Climate

An analysis of the successes and failures of past electrical power projects across Africa suggests the continent isn’t likely to go green before 2030. More

The New Climate WarMichael E. MannPublic Affairs, $29
Sometime around the fifth century B.C., the Chinese general and military strategist Sun Tzu wrote in his highly quotable treatise The Art of War, “If you know the enemy and know yourself, you need not fear the result of a hundred battles.”
In The New Climate War, climate scientist Michael Mann channels Sun Tzu to demystify the myriad tactics of “the enemy” — in this case, “the fossil fuel companies, right-wing plutocrats and oil-funded governments” and other forces standing in the way of large-scale action to combat climate change. “Any plan for victory requires recognizing and defeating the tactics now being used by inactivists as they continue to wage war,” he writes.
Mann is a veteran of the climate wars of the 1990s and early 2000s, when the scientific evidence that the climate is changing due to human emissions of greenhouse gases was under attack. Now, with the effects of climate change all around us (SN: 12/21/20), we are in a new phase of those wars, he argues. Outright denial has morphed into “deception, distraction and delay.”
Such tactics, he says, are direct descendants of earlier public relations battles over whether producers or consumers must bear ultimate responsibility for, say, smoking-related deaths. When it comes to the climate, Mann warns, an overemphasis on individual actions could eclipse efforts to achieve the real prize: industrial-scale emissions reductions.

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He pulls no punches, calling out sources of “friendly fire” from climate advocates who he says divide the climate community and play into the “enemy’s” hands. These advocates include climate purists who lambaste scientists for flying or eating meat; science communicators who push fatalistic visions of catastrophic futures; and idealistic technocrats who advocate for risky, pie-in-the-sky geoengineering ideas. All, Mann says, distract from what we can do in the here and now: regulate emissions and invest in renewable energy.
The New Climate War’s main focus is to combat psychological warfare, and on this front, the book is fascinating and often entertaining. It’s an engrossing mix of footnoted history, acerbic political commentary and personal anecdotes. As far as what readers can do to assist in the battle, Mann advocates four strategies: Disregard the doomsayers; get inspired by youth activists like Greta Thunberg; focus on educating the people who will listen; and don’t be fooled into thinking it’s too late to take action to change the political system.
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2020 is in a “dead heat” with 2016 for the hottest year on record, scientists with NASA and the National Oceanic and Atmospheric Administration announced January 14.
Based on ocean temperature data from buoys, floats and ships, as well as temperatures measured over land at weather stations around the globe, the U.S. agencies conducted independent analyses and arrived at a similar conclusion.
NASA’s analysis showed 2020 to be slightly hotter, while NOAA’s showed that 2016 was still slightly ahead. But the differences in those assessments are within margins of error, “so it’s effectively a statistical tie,” said NASA climatologist Gavin Schmidt of the Goddard Institute for Space Studies in New York City at a Jan. 14 news conference.
NOAA climate scientist Russell Vose, who is also based in New York City, described in the news conference the extreme warmth that occurred over land last year, including a months-long heat wave in Siberia (SN: 12/21/20). Europe and Asia recorded their hottest average temperatures on record in 2020, with South America recording its second warmest.
It’s possible that 2020’s temperatures in some areas might have been even higher if not for massive wildfires. Vose noted that smoke lofted high into the stratosphere as a result of Australia’s intense fires in early 2020 may have slightly decreased temperatures in the Northern Hemisphere, though this is not yet known (SN: 12/15/20).
The ocean-climate pattern known as the El Niño Southern Oscillation can boost or decrease global temperatures, depending on whether it’s in an El Niño or La Niña phase, respectively, Schmidt said (SN: 5/2/16). The El Niño phase was waning at the start of 2020, and a La Niña was starting, so the overall impact of this pattern was muted for the year. 2016, on the other hand, got a large temperature boost from El Niño. Without that, “2020 would have been by far the warmest year on record,” he said.
But placed in the bigger picture, these rankings “don’t tell the whole story,” Vose said. “The last six to seven years really stand out above the rest of the record, suggesting the kind of rapid warming we’re seeing. [And] each of the past four decades was warmer than the one preceding it.” More

