populations

“It’s a health issue, first and foremost,” said Nazarian, who pointed out that the effects of extreme heat fall disproportionately on vulnerable populations like those who are chronically ill.

In California and across the country, researchers subsequently compiled massive evidence of delayed or lost learning during this period, with the academic damage affecting school populations even in places that re-opened campuses more quickly.

"We are aware of reports of fish struggling in Aberhafesp and we understand the public concern about the impact on fish populations here and across the region," they said.

"Their populations can build to a point where they can overcome the tree defences - there are millions, billions of beetles," explained Dr Max Blake, head of tree health at the UK government-funded Forestry Research.

Oliver said the CCN's analysis showed "that splitting county areas into unitary councils with populations as small as 300,000 will create hundreds of millions of new unsustainable costs for local taxpayers".