Revisited an old post on Lomborg’s economic analysis of the cost of warming.There seems to be a consensus around 3% of GDP. Is that happening at present, or is it a projection 80 to 100 years out with the assumption of more warming?
As to the impact of warming currently, accepting a rise in mean global temp of about 0.8C since the industrial revolution or 1850 I can’t see how there is any negative impact at all, given we are emerging from a little ice age and warming from that point is good not bad at all. Add to that the greening from additional CO2 which is vital plant food and sub-optimal at present by a factor of 5 or so.
Another old post with a link suggesting that extra CO2 does more good than harm.
To anticipate comments on the high cost of recent extreme weather events, bear in mind we are talking about the incidence of the events and the records show no upward trend in incidence of droughts, floods and other extreme weather events. The increase in costs comes from inflation and also the massive increase in the amount and cost of things that are built in vulnerable locations. That is a result of economic development, not warming. Beware of confusing correlation with causation.
A nice example of radical confusion of cause and effect comes from a paper by Karoly and others for the World Wildlife Fund on a drought in the Murray Darling Basin caused by the 2002-3 El Nino. They wrote:
The higher temperatures caused a marked increase in evaporation rates which sped up the loss of soil moisture and the drying of vegetation and watercourses. This is the first drought in Australia where the impact of human-induced global warming can be clearly observed.
They actually got it the wrong way around, when the solid is full of water the incoming energy evaporates the moisture in the surface layers of soil and when they are dry the surface temperature rises. First the evaporation then the higher local surface temperature. When the surface layers are dry there is no way that increased temperature can accelerate evaporation because there is no moisture there to evaporate.
Another blast from the past, my suggestion in 2011 to delay mitigation efforts for a decade or two to get a better fix on the trajectory of warming and the role of CO2.