Climate

Climate change amped up the rains that pounded southeastern Africa and killed hundreds of people during two powerful storms in early 2022.

But a dearth of regional data made it difficult to pinpoint just how large of a role climate change played, scientists said April 11 at a news conference.

The findings were described in a study, published online April 11, by a consortium of climate scientists and disaster experts called the World Weather Attribution network.

A series of tropical storms and heavy rain events battered southeast Africa in quick succession from January through March. For this study, the researchers focused on two events: Tropical Storm Ana, which led to flooding in northern Madagascar, Malawi and Mozambique in January and killed at least 70 people; and Cyclone Batsirai, which inundated southern Madagascar in February and caused hundreds more deaths.

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To search for the fingerprints of climate change, the team first selected a three-day period of heavy rain for each storm. Then the researchers tried to amass observational data from the region to reconstruct historical daily rainfall records from 1981 to 2022.

Only four weather stations, all in Mozambique, had consistent, high-quality data spanning those decades. But, using the data on hand, the team was able to construct simulations for the region that represented climate with and without human-caused greenhouse gas emissions.

The aggregate of those simulations revealed that climate change did play a role in intensifying the rains, Izidine Pinto, a climatologist at the University of Cape Town in South Africa, said at the news event. But with insufficient historical rainfall data, the team “could not quantify the precise contribution” of climate change, Pinto said.

The study highlights how information on extreme weather events “is very much biased toward the Global North … [whereas] there are big gaps in the Global South,” said climate scientist Friedericke Otto of Imperial College London.

That’s an issue also highlighted by the Intergovernmental Panel on Climate Change. The IPCC cites insufficient Southern Hemisphere data as a barrier to assessing the likelihood of increasing frequency and intensity of tropical cyclones beyond the North Atlantic Ocean (SN: 8/9/21). More

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. 

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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,” Inger Andersen, the executive director of the United Nations Environment Programme, 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,” Diana Ürge-Vorsatz, the vice chair of the IPCC’s Working Group III, said at the news event. 

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.” More

It was the mid-1980s, at a meeting in Switzerland, when Wally Broecker’s ears perked up. Scientist Hans Oeschger was describing an ice core drilled at a military radar station in southern Greenland. Layer by layer, the 2-kilometer-long core revealed what the climate there was like thousands of years ago. Climate shifts, inferred from the amounts of carbon dioxide and of a form of oxygen in the core, played out surprisingly quickly — within just a few decades. It seemed almost too fast to be true.      

Broecker returned home, to Columbia University’s Lamont-Doherty Earth Observatory, and began wondering what could cause such dramatic shifts. Some of Oeschger’s data turned out to be incorrect, but the seed they planted in Broecker’s mind flowered — and ultimately changed the way scientists think about past and future climate.

A geochemist who studied the oceans, Broecker proposed that the shutdown of a major ocean circulation pattern, which he named the great ocean conveyor, could cause the North Atlantic climate to change abruptly. In the past, he argued, melting ice sheets released huge pulses of water into the North Atlantic, turning the water fresher and halting circulation patterns that rely on salty water. The result: a sudden atmospheric cooling that plunged the region, including Greenland, into a big chill. (In the 2004 movie The Day After Tomorrow, an overly dramatized oceanic shutdown coats the Statue of Liberty in ice.)

It was a leap of insight unprecedented for the time, when most researchers had yet to accept that climate could shift abruptly, much less ponder what might cause such shifts.

Broecker not only explained the changes seen in the Greenland ice core, he also went on to found a new field. He prodded, cajoled and brought together other scientists to study the entire climate system and how it could shift on a dime. “He was a really big thinker,” says Dorothy Peteet, a paleoclimatologist at NASA’s Goddard Institute for Space Studies in New York City who worked with Broecker for decades. “It was just his genuine curiosity about how the world worked.”

Broecker was born in 1931 into a fundamentalist family who believed the Earth was 6,000 years old, so he was not an obvious candidate to become a pathbreaking geoscientist. Because of his dyslexia, he relied on conversations and visual aids to soak up information. Throughout his life, he did not use computers, a linchpin of modern science, yet became an expert in radiocarbon dating. And, contrary to the siloing common in the sciences, he worked expansively to understand the oceans, the atmosphere, the land, and thus the entire Earth system.

