Sign up for our daily briefing

Make your busy days simpler with the Axios AM and PM newsletters. Catch up on what's new and why it matters in just 5 minutes.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on the day's biggest business stories

Subscribe to the Axios Closer newsletter for insights into the day’s business news and trends and why they matter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sign up for Axios Pro Rata

Dive into the world of dealmakers across VC, PE and M&A with Axios Pro Rata. Delivered daily to your inbox by Dan Primack and Kia Kokalitcheva.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sports news worthy of your time

Binge on the stats and stories that drive the sports world with the Axios Sports newsletter. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Tech news worthy of your time

Get our smart take on technology from the Valley and D.C. with Axios Login. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Get the inside stories

Get an insider's guide to the new White House with Axios Sneak Peek. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Denver news?

Get a daily digest of the most important stories affecting your hometown with Axios Denver

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Des Moines news?

Get a daily digest of the most important stories affecting your hometown with the Axios Des Moines newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Twin Cities news?

Get a daily digest of the most important stories affecting your hometown with Axios Twin Cities

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Tampa Bay news?

Get a daily digest of the most important stories affecting your hometown with the Axios Tampa Bay newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Charlotte news?

Get a daily digest of the most important stories affecting your hometown with Axios Charlotte

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Nashville news?

Get a daily digest of the most important stories affecting your hometown with the Axios Nashville newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Columbus news?

Get a daily digest of the most important stories affecting your hometown with the Axios Columbus newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Dallas news?

Get a daily digest of the most important stories affecting your hometown with the Axios Dallas newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Austin news?

Get a daily digest of the most important stories affecting your hometown with the Axios Austin newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Atlanta news?

Get a daily digest of the most important stories affecting your hometown with the Axios Atlanta newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Philadelphia news?

Get a daily digest of the most important stories affecting your hometown with the Axios Philadelphia newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Chicago news?

Get a daily digest of the most important stories affecting your hometown with the Axios Chicago newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sign up for Axios NW Arkansas

Stay up-to-date on the most important and interesting stories affecting NW Arkansas, authored by local reporters

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top DC news?

Get a daily digest of the most important stories affecting your hometown with the Axios DC newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

California's Fannette Island in at Lake Tahoe, which straddles the border of California and Nevada. Scientists reported last year that climate change has affected the water temperature and its clarity, per CBS News. Photo: George Rose/Getty Images

Oxygen levels in hundreds of freshwater lakes in the U.S. and around the world are plummeting — and climate change is largely to blame, according to a study published Wednesday.

Why it matters: Per a statement from study co-author Kevin Rose, a professor of biology at Rensselaer Polytechnic Institute: "All complex life depends on oxygen. ... when you start losing oxygen, you have the potential to lose species."

Driving the news: The study published in the journal Nature, analyzed temperature and dissolved oxygen — a measure of how much oxygen is in water — in almost 400 lakes across the temperate zone, mostly in the U.S. and Europe. Several lakes in New Zealand and one in Japan were also examined.

  • "Warmer surface water temperatures caused by climate change reduce oxygen levels due to lower solubility of oxygen in warmer water," said Rose in an email to Axios Wednesday night.

What they found: The researchers discovered that since 1980, oxygen levels have dropped 5.5% at the surface and 18.6% in deep waters. The fall is 2.75 to 9.3 times faster than the world's oceans.

  • Warming temperatures are leading to widespread losses in dissolved oxygen across the studied lakes, linked to climate change and human activity.
  • Some lakes saw increasing dissolved oxygen concentrations and warming temperatures, caused by pollution such as agricultural runoff.

Between the lines: "When there is no oxygen in deep waters, methane is produced, which is a greenhouse gas that is about 23 times as powerful as carbon dioxide," Rose noted to Axios.

  • A lack of oxygen in deeper waters "permits nutrients to come out of the nutrient-rich sediments, increasing algal growth, and potentially contributing to harmful algal blooms of toxic cyanobacteria," Rose added.

Our thought bubble, via Axios' Andrew Freedman: Just as global warming is fundamentally altering marine ecosystems, making ocean waters more acidic, increasing temperatures, and altering ocean currents, it's now clear that sweeping changes are happening in water bodies on land.

  • At risk are ecosystems long dependent on a particular temperature and oxygen structure within a lake. In other words, fish and other marine creatures are facing challenges wherever scientists look.

Of note: Researchers have previously documented dissolved oxygen losses in lakes over a sustained period, but "none" have surveyed so many lakes around the globe, noted Samuel Fey, a Reed College biology professor who studies lakes and wasn't involved in this study, to AP.

The bottom line: Rose told Axios that low oxygen can lead to fish kills, and cold-water fish are particularly sensitive.

  • "This is a particularly severe problem in regions where local populations depend on fish as a primary source of protein," he said.

Editor's note: This article has been updated with comment from Rose.

Go deeper

May 31, 2021 - World

Study: Climate change directly linked to over a third of global heat deaths

An elderly woman suffering from a heatstroke in a hospital in Karachi, Pakistan in 2015. Photo: Sabir Mazhar/Anadolu Agency/Getty Images

More than one-third of heat deaths each year can be directly linked to climate change, according to a study published Monday in the journal Nature Climate Change.

Why it matters: The findings require global actors to take "more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change," the study said.

Updated 2 hours ago - Economy & Business

Tax season nightmare ahead for understaffed IRS

Illustration: Shoshana Gordon/Axios

The IRS will start accepting 2021 tax returns in less than a week, and the filing delays and administrative headaches to come might eclipse last year — which was “one of the worst filing seasons," according to an independent advocacy agency within the IRS.

Why it matters: For taxpayers, especially with complex or paper filings, this means headaches, delayed refunds, and mistakes.

China builds its own movie empire

Expand chart
Data: Gower Street citing Comscore; Chart: Kavya Beheraj/Axios

China blocked all four of Disney's Marvel movies from being released in its theaters last year, a grim sign for U.S. film giants being squeezed out of the world's fastest-growing box office.

Why it matters: The Chinese Communist Party is using domestic films as a key conduit for mass messaging aimed at achieving political goals, leaving little room for foreign views.

You’ve caught up. Now what?

Sign up for Mike Allen’s daily Axios AM and PM newsletters to get smarter, faster on the news that matters.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!