Climate
By Carl PopeClimate
Big Oil’s Nightmare Comes True

"This was retail politics and oil lost," was how Adrienne Alvord of Union of Concerned Scientists summed up the stunning environmental victory Tuesday in the California legislature, a victory which cemented the state's commitment to a 40 percent reduction in climate pollution by 2030.

It's not accidental that states providing climate leadership are the states with the biggest clean energy sectors, including California.

Only a few weeks ago there was a strong consensus that the oil industry, by spending millions of dollars on behalf of a cadre of moderate Democrats in the Assembly, had blocked just such a doubling down on the state's existing 2020 goals. For the oil industry, victory was an existential necessity. Only by holding future climate commitments hostage could the industry hope to get Gov. Brown to abandon the state's existing mandate that by 2020 the carbon content of fuels be cut by 10 percent. As a practical matter, the requirement means roughly 20 percent of California's more vehicles will be driving on something other than oil—electricity, natural gas or biofuels.

And oil knows it cannot withstand a competitive transportation fuels market. Once California creates such a market and builds businesses that can produce low carbon fuels at scale, fuels competition will go global and oil's empire will wither. But it looked like oil had survived to fight another day. Gov. Brown had signaled his next move by forming a ballot committee for a (high-risk) initiative for the fall of 2018. But a small group of climate and environmental justice advocates refused to let the Assembly moderates off the hook. Demanding a vote, they re-energized their broad coalition of main-line businesses, EJ advocates, labor, climate greens, the faith community, clean tech and clean fuels businesses, local government and public health advocates.

Assembly Speaker Anthony Rendon told them he would give them a vote once they had the votes—and on Tuesday he pulled the trigger, giving the oil industry, which thought it had won, only 24 hours to regroup. It wasn't enough and the Assembly passed SB32 by 47 votes, a six vote margin over the 41 needed. The California Nurses Association was heard from, but so was Ebay. Gov. Brown and the White House weighed in, but a lone Republican, Assemblywoman Catherine Baker joined them in supporting progress. Wednesday the Senate concurred and the bill, linked to an environmental justice focused companion bill, went to the governor for his signature.

Why the victory? Quite simply, retail politics. Clean energy now provides far more stimulus and creates far more jobs than fossil fuels. Clean power is seen by the public as the linch-pin of the state's economic future. Jobs on the ground trump oil industry ads on the screen. It's not accidental that states providing climate leadership are the states with the biggest clean energy sectors—California, Washington, Nevada, Oregon—and Iowa, with its nation leading wind sector and a public utility, Mid-America, that is planning to shortly hit 85 percent renewables and go on to 100 percent.

And it's cheaper.

The oil industry is in a state of shock. Their press release bizarrely asserted that Rendon had scheduled the vote to "cover up" the fact that the state's latest auction for carbon emission permits had attracted few buyers—a result oil called "terrible." The auction simply reflected the fact that emitters, uncertain if the law would be extended past 2020, did not know how many permits they needed to buy. The oil industry conceded as much, saying "Today's miserable auction result reflects the market's lack of certainty." But it is revealing that oil called it "terrible" and "miserable" that the cost of carbon permits was low—demonstrating again that what they fear is not that decarbonizing will cost too much and hurt the economy, but that it will prove irresistibly cheap and strand them. Also revealing—SB32 was written precisely to provide the certainty whose absence the oil industry allegedly deplores!

(In fact, the legislature is going home next week and Rendon had to bring the bill up more or less when he did. The short notice was tactical—but hardly conspiratorial).

Ideological, right-wing opponents of climate progress and clean energy stayed more on message, releasing a poll purporting to show that the public, all the other evidence to the contrary, didn't really favor tougher clean-up of carbon pollution or California climate leadership after all.

Read carefully, however, the poll says something quite different. It confirms that most Californians want to move forward on clean energy and climate, believe that such progress is good for California even if others do not lead and want action. Even California Republicans are part of this consensus. Sixty-two percent of California Republican voters think that climate change is either a very serious or somewhat serious threat to the state. Again, of Republicans, 67 percent expect the changes resulting from global warming to occur in their lifetimes. A majority favor the state's current climate goals and a plurality favor the longer-term, more ambitious goals just passed.

It is true that, if nudged to believe that after such action, "hundreds of local manufacturing facilities would be shut down and thousands of middle-class jobs would be lost in California" large majorities of Republicans, and Democrats and Independents, lose their appetite. But if you said to the same sample that ambitious climate progress would mean "continued economic growth, an end to air pollution, cheaper gas and billions of dollars of new exports for California industries" the supportive numbers among Republicans would probably jump from a plurality to a super-majority. The latter statement is the true one, it turns out—and, more or less, it is what most California voters are experiencing—which explains why, un-manipulated, even Republicans are happy that the state continues to move forward.