By the 1970s, scientists knew that humans were pouring excess carbon dioxide into the atmosphere, through burning fossil fuels and cutting down carbon-storing forests, and that those changes were tinkering with Earth’s natural thermostat. Scientists knew that climate had changed in the past; geologic evidence over billions of years revealed hot or dry, cold or wet periods. But many scientists focused on long-term climate changes, paced by shifts in the way Earth rotates on its axis and circles the sun — both of which change the amount of sunlight the planet receives. A highly influential 1976 paper referred to these orbital shifts as the “pacemaker of the ice ages.”

Ice cores from Antarctica and Greenland changed the game. In 1969, Willi Dansgaard of the University of Copenhagen and colleagues reported results from a Greenland ice core covering the last 100,000 years. They found large, rapid fluctuations in oxygen-18 that suggested wild temperature swings. Climate could oscillate quickly, it seemed — but it took another Greenland ice core and more than a decade before Broecker had the idea that the shutdown of the great ocean conveyor system could be to blame.

Pulled from southern Greenland beginning in 1979, the Dye-3 ice core (the drill used to retrieve the core is shown) revealed that abrupt climate change had occurred in the past.The Niels Bohr Institute

Broecker proposed that such a shutdown was responsible for a known cold snap that started around 12,900 years ago. As the Earth began to emerge from its orbitally influenced ice age, water melted off the northern ice sheets and washed into the North Atlantic. Ocean circulation halted, plunging Europe into a sudden chill, he said. The period, which lasted just over a millennium, is known as the Younger Dryas after an Arctic flower that thrived during the cold snap. It was the last hurrah of the last ice age.

Evidence that an ocean conveyor shutdown could cause dramatic climate shifts soon piled up in Broecker’s favor. For instance, Peteet found evidence of rapid Younger Dryas cooling in bogs near New York City — thus establishing that the cooling was not just a European phenomenon but also extended to the other side of the Atlantic. Changes were real, widespread and fast.

By the late 1980s and early ’90s, there was enough evidence supporting abrupt climate change that two major projects — one European, one American — began to drill a pair of fresh cores into the Greenland ice sheet. Richard Alley, a geoscientist at Penn State, remembers working through the layers and documenting small climatic changes over thousands of years. “Then we hit the end of the Younger Dryas and it was like falling off a cliff,” he says. It was “a huge change after many small changes,” he says. “Breathtaking.”

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The new Greenland cores cemented scientific recognition of abrupt climate change. Though the shutdown of the ocean conveyor could not explain all abrupt climate changes that had ever occurred, it showed how a single physical mechanism could trigger major planet-wide disruptions. It also opened discussions about how rapidly climate might change in the future.

Broecker, who died in 2019, spent his last decades exploring abrupt shifts that are already happening. He worked, for example, with billionaire Gary Comer, who during a yacht trip in 2001 was shocked by the shrinking of Arctic sea ice, to brainstorm new directions for climate research and climate solutions.

Broecker knew more than almost anyone about what might be coming. He often described Earth’s climate system as an angry beast that humans are poking with sticks. And one of his most famous papers was titled “Climatic change: Are we on the brink of a pronounced global warming?”

It was published in 1975. More

When it comes to cooling the planet, forests have more than one trick up their trees.  

Tropical forests help cool the average global temperature by more than 1 degree Celsius, a new study finds. The effect stems largely from forests’ capacity to capture and store atmospheric carbon (SN: 11/18/21). But around one-third of that tropical cooling effect comes from several other processes, such as the release of water vapor and aerosols, researchers report March 24 in Frontiers in Forests and Global Change.

“We tend to focus on carbon dioxide and other greenhouse gases, but forests are not just carbon sponges,” says Deborah Lawrence, an environmental scientist at the University of Virginia in Charlottesville. “It’s time to think about what else forests are doing for us besides just absorbing carbon dioxide.”

Researchers already knew that forests influence their local climates through various physical and chemical processes. Trees release water vapor through pores in their leaves — a process called evapotranspiration — and, like human sweating, this cools the trees and their surroundings. Also, uneven forest canopies can have a cooling effect, as they provide an undulating surface that can bump hot, overpassing fronts of air upward and away. What’s more, trees generate aerosols that can lower temperatures by reflecting sunlight and seeding clouds.

But on a global scale, it wasn’t clear how these other cooling benefits compared with the cooling provided by forests’ capturing of carbon dioxide, Lawrence says.

