Friday, 5 May 2023

Does Climate Change - Cause More Extremal Events.

There are always extreme weather events, (1920s dust bowl America for example), there is a claim (very much used by the media and which is unconnected from the claim of increasing global average temperature), that an increase in temperature leads to an increase in variation from the average temperature. This claim entered the popular green culture, via the BBC Chris Packem title, Global Wierdening, but doesn't have much behind it in the Scienfic Literature. For observation, deaths from extreme weather are down hugely over the last 100 years. https://worldindata.org/grapher/number-of-deaths-from-natural-disasters (mostly due to better shelter and weather managment though). The IPCC does indeed claim, that climate change lead to more extremely events. There are several claims, IPCC make there. 1. That the temperature is observed to be raising. 2. That CO2 is the cause of temperature raise. 3. That if the temperature rises there will be more extreme events of draught and flood. 4. That if the temperature rise there will be more extreme events of both high and low temperature. Each of which could be true of false, seperately, and any one of the statments does not imply any other. Each statement needs to be predicted with both a solid theory, and also match historical observations. The IPCC Summary makes these claims, and states there are high confidence, but instead of listing citation for each of the claim. The citations on the reference pages, with a reference number between the IPCC assertion, and the studies. I looke4d at a few of the papers in the references. For Assert 2, I found, Attribution of twentieth century temperature change to natural and anthropogenic causes. There it states Solar Variations are a significant contribution (to global temperatures), in one irradiance dataset but not another. It does state CO2 causes some increase. And also finds evidence that a reduction of Volcanic Activity led to temperature increases. No Numbers for the amounts of contribution of each factor, or the statistical or systematic uncertainance of either amount. Please scientists put your claims in the abstract with numbers include statistical and systematic errors. For 3, for Rainfall. Most of the claims of Rainfall increase are based on the CIMP5 and CIMP6 models of future rainfall for a given temperature range. In Agel and Barlow. State the CIMP6 wasn't an improvement on CIMP5, and the models produce more frequent precipation that the observations and
distribution of precipitation does not necessarily correspond to a realistic simulation of the circulation patterns
For 4. for temperature. For example Turkey since 1970. The weather station data finds an increasing (trend in) number of hot days, at 46% of weather stations, and a decrease at 15% of weather stations, (so presumably, no trend at 39%. The number of colder days, should a decrease. So these first checks of references don't show any strong proof, of any assertions, 2-4. But there are lots chapter references to read though and critic.