Measuring Error Can Explain Claimed Climate Temperature Rise

Written by Kenneth Richard on October 10, 2018. Posted in Current News

A new paper in the Journal of Geophysical Research documents “remarkably different” land temperatures from one instrumental dataset to another. In some regions, there is as much as a 0.8°C conflict in recorded temperature anomalies for CRU, NASA, BEST, and NOAA.

The relative temperature trend differences can reach 90{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} when comparing instrumental records.

Consequently, the uncertainty in instrumental temperature trends — “0.097–0.305°C per decade for recent decades (i.e., 1981–2017)” — is as large or larger than the alleged overall warming trend itself for this period.

In a just-published audit of the IPCC-preferred HadCRUT temperature dataset, Dr. John McClean identified 70 problems that seriously compromise the reliability and accuracy of this IPCC-preferred instrumental record dating back to 1850.

Joanne Nova provides a summary of the main points from the paper, McLean’s Ph.D. thesis.

McLean found freakishly improbable data, and systematic adjustment errors, large gaps where there is no data, location errors, Fahrenheit temperatures reported as Celsius, and spelling errors.
Almost no quality control checks have been done: outliers that are obvious mistakes have not been corrected – one town in Columbia spent three months in 1978 at an average daily temperature of over 80 degrees C. One town in Romania stepped out from summer in 1953 straight into a month of Spring at minus 46°C. These are supposedly “average” temperatures for a full month at a time. St Kitts, a Caribbean island, was recorded at 0°C for a whole month, and twice!
Temperatures for the entire Southern Hemisphere in 1850 and for the next three years are calculated from just one site in Indonesia and some random ships.
Sea surface temperatures represent 70{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} of the Earth’s surface, but some measurements come from ships which are logged at locations 100km inland. Others are in harbors which are hardly representative of the open ocean.

Are Any Of The Temperature Datasets Reliable?

A new paper published in the Journal of Geophysical Research reveals that the recorded land temperature data from the four most commonly-referenced instrumental datasets — CRU, NASA, BEST, and NOAA — are “remarkably different” from one another.

In fact, the authors find that “for some areas, different datasets produce conflicting results of whether warming exists” due especially to variations in the use of “infilling techniques” — adding artificial temperatures to areas where there are no real-world measurements.

One dataset trend can be “nearly 90{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117}” different than another dataset trend, which ratchets up the uncertainty to levels that undermine confidence in the overall reliability of the instrumental record.

Excerpts from the paper’s abstract and discussion/conclusion are provided below.

Rao et al., 2018

Land Surface Air Temperature Data Are Considerably Different

Among BEST‐LAND, CRU‐TEM4v, NASA‐GISS, and NOAA‐NCEI

Several groups routinely produce gridded land surface air temperature (LSAT) datasets using station measurements to assess the status and impact of climate change.

The Intergovernmental Panel on Climate Change Fifth Assessment Report suggests that estimated global and hemispheric mean LSAT trends of different datasets are consistent. However, less attention has been paid to the intercomparison at local/regional scales, which is important for local/regional studies.

In this study we comprehensively compare four datasets at different spatial and temporal scales, including Berkley Earth Surface Temperature land surface air temperature dataset (BEST‐LAND), Climate Research Unit Temperature Dataset version 4 (CRU‐TEM4v), National Aeronautics and Space Administration Goddard Institute for Space Studies data (NASA‐GISS), and data provided by National Oceanic and Atmospheric Administration National Center for Environmental Information (NOAA‐NCEI).

The mean LSAT [land surface air temperature] anomalies are remarkably different because of the data coverage differences, with the magnitude nearly 0.4°C for the global and Northern Hemisphere and 0.6°C for the Southern Hemisphere.

This study additionally finds that on the regional scale, northern high latitudes, southern middle‐to‐high latitudes, and the equator show the largest differences nearly 0.8°C.

These differences cause notable differences in the trend calculation at regional scales. At the local scale, four datasets show significant variations over South America, Africa, Maritime Continent, central Australia, and Antarctica, which leads to remarkable differences in the local trend analysis.

For some areas, different datasets produce conflicting results of whether warming exists.

Our analysis shows that the differences across scales are associated with the availability of stations and the use of infilling techniques. Our results suggest that conventional LSAT datasets using only station observations have large uncertainties across scales, especially over station‐sparse areas.

“The relative difference of trends estimated from different datasets can reach nearly 90{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} for different regions and time periods. CRU-TEM4v generally appears to have the largest grid box scale differences, while NASA-GISS has the smallest differences compared to BEST-LAND.

The uncertainty of the LSAT [land surface air temperature] trend estimation caused by the dataset differences (i.e., RMSD) ranges from 0.035 to 0.086°C per decade for the long-term trend (i.e., 1901–2017) to 0.097–0.305°C per decade for recent decades (i.e., 1981–2017).

In developing future LSAT datasets, the data uncertainty caused by limited and unevenly distributed station observations must be reduced.