A more acidic ocean could give some species a glow-up.
As the pH of the ocean decreases as a result of climate change, some bioluminescent organisms might get brighter, while others see their lights dim, scientists report January 2 at the virtual annual meeting of the Society for Integrative and Comparative Biology.
Bioluminescence is de rigueur in parts of the ocean (SN: 5/19/20). The ability to light the dark has evolved more than 90 times in different species. As a result, the chemical structures that create bioluminescence vary wildly — from single chains of atoms to massive ringed complexes.
With such variability, changes in pH could have unpredictable effects on creatures’ ability to glow (SN: 7/6/10). If fossil fuel emissions continue as they are, average ocean pH is expected to drop from 8.1 to 7.7 by 2100. To find out how bioluminescence might be affected by that decrease, sensory biologist Tom Iwanicki and colleagues at the University of Hawaii at Manoa gathered 49 studies on bioluminescence across nine different phyla. The team then analyzed data from those studies to see how the brightness of the creatures’ bioluminescent compounds varied at pH levels from 8.1 to 7.7.

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As pH drops, the bioluminescent chemicals in some species, such as the sea pansy (Renilla reniformis), increase light production twofold, the data showed. Other compounds, such as those in the sea firefly (Vargula hilgendorfii), have modest increases of only about 20 percent. And some species, like the firefly squid (Watasenia scintillans), actually appear to have a 70 percent decrease in light production.
For the sea firefly — which uses glowing trails to attract mates — a small increase could give it a sexy advantage. But for the firefly squid — which also uses luminescence for communication — low pH and less light might not be a good thing.
Because the work was an analysis of previously published research, “I’m interpreting this as a first step, not a definitive result,” says Karen Chan, a marine biologist at Swarthmore College in Pennsylvania who wasn’t involved in the study. It “provides [a] testable hypothesis that we should … look into.”
The next step is definitely testing, Iwanicki agrees. Most of the analyzed studies took the luminescing chemicals out of an organism to test them. Finding out how the compounds function in creatures in the ocean will be key. “Throughout our oceans, upward of 75 percent of visible critters are capable of bioluminescence,” Iwanicki says. “When we’re wholescale changing the conditions in which they can use that [ability] … that’ll have a world of impacts.” More

The COVID-19 pandemic wasn’t just a shock to the human immune system. It was also a shock to the Earth system, dramatically changing the air quality in cities around the globe.
As countries around the globe struggled to contain the disease, they imposed temporary shutdowns. Scientists are now sifting through data collected by satellite and on the ground to understand what this hiatus in human activities can tell us about the atmospheric cocktail that generates city pollution. Much of this preliminary data was shared at the American Geophysical Union annual meeting in December.
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It was already known that peoples’ activities were curtailed enough to result in a dramatic drop in emissions of greenhouse gases in April, as well as a dip in the seismic noises produced by humans (SN: 5/19/20; SN: 7/23/20). That quiet period didn’t last, though, and carbon dioxide emissions began to climb back upward by the summer. April 2020 saw a drop of about 17 percent in global monthly CO2 emissions from fossil fuels, but by year’s end, annual CO2 emissions for the globe were only 7 percent lower than they were in 2019. That reduction was too brief, compared with the hundreds of years that the gas can linger in Earth’s atmosphere, to put a dent in the planet’s atmospheric CO2 level (SN: 8/7/20).

