A tabulated ratio of record highs to record lows: a useful marker for on-going climate warming in the United StatesInternational Research Institute for Climate and SocietyInternational Research Institute for Climate and Society—An Update

Since January 2000 the author has produced a weekly tabulation of high temperature and low temperature records attained at about 200 first-order stations in the U.S. It was very clear from the outset that the running tally or ratio of high temperature records to low was consistently running about 2:1 - which is counter to what one would expect from a stable or steady climate. Since the author initially presenting the findings to the AMS in January 2010, more data has been cataloged for the decade of the 2010's. In particular the data for 2012 was startling, in which the ratio of daily record highs to daily record lows was more than 4 to 1...more than any other year recorded by the National Climatic Data Center (NCDC) since 1900. The author has now converted his own manual tracking of US records to NCDC's national database dating back to 1900.

The trend of the simple high/low temperature ratio does in fact show a value near 1:1 in the early 1980's that then rises well above 2:1 as it approaches present time. Most recently for the early part of this decade the ratio has risen to near 3:1. The rate of increase in the ratio over the period from the early 1980's amounts to about 4-5% annually. The week to week noise or variability of the high/low ratio is pronounced, but with time averaging over seasons or years, the ever increasing ratio readily emerges from the data. The High/Low ratio statistic is the centerpiece of the climate scorecards for such organizations as Climate Central. It also provides a concrete linkage between climate and weather, which is often in short supply in the broader discussion on AGW. This presentation will be an update on how the Meehl Records Study has been verifying since 2009.