Illustration: Sarah Grillo/Axios

A new study concludes that rising temperatures have trimmed rural-to-urban migration within very poor nations while slightly increasing it in middle-income countries.

Why it matters: The analysis, released via the National Bureau of Economic Research, provides a deeper understanding about how warming has already begun affecting human movement — and will in the future.

The impact: "We project that expected warming in the next century will encourage further urbanization in middle-income countries such as Argentina, but it will slow down urban transition in poor countries like Malawi and Niger."

What they did: Researchers with UC Davis and the University of Idaho looked at migration data for huge numbers of relatively small geographic "cells" worldwide from 1970 to 2000.

  • They combined it with other data on temperatures, population and precipitation in the same regions.
  • They broke up countries into 3 wide groups: nations in the bottom 25% of per capita GDP, the middle 50%, and the top 25%.

What they found: The middle-income group showed the most internal migration to cities. A big takeaway: Declines in rural productivity, including lower crop yields stemming from climate change, have different effects on poor vs. middle-income nations.

  • Why? They see a vicious cycle in very poor places: Hotter temperatures cut rural productivity, making migration costs even less feasible.
  • "On the other hand, rising temperatures increase out-migration from rural areas in middle-income countries because temperature shocks widen the rural-urban income gaps, which work to strengthen individuals’ incentives to migrate, once they can pay for migration costs," the study states.

Go deeper: Youth protests sweep the globe demanding action on climate change

Go deeper

Robert Mueller speaks out on Roger Stone commutation

Former Special Counsel Robert Mueller testifies before the House Permanent Select Committee on Intelligence on Capitol Hill on Wednesday July 24, 2019. Photo: The Washington Post / Contributor

Former special counsel Robert Mueller responded to claims from President Trump and his allies that Roger Stone was a "victim" in the Justice Department's investigation into Russian interference in the 2016 election, writing in a Washington Post op-ed published Saturday: "He remains a convicted felon, and rightly so."

Why it matters: The rare public comments by Mueller come on the heels of President Trump's move to commute the sentence of his longtime associate, who was sentenced in February to 40 months in prison for crimes stemming from the Russia investigation. The controversial decision brought an abrupt end to the possibility of Stone spending time behind bars.

Trump dons face mask during Walter Reed visit

Trump wearing a face mask in Walter Reed National Military Medical Center on July 11. Photo: Alex Edelman/AFP via Getty Images

President Trump wore a face mask during his Saturday visit to Walter Reed National Military Medical Center, according to AP.

Why it matters: This is the first known occasion the president has appeared publicly with a facial covering as recommended by health officials since the coronavirus pandemic began, AP writes.

Updated 5 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

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  2. U.S.: Total confirmed cases as of 5:30 p.m. ET: 3,228,884 — Total deaths: 134,600 — Total recoveries: 983,185 — Total tested: 38,919,421Map.
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