Scientists have picked the bottom of Crawford Lake in Ontario as the “golden spike” to mark the start of a new proposed geological epoch — the Anthropocene. The announcement was made at a media conference in Berlin Tuesday by a group of scientists called the Anthropocene Working Group — more on them later.
Here’s why the lake was chosen and what evidence it provides that humans have made such big changes to the Earth that we may be in a new geologic time period.
Crawford Lake is unusually deep compared to its surface area. That gives it qualities that help it preserve climatic, ecological and environmental records. (Cole Burston/The Canadian Press)
What’s an epoch? And why are scientists proposing a new one called the Anthropocene?
Geologists measure the history of the Earth using the geologic time scale (its official name is the International Chronostratigraphic Chart) — kind of like a calendar, except that it’s divided into much bigger divisions than days, weeks or months.
For example, “periods” like the Jurassic and Cretaceous are tens of millions of years long and divided into epochs that are typically millions of years long.
Until now, our current epoch has been the Holocene, which started at the end of the last ice age 11,700 years ago.
But in many fields, including science, researchers and thinkers had already been discussing the huge impact humans have had on the Earth — including mass extinction and climate change, the kind of changes that typically mark the start and end of epochs.
About two decades ago, Nobel prizing winning chemist Paul Crutzen popularized the idea that science should recognize that impact with a new geological epoch, the Anthropocene, Prof. Jürgen Renn,director at the Max Planck Institute for the History of Science in Berlin, said at a news briefing about the new announcement.
“He said, ‘You know, we cannot say with all these changes that we are living still in the Holocene,'” Renn said. “It’s not just about climate change. It’s not just biodiversity loss. It’s not just the sediments that humans are moving. It’s all of this together.”
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He added that much of the ongoing change is effectively irreversible, such as the melting of glaciers around the world: “These changes that we have induced already will only unfold in the next decades and centuries.”
The International Commission on Stratigraphy, a group of geologists within the International Union of Geological Sciences, is the scientific body that officially decides when epochs begin and end. In 2009, it asked a group of geologists, paleontologists and other scientists, the Anthropocene Working Group, to look into whether there was enough scientific evidence to back up Crutzen’s proposal of a new epoch.
One of the group’s key jobs has been to identify and describe a “golden spike” marking the start of the new proposed epoch.
Crawford Lake was chosen among 12 “golden spike” candidates around the world after a series of votes by the Anthropocene Working Group.
People look out on the water from the shore of Crawford Lake in Milton, Ont., on Friday, July 7, 2023. Scientists have picked the Canadian lake as the ‘golden spike’ to mark the start of a new proposed epoch, the Anthropocene. (Cole Burston/The Canadian Press)
What exactly is a ‘golden spike?’
A “golden spike” is the ideal marker showing where one epoch ends and another begins — typically at a major global event such as a mass extinction or climatic shift. Such events are generally visible in the form of layered evidence like changing fossils in rock deposited over time.
Layers in the sediment core from Crawford Lake show a distinct white layer in 1935 from dust storms during the Great Depression and accompanying droughts. The 1950 layer contains plutonium and is proposed as the start of the Anthropocene epoch. (Krysten Serack-Lafond)
As you might guess, “golden spike” is actually a nickname for a more technical scientific term: global boundary stratotype section and point (GSSP).
Thesection is the series of layers (also called “strata”, which is what makes it a “stratotype” section) where there’s physical evidence of the big event (the point) that marks the end of one epoch and the start of the next.
It’s chosen as a reference that can be used to compare evidence of that event in other parts of the world.
Where is Crawford Lake and what’s so special about it?
Crawford Lake is a relatively small lake about 60 kilometres west of Toronto. The lake is inside a conservation area that shares its name outside the town of Milton. It’s on the Niagara Escarpment, which is made of limestone rock. The rock forms a bowl that holds the lake.
The park has hiking trails, as well as a reconstructed 15th-century longhouse village. Archaeological excavations show several hundred Attawonderon or Wendat people lived near the lakeshore from the 13th to 15th centuries.
The park surrounding Crawford Lake has hiking trails, as well as a reconstructed 15th-century longhouse village. Archaeological excavations show several hundred Attawonderon or Wendat people lived near the lakeshore from the 13th to 15th centuries. (Turgut Yeter/CBC)
The lake itself is less than 300 metres across at its widest point, but very deep for its size — 24 metres, meaning a seven- or eight-storey building sitting on the lake bottom would just barely break the surface.
