NCA deputy director general Phil Gormley said the scale of offending discovered by the child abuse operation was "shocking".
His colleague, chief constable Simon Bailey, said the number of indecent images of children has risen from under 10,000 in the 1990s to a figure in the tens of millions today.
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The study is expected to warn of the impacts of melting ice and permafrost.
Some northern and eastern areas may stay bright and warm but heavy rain or showers will affect most parts.
Police used tear gas and rubber rounds against protesters on Saturday