Global warming

After two years of intense public debate, the U.S. Securities and Exchange Commission approved the nation’s first national climate disclosure rules on March 6, 2024, setting out requirements for publicly listed companies to report their climate-related risks and in some cases their greenhouse gas emissions. The new rules are much weaker than those originally proposed. Significantly, the SEC dropped a controversial plan to require companies to report Scope 3 emissions – emissions generated throughout the company’s supply chain and customers’ use of its products. The rules do require larger companies to disclose Scope 1 and 2 emissions, which are emissions from their operations and energy use. But those disclosures are required only to the extent that the company believes the information would be financially “material” to a reasonable investor’s decision making. More broadly, the new rules require publicly listed companies to disclose cli...

When people talk about the “Anthropocene,” they typically picture the vast impact human societies are having on the planet, from rapid declines in biodiversity to increases in Earth’s temperature by burning fossil fuels. Such massive planetary changes did not begin all at once at any single place or time. That’s why it was controversial when, after over a decade of study and debate, an international committee of scientists – the Anthropocene Working Group – proposed to mark the Anthropocene as an epoch in the geologic time scale starting precisely in 1952. The marker was radioactive fallout from hydrogen bomb tests. On March 4, 2024, the commission responsible for recognizing time units within our most recent period of geologic time – the Subcommission on Quarternary Stratigraphy – rejected that proposal, with 12 of 18 members voting no. These are the scientists most expert at reconstructing Earth’s history from the evidence...

As the Arctic warms, its mighty rivers are changing in ways that could have vast consequences – not only for the Arctic region but for the world. Rivers represent the land branch of the earth’s hydrological cycle. As rain and snow fall, rivers transport freshwater runoff along with dissolved organic and particulate materials, including carbon, to coastal areas. With the Arctic now warming nearly four times faster than the rest of the world, the region is seeing more precipitation and the permafrost is thawing, leading to stronger river flows. Major river basins of the Arctic region. NOAA Arctic Report Card We’re climate scientists who study how warming is influencing the water cycle and ecosystems. In a new study using historical data and sophisticated computer models of Earth’s climate and hydrology, we explored how climate change is altering Arctic rivers. We found that th...

Superstorms, abrupt climate shifts and New York City frozen in ice. That’s how the blockbuster Hollywood movie “The Day After Tomorrow” depicted an abrupt shutdown of the Atlantic Ocean’s circulation and the catastrophic consequences. While Hollywood’s vision was over the top, the 2004 movie raised a serious question: If global warming shuts down the Atlantic Meridional Overturning Circulation, which is crucial for carrying heat from the tropics to the northern latitudes, how abrupt and severe would the climate changes be? Twenty years after the movie’s release, we know a lot more about the Atlantic Ocean’s circulation. Instruments deployed in the ocean starting in 2004 show that the Atlantic Ocean circulation has observably slowed over the past two decades, possibly to its weakest state in almost a millennium. Studies also suggest that the circulation has reached a dangerous tipping point in the past that sent it into a precipitous, uns...

Central Appalachia is home to the third-largest concentration of forest carbon offsets traded on the California carbon market. But while these projects bring new investments to Appalachia, most people in Appalachia are not benefiting. The effect of this new economic activity is evident in the Clearfork Valley, a forested region of steep hills and meandering creeks on the Kentucky-Tennessee border. Rural communities here once relied on coal mining jobs. As the mines shut down, with the last closing in 2022, the valley was left with thousands of acres of forests and strip-mined land but fewer ways to make a good living. Today, corporate landowners and investment funds have placed most of that forest land into carbon offset projects – valuing the trees for their ability to absorb carbon dioxide emissions to help protect the climate. These carbon offset projects can be lucrative for the landowner, with proceeds that can run into the millions of dollars. Companies subject...