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So she and her colleagues analyzed how the complete deforestation of different regions would impact global temperatures, using data gathered from other studies. For instance, the researchers used forest biomass data to determine how much the release of carbon stored by those forests would warm the global temperature. They then compared those results with other studies’ estimates of how much the loss of other aspects of forests — such as evapotranspiration, uneven canopies and aerosol production — affected regional and global temperatures.

The researchers found that in forests at latitudes from around 50° S of the equator to 50° N, the primary way that forests influenced the global average temperature was through carbon sequestration. But those other cooling factors still played large roles.

Forests located from 30° N to 30° S provided alternative benefits that cool the planet by over 0.3 degrees C, about half as much cooling as carbon sequestration provided. And the bulk of that cooling, around 0.2 degrees C, came from forests in the core of the tropics (within 10° of the equator). Canopy topography generally provided the greatest cooling, followed by evapotranspiration and then aerosols.

Forests in the far north, however, appear to have a net warming effect, the team reports. Clearing the boreal forests — which stretch across Canada, Alaska, Russia and Scandinavia — would expose more snow cover during the winter. This would decrease ground level temperatures because snow reflects much of the incoming sunlight back into the sky. Still, the researchers found that altogether, the world’s forests cool the global average temperature about 0.5 degrees C.

The findings suggest that global and regional climate action efforts should refrain from focusing solely on carbon emissions, Lawrence says. “There’s this whole service that tropical forests are providing that simply are not visible to us or to policy makers.”

The research shows that clearing tropical forests robs us of many climate-cooling benefits, says Gabriel de Oliveira, a geographer from the University of South Alabama in Mobile. But deforestation isn’t the only way that humans impair forests’ cooling ability, he says. Many forests are damaged by fires or selective logging, and are less able to help with cooling (SN: 9/1/21). It would be useful to consider how forest degradation, in addition to deforestation, impacts regional and global climate temperatures, de Oliveira says, to assess the impact of restoring and protecting forests (SN: 7/13/21). “It’s cool to see beyond carbon dioxide, but it’s also very important to see beyond deforestation.” More

Towers of smoke that rose high into the stratosphere during Australia’s “black summer” fires in 2019 and 2020 destroyed some of Earth’s protective ozone layer, researchers report in the March 18 Science.

Chemist Peter Bernath of Old Dominion University in Norfolk, Va., and his colleagues analyzed data collected in the lower stratosphere during 2020 by a satellite instrument called the Atmospheric Chemistry Experiment. It measures how different particles in the atmosphere absorb light at different wavelengths. Such absorption patterns are like fingerprints, identifying what molecules are present in the particles.

The team’s analyses revealed that the particles of smoke, shot into the stratosphere by fire-fueled thunderstorms called pyrocumulonimbus clouds, contained a variety of mischief-making organic molecules (SN: 12/15/20). The molecules, the team reports, kicked off a series of chemical reactions that altered the balances of gases in Earth’s stratosphere to a degree never before observed in 15 years of satellite measurements. That shuffle included boosting levels of chlorine-containing molecules that ultimately ate away at the ozone.

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Ozone concentrations in the stratosphere initially increased from January to March 2020, due to similar chemical reactions — sometimes with the contribution of wildfire smoke — that produce ozone  pollution at ground level (SN: 12/8/21). But from April to December 2020, the ozone levels not only fell, but sank below the average ozone concentration from 2005 to 2019.

Earth’s ozone layer shields the planet from much of the sun’s ultraviolet radiation. Once depleted by human emissions of chlorofluorocarbons and other ozone-damaging substances, the layer has been showing signs of recovery thanks to the Montreal Protocol, an international agreement to reduce the atmospheric concentrations of those substances (SN: 2/10/21).

But the increasing frequency of large wildfires due to climate change — and their ozone-destroying potential — could become a setback for that rare climate success story, the researchers say (SN: 3/4/20). More

Neither adaptation by humankind nor mitigation alone is enough to reduce the risk from climate impacts, hundreds of the world’s scientists say. Nothing less than a concerted, global effort to both drastically curb carbon emissions and proactively adapt to climate change can stave off the most disastrous consequences, according to the latest report from the United Nations’ Intergovernmental Panel on Climate Change, or IPCC.

That dire warning comes as the effects of climate change on people and nature are playing out across the globe in a more widespread and severe manner than previously anticipated. And the most vulnerable communities — often low-income or Indigenous — are being hit the hardest, the report says.

