Sep 29, 2017

Disturbed rainforests release more carbon dioxide than they absorb

Deforestation in the Amazon. Photo: Marcelo Horn / iStock

Tropical rainforests are known for their greenhouse gas gobbling abilities, but human impacts may have changed that. According to a study published Thursday in Science, tropical rainforests may be emitting more CO2 than they soak up.

"Much of that carbon contribution is due to deforestation … but more than two-thirds comes from a less visible source: a decline in the number and diversity of trees in remaining forests," writes Carolyn Gramling for Science News.

Yes, but: NASA scientist Joshua Fisher told Science News that this study only looked at above-ground carbon. Much CO2 is absorbed by rainforest soils, and atmospheric data still indicates that rainforests are net carbon absorbers, not emitters.

What they did: The researchers developed an algorithm that allowed them to measure the carbon density of forests from satellite images, taken yearly from 2003-2014.

What they found: According to the study, rainforests emit 862 tetragrams of carbon a year, but only absorb 436 tetragrams/year.

Go deeper:

  • Forest destruction emits more carbon than trucks and cars, says Reuters.
  • "This shows that we can't just sit back. The forest is not doing what we thought it was doing," study author Alessandro Baccini told the Guardian. He adds that when it comes to reducing carbon, fixing forests is "low-hanging fruit. We know how to protect and sustain forests. It's relatively cost effective"

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Older candidates take the lead on social media

Illustration: Eniola Odetunde/Axios

Michael Bloomberg, Bernie Sanders and Joe Biden — all close to 80 — are pushing the boundaries on social media, while their younger Democratic presidential rivals are comparatively staying out of the fray.

The big picture: President Trump's unexpected rise to political power has shown Democrats and world leaders the power of harnessing popular internet culture to get elected.

South Korea and Italy step up emergency measures as coronavirus cases jump

Data: The Center for Systems Science and Engineering at Johns Hopkins, the CDC, and China's Health Ministry. Note: China numbers are for the mainland only and U.S. numbers include repatriated citizens.

The novel coronavirus has spread to more nations as South Korea and Italy step up emergency measures in their countries amid rising case numbers on Sunday.

The big picture: COVID-19 has killed at least 2,462 people and infected almost 79,000 others, mostly in mainland China. South Korea increased the infectious disease alert to red, the highest possible, as its case numbers jumped to 602 and the death toll to five. Italy's government announced emergency measures, with several towns in the north effectively placed in lockdown, as it confirmed two deaths and infections rose to 79.

Go deeperArrowUpdated 4 hours ago - Health

Bernie Sanders wins Nevada caucus

Democratic presidential candidate Sen. Bernie Sanders waves to supporters at a campaign rally on Friday in Las Vegas. Photo: Mario Tama/Getty Images

Sen. Bernie Sanders is projected to handily win the Nevada Democratic primary caucus, becoming the clear frontrunner among 2020 Democratic presidential primary election candidates.

Why it matters: Nevada is the first state with a diverse population to hold a nominating contest, highlighting candidates' abilities to connect with voters of color — particularly Latino voters.

Go deeperArrowUpdated 4 hours ago - Politics & Policy