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But in addition to briefly reducing emissions of climate-warming gases, this abrupt halt in many human activities — particularly commuter traffic — also created an unprecedented experiment for scientists to examine the complicated chemistry of atmospheric pollutants in cities. By altering the usual mix of pollutants hovering over cities, the shutdowns may help scientists better understand another longstanding misery for human health: poor air quality in many cities.
That’s not to say that the pandemic has a silver lining, says Jessica Gilman, a tropospheric chemist at the National Oceanic and Atmospheric Administration in Boulder, Colo. “Misery is no solution to our global environmental challenges.”
But there’s now a wealth of data from cities around the globe on how the pandemic altered regional or local concentrations of the precursors of ozone, a primary component of smog. Those precursors include nitrogen oxides and volatile organic compounds — both produced by traffic — as well as methane, produced by the oil and gas industry. With satellites, scientists are also able to assess how levels of these pollutants changed around the globe.
Building a global picture of altered city pollution is no easy task, though. Researchers are finding that the pandemic’s impact on levels of various pollutants was highly regional, affected by differences in wind and rain as well as by photochemical interactions with sunlight — the intensity of which also changes with the season.  
That stark variety of regional effects was evident in, for example, the different post-pandemic ozone levels in Denver and New York City. Nitrogen oxide gases produced by traffic are a powerful precursor to cities’ elevated ozone levels, which can damage the lungs and trigger respiratory ailments. The United States has made strides in reducing these gases over the last few decades — but there hasn’t been a corresponding drop in ozone levels, Dan Jaffe, an environmental chemist at the University of Washington Bothell, reported at the meeting on December 9.
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The shutdowns gave researchers some insight into why, Jaffe says. From March 15 through July 23, New York City had a 21 percent decrease in nitrogen dioxide, one of several nitrogen oxide gases, in comparison with 2019 levels. Although the shutdowns were more stringent during the spring months, it turned out that summertime reductions in nitrogen dioxide were most strongly linked to the city’s change in ozone levels, the researchers found. “We see very strong reduction in summertime ozone this year,” Jaffe said at the meeting, citing unpublished data.
That’s because in the summer months, heat and sunlight react with the precursor gases in the atmosphere, like nitrogen dioxide, creating a toxic cocktail. This kind of insight can be a boon to policy makers in a non-pandemic year, suggesting that nitrogen oxide regulations should focus most strongly on the summer, Jaffe says. “It’s really good evidence that NOx reductions extending into July in 2020 had an important impact.”
In Denver, however, ozone didn’t drop so consistently — possibly because wildfires were beginning to rage across the U.S. West by the end of the summer (SN: 12/21/20). The fires produce nitrogen oxides, carbon monoxide and fine particles that can also help to increase ground-level ozone.
“There are different patterns in different cities,” Jaffe says. “There are a lot of factors to sort out, and a lot of work to be done.” Armed with a wealth of new data from 2020, scientists hope to be able to make some headway. More

2020 was a year of unremitting extreme climate events, from heat waves to wildfires to hurricanes, many of which scientists have directly linked to human-caused climate change (SN: 8/27/20). Each event has taken a huge toll in lives lost and damages incurred. As of early October, the United States alone had weathered at least 16 climate- or weather-related disasters each costing more than $1 billion. The price tags of the late-season hurricanes Delta, Zeta and Eta could push the final 2020 tally of such expensive disasters even higher, setting a new record.
With the COVID-19 pandemic dominating the news, some of these events may have already faded into memory. Here, Science News takes a look at this year of climate extremes.