Because of that, Crawford Lake is meromictic — that is, it’s a rare type of lake where the bottom layer of water doesn’t mix with upper layers.
Francine McCarthy, an earth sciences professor at Brock University in St. Catharines, Ont., who has been studying the lake, said that means the bottom of the lake is “completely isolated from the rest of the planet, except for what gently sinks to the bottom and accumulates in sediment.”
There is also some handy chemistry happening in the water. Remember how it’s surrounded by limestone? The rock contains calcium and carbonate that dissolve in the water, but crystallize out in the surface waters when it gets warm — how much depends on that year’s climate. The crystals fall down as white layers that mark each summer like tree rings, covering the pollen, dead microorganisms, pollution particles and other debris that accumulate the rest of the year.
Together they provide a record of the climate, environmental and ecological conditions each year. Because the shores of Crawford Lake were inhabited by humans hundreds of years ago, it also allowed scientists to compare human impacts then and now.
McCarthy and her team have drilled cylinders called sediment cores out of the bottom of the lake that preserve the annual layers so that they can be examined and tested in the lab.
Francine McCarthy from Brock University points at the layer of sediment in a Crawford Lake mud core that shows the global plutonium spike from nuclear weapons testing that marks the beginning of the proposed Anthropocene epoch. (Mercury Films Inc./Nick de Pencier)
What’s the global event that’s been proposed to mark the start of the Anthropocene?
Originally, Crutzen had proposed the Industrial Revolution of the 19th century as the start of the Anthropocene.
But it turns out scientific evidence of the Industrial Revolution from that time is mostly only seen in Europe and not other parts of the world, said Colin Waters, honorary professor of geography, geology and the environment at the University of Leicester in the U.K. and chair of the Anthropocene Working Group.
Because of that, scientists began proposing that the start of the Anthropocene should be marked by evidence of nuclear weapons tests in the 1950s, such as radioactive plutonium, which is detectable worldwide.
“It’s a very clear marker,” Waters said.
But it also coincides with increased burning of fossil fuels, use of industrial fertilizers and other human impacts that leave a clear scientific signal — together called “The Great Acceleration” by environmental historian John McNeill.
And so radioactive plutonium has been chosen as the marker for the start of the Anthropocene in the Crawford Lake sediment core.
Samples from each year in the Crawford Lake sediment core sit in a tray, ready to be tested for plutonium. (University of Southampton)
Why is the Anthropocene epoch controversial?
Members of the Anthropocene Working Group themselves acknowledge that this isn’t a typical geological division.
Typically, layers of rock and often fossils are used as markers between different periods of time, but in this case, rock hasn’t had time to be deposited.
Renn said the “geology of the present” is a new challenge. “That’s very, very unusual.”
It’s not only that rocks haven’t had time to form, but also the materials and signals being measured and referenced, such as plutonium and microplastics, are very new and different from those of the past.
The mushroom cloud of the first test of a hydrogen bomb, Ivy Mike, looms over the Pacific Ocean in 1952. The plutonium is detectable all over the world, but isn’t one of the usual materials referenced in the geologic time scale. (Reuters)
But some researchers argue it’s just too soon to call this a new epoch.
John-Paul Zonneveld, a professor at the University of Alberta and a member of the North American Commission on Stratigraphic Nomenclature, acknowledged that humans have made big changes and left their permanent mark all over the Earth, but he said he feels “we’re in the middle of the event. We’re not in the new time stage yet.”
Joseph Deloges, a professor of geography and earth sciences at the University of Toronto who hasn’t been involved with the Anthropocene Working Group, has a similar perspective, and says it’s a challenge.
“Whatever you try and define in terms of the Anthropocene means it’s changing as you go along. And so some would argue that’s not what the nomenclature is set up for,” he said.
He added that while climate change has been quite dramatic, it may not yet match the scale events like asteroid impacts that have ushered in some other new time periods on the geologic timescale: “Some would argue we’re not quite there yet in terms of the catastrophe.”
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The Anthropocene is still just a proposal. What needs to happen for it to become an actual epoch?
The Anthropocene Working Group still needs to come up with an “auxiliary” GSSP out of eight other sites. Then the proposal needs to pass three more votes with a “supermajority” of more than 60 per cent, including one at the International Commission on Stratigraphy and a final one from the International Union of Geological Sciences.
“It’s a very conservative process, you know,” said Waters, “and probably there’s good reason for that because you don’t want to establish the formalization of the unit if it’s not grounded on very strong evidence.”
