I saw a post
recently from a right-wing outlet arguing that according to a (sympathetic)
meteorologist associated with the conservative Heartland Institute that 96% of
temperature measurement stations in the U.S. were in places deemed unacceptable
by NOAA standards. The post claimed that thermometers were predominantly on
buildings, in cities near pavement, and in other places with human influence,
which makes them read higher due mainly to urban heat island effects. Other
posts I have been seeing claim that recent high temperatures in Europe in
particular were ground temperatures rather than air temperatures. At first
glance, this seems quite unlikely to me. Apparently, a few previous studies
concluded that this is not the case regarding thermometer placement. Urban heat
island effects are considered to have been minimized according to those
studies. The serious charge of faked science, if true, would be shocking and entirely
unacceptable. However, I seriously doubt this is the case. The post also went
on about the climate agenda of the ‘global elite’, specifically mentioning the
World Economic Forum and the UN as part of that global elite. Such a charge
alleges a vast conspiracy to manipulate data that would be unacceptable by a vast
majority of the world’s climate scientists.
An opinion
piece in Fox News claims that it is not climate change that is causing the heatwaves,
but that evidence indicates that heatwaves in the 1930’s were worse. Data from
the U.S. Climate Change Science Program shows data from 1961 to current which shows
without a doubt that heatwaves have increased steadily in frequency and length
of heatwave season since 1961. Heatwave duration and intensity have also
increased through this time period, but both have showed slight decreases in
the 2020’s compared to the 2010’s. The data comes from temperature averages
across 50 metropolitan areas and EPA notes: “Heat waves are occurring more
often than they used to in major cities across the United States.” I would
not dispute that at all but if we are trying to determine the effects of
climate change on heatwaves. However, I would question why the data given are
concentrated in metropolitan areas and major cities. The data for cities is
important to know to mitigate the very real dangers of heatwaves, but did the
data filter out urban heat island effects? Is it corroborated by heatwave data
from rural areas? There is no information given there about that and that is
concerning to me. I had expected to put these assertions by Fox News and Heartland
Institute to rest pretty quickly but now I am not so sure. I hate to say this,
but the data seem misleading as an indicator of climate change influence, and
yet the title of the section at the EPA is indeed Climate Change Indicators:
Heat Waves. Below the title are the words: “This indicator describes
trends in multi-day extreme heat events across the United States.” Then it
states: “These data were analyzed from 1961 to 2021 for 50 large
metropolitan areas. The graphs show averages across all 50 metropolitan areas by
decade.” First in a list of key points is this statement: “Heat waves
are occurring more often than they used to in major cities across the United
States.”
EPA does
acknowledge the rather extreme data in the 1930’s reflected in the U.S. Annual
Heat Wave Index, 1895–2021 shown below:
Source: U.S. EPA
EPA explains the significant 1930’s anomaly here:
“Longer-term records show that heat waves in the 1930s
remain the most severe in recorded U.S. history (see Figure 3). The spike in
Figure 3 reflects extreme, persistent heat waves in the Great Plains region
during a period known as the “Dust Bowl.” Poor land use practices and many
years of intense drought contributed to these heat waves by depleting soil
moisture and reducing the moderating effects of evaporation.”
The urban heat
island effect (UHI) is measured simply as the differences in air temperatures
between urban and nearby rural areas. In contrast land surface temperatures
(LST), often captured by satellite sensors, measure the Surface Urban Heat
Island (SUHI). “The Moderate Resolution Imaging Spectroradiometer (MODIS) is
a sensor aboard the Terra and Aqua satellites that provides daily global LST
observations.” A study by Krehbiel and Henebry published in 2016 noted: “In
Minneapolis-St. Paul, the median urban MODIS-Aqua daytime LST was 297.8 K (24.6
°C, 76.4 °F) compared to the median rural LST, which was 294.7 K (21.6 °C, 70.8
°F).” That is a pretty significant urban-rural temperature difference of 3
deg C and 5.6 deg F. Similar urban-rural differences were observed in several
other cities. That map below shows the significant urban-rural temperature differences
in the wider region. One can only ask the question: Why is EPA relying on urban
temperature data in determining heatwave changes over time? This is concerning
to me. As stated, I had expected to quickly refute the assertions of the
right-leaning outlets but now I am not so sure, and I am actually concerned and
dismayed that there may be some significant scientific bias going on here. It
is quite likely that urban heat island effects have been increasing significantly
since 1961 and that they account for some of the changes in the EPA data for
cities. I would like to know about heatwave data from rural weather stations only
as that would be one simple way to filter out UHI effects.