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Australia’s ‘black summer’
The bushfires that burned southeastern Australia between July 2019 and March 2020 scorched roughly 11 million hectares and killed dozens of people. Climate change made those devastating fires at least 30 percent more likely to occur, researchers reported (SN: 3/4/20). The primary reason: a prolonged and severe heat wave that baked the country in 2019 and 2020, which itself was exacerbated by climate change.
The intensity of Australia’s fires produced some striking sights. A particularly intense fire led to the formation of towering pyrocumulonimbus clouds that launched hundreds of thousands of metric tons of smoke into the stratosphere (SN: 6/15/20).
One massive plume of smoke, wrapped in rotating winds, ascended to a record 31 kilometers in the atmosphere, deep into Earth’s protective ozone layer. Although it’s not clear what chemical scars it left, such a large smoke plume has the potential to trigger chemical reactions that destroy ozone.
This injured koala, cared for at the Kangaroo Island Wildlife Park in January, was among the countless animals harmed or killed by the bushfires that blazed across Australia this year.Lisa Maree Williams/Getty Images
The West on fire
Record-setting wildfires in the U.S. West also produced heartbreaking images: raging blazes, orange skies, destroyed homes, neighborhoods enveloped in acrid smoke (SN: 9/18/20). By mid-November, more than 9,200 fires in California had burned about 1.7 million hectares — more than double the acreage burned in 2018, the state’s previous record fire year. Meanwhile, Colorado battled three of the largest wildfires in the state’s history. Combined, those fires burned more than 219,000 hectares.
The role of climate change in these blazes is multipronged. From California to Colorado, rising temperatures due to climate change have led to earlier spring snow melting, resulting in drier vegetation by summer. In California, that extremely dry vegetation combined with a record-breaking heat wave primed the landscape for runaway fires (SN: 8/17/20).
Climate change is increasing the frequency of extreme climate conditions. California’s average heat and dryness in both summer and autumn have become more severe, dramatically increasing the number of days each year prone to extreme fire weather conditions (SN: 8/27/20). Simulations of future climate change project increasing dryness over at least the next few decades — which means 2020’s fire records aren’t likely to stand for long.
Siberian meltdown
From January through July, Siberia was in the grips of a powerful heat wave that led to record-breaking temperatures (SN: 6/23/20), unprecedented wildfires in the Arctic and thawing permafrost, which in turn may have led to the collapse of a fuel storage tank that flooded nearby rivers with diesel fuel (SN: 7/1/20).
A worker takes part in cleanup operations at a fuel spill in northern Russia. A heat wave thawed permafrost, which may have caused the collapse of a fuel tank in May that released about 20 million liters of diesel fuel.Denis Kozhevnikov/TASS/Getty Images
Such heat in Siberia — with temperatures as high as 38° Celsius (about 100° Fahrenheit) — would have been impossible without climate change (SN: 7/15/20). Human influence made the heat wave at least 600 times as likely — and possibly as much as 99,000 times as likely, scientists reported. Moreover, the carbon dioxide churned into the atmosphere by this year’s Arctic wildfires also smashed the previous record for the region, set in 2019 (SN: 8/2/19). That CO2 can beget further warming, and the fires can also speed up permafrost thaw, which could add more of another greenhouse gas, methane, to the atmosphere.
This year also saw the second-lowest extent of Arctic sea ice on record. Meanwhile, a roughly Manhattan-sized chunk of Canada’s Milne ice shelf — close to half of what had been the country’s last intact ice shelf — suddenly collapsed into the Arctic Ocean in August, carrying an ice-observing station away with it.
Supercharged hurricanes
As early as April, scientists predicted that the Atlantic hurricane season, which lasts from June 1 through November 30, would be busy, with about 18 named storms, compared with an average of 12 (SN: 4/16/20). By August, scientists upped their predictions to as many as 25 (SN: 8/7/20). But 2020 surpassed those expectations too: By mid-November, there were 30 named storms, eclipsing a record set in 2005 (SN: 11/10/20).
Hurricane Laura (shown whipping up the waves near Galveston, Texas, on August 26) rapidly intensified into a Category 4 storm before making landfall on August 27 in Louisiana.Thomas B. Shea/Getty Images
It’s difficult to link climate change to the number of storms that form in a given year. Very warm ocean waters, such as in the Atlantic Ocean this year, foster tropical cyclone formation. It’s true that those warm waters are linked to climate change, as the surface ocean swallows up excess heat from the atmosphere. But other factors are also involved in hurricane formation, including wind conditions, making it difficult to establish a link.
But there are established links between warming oceans and increasing hurricane intensity, as well as rainfall (SN: 9/13/18). Warm Atlantic waters gave a boost to the intense storms of the 2017 hurricane season, for example (SN: 9/28/18). The warm waters can also provide enough energy to give hurricanes extra staying power even after landfall (SN: 11/11/20).
And, as the world saw in 2020, very warm ocean waters can also speed up how quickly a storm strengthens — leading to dangerous, difficult-to-predict, suddenly supercharged storms. Such rapid intensification is defined as sustained wind speeds increasing by at least 55 kilometers per hour within just 24 hours. 2020 saw that in abundance, with 10 Atlantic storms rapidly intensifying in the region’s bathlike waters before making landfall. More

