This sounds about right. Although I would regard it as a minimum number. It's probably going to be worse.

Allow me to visually describe the problem for you.

Adding CO2 to the atmosphere increases the amount of energy in the Climate System.

90% of that energy goes into the Oceans.

GLOBAL WARMING IS OCEAN WARMING.

Between 1975-2015 the amount of extra energy being added to the Climate System worked out to about 5 Hiroshima class atomic bombs (Hiros) PER SECOND.

Between 1975-2015 this works out to 33 Hiros PER SQUARE MILE of ocean.

This is also equal to about 40% of the energy the "Dinosaur Killer" asteriod dumped into the Earth’s Climate System 65 million years ago.

SINCE 2015 THE RATE OF GLOBAL WARMING HAS DOUBLED. THE EARTH'S ALBEDO HAS DIMMED.

The amount of energy going into the oceans is now about 10 Hiros per second.

In about 30 years we will have dumped the same amount of extra energy into the Climate System as the Dinosaur Killer Asteroid did 65 million years ago.

NOTHING WEIGHING OVER 30 POUNDS SURVIVED THAT EXTICTION.

Which is why I think the study authors are being optimistic.