But California is not the only arena where oil's long regime is coming to an end. Investors are watching warily as the majors—Chevron, Exxon, BP and Shell have now accumulated an unprecedented $184 billion in debt, fallen far short ($40 billion short in the first half of 2016) of their promised goals of paying their dividends from profits, not borrowing. Shell, Chevron, Exxon and BP have all seen their previous platinum grade credit ratings cut a notch. To placate investors, the majors pledge that they have new (but far from transparent) business plans to someday make money again—if only oil will stay at some magic level. For BP it's $50-55/barrel. Unfortunately, it has not been in that range since 2014.

Many of the independent oil producers, of course, have gone bankrupt. Oil remains stubbornly below $50. Most independent analysts believe that for the oil majors, prices in the $75 range are required to compete with Persian Gulf and other OPEC members in the long term. And those prices, unequivocally, require one thing: a continuation of oil's monopoly in transportation fuel.

California this week called the question. That monopoly is going away. Oil has lost before, but never because the retail politics of its competitors proved more compelling. This was no decisive battle. There may be none, just as there is no moment when the fate of the Roman Empire was sealed.

But the sands of time are running. Oil's empire is in its decline and fall.

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By Dan ZukowskiClimate
Mount Everest Climbers May One Day Climb Ice-Free

The Himalayan Mountains and Tibetan Plateau, dubbed the "Third Pole" for having the largest ice mass on Earth after the polar regions, are rapidly losing their glaciers. Eighteen percent of China's glaciers have vanished in the past 50 years according to the Chinese Academy of Sciences. Air pollution and rising air temperatures are combining to increase glacial melt, threatening water supplies for one billion people.

Mount Everest is Earth's highest mountain.

Glacial surfaces are vulnerable to the effects of black carbon. What, exactly, is black carbon? The U.S. Environmental Protection Agency (EPA) defines it as "the most strongly light-absorbing component of particulate matter (PM), and is formed by the incomplete combustion of fossil fuels, biofuels and biomass." Airborne black carbon absorbs sunlight, creating local atmospheric warming. Deposited on glaciers, it darkens the surface, allowing the sun to warm the snow and ice just as wearing dark clothing on a summer day can make you feel the heat.

Source: Nature Communications

It's not just China's famous pollution or fossil fuel burning that's to blame. It's also yak dung.

Traditional Tibetan use of biomass such as animal dung for cooking and heating, along with open burning of garbage and crop waste, was found to be a greater contributor to the creation of black carbon in certain areas of the Himalaya-Hindu-Kush and Tibetan Plateau than burning of fossil fuels. A new study published this week in Nature Communications concludes that "the results of this extensive observation-based source-diagnostic study provide strong isotope-based evidence that biomass-sourced BC [black carbon] plays a quantitatively more important role in TP [Tibetan Plateau] glacier melting than fossil fuel-sourced BC, especially in the inland TP, and presumably arises mainly from domestic sources." The research was conducted by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences.

The mineral-rich lands of Tibet are a source of diamonds, gold, uranium and copper, bringing extractive industries to the region. China is the world's fourth largest lithium producer, most of it coming from the Chang Tang plain in Western Tibet.The Tibet Express stated, "Glacier-water mining has major environmental costs in terms of biodiversity loss, impairment of some ecosystem services due to insufficient runoff water, and potential depletion or degradation of glacial springs."

Degrading glaciers threatens a critical Asian water source.

China, India and other countries surrounding the Tibetan Plateau have looked to it to supply growing water needs as populations increase and fresh-water sources suffer from industrial and human-waste pollution. China is also tapping the glaciers of the Himalaya's to support its bottled-water market, the world largest. At least 30 companies have been granted licenses to tap Tibetan glaciers.

Fossil fuels are by no means blameless in the degradation of the Himalayan glaciers. In the Himalayas, the Chinese study found fossil fuels accounted for 46 percent of black carbon versus 54 percent for biomass burning. Fossil fuel sources ranged as high as 70 percent in the Langtang and Mustang Valleys, largely from sources in Kathmandu and Northern India. The study also saw seasonal variations. Biomass-sourced black carbon decreased during monsoon season, presumably because these particles are more efficiently flushed out by precipitation.

Most of the 5,500 glaciers in the Himalaya-Hindu-Kush region—home of Mount Everest—may vanish by the end of this century. The long history of climbing through the Khumbu Icefall and up the Lhotse Face may become a rock scramble instead.