A 2023 study of
the heatwave in U.S. west in 2021 did offer some interesting information about the
different effects of heatwaves on urban and rural areas. It suggested that heatwaves
actually make temperatures rise more in rural areas:
“… heatwaves have stronger temperature effects in
rural areas due to the synoptic scale of the high-pressure systems that lead to
low wind speeds, decreased humidity and elevated temperatures across a large
area (e.g., thousands of km). The uniform temperature increases across both
rural and urban areas during heatwaves confirm the importance of mitigating
urban heat and not the UHI as suggested by Martilli et al.19. To isolate the
specific contributions, e.g., urban vegetation and lake/sea breezes, on urban
temperatures, future modeling investigations can be designed to focus on model
perturbations of these processes so the results can provide a quantitative
estimate of their specific impacts on urban heat.”
This suggests that my concerns about possible scientific bias
may not be well founded so I will leave it at that for now.
Image of annual mean
accumulated growing degree-days (AGDD) for 2003-2012. AGDD is calculated from
the MODIS-Aqua and MODIS-Terra 1,000 meter 8-day composites of daytime and
nighttime land surface temperature (LST). Five of the eleven study sites from
Krehbiel and Henebry (2016) are labeled in this image. Areas with higher mean
annual AGDD are shaded red, including major cities such as Minneapolis-St.
Paul, MN, and Chicago, IL.
Is Weather Station Placement Corrupting Data?
I now return
to the assertions of meteorologist Anthony Watts and the Heartland Institute’s study
about placement of U.S. weather stations not meeting NOAA standards. Watts released
a similar study in 2009 - Is the U.S. Surface Temperature Record Reliable?
- that concluded that about 90% of U.S.
weather stations did not meet the National Weather Service’s requirements for
placement. Watts traveled around the country to observe weather station
placement and noted:
“We found stations located next to the exhaust fans of
air conditioning units, surrounded by asphalt parking lots and roads, on
blistering-hot rooftops, and near sidewalks and buildings that absorb and
radiate heat. We found 68 stations located at wastewater treatment plants,
where the process of waste digestion causes temperatures to be higher than in
surrounding areas.”
I should note that Watts is a well-known climate skeptic
and founder of Watts Up With That, which is touted as “the world’s most
viewed site on global warming and climate change.” The new 62-page report is
based on further visits to weather stations and has about 17 pages of photos of
weather stations that could be influenced by placement effects. The NOAA’s
National Climatic Data Center did respond to the 2009 report first with a set
of ‘talking points’ now no longer available and concluded that the data from
the stations were not biased. Specifically, according to Watts, they noted:
“The issues related to poor station siting are described
and an analysis of the potential bias that poor station siting caused in the
U.S. temperature time series is presented. In the U.S. Historical Climatology
Network, a data set used for climate change analysis because station time
series have been adjusted to remove the effects of changes in the observing
system such as changes in the instrumentation or location of the instrument
shelter, the analysis found no indication of a bias caused by poor station
siting.”
Watts notes in the report that: “The majority of USHCN
stations that were closed since the 2009 report were stations that received
wide publicity for their unacceptable siting. Other equally poor stations that
did not receive a similar amount of publicity remain open.” In addition as
Watts notes some peer reviewed papers did acknowledge significant ‘heat sink’
effects on weather stations, specifically effects from proximity to asphalt,
brick, concrete, and buildings.
While I acknowledge that Watts’ research should be taken
into account and that more weather stations should be relocated, I doubt that nationwide
temperature data is somehow compromised. As a scientist, though, I do believe
that all legitimate concerns about inaccurate data should be investigated and mitigated and that individual stations in question should be relocated.
References:
It’s
not climate change that’s causing heat waves this summer but no one wants to
explain why. Justin Haskins. Fox News (Opinion). July 27, 2023. It’s
not climate change that’s causing heat waves this summer but no one wants to
explain