“It’s the strongest rebuttal that we’ve seen yet of this idea that we can just adapt our way out of climate change and we don’t have to mitigate emissions,” says Anne Christianson, the director of international climate policy at the Center for American Progress in Washington, D.C., who was not involved in the report.

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A consortium of 270 scientists from 67 countries synthesized the report after reviewing over 34,000 studies. Released February 28 as part of the IPCC’s sixth assessment of climate science, the report details how the impacts of climate change are playing out today in different regions, and assessed the capacities of communities and regions to adapt.

Many countries understand the need for climate adaptation. And modern solutions, such as the building of urban gardens or adoption of agroforestry, where implemented, appear to show promise. But, the report finds, efforts to adapt are, by and large, reactionary, small and drastically underfunded. As a result, about 3.3 billion to 3.6 billion people remain highly vulnerable to climate risks such as extreme weather events, sea level rise and food and water shortages. The need for adaptation is greatest — and growing larger — in low-income regions, most notably in parts of Africa, South Asia, small island states and Central and South America.

The report also underscores the importance of involving those who are impacted the most in climate plans. “We can no longer just make these decisions at the highest level; we need to include local stakeholders, Indigenous groups, local communities and those who are most as at risk for climate change, such as women, racial minorities, the elderly and children,” Christianson says.

Last August, a previous report, also part of the IPCC’s sixth assessment, covered the physical science underpinning climate change (SN: 8/9/21). In that report, scientists stated loud and clear that there was no time to waste. By 2030, carbon emissions need to be cut in half, compared with 2017 levels, to prevent global temperatures from climbing 1.5° Celsius above the preindustrial baseline, the report found. Beyond that baseline, the capacity for humankind and nature to adapt severely deteriorates. In a bit of good news, the authors of that 2021 report also found that if all carbon emissions were to cease today, global temperatures would stop rising in about three years, not the 30 to 40 years once thought. In other words, we can make a big difference in very little time.

Still, climate change is already affecting many parts of Earth. And some of the consequences aren’t going away anytime soon. Sea level will continue to rise for decades, driven in part by the runaway melting of Greenland’s ice sheet (SN: 9/30/20). By 2050, sea level along U.S. coastlines will have risen by 25 to 30 centimeters, or roughly one foot, the National Oceanic and Atmospheric Administration estimates.

The latest IPCC report reveals that the effects of climate change, which include an increased frequency of wildfires (such as these in Turkey), are more widespread and severe than had been expected.YASIN AKGUL/AFP via Getty Images

Extreme weather events and climate-fueled wildfires have already caused mass mortalities of corals and other animals and trees, and pushed entire species toward the brink of extinction (SN: 3/9/21). What’s more, climate change is forcing many people to relocate, as well as detrimentally affecting mental health and spreading disease as vectors such as mosquitoes shift to new habitats (SN: 5/12/20; SN: 10/7/19).

Adaptation is especially needed in cities, which are growing and expected to contain two-thirds of the world’s population by 2050, including climate refugees from elsewhere, the new report finds. Urban communities are becoming increasingly vulnerable to extreme heat waves, urban heat island effects, floods and storm surges (SN: 9/18/21).

Outside of cities, the breakdown of ecosystems and loss of biodiversity severely impacts the people who rely on natural systems for their livelihoods, the report emphasizes. Farmers in the global south are finding it increasingly challenging to grow crops as a result of droughts, heat waves, floods and sea-level rise (SN: 9/24/21). People who make their living fishing are being forced to travel greater distances to pursue species that are altering their natural ranges as ocean temperatures warm.

Key to adapting to these impacts is the restoration and preservation of natural ecosystems, the report states. Conserving 30 to 50 percent of the planet’s land, ocean and freshwater ecosystems will help support biodiversity and enhance climate resilience (SN: 4/22/20). Preserving mangrove forests, for instance, along less developed coastlines sequesters large amounts of carbon and protects against storm surges (SN:5/7/21, SN: 6/4/20).

“The truth is that nature can be our savior,” said Inger Andersen, executive director of the U.N. Environment Programme, at a February 28 news conference announcing the report’s release. “But only if we save it first.”

Still, the natural world and many of the “services” it provides to humankind, such as carbon storage and flood control, begin to break down more rapidly at about 1.5° C above preindustrial temperatures, the report notes. And the window to prevent that from happening is closing. “We are on a trajectory to losing many of these systems and the services they provide” says Borja Reguero, a coastal science researcher at the University of California, Santa Cruz who reviewed the report.

