>I've seen that posted several times on climate alarmist websites over the years. It's a simplistic and arrogant response meant to appear clever and thoughtful. It presents black-and-white conclusions from the alarmist standpoint and presents them as fact without definition. For instance, what if GW is real and we do nothing and the planet adjusts, flourishes and we as a species advance. Since this has already occurred at least once that we know of (950-1250) and the chart's assumption has no historical basis, it seems odd to arbitrarily choose the opposite consequence.

At the risk of quoting Wikipedia:
Global warming is the current rise in the average temperature of Earth's oceans and atmosphere and its projected continuation. The scientific consensus is that global warming is occurring and was initiated by human activities, especially those that increase concentrations of greenhouse gases in the atmosphere, such as deforestation and burning of fossil fuels. This finding is recognized by the national science academies of all the major industrialized countries and is not rejected by any scientific body of national or international standing.

An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.[12] Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include more frequent occurrence of extreme weather events including heatwaves, droughts and heavy rainfall events, species extinctions due to shifting temperature regimes, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional changes is uncertain.[13] In a 4°C world, the limits for human adaptation are likely to be exceeded in many parts of the world, while the limits for adaptation for natural systems would largely be exceeded throughout the world. Hence, the ecosystem services upon which human livelihoods depend would not be preserved.[14]

If that's true, then the world adapting easily to a new warmer earth is not a likely scenario. Does it mean extinction. Maybe. Maybe not.

Yes, that chart is overly-simplistic. That's kind of the point!