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Smoke and steam rise from a coal-fired power plant in Germany. Photo: Oliver Berg/picture alliance via Getty Images

The concentration of carbon dioxide, the main, long-lived greenhouse gas causing global climate change, in Earth's atmosphere has reached new heights, according to scientists at Scripps Institution of Oceanography.

Why it matters: The new reading of 415.26 parts per million (ppm) on May 11 was the first daily baseline at Hawaii's Mauna Loa Observatory to eclipse 415 ppm. That observatory has kept long-term record of carbon dioxide in the atmosphere since 1958. That data, known as the Keeling Curve, traces the continuous increase in the amount of this greenhouse gas in the Earth's atmosphere since the Industrial Revolution.

  • Other observatories around the world also track this increase, which mainly results from burning fossil fuels, deforestation and other human activities. Studies of so-called proxy records detailing the composition of the atmosphere throughout Earth's history show that carbon dioxide levels are now at their highest point in at least 800,000 — and possibly as many as 3 million — years.

Details: The daily carbon dioxide milestone is largely symbolic, as peaks tend to occur in the Northern Hemisphere each spring. Scientists pay more attention to longer-term trends, rather than the daily data.

  • "The average growth rate is remaining on the high end," says Ralph Keeling, director of Scripps Institution of Oceanography's CO2 program, via Twitter. Keeling's father, Charles, began the original CO2 observations in Hawaii.
  • "The increase from last year will probably be around three parts per million whereas the recent average has been 2.5 ppm," Keeling said.

The big picture: Scientists have warned that if the world is to limit global warming to 1.5°C, or 2.7°F, above pre-industrial levels, then sharp emissions cuts have to begin in the next few years, with the world headed for negative emissions — meaning more carbon dioxide is removed by the planet's oceans, forests and other systems — than is emitted by the end of the century.

  • Otherwise Earth will see carbon dioxide concentrations exceeding 450 ppm, which will yield larger increases in global sea levels than we've seen so far, along with increasingly severe extreme weather events, such as heat waves and heavy precipitation events.

What's next: Scientists from Scripps and the National Oceanic and Atmospheric Administration will likely announce a new carbon dioxide monthly record in early June. A new annual figure will come out in early 2020.

Go deeper: Global carbon dioxide emissions reached record high in 2018

Go deeper

32 mins ago - World

In photos: Global protests over Israeli–Palestinian conflict

A protest march in support of Palestinians near the Washington monument in Washington, D.C. on May 15. Photo: Andrew Caballero-Reynolds/AFP via Getty Images

Thousands of people rallied across the U.S. and the world Saturday following days of violence in Gaza and Israel that's killed at least 145 Palestinians, including 41 children, and eight Israelis, per AP.

The big picture: Most demonstrations were in support of Palestinians. There were tense scenes between pro-Israeli government protesters and pro-Palestinian demonstrators in Winnipeg, Canada, and Leipzig, Germany, but no arrests were made, CBS News and DW.com report.

Updated 8 hours ago - World

Biden in call with Netanyahu raises concerns about civilian casualties in Gaza

Photo: Ahmad Gharabli/Nicholas Kamm/Getty Images

President Biden spoke to Israeli Prime Minister Benjamin Netanyahu Saturday and raised concerns about civilian casualties in Gaza and the bombing of the building that housed AP and other media offices, according to Israeli officials.

The big picture: At least 140 Palestinians, including dozens of children, have been killed in Gaza since fighting between Israel and Hamas began Monday, according to Palestinian health officials. Nine people, including two children, have been killed by Hamas rockets in Israel.

Updated 9 hours ago - Politics & Policy

"Horrified": AP, Al Jazeera condemn Israel's bombing of their offices in Gaza

A ball of fire erupts from the Jalaa Tower as it is destroyed in an Israeli airstrike in Gaza. Photo: Majdi Fathi/NurPhoto via Getty Images

The Associated Press and Al Jazeera on Saturday condemned the Israeli airstrike that destroyed a high-rise building in Gaza that housed their and other media offices.

What they're saying: The White House, meanwhile, said it had "communicated directly to the Israelis that ensuring the safety and security of journalists and independent media is a paramount responsibility," according to press secretary Jen Psaki.