He added that it’s also possible that the geological community will decide that the Anthropocene is simply a new stage within the Holocene epoch (after the Meghalayan, which started 4,200 years ago), and not a new epoch in itself.
In any case, the Anthropocene Working Group hopes a decision will be made in time for the International Geological Congress in Busan, Korea, in August 2024.
PHOENIX (AP) — Arizona voters have approved a constitutional amendment guaranteeing abortion access up to fetal viability, typically after 21 weeks — a major win for advocates of the measure in the presidential battleground state who have been seeking to expand access beyond the current 15-week limit.
Arizona was one of nine states with abortion on the ballot. Democrats have centered abortion rights in their campaigns since the U.S. Supreme Court overturned Roe v. Wade in 2022. Abortion-rights supporters prevailed in all seven abortion ballot questions in 2022 and 2023, including in conservative-leaning states.
Arizona for Abortion Access, the coalition leading the state campaign, gathered well over the 383,923 signatures required to put it on the ballot, and the secretary of state’s office verified that enough were valid. The coalition far outpaced the opposition campaign, It Goes Too Far, in fundraising. The opposing campaign argued the measure was too far-reaching and cited its own polling in saying a majority of Arizonans support the 15-week limit. The measure allows post-viability abortions if they are necessary to protect the life or physical or mental health of the mother.
Access to abortion has been a cloudy issue in Arizona. In April, the state Supreme Court cleared the way for the enforcement of a long-dormant 1864 law banning nearly all abortions. The state Legislature swiftly repealed it.
Voters in Arizona are divided on abortion. Maddy Pennell, a junior at Arizona State University, said the possibility of a near-total abortion ban made her “depressed” and strengthened her desire to vote for the abortion ballot measure.
“I feel very strongly about having access to abortion,” she said.
Kyle Lee, an independent Arizona voter, does not support the abortion ballot measure.
“All abortion is pretty much, in my opinion, murder from beginning to end,” Lee said.
The Civil War-era ban also shaped the contours of tight legislative races. State Sen. Shawnna Bolick and state Rep. Matt Gress are among the handful of vulnerable Republican incumbents in competitive districts who crossed party lines to give the repeal vote the final push — a vote that will be tested as both parties vie for control of the narrowly GOP-held state Legislature.
Both of the Phoenix-area lawmakers were rebuked by some of their Republican colleagues for siding with Democrats. Gress made a motion on the House floor to initiate the repeal of the 1864 law. Bolick, explaining her repeal vote to her Senate colleagues, gave a 20-minute floor speech describing her three difficult pregnancies.
While Gress was first elected to his seat in 2022, Bolick is facing voters for the first time. She was appointed by the Maricopa County Board of Supervisors to fill a seat vacancy in 2023. She has not emphasized her role in the repeal vote as she has campaigned, instead playing up traditional conservative issues — one of her signs reads “Bolick Backs the Blue.”
Voters rejected a measure to eliminate retention elections for state Superior Court judges and Supreme Court justices.
The measure was put on the ballot by Republican legislators hoping to protect two conservative justices up for a routine retention vote who favored allowing the Civil War-era ban to be enforced — Shawnna Bolick’s husband, Supreme Court Justice Clint Bolick, and Justice Kathryn Hackett King. Since the measure did not pass, both are still vulnerable to voter ouster, though those races hadn’t been decided by early Wednesday morning.
Under the existing system, voters decide every four to six years whether judges and justices should remain on the bench. The proposed measure would have allowed the judges and justices to stay on the bench without a popular vote unless one is triggered by felony convictions, crimes involving fraud and dishonesty, personal bankruptcy or mortgage foreclosure.
OMAHA, Neb. (AP) — Nebraska voters supported a measure Tuesday that enshrines the state’s current ban on abortions after the 12th week of pregnancy in the state constitution, and they rejected a competing measure that sought to expand abortion rights. Nebraska was the first state to have competing abortion amendments on the same ballot since the U.S. Supreme Court overturned Roe v. Wade in 2022, ending the nationwide right to abortion and allowing states to decide for themselves. The dueling measures were among a record number of petition-initiated measures on Nebraska’s ballot Tuesday.
What were the competing abortion measures?
A majority of voters supported a measure enshrining the state’s current ban on abortion after the first 12 weeks of pregnancy in the state constitution. The measure will also allow for further restrictions. Last year, the Legislature passed the 12-week ban, which includes exceptions for cases of rape and incest and to protect the life of the pregnant woman.