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By Climate NexusClimate
Obama to Create World’s Largest Marine Reserve in Hawaii

Citing the danger that climate change poses to the oceans, President Obama will establish the largest marine reserve in the world today, protecting nearly 600,000 square miles off the coast of Hawaii.

Commercial fishing, mining and extraction are prohibited in the expanded Papahānaumokuākea Marine National Monument, though subsistence fishing and scientific research will be allowed.

"The oceans are the untold story when it comes to climate change and we have to feel a sense of urgency when it comes to protecting the ocean that sustains us," said Sen. Brian Schatz of Hawaii. George W. Bush originally established the reserve a decade ago, protecting 140,000 square miles.


"President Obama's expansion of the Papahānaumokuākea Marine National makes it the largest sanctuary for ocean life in the world," Greenpeace oceans campaign director John Hocevar said.

"This is a bold decision that will have lasting benefits for Hawaii's unique ecosystem. Networks of sanctuaries have proven to be powerful tools to ensure the health of our oceans. Setting aside areas closed to fishing, drilling and other extractive uses is the best way to protect biodiversity, rebuild depleted fish populations, and increase the resilience of marine ecosystems so they can better withstand the impacts of climate change.

"Bolder steps are still needed. Less than two percent of the world's oceans are protected from fishing, and many scientists suggest a target of 40 percent. It is vital that we take steps like President Obama did in Hawaii to prevent future expansion of industrial fisheries, but we also need to look at areas closer to our population centers. Most of the world's coastal fisheries have been severely depleted. With few limitations on fishing in these areas, recovery is slow. Our coasts are dotted with former fishing communities that are no longer able to find enough fish to sustain their livelihoods.

"Setting aside 40 percent of our marine ecosystems—in remote areas as well as those closer to home—will help preserve the health of our oceans and our communities."

For a deeper dive:

News: Washington Post, New York Times, Buzzfeed, Reuters, AP, IB Times, USA Today, National Geographic, The Hill, Discover

For more climate change and clean energy news, you can follow Climate Nexus on Twitter and Facebook, and sign up for daily Hot News.

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By Jax JacobsenClimate
Biofuels Worse for Climate Than Gasoline, New Study Finds

A new study released by the University of Michigan in the Aug. 25 journal of Climate Change is causing a ripple through the fuel industry, as it contends that more carbon dioxide is actually released through biofuels than gasoline.

Biofuels were always pegged as being more environmentally friendly because it was assumed they emitted little to no carbon when being grown. The study challenges this assumption.

"To verify the extent to which that assumption is true, you really need to analyze what's going on on the farmland, where the biofuels are being grown," University of Michigan Energy Institute research professor and study author John DeCicco told The Detroit Free Press.

"People haven't done that in the past—they felt like they didn't need to."

The study incorporates tailpipe emissions and crop growth—which are instrumental in the growing of crops used for biofuels—and found that carbon emissions during that period actually only absorbed 37 percent of biofuel production from 2005 to 2013, directly contradicting previous studies that claimed that using biofuels emitted less carbon than using gasoline.

Promotion of biofuel use is based on what's known as the lifecycle analysis, which contends that CO2 released when the fuel is burned originates from carbon dioxide that biofuels removed from the atmosphere during the photosynthetic process.

"When you look at what's actually happening on the land, you find that not enough carbon is being removed from the atmosphere to balance what's coming out of the tailpipe," DeCicco said. "[Biofuels] is unambiguously worse than petroleum gasoline," he added.

To calculate carbon emissions, DeCicco employed his Annual Basis Carbon method, which counts carbon emissions using chemistry of the location where it is generated. It differs from the lifecycle analysis in that it incorporates the stock-and-flow nature of the carbon cycle.

The use of biofuel and other products, including ethanol, tripled from 4.2 billion gallons in 2005 to 14.6 billion gallons in 2013, supported by the U.S. Renewable Fuel Standard and California's Low-Carbon Fuel Standard to promote these types of fuels for transportation purposes. Biofuels, usually consisting of corn or soybeans, accounted for approximately 6 percent of all fuel sources in the U.S. in 2013.

Emily Cassidy, a research analyst with the Environmental Working Group, welcomed the report, saying the Renewable Fuel Standard needs to be looked at more closely.

"There is mounting evidence that the Renewable Fuel Standard has been bad for the environment and the climate, and this paper is a new take on that," she told The Detroit Free Press.

Other scientists are taking issue with the study, pointing out that it was funded by the American Petroleum Institute.

DeCicco said the API was the only group willing to finance the study, and emphasized that the report is peer-reviewed.

