No doubt there’ll be, as Dr Schmidt says, a howl of protests that the data are “being manipulated”. There’s more discussion by Professor Mann.
And here’s the link to the original scientific report.
I’m reading the report now. A chunk of the corrections are due to the improvements in techniques described by Smith, Reynolds, Peterson, and Lawrimore, using empirical orthogonal teleconnections. See also the paper by Huang, Banzon, Freeman, Lawrimore, Liu, Peterson, Smith, Thorne, Woodrull, Zhang, which had been implemenet in the reot package for R, but seemingly has not been kept up to date, and in the package remote, which has been.
And from NOAA itself.