Atlantic hurricanes are taking longer to weaken after making landfall than they did 50 years ago, thanks to climate change. Over the past 50 years, increasingly warm ocean waters have juiced up the storms, giving them more staying power after they roar ashore, scientists report in the Nov. 12 Nature. That could potentially extend storms’ destructive power farther inland, the researchers say.
As ocean waters warm, tropical cyclones — called hurricanes in the Atlantic Ocean — are likely to gain in intensity, studies show (SN: 9/28/18). They can also hold more moisture, leading to seemingly unremitting rainfall (SN: 9/13/18). And they may move more slowly, allowing more time to dump that rain on coastal communities. All of this increases the potential hazard on land (SN: 6/6/18).
Once a storm hits land, its energy begins to dissipate. But that relief is coming later than it once did, report physicists Lin Li and Pinaki Chakraborty, both of the Okinawa Institute of Science and Technology in Japan.
Li and Chakraborty analyzed the intensity of historical Atlantic hurricanes over the first 24 hours after landfall. In 1967, a typical storm’s intensity decayed by 76 percent within the first day after landfall. But by 2018, storms were only 52 percent less intense after 24 hours. That trend, the researchers say, aligns with increasing sea-surface temperatures in the Gulf of Mexico and the western Caribbean Sea.
That’s because the intense winds of cyclones feed on moisture and heat picked up from the warm waters, and warmer air can also hold more moisture. So as the oceans heat up, they not only add more moisture, making hurricanes rainier, but also add more heat — like a portable engine the storm uses to fuel its fury for just a bit longer. More

By 2100, Greenland will be shedding ice faster than at any time in the past 12,000 years, scientists report October 1 in Nature.
Since the 1990s, Greenland has shed its ice at an increasing rate (SN: 8/2/19). Meltwater from the island’s ice sheet now contributes about 0.7 millimeters per year to global sea level rise (SN: 9/25/19). But how does this rapid loss stack up against the ice sheet’s recent history, including during a 3,000-year-long warm period?
Glacial geologist Jason Briner of the University at Buffalo in New York and colleagues created a master timeline of ice sheet changes spanning nearly 12,000 years, from the dawn of the Holocene Epoch 11,700 years ago and projected out to 2100.
The researchers combined climate and ice physics simulations with observations of the extent of past ice sheets, marked by moraines. Those rocky deposits denote the edges of ancient, bulldozing glaciers. New fine-tuned climate simulations that include spatial variations in temperature and precipitation across the island also improved on past temperature reconstructions.
During the past warm episode from about 10,000 to 7,000 years ago, Greenland lost ice at a rate of about 6,000 billion metric tons each century, the team estimates. That rate remained unmatched until the past two decades: From 2000 to 2018, the average rate of ice loss was similar, at about 6,100 billion tons per century.
Over the next century, that pace will accelerate, the team says. How much depends on future greenhouse gas emissions: Under a lower-emissions scenario, ice loss is projected to average around 8,800 billion tons per century by 2100. With higher emissions, the rate of loss could ramp up to 35,900 billion tons per century.
Lower emissions could slow the loss, but “no matter what humanity does, the ice will melt this century at a faster clip than it did during that warm period,” Briner says. More