If this person were actually concerned with human welfare, wouldn't he want to provide strong evidence that his actions would not decrease human life expectancy? (realclimate.org)
If human life expectancy were measured from conception, rather than birth, we would be looking at a gender gap not of 6 years, but more like 16. (newscientist.com)
Was human life expectancy significantly less when carbon dioxide was lower? (realclimate.org)