Voters rejected the other abortion measure. If they had passed it by a larger number of “for” votes than the 12-week measure, it would have amended the constitution to guarantee the right to have an abortion until viability — the standard under Roe that is the point at which a fetus might survive outside the womb. Some babies can survive with medical help after 21 weeks of gestation.
Abortion was on the ballot in several other states, as well. Coming into the election, voters in all seven states that had decided on abortion-related ballot measures since the reversal of Roe had favored abortion rights, including in some conservative states.
Who is behind the Nebraska abortion measures?
The 12-week ban measure was bankrolled by some of Nebraska’s wealthiest people, including Republican Sen. Pete Ricketts, who previously served as governor and donated more than $1.1 million. His mother, Marlene Ricketts, gave $4 million to the cause. Members of the Peed family, which owns publishing company Sandhills Global, also gave $1 million.
The effort was organized under the name Protect Women and Children and was heavily backed by religious organizations, including the Nebraska Catholic Conference, a lobbying group that has organized rallies, phone banks and community townhalls to drum up support for the measure.
The effort to enshrine viability as the standard was called Protect Our Rights Nebraska and had the backing of several medical, advocacy and social justice groups. Planned Parenthood donated nearly $1 million to the cause, with the American Civil Liberties Union, I Be Black Girl, Nebraska Appleseed and the Women’s Fund of Omaha also contributing significantly to the roughly $3.7 million raised by Protect Our Rights.
What other initiatives were on Nebraska’s ballot?
Nebraska voters approved two measures Tuesday that will create a system for the use and manufacture of medical marijuana, if the measures survive an ongoing legal challenge.
The measures legalize the possession and use of medical marijuana, and allow for the manufacture, distribution and delivery of the drug. One would let patients and caregivers possess up to 5 ounces (142 grams) of marijuana if recommended by a doctor. The other would create the Nebraska Medical Cannabis Commission, which would oversee the private groups that would manufacture and dispense the drug.
Those initiatives were challenged over allegations that the petition campaign that put them on the ballot broke election rules. Nebraska’s attorney general said supporters of the measures may have submitted several thousand invalid signatures, and one man has been charged in connection with 164 allegedly fraudulent signatures. That means a judge could still invalidate the measures.
Voters also opted Tuesday to repeal a new conservative-backed law that allocates millions of dollars in taxpayer money to fund private school tuition.
Finally, they approved a measure that will require all Nebraska employers to provide at least 40 hours of paid sick leave to their employees.
WASHINGTON (AP) — Voters in Missouri cleared the way to undo one of the nation’s most restrictive abortion bans in one of seven victories for abortion rights advocates, while Florida, Nebraska and South Dakota defeated similar constitutional amendments, leaving bans in place.
Abortion rights amendments also passed in Arizona, Colorado, Maryland and Montana. Nevada voters also approved an amendment, but they’ll need to pass it again it 2026 for it to take effect. Another that bans discrimination on the basis of “pregnancy outcomes” prevailed in New York.
The results include firsts for the abortion landscape, which underwent a seismic shift in 2022 when the U.S. Supreme Court overturned Roe v. Wade, a ruling that ended a nationwide right to abortion and cleared the way for bans to take effect in most Republican-controlled states.
They also came in the same election that Republican Donald Trump won the presidency. Among his inconsistent positions on abortion has been an insistence that it’s an issue best left to the states. Still, the president can have a major impact on abortion policy through executive action.
In the meantime, Missouri is positioned to be the first state where a vote will undo a ban on abortion at all stages of pregnancy, with an amendment that would allow lawmakers to restrict abortions only past the point of a fetus’ viability — usually considered after 21 weeks, although there’s no exact defined time frame.
But the ban, and other restrictive laws, are not automatically repealed. Advocates now have to ask courts to overturn laws to square with the new amendment.
“Today, Missourians made history and sent a clear message: decisions around pregnancy, including abortion, birth control, and miscarriage care are personal and private and should be left up to patients and their families, not politicians,” Rachel Sweet, campaign manager of Missourians for Constitutional Freedom, said in a statement.
Roughly half of Missouri’s voters said abortion should be legal in all or most cases, according to AP VoteCast, a survey of more than 2,200 of the state’s voters. But only about 1 in 10 said abortion should be illegal in all cases; nearly 4 in 10 said abortion should be illegal in most cases.
