Tarmo Virtanen, University of Helsinki

Scientists have long predicted that rapidly warming temperatures in the Arctic could unleash huge amounts of carbon trapped beneath the permafrost. It's one of the tipping points in Earth's climate system that scientists are tracking closely. Now, researchers say thawing in the Arctic could also release significant amounts of nitrous oxide, an even more powerful greenhouse gas trapped below the permafrost, a new study finds.

Why it matters: Nitrous oxide is about 300 times more effective at trapping heat than carbon dioxide. But, despite the fact that more than 67 billion tons of nitrogen are stored in the Arctic permafrost, nearly all of the research on the impacts in the Arctic have focused on carbon releases. Vegetation and water can decrease the amount of nitrous oxide released to varying degrees, but this new study shows that up to a quarter of the Arctic could see significant releases of the gas along with carbon dioxide.

How they did it: Finnish scientists collected 16 samples of peat from Finland's Lapland region and slowly warmed them from underneath to simulate thawing in the lab.

The results: There was a fivefold increase in nitrous oxide emissions from samples of bare peat compared to the amount released when only the surface thaws, which happens seasonally. When plants or lichen were growing on top of a sample, emissions decreased by 90% and they were entirely suppressed in wet samples.

Go deeper

Scoop: Instacart raises another $100 million

Illustration: Sarah Grillo/Axios Visuals

Grocery delivery company Instacart has raised $100 million in new funding, on top of the $225 million it announced last month, the company tells Axios. This brings its valuation to $13.8 billion.

Why it matters: This funding comes at what could be an inflection point for Instacart, as customers it acquired during coronavirus lockdowns decide whether they want to continue with the service or resume in-person grocery shopping.

Updated 42 mins ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 10 a.m. ET: 10,902,347 — Total deaths: 521,940 — Total recoveries — 5,777,662Map.
  2. U.S.: Total confirmed cases as of 10 a.m. ET: 2,739,879 — Total deaths: 128,740 — Total recoveries: 781,970 — Total tested: 33,462,181Map.
  3. Public health: The states where face coverings are mandatory Regeneron stops trial after drug fails to help patientsWhat we know about the coronavirus immune response — Fauci says it has been a "very disturbing week" for the spread of the coronavirus in the U.S.
  4. Business: Top business leaders urge the White House to develop mandatory mask guidelines.
  5. Politics: Herman Cain hospitalized for COVID-19 after attending Trump Tulsa rally — Biden downplays jobs number, rebukes Trump for ignoring health crisis.
  6. Economy: The economy may recover just quickly enough to kill political interest in more stimulus.
  7. States: Texas mandates face masks in public spaces Florida reports more than 10,000 new coronavirus cases, and its most-infected county issues curfew.

Markets swell as the economy shrinks

Illustration: Eniola Odetunde/Axios

The economy is sputtering, but the markets are thriving — a highly unusual event that shows how the coronavirus has thrown all bets off.

Why it matters: The disconnect adds to the wealth gap. The richest 10% of households — who own 84% of stocks — are getting richer, while millions of out-of-work Americans cross their fingers that pandemic unemployment benefits will be extended.