This planet has warmed up and cooled down by itself for hundreds of millions of years and will continue to do so, which geological evidence of previous tropical and ice age climates in this country clearly demonstrates. Why should it stop now?
Indeed it has. However:
- Complex human civilisation emerged and existed only within the last ten thousand years, a period when global climates have been more stable than average. Relative climate stability enabled agriculture, which in turn made it possible for specialisation, written records and most modern knowledge, thought and technologies to emerge, and the current large populations. All of which has accelerated markedly in the last 200 years since the industrial revolution and the use of fossil fuels.
Climate instability will make it more difficult for food to be grown in areas where humanity is accustomed to growing it , without opening up enough other areas in return. Changing weather patterns will be less conducive to the good and reliable harvests Europeans and North Americans are accustomed to. You can engineer crops to some extent, but to do without any rain for years on end, or for seeds not to be washed away by floods and torrential rain, isn't possible.
Some humans will survive that sort of thing, of course, they are a very resilient species. So if you're laid-back on that larger scale, fine, I've no argument with that. Humanity as a species has survived all kinds of natural disasters and epidemics, although the process wasn't exactly fun for those caught up in it.
-
Speed of warming is almost unprecedented in the archaeological record. It does not give enough time for ecosystems and animals to adapt and move their ranges, let alone when populations are already stressed and diminished by human encroachment and hunting and looking like one of the great extinctions of the planet's history even before it's got that much warmer. The combination of species fragility plus the rapid warming can look like a recipe for something similar to the Permian extinction, the biggest ever.
There does tend to be some division anyway, between whether people view other species and nature as an intrinsic value in and for themselves or simply as complex systems which enable human survival in ways that may not be immediately apparent, but from either angle, it doesn't look good.