The hits to GDP from climate change are overstated on purpose. That does not make the threat any less serious.
We need adults running energy policy in DC so that the cure to global warming is not worse than the disease.
When you have TDS-afflicted, messianic, Chicken Littles running energy policy in Washington, you get the bad policy that produced the current price spikes in oil and gas markets and ensuing economic misery. On other hand, if you have climate change deniers running energy policy, you will not make the balanced, sensible, and sustainable advancements in energy sourcing and carbon mitigation that will forestall global warming without tanking the global economy.
The truth is that the hits to GDP from even the most apocalyptic climate change scenarios will be manageable. That does not make them any less serious. This excellent piece from the Center for Global Development articulates the challenge and solvency with remarkable finesse.
https://www.cgdev.org/publication/climate-change-may-have-only-small-effects-long-run-global-gdp-so-what