Others are critiquing the study's short-sightedness. Harvard University geologist Daniel Schrag told Climate Central that eight years is not sufficient to measure bioenergy's ultimate contribution to improving the climate.

"In the long run, there's no question that biofuels replacing petroleum is a benefit," he said.

Choosing a timeline on which to measure biofuels' impact is one of the key difficulties in determining the actual benefit of using biofuels, and is the subject of continuing debate at the U.S. Environmental Protection Agency (EPA).

The University of Michigan report only focused on the eight years in question. However, other scientists contend that the benefit to biofuel use is that the increased number of crops will suck in excess carbon dioxide emitted by biofuel production.

Another biofuel supporter, Jim Zook, contends that other studies have decisively shown that biofuels substantially lower greenhouse emissions, compared to gasoline. Zook is the executive director of the Corn Marketing Program of Michigan and Michigan Corn Growers Association.

To Zook, biofuels have an added advantage: they produce a byproduct which can then be used for a high-protein livestock feed.

"We are actually getting more products by going through the ethanol process, and being better stewards of our resources by doing that," Zook told the Detroit Free Press.

Princeton University researcher Timothy Searchinger has long criticized biofuels as a less than ideal solution to curb increasing carbon emissions.

"The U.S. is not coming close to offsetting the carbon released by burning biofuels through additional crop growth," Searchinger told Climate Central.

The controversial study was published shortly after Reuters reported that the EPA has not issued a report to Congress on the environmental impact of the Renewable Fuel Standard since 2011. Federal law mandates the EPA provide a report every three years.

The EPA said it will complete a report by the end of next year. The reports are used to set the amounts of biofuels that must be incorporated into American diesel and gasoline supplies each year.

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By Dan ZukowskiClimate
Delaware-Sized Chunk of Ice Could Dislodge from Antarctic Shelf

An 80-mile long crack in the Larsen C ice shelf threatens to dislodge a chunk of ice measuring about 2,300 square miles, nearly the size of Delaware and twice the size of the massive Larsen B ice shelf collapse in 2002.

As the long Southern Hemisphere polar night is ending, satellites have been able to see that the rift has grown nearly 14 miles, or about three miles per month, since it was last observed in March 2016. The fracture in the ice has also widened from 200 meters (656 feet) to about 350 meters, or 1,148 feet. According to Project MIDAS, a UK-based Antarctic research project, "As this rift continues to extend, it will eventually cause a large section of the ice shelf to break away as an iceberg."

Researchers who have reviewed satellite imagery dating back to 1963 have determined that destabilization of the Larsen B ice shelf was already underway at that time, and began accelerating in more recent decades. Prior to that, it had been stable for 12,000 years. Between January and April of 2002, the ice shelf began to break apart, eventually losing a 1,235 square mile area into the sea. At that time, it was the largest collapse ever seen.

Antarctic ice shelves, which ride atop ocean waters, ring the continent and hold back land-based glaciers. The most vulnerable regions are in West Antarctica and the Antarctic Peninsula. Ice shelves in this region protect a very large portion of glacial ice. The Earth's crust jumped upward following the collapse of Larsen B. Sensitive GPS instrumentation around the ice shelf show that tectonic uplift is now 1.8 centimeters per year as the disappearance of glaciers allows the Earth below to rebound.

However, some of the ice in the shelves is considered "passive" by scientists, in that it doesn't play any role in buttressing glaciers. Some scientists think this may be the case with the Larsen C ice shelf.

The most recent event was the disintegration of the Wilkins Ice Shelf in 2009, the tenth major ice shelf collapse in modern times. Scientists cannot predict the timing of the Larsen C collapse, but say it could happen in the next two to three years. A study published in 2015 showed that Larsen C is rapidly thinning, having lost four meters, or 13 feet, between 1998 and 2012. As the ice thins, it is susceptible to melting from underneath.

Of itself, the loss of this portion of the ice shelf will not raise sea levels as it is already floating on the water. However, as these ice shelves disintegrate, the land-locked glaciers they hold back may begin sliding into the sea. If all of the ice the Larsen C ice shelf holds back slides into the ocean, it will raise sea levels globally by four inches.

Warmer air temperatures were blamed for the collapse of Larsen B. By melting the top layer, pools of meltwater form and seep through crevasses causing fracturing of the ice. This process is now being seen on the Langhovde Glacier in East Antarctica, on the opposite side of the continent from the Larsen ice shelf.

Temperatures at the Antarctic Peninsula, where the Larsen ice shelf is found, have risen by 2.5 degrees Celsius in the past 50 years. On March 24, 2015, a record high of 63.5 degrees Fahrenheit was recorded on the peninsula at Esperanza Base.

