A UN report says stopping climate change is possible but action is needed now

The world already has the tools to cut global greenhouse gas emissions in half by 2030

aerial photo of floating solar panels on a lake in Haltern, Germany

A lily pad of solar panels, part of an electricity plant in the making, floats on a lake in Haltern, Germany, on April 1. A new U.N. report outlines numerous changes the world can make now, including shifting to solar and other sources of renewable energy, that would halve global greenhouse gas emissions by 2030.

Martin Meissner/AP images

It doesn’t have to be this way.

The world already has the know-how and tools to dramatically reduce emissions from fossil fuels — but we need to use those tools immediately if we hope to forestall the worst impacts of climate change. That’s the message of the third and final installment of the massive sixth assessment of climate science by the United Nations’ Intergovernmental Panel on Climate Change, which was released April 4.

“We know what to do, we know how to do it, and now it’s up to us to take action,” said sustainable energy researcher Jim Skea of Imperial College London, who cochaired the report, at a news event announcing its release.

Earth is on track to warm by an average of about 3.2 degrees Celsius above preindustrial levels by the end of the century (SN: 11/26/19). Altering that course and limiting warming to 1.5 degrees or even 2 degrees means that global fossil fuel emissions will need to peak no later than the year 2025, the new report states.

Right now, meeting that goal looks extremely unlikely. National pledges to reduce fossil fuel emissions to date amount to “a litany of broken climate promises,” said United Nations Secretary-General António Guterres at the event.

The previous two installments of the IPCC’s sixth assessment described how climate change is already fueling extreme weather events around the globe — and noted that adaptation alone will not be enough to shield people from those hazards (SN: 8/9/21; SN: 2/28/22).

The looming climate crisis “is horrifying, and I don’t want to sugarcoat that,” says Bronson Griscom, a forest ecologist and the director of Natural Climate Solutions at the environmental organization Conservation International, based in Arlington, Va.

But Griscom, who was not an author on the new IPCC report, says its findings also give him hope. It’s “what I would call a double-or-nothing bet that we’re confronted with right now,” he says. “There [are] multiple ways that this report is basically saying, ‘Look, if we don’t do anything, it’s increasingly grim.’ But the reasons to do something are incredibly powerful and the tools in the toolbox are very powerful.”

Tools in the toolbox

Those tools are strategies that governments, industries and individuals can use to cut emissions immediately in multiple sectors of the global economy, including transportation, energy, building, agriculture and forestry, and urban development. Taking immediate advantage of opportunities to reduce emissions in each of those sectors would halve global emissions by 2030, the report states.

Consider the transportation sector, which contributed 15 percent of human-related greenhouse gas emissions in 2019. Globally, electric vehicle sales have surged in the last few years, driven largely by government policies and tougher emissions laws for the auto industry (SN: 12/22/21).

If that surge continues, “electric vehicles offer us the greatest potential [to reduce transportation emissions on land], as long as they’re combined with low or zero carbon electricity sources,” Diana Ürge-Vorsatz, the vice chair of the IPCC’s Working Group III, said at the news event. But for aviation and long-haul shipping, which are more difficult to electrify, reduced carbon emissions could be achieved with low-carbon hydrogen fuels or biofuels, though these alternatives require further research and development.

Then there are urban areas, which are contributing a growing proportion of global greenhouse gas emissions, from 62 percent in 2015 to between 67 and 72 percent in 2020, the report notes. In established cities, buildings can be retrofitted, renovated or repurposed to make city layouts more walkable and provide more accessible public transportation options.

And growing cities can incorporate energy-efficient infrastructure and construct buildings using zero-emissions materials. Additionally, urban planners can take advantage of green roofs, urban forests, rivers and lakes to help capture and store carbon, as well as provide other climate benefits such as cleaner air and local cooling to counter urban heat waves (SN: 4/3/18).

Meanwhile, “reducing emissions in industry will involve using materials and energy more efficiently, reusing and recycling products and minimizing waste,” Ürge-Vorsatz said.

As for agriculture and forestry, these and other land-use industries contribute about 22 percent of the world’s greenhouse gas emissions, with half of those emissions coming from deforestation (SN: 7/13/21). So reforestation and reduced deforestation are key to flipping the balance between CO₂ emissions and removal from the atmosphere (SN: 7/9/21; SN: 1/3/22). But there are a lot of other strategies that the world can employ at the same time, the report emphasizes. Better management of forests, coastal wetlands, grasslands and other ecosystems, more sustainable crop and livestock management, soil carbon management in agriculture and agroforestry can all bring down emissions (SN: 7/14/21).

The report also includes, for the first time in the IPCC’s reports, a chapter on the “untapped potential” of lifestyle changes to reduce emissions. Such changes include opting for walking or cycling or using public transportation rather than driving, shifting toward plant-based diets and reducing air travel (SN: 5/14/20).

Those lifestyle changes could reduce emissions by 40 to 70 percent by 2050, the report suggests. To enable those changes, however, government policies, infrastructure and technology would need to be in place.

Government policies are also key to financing these transformational changes. Globally, the investment in climate-related technologies needs to ramp up, and quickly, to limit warming below 2 degrees C, the report states. Right now, investments are three to six times lower than they need to be by 2030. And a combination of public and private investments will be essential to aiding the transition away from fossil fuels and toward renewable energy in developing nations (SN: 1/25/21).

Future strategies

Still, reducing emissions alone won’t be enough: We will need to actively remove carbon from the atmosphere to achieve net zero emissions and keep the planet well below 2 degrees C of warming, the report notes. “One thing that’s clear in this report, as opposed to previous reports, is that carbon removal is going to be necessary in the near term,” says Simon Nicholson, director of the Institute for Carbon Removal Law and Policy at American University in Washington, D.C., who was not involved in the report.

Such strategies include existing approaches such as protecting or restoring carbon dioxide–absorbing forests, but also technologies that are not yet widely available commercially, such as directly capturing carbon dioxide from the air, or converting the gas to a mineral form and storing it underground (SN: 12/17/18).

These options are still in their infancy, and we don’t know how much of an impact they’ll have yet, Nicholson says. “We need massive investment now in research.”

An emphasis on acting “now,” on eliminating further delay, on the urgency of the moment has been a recurring theme through all three sections of the IPCC’s sixth assessment report released over the last year. What impact these scientists’ stark statements will have is unclear.

But “the jury has reached a verdict, and it is damning,” U.N. Secretary-General Guterres said. “If you care about justice and our children’s future, I am appealing directly to you.”

Carolyn Gramling is the earth & climate writer. She has bachelor’s degrees in geology and European history and a Ph.D. in marine geochemistry from MIT and the Woods Hole Oceanographic Institution.

Nikk Ogasa is a staff writer who focuses on the physical sciences for Foogue. He has a master's degree in geology from McGill University, and a master's degree in science communication from the University of California, Santa Cruz.

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