indeed, rather than being universally accepted as a harbinger of doom, the report is serving as a wake-up call to take action. There’s a solutions chapter for a reason, and many of the climate-friendly actions are already happening—just not at the speed or scale that’s needed. The bigger challenge is whether there is the political will to change, particularly in the United States, which is the second-biggest carbon polluter, after China.

Trump is working to withdraw the United States from the Paris Agreement altogether. But the administration is not simply shirking its responsibility to address climate change; it’s actively taking steps to accelerate warming. The administration has proposed gutting the Clean Power Plan, which reduces emissions from power plants, and doing away with fuel efficiency standards on our cars and trucks, the biggest source of carbon pollution. And officials have worked to undermine the critical role of science in protecting the environment and public health.

Still, humanity has summoned the gumption to make dramatic change before—whether it has meant nearly eradicating polio or unifying against a common threat during World War II. Though preparations to fight a war and to stave off climate change are clearly very different, the comparison is still apt: Both require political determination and buy-in from every level of society, but particularly from government leaders.

Of course, successful climate action doesn’t look like just one thing—it looks like many things, happening all at once. It means ending our addiction to fossil fuels. But it also means electric cars and offshore wind farms and reducing our food waste. It means rewriting building codes to be more energy efficient and developing higher-capacity energy storage. It means growing forests and using less land to raise methane-producing livestock. And it’s not just mitigation—trying to reduce greenhouse gases—it’s about building resilience to the impacts of a changing climate.

For individuals, taking action may look like buying less plastic, installing LEDs, or using more public transportation. It also means making our voices heard to convince our leaders that urgent climate action is not only necessary but possible. Most important, it’s about knowing that every action we take to fight climate change matters.