What that means is there is no time to waste. “We simultaneously need to reduce our greenhouse gas emissions, adapt to reduce the risks of climate change and also address losses and damages that are already being experienced,” Adelle Thomas, a climate scientist at the University of the Bahamas in Nassau, said at a February 27 news briefing. Thomas is the lead author of the new report’s chapter on key risks across sectors and regions.

“And we have a very limited amount of time left to do this,” she stressed. More

A small number of “ultra-emitters” of methane from oil and gas production contribute as much as 12 percent of emissions of the greenhouse gas to the atmosphere every year — and now scientists know where many of these sources are.

Analyses of satellite images from 2019 and 2020 reveal that a majority of the 1,800 biggest methane sources come from six major oil- and gas-producing countries: Turkmenistan led the pack, followed by Russia, the United States, Iran, Kazakhstan and Algeria.

Plugging those leaks would not only be a boon to the planet, but also could save those countries billions in U.S. dollars, climate scientist Thomas Lauvaux of the University of Paris-Saclay and colleagues report in the Feb. 4 Science.

Ultra-emitters are sources that spurt at least 25 metric tons of methane per hour into the atmosphere. These occasional massive bursts make up only a fraction — but a sizable one — of the methane shunted into Earth’s atmosphere annually.

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Cleaning up such leaks would be a big first step in reducing overall emissions, says Euan Nisbet, a geochemist at Royal Holloway, University of London in Egham, who was not involved in the study. “If you see somebody badly injured in a road accident, you bandage up the bits that are bleeding hardest.”

Methane has about 80 times the atmosphere-warming potential of carbon dioxide, though it tends to have a much shorter lifetime in the atmosphere — 10 to 20 years or so, compared with hundreds of years. The greenhouse gas can seep into the atmosphere from both natural and human-made sources (SN: 2/19/20).

In oil and gas production, massive methane bursts might be the result of accidents or leaky pipelines or other facilities, Lauvaux says. But these leaks are often the result of routine maintenance practices, the team found. Rather than shut down for days to clear gas from pipelines, for example, managers might open valves on both ends of the line, releasing and burning off the gas quickly. That sort of practice stood out starkly in satellite images as “two giant plumes” along a pipeline track, Lauvaux says.

Stopping such practices and repairing leaky facilities are relatively easy, which is why such changes may be the low-hanging fruit when it comes to addressing greenhouse gas emissions. But identifying the particular sources of those huge methane emissions has been the challenge. Airborne studies can help pinpoint some large sources, such as landfills, dairy farms and oil and gas producers, but such flights are limited by being both regional and of short duration (SN: 11/14/19).

Satellites, such as the European Space Agency’s Tropospheric Monitoring Instrument, or TROPOMI, offer a much bigger window in both space and time. Scientists have previously used TROPOMI to estimate the overall leakiness of oil and gas production in Texas’s massive Permian Basin, finding that the region sends twice as much methane to the atmosphere as previously thought (SN: 4/22/20).

In the new study, the team didn’t include sources in the Permian Basin among the ultra-emitters; the large emissions from that region are the result of numerous tightly clustered but smaller emissions sources. Because TROPOMI doesn’t peer well through clouds, other regions around the globe, such as Canada and the equatorial tropics, also weren’t included.

But that doesn’t mean those regions are off the hook, Lauvaux says. “There’s just no data available.” On the heels of this broad-brush view from TROPOMI, Lauvaux and other scientists are now working to plug those data gaps using other satellites with better resolution and the ability to penetrate clouds.

Stopping all of these big leaks, which amount to an estimated 8 to 12 percent of total annual methane emissions, could save these countries billions of dollars, the researchers say. And the reduction in those emissions would be about as beneficial to the planet as cutting all emissions from Australia since 2005, or removing 20 million vehicles from the roads for a year.

Such a global map can also be helpful to countries in meeting their goals under the Global Methane Pledge launched in November at the United Nations’ annual climate summit, says Daniel Jacob, an atmospheric chemist at Harvard University who was not involved in the study (SN: 1/11/22).

Signatories to the pledge agreed to reduce global emissions of the gas by at least 30 percent relative to 2020 levels by 2030. These new findings, Jacob says, can help achieve that target because it “encourages action rather than despair.”  More