Antarctica is losing ice at a rate of 25 cubic kilometers, or 6 miles, per year. Current Intergovernmental Panel on Climate Change estimates of sea level rise do not account for this rate of loss.

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Protecting Our National Parks for Another 100 Years

By Jillian Mackenzie

"Europe has cathedrals. We have national parks," said Stephen Saunders, president of the Rocky Mountain Climate Organization, neatly capturing the significance of these 59 national treasures, which include important monuments as well as parklands. But as we honor their majesty on this 100th anniversary of the National Park Service, we must also recognize and address the biggest threats to our natural versions of Notre Dame.

Fort Jefferson in the Dry Tortugas National Park, Florida.Deatonphotos / Shutterstock

Climate Change

"We have never before lost a national park," Saunders said. "But we are on track now to lose some to higher seas."

New York's Ellis Island, part of the Statue of Liberty National Monument and Dry Tortugas, the 100-square-mile national park off Key West, are just above sea level. Thanks to heat-trapping pollution, which warms and expands ocean waters, "these parks are at risk of being submerged and disappearing—not just in storm surges, but entirely," Saunders said.

That pollution also puts our parks at risk for uncharacteristically fierce wildfires.

"Hotter, drier conditions mean more intense fires that can permanently change forest to scrubland in beloved landscapes like Yosemite," noted Niel Lawrence, the Natural Resources Defense Council's (NRDC) senior expert on federal forestlands.

Funding Struggles

The enjoyment of national parks is at a record-breaking level, with a predicted 315 million visitors this year (up from 307 million in 2015). While that seems like happy news, the parks are straining under the pressure.

"There is a $12 billion backlog of unfunded projects," said Ani Kame'enui, director of legislation and policy at the National Parks Conservation Association. "There are cracks in the Washington Monument, potholes at Glacier National Park, nonworking faucets at the Grand Canyon—the list goes on."

On the surface, the most recent government spending bill, passed by the House this summer, seems like an environmental win. It proposes a $2.9 billion budget for the National Parks Service for 2017, which is $79 million more than the previous year's allocation. But look closer, Kame'enui said and you'll see not only that the money is shy of the funds needed to address the backlog, but that tacked on to the bill are a pile of policy riders that undermine the natural resources national parks aim to protect. "For instance, the bill includes provisions to prevent implementation of the Stream Protection Rule, a measure to improve the health of communities near streams from the mountains of West Virginia to the valleys of Tennessee," she said.

Well pads along Little Missouri River with Theodore Roosevelt National Park in background.Chris Boyer / Kestrel Aerial Services, Inc.

Fossil Fuel Extraction

Areas near national parks are continually subject to the pollution and environmental damage that comes with dirty energy projects, such as oil drilling in the Bakken formation near North Dakota's Theodore Roosevelt National Park; a large coal mine outside Utah's Bryce Canyon National Park; and oil and gas drilling around the boundaries of Canyonlands, also in Utah. Big Cypress National Preserve, which recharges aquifers that supply drinking water to much of southern Florida and serves as a watershed for Everglades National Park, is facing threats from extensive oil and gas exploration in pristine wetland areas in the preserve.

Theodore Roosevelt National Park

"Oil exploration has historically happened in Big Cypress preserve," said Alison Kelly, a staff attorney with NRDC. "But now an oil company is starting one of the largest explorations ever proposed in a national park unit." The first phase of the four-phase project was just approved, though it is being contested by a lawsuit filed by NRDC and other environmental groups.

Mount Gould is a peak on the Continental Divide in Glacier National Park.Wikipedia

Antigovernment Extremists

Long-standing disputes over whether the federal government has the right to own and manage land in the West have boiled over in recent years. In 2014, Nevada rancher Cliven Bundy led an armed standoff against Bureau of Land Management (BLM) officers; they were trying to confiscate his cattle because he'd refused to pay BLM fees dating back to 1993 for illegally grazing the animals on protected land.

In 2015 his son, Ammon Bundy, led a 40-day occupation of Malheur National Wildlife Refuge in Harney County, Oregon, in support of ranchers Dwight and Steven Hammond, a father and son who were convicted of arson for lighting fires on BLM-managed land where they had leased grazing privileges for their cattle. The Hammonds' attorney said the Bundys did not speak for them, but regardless, the standoff seemed aimed to galvanize opposition to federal control of land. As the local sheriff said in a statement at the time, "These men had alternative motives, to attempt to overthrow the county and federal government in hopes to spark a movement across the United States."

