In the latest UN climate "warning,"  the UN argues that the costs of CO2 abatement are not all that high because we have to offset these costs with ancillary benefits of these actions.   Many, many folks have demonstrated that these numbers are way understated, but let’s accept this premise for a moment.  If this approach is correct, then should we not also offset the expected harms from global warming with expected benefits, like a longer growing season, and this:

Carbon dioxide is not the dreaded greenhouse gas that the global warmers crack it up to be. It is in fact the most important airborne fertiliser in the world and without it there would be no green plants at all. In fact, a doubling of the levels of this gas in the atmosphere would bring about a marked rise in plant production — good news for everyone, especially those malnourished millions who can’t afford chemical fertilisers. Perhaps the time is ripe to really start worrying (again) about the fact that for the last 200 million years the concentration of carbon dioxide in our atmosphere has been falling. Indeed it dropped to dangerously low levels during recent ice ages. The Plant Kingdom responded to this potentially catastrophic (no carbon no food) situation by producing the so-called C4 plants that can survive low CO2 by using sunlight more efficiently.