Another writer, Elizabeth Kolbert (degree in “literature“), cites as her sole authority last week’s awful Newsweek story (written by another non-scientist) about global warming to let us know that this year’s storm season has been caused by global warming. I’ll break down her key paragraph:
For decades, climate scientists have predicted that, as global temperatures rose, the side effects would include deeper droughts, more intense flooding, and more ferocious storms.
The details of these forecasts are immensely complicated, but the underlying science is pretty simple. Warm air can hold more moisture. This means that there is greater evaporation. It also means that there is more water, and hence more energy, available to the system.
Here are the problems with the two assertions.
#1. Temperatures are not rising. Here are the temperatures of the last 20 years. I have highlighted the last decade. See any rise? Didn’t think so.
If tornadoes are correlated to world temperatures, why was April, 2011 — the month with more tornadoes than any other in recorded history (300+) — 0.2°C colder than April, 2010 when only 139 tornadoes were recorded?!
Tornado occurrences are not correlated to mean global temperatures!
#2. The science isn’t simple. Anyone who has taken a Meteorology 101 class knows that the relative humidity (RH) has to come close to 100% in order for a cloud to form. RH is the humidity (expressed as the percent of water vapor the air is holding relative to its capacity). If the RH is 50%, it is holding half of the water it can hold at that temperature. The higher the temperature, the more water the air can hold.
OK, now that you know this piece of meteorological science. Consider these two sentences:
Warm air can hold more moisture. This means that there is greater evaporation.
The above statement is true!
But, by definition, in order for greater evaporation to occur, the air must remain unsaturated which means a storm cannot form! So, by her reasoning, the Joplin (and the other tornadoes) cannot have been caused by ‘global warming.’
Now, of course, storm formation is more complicated than this (even though what I just stated is absolutely correct) but she doesn’t go into that. She relies on the Newsweek story (which doesn’t interview a single atmospheric scientist) as her authority.
This is the forth time I have posted on this subject because I believe it is important. But, you may be getting tired of hearing from me.
Here is what a genuine, and rigorously fair (she is hardly a skeptic), climate scientist — Judy Curry — has to say on the subject:
Judith Curry, chair of Georgia Institute of Technology’s School of Earth and Atmospheric Sciences.
The substantial interest in attributing extreme weather events to global warming seems rooted in the perceived need for some sort of a disaster to drive public opinion and the political process in the direction of taking action on climate change. However, attempts to attribute individual extreme weather events, or collections of extreme weather events, may be fundamentally ill-posed in the context of the complex climate system, which is characterized by spatiotemporal chaos. There are substantial difficulties and problems associated with attributing changes in the average climate to natural variability versus anthropogenic forcing, which I have argued are oversimplified by the IPCC assessments. Attribution of extreme weather events is further complicated by their dependence on weather regimes and internal multi-decadal oscillations that are simulated poorly by climate models.
I have been completely unconvinced by any of the arguments that I have seen that attributes a single extreme weather event, a cluster of extreme weather events, or statistics of extreme weather events to anthropogenic forcing. Improved analysis of the attribution of extreme weather events requires a substantially improved and longer database of the events. Interpretation of these events in connection with natural climate regimes such as El Nino is needed to increase our understanding of the role of natural climate variability in determining their frequency and intensity. Improved methods of evaluating climate model simulations of distributions of extreme event intensity and frequency in the context of natural variability is needed before any confidence can be placed in inferences about the impact of anthropogenic influences on extreme weather events.
There are a number of reasons for the high tornado death toll this year. They are related to more violent tornadoes than usual that, by coincidence, have struck densely populated areas, overwarning by some local authorities, and freak power failures potentially preventing hundreds of thousands from receiving timely warnings. We’ll know when those on the post-storm survey teams report their results (unfortunately, months away).
This type of bad journalism is misleading and harmful. The New Yorker can do much better than this.