Sharon Buccino, director of NRDC's Land and Wildlife program, fears that national parks could be the next targets. "Our public lands are a place for us to unite and connect," she said. "Extremists like the Bundys seek to monopolize what belongs to us all for their own individual profit and glorify their own freedom at the expense of the freedom of others."

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By Stefanie SpearClimate
Bill Nye: 'There's Enough Wind and Solar' to Power the World

If you're wondering if the epic flooding in Louisiana is related to climate change, CNN has your answer.

Bill Nye the Science Guy was on CNN's New Day Tuesday to talk about the flooding in Louisiana, where at least 13 people have been killed and 60,000 homes damaged.

"For us, on my side of this, this is a result of climate change," Nye told CNN's Chris Cuomo. "It's only going to get worse."

"As the ocean gets warmer, which it is getting, it expands," he continued. "Molecules spread apart and then as the sea surface is warmer more water evaporates. And so it's very reasonable that these storms are connected to these big effects."

In addition to discussing impacts of climate change, Nye shared what he believes is a solution to the problem of a warming planet.

"The big unexploited renewable resource on the East Coast of the United States, and Canada and Mexico, is wind," Nye said. "So, I encourage you, I am not a member of this, but I encourage everybody to check out The Solutions Project, a bunch of civil engineers who have done an analysis that you could power the United States, you could power most of the world, renewably if you just decided to do it, right now. There's enough wind and solar resources, a little bit of tidal and some geothermal, to run the whole place."

Nye did not just leave the conversation about climate change and renewables, he also called out CNN for having "essentially a climate change denier meteorologist."

Nye didn't mention any names, but, according to Huffington Post, he appeared to be referring to CNN meteorologist Chad Myers, who has a track record of making comments on climate change that run counter to established science.

"You know, to think that we could affect weather all that much is pretty arrogant," Myers said in 2008.

However, on Twitter, Myers said that he has since come around:

He followed up that tweet with this one:

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By The ConversationClimate
Industrial Revolution Kick-Started Climate Change Much Earlier Than Previously Thought

By Helen McGregor, Joelle Gergis, Nerilie Abram and Steven Phipps

In the early days of the Industrial Revolution, no one would have thought that their burning of fossil fuels would have an almost immediate effect on the climate. But our new study, published Wednesday in Nature, reveals that warming in some regions actually began as early as the 1830s.

That is much earlier than previously thought, so our discovery redefines our understanding of when human activity began to influence our climate.

Britain's industrial pioneers couldn't have known how they would affect the climate. Henry Gastineau

Determining when global warming began and how quickly the planet has warmed since then, is essential for understanding how much we have altered the climate in different parts of the world. Our study helps to answer the question of whether our climate is already operating outside thresholds that are considered safe for human society and functional ecosystems.

Our findings show that warming did not develop at the same time across the planet. The tropical oceans and the Arctic were the first regions to begin warming, in the 1830s. Europe, North America and Asia followed roughly two decades later.

Surprisingly, the results show that the southern hemisphere began warming much later, with Australasia and South America starting to warm from the early 20th century. This continental-scale time lag is still evident today: while some parts of Antarctica have begun to warm, a clear warming signal over the entire continent is still not detectable.

The warming in most regions reversed what would otherwise have been a cooling trend related to high volcanic activity during the preceding centuries.

By pinpointing the date when human-induced climate change started, we can then begin to work out when the warming trend broke through the boundaries of the climate's natural fluctuations, because it takes some decades for the global warming signal to "emerge" above the natural climate variability.

According to our evidence, in all regions except for Antarctica, we are now well and truly operating in a greenhouse-influenced world. We know this because the only climate models that can reproduce the results seen in our records of past climate are those models that factor in the effect of the carbon dioxide released into the atmosphere by humans.

These remarkable findings were pieced together from the most unusual of sources—not thermometers or satellites, but rather from natural climate archives. These include coral skeletons, ice cores, tree rings, cave deposits and ocean and lake sediment layers, all of which record the climate as they grow or accumulate.

These archives provide long records that extend back 500 years—well before the Industrial Revolution—and provide a critical baseline for the planet's past climate, one that is impossible to obtain otherwise.

Corals can help reveal the climate of centuries past, long before weather records began.Eric Matson / AIMS

But why is there no clear warming fingerprint yet seen across Antarctica? The answer most likely lies in the vast Southern Ocean, which isolates the frozen continent from the warming happening elsewhere.

The westerly winds that circulate through the Southern Ocean around Antarctica keep warm air masses from lower latitudes at bay. Ozone depletion and rising greenhouse gas concentrations during the 20th century have also caused this wind barrier to get stronger.

