Air has a specific heat (~1) less than a quarter per unit mass than water (~4.1). The atmosphere has a mass of ~5 billion kgs and the ocean has a mass of ~1.4*10^21 kgs.

It requires a lot less trapped energy to warm the atmosphere by 1 C than the ocean. We're well on track for 2.5 C increase since preindustrial levels.

As long as we are doing absolutely useless comparisons of enormous numbers that could potentially be used as disinformation to vastly understate the impact of global warming: To heat the entire planet Earth down to the core by 1 degree Celsius would require the energy equivalent of (~order of magnitude) 1 quadrillion Hiroshima-sized atomic bombs.

The death toll from Hiroshima was between 90-160 thousand people. The amount of excess deaths due to heat waves in 2023 was around 178,000. There are projections that the El Nino related heat waves could cause up to half a million, and longer term projections grow to 300,000 a year just from heat in the next few years. Just from heat.

Add in crop failure, ecosystem collapses, and other unexpected disasters, and it's easy to see why.

It might be crass, but it's mostly poor people and poor countries that are going to be affected.

At the same time, I have a hard time thinking that the destruction of the environment is either necessary or natural. So the death caused by climate change also seems like a particular kind of massacre.

Where I was raised, it was a commonplace to think of the firebombings and nuclear incineration of vast amounts of civilian populations as regrettable but necessary and perhaps even a natural outcome of technological growth.

I hadn't really considered that position until your comment, but my rejoinder would be "perhaps the comparison is unfortunately apt and it is crass to ignore the death caused by climate change."