Bans remain in place in three states after votes
Florida, Nebraska and South Dakota became the first states since Roe was overturned where abortion opponents prevailed on a ballot measure. Most voters supported the Florida measure, but it fell short of the required 60% to pass constitutional amendments in the state. Most states require a simple majority.
The result was a political win for Gov. Ron DeSantis, a Republican with a national profile, who had steered state GOP funds to the cause. His administration has weighed in, too, with a campaign against the measure, investigators questioning people who signed petitions to add it to the ballot and threats to TV stations that aired one commercial supporting it.
Marjorie Dannenfelser, president of the national anti-abortion group SBA Pro-Life America, said in a statement that the result is “a momentous victory for life in Florida and for our entire country,” praising DeSantis for leading the charge against the measure.
The defeat makes permanent a shift in the Southern abortion landscape that began when the state’s six-week ban took effect in May. That removed Florida as a destination for abortion for many women from nearby states with deeper bans and also led to far more women from the state traveling to obtain abortion. The nearest states with looser restrictions are North Carolina and Virginia — hundreds of miles away.
“The reality is because of Florida’s constitution a minority of Florida voters have decided Amendment 4 will not be adopted,” said Lauren Brenzel, campaign director for the Yes on 4 Campaign said while wiping away tears. “The reality is a majority of Floridians just voted to end Florida’s abortion ban.”
In South Dakota, another state with a ban on abortion throughout pregnancy with some exceptions, the defeat of an abortion measure was more decisive. It would have allowed some regulations related to the health of the woman after 12 weeks. Because of that wrinkle, most national abortion-rights groups did not support it.
Voters in Nebraska adopted a measure that allows more abortion restrictions and enshrines the state’s current 12-week ban and rejected a competing measure that would have ensured abortion rights.
Other states guaranteed abortion rights
Arizona’s amendment will mean replacing the current law that bans abortion after the first 15 weeks of pregnancy. The new measure ensures abortion access until viability. A ballot measure there gained momentum after a state Supreme Court ruling in April found that the state could enforce a strict abortion ban adopted in 1864. Some GOP lawmakers joined with Democrats to repeal the law before it could be enforced.
In Maryland, the abortion rights amendment is a legal change that won’t make an immediate difference to abortion access in a state that already allows it.
It’s a similar situation in Montana, where abortion is already legal until viability.
The Colorado measure exceeded the 55% of support required to pass. Besides enshrining access, it also undoes an earlier amendment that barred using state and local government funding for abortion, opening the possibility of state Medicaid and government employee insurance plans covering care.
A New York equal rights law that abortion rights group say will bolster abortion rights also passed. It doesn’t contain the word “abortion” but rather bans discrimination on the basis of “pregnancy outcomes, and reproductive healthcare and autonomy.” Sasha Ahuja, campaign director of New Yorkers for Equal Rights, called the result “a monumental victory for all New Yorkers” and a vote against opponents who she says used misleading parental rights and anti-trans messages to thwart the measure.
The results end a win streak for abortion-rights advocates
Until Tuesday, abortion rights advocates had prevailed on all seven measures that have appeared on statewide ballots since the fall of Roe.
The abortion rights campaigns have a big fundraising advantage this year. Their opponents’ efforts are focused on portraying the amendments as too extreme rather than abortion as immoral.
Currently, 13 states are enforcing bans at all stages of pregnancy, with some exceptions. Four more bar abortion in most cases after about six weeks of pregnancy — before women often realize they’re pregnant. Despite the bans, the number of monthly abortions in the U.S. has risen slightly, because of the growing use of abortion pills and organized efforts to help women travel for abortion. Still, advocates say the bans have reduced access, especially for lower-income and minority residents of the states with bans.
The issue is resonating with voters. About one-fourth said abortion policy was the single most important factor for their vote, according to AP VoteCast, a sweeping survey of more than 110,000 voters nationwide. Close to half said it was an important factor, but not the most important. Just over 1 in 10 said it was a minor factor.
The outcomes of ballot initiatives that sought to overturn strict abortion bans in Florida and Missouri were very important to a majority of voters in the states. More than half of Florida voters identified the result of the amendment as very important, while roughly 6 in 10 of Missouri’s voters said the same, the survey found.
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Associated Press reporters Hannah Fingerhut and Amanda Seitz contributed to this article.
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This article has been corrected to reflect in the ‘other states’ section that Montana, not Missouri, currently allows abortion until viability.