The Southern Ocean currents that flow around Antarctica also tend to move warmer surface waters away from the continent, to be replaced with cold deeper water that hasn't yet been affected by surface greenhouse warming. This process could potentially delay Antarctica's warming by centuries.

Ocean Insulation

The delay in warming observed in the rest of the southern hemisphere is something we do not yet fully understand. It could simply be because fewer records are available from the southern hemisphere, meaning that we still don't have a full picture of what is happening.

Alternatively, like Antarctica, the southern hemisphere's oceans could be holding back warming—partly through winds and currents, but perhaps also because of "thermal inertia", whereby the ocean can absorb far more heat energy than the atmosphere or the land before its temperature markedly increases. Bear in mind that the southern half of the globe has much more ocean than the north.

Essentially, then, the coolness of the southern hemisphere's vast oceans could be "insulating" Australasia and South America from the impact of global warming. The question is, for how long?

If our evidence of delayed warming in the southern hemisphere holds true, it could mean we are in in for more climate surprises as global warming begins to overcome the thermal inertia of our surrounding oceans. Could the recent record warming of Australian waters and the subsequent damage to the Great Barrier Reef, be an early sign that this is already occurring?

Recent research suggest that the mass bleaching event of the reef was made 175 times more likely by climate change. Following the recent severity of such extremes, a better understanding of how anthropogenic greenhouse warming is already impacting the southern hemisphere is critical.

What to Do About It

Leading scientists from around the world met in Geneva last week to discuss the goal of limiting average global warming to 1.5C—the more ambitious of the two targets enshrined in the Paris climate agreement.

Last year, global temperatures crossed the 1C threshold, and 2016 is on track to be 1.2-1.3C above our climate baseline.

But here's the kicker. That baseline is relative to 1850–1900, when most of our thermometer-based temperature records began. What our study shows is that for many parts of the world that estimate isn't good enough, because global warming was already under way, so the real baseline would be lower.

The small increases in greenhouse gases during the 19th century had a small effect on Earth's temperatures, but with the longer perspective we get from our natural climate records we see that big changes occurred. These fractions of a degree of extra warming might seem insignificant at first, but as we nudge ever closer to the 1.5C guardrail (and potentially beyond), the past tells us that small changes matter.

This article was reposted with permission from our media associate The Conversation.

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Why Natural Gas Is Not a Bridge Fuel

By Zeke Hausfather

For the past century, coal has been king, providing the majority of U.S. energy for electricity generation.

But a combination of new federal and state environmental policies and a glut of cheap natural gas (mostly from hydraulic fracturing or fracking) have led to a dramatic shift during the past decade, with coal dropping from 50 percent to 32 percent of our electricity generation and gas increasing from 18 percent to 33 percent.

Just under a third of existing coal-based power generation in the U.S. has been shut down and the Obama administration has aggressively embraced the replacement of coal with gas as a key part of meeting its 2030 climate targets. We are quickly traveling down a gas bridge away from coal. But will this shift actually be a good thing for the climate?

Slashing Emissions at the Plant

At first glance, replacing coal with natural gas seems like a good (though not great) step in combating climate change.

Overall, carbon dioxide emissions from new gas power plants are as much as 66 percent lower than those of existing coal power plants. About half of this reduction is due to differing carbon intensities of the fuels (natural gas emits 40 percent less carbon than coal per unit of heat). The other half is due to the higher generation efficiency of natural gas (new natural gas plants convert heat to power at upwards of 50 percent efficiency, while typical coal plants only operate at about 33 percent efficiency).

A way to reduce emissions by as much as two thirds while also saving money seems like a no-brainer for climate policy. But natural gas has an Achilles' heel that makes the question much harder to answer.

Direct CO2 emissions from electricity generation in grams per kWh. Based on calculations from Hausfather 2015.

Leaking Gas

Natural gas is predominately composed of methane. When methane is burned to produce electricity or heat, it releases carbon dioxide and water vapor.

But not all natural gas produced is burned. Some of it is leaked at gas wells, in compressor stations, from pipelines or in storage. Methane is a powerful but short-lived greenhouse gas. While it is in the atmosphere, it is around 120 times more powerful than carbon dioxide per ton, but it quickly decomposes through chemical reactions and only about 20 percent of the methane emitted today will remain after 20 years.

Carbon dioxide, on the other hand, has a much longer atmospheric lifetime. About half of the carbon dioxide emitted today will be around in 100 years (and virtually none of the methane will be) and about 15 percent of today's carbon dioxide will still be in the atmosphere in 10,000 years.

This difference in longevity makes a comparison between the two tricky. Essentially, how much methane emissions today matter for the climate depends largely on the timeframe you are considering. If you care about avoiding warming later in the century (as the United Nations does with its 2C warming by 2100 target), there is relatively little problem with short-term methane emissions, as long as they are phased out in the next few decades. If you care about short-term changes, however, methane is a much bigger deal.

How much methane leaks from the natural gas system is very much an open question. For a long time official U.S. Environmental Protection Agency (EPA) numbers suggested the emissions were small and falling fast, only amounting to around 1.5 percent of total production.

But dozens of independent academics doing research using aircraft, satellite data and other instruments have consistently found higher emissions than officially reported.

Adam Brandt at Stanford University published a high-profile paper in the journal Science in 2014 summarizing all the research to date. He found that overall emissions were likely between 25 and 75 percent higher than reported by EPA, suggesting that actual natural gas leakage rates are probably somewhere between 2 and 4 percent of gas production. (Some researchers have found leakage as high as 10 percent for individual fields, but there isn't evidence that those findings are characteristic of the sector as a whole).

How Much Do Leaks Matter?

What do these leakage rates mean for the viability of natural gas as a bridge fuel? Again, it comes down to a question of time frame.

Let's look at a simple example of a big coal power plant. One option is to leave it alone for the next 30 years, at which point it will be replaced by renewable energy.

Another option is to replace it with gas today and replace that gas with renewables in 30 years.

The figure below shows the climate impacts over time (measured in units called radiative forcing) of existing coal (the dashed black line), new high-efficient coal plants (the solid black line) and new gas plants (the green line). The potential range of natural gas leakage is expressed by the gray envelope around the green line, with 1 percent leakage at the bottom and 6 percent leakage at the top (the green line itself shows a 3 percent leakage case).

Adapted from Figure 3 of Hausfather 2015.

If leakage is higher than 3 percent, there are some periods in the next 30 years when gas will result in more climate impact than new coal plants. If leakage is higher than 4 percent, there are some periods when gas will be worse for the climate than existing coal plants.

But no matter what the leakage rate is, gas will still cut the climate impact by 50 percent in 2100 compared to new coal and 66 percent compared to existing coal. So whether switching from coal to gas is beneficial in this simple example depends on how you value near-term or longer-term warming.

The importance of near-term warming is tough to assess. Climate models, by and large, don't predict any irreversible changes in periods as short as 30 years and potential tipping points in the climate generally depend more on the peak warming that occurs (which in nearly all foreseeable cases would occur after 2050).

But there is much about the Earth's climate that is still unknown and scientists can't categorically rule out the potential for shorter-term warming to cause unforeseen impacts.

With longer-term warming, the impacts are much more clear (and generally more dire). By the end of the century, we'd expect around 4C warming in a world where we didn't take any action to slow emissions. As the damages of climate change tend to increase exponentially with rising temperatures, many economists argue that the biggest impacts of climate change will occur later in the century and that the main focus should be on reducing longer-term warming.

What About Choosing Neither Coal Nor Natural Gas?

There is yet another wrinkle in the comparison of gas and coal. If they were the only two ways we could generate electricity, the analysis would be fairly straightforward.

But there are many zero or near-zero carbon energy sources that are preferable to both coal and gas, including wind, solar and nuclear power. In a perfect world, we would skip the gas bridge entirely and immediately replace all the coal plants with renewables.

The challenge is that although renewables are increasingly cost competitive with coal in some parts of the country, on average, they are still more expensive. Renewables are also often intermittent, producing less power when the sun doesn't shine or the wind doesn't blow and incurring additional expenses for energy storage technologies to help balance out the grid, at least once renewables reach a high enough percent of generation.

On the other hand, renewables are getting cheaper and although it might not be practical to replace all coal plants with renewables immediately, it's definitely possible to do so in the next decade if renewables continue to fall in price. If we replace coal with gas today, we've sunk costs into new gas infrastructure that we might be loath to replace a few years later with renewables. In this way, a gas bridge could delay the widespread adoption of renewables.

It comes down to this: If we think that coal plants would stick around for 15 years or more in the absence of gas, its probably better to replace them with gas today. If we think we will have the political will to retire gas plants early, we could also potentially benefit from a gas bridge.

But if we end up locking in gas infrastructure that sticks around and delays renewables, we might be better off eschewing a gas bridge even if it means sticking around with coal a bit longer.

It's a tough problem with no simple answers, but the one thing we know for sure is that if natural gas is to serve as a bridge away from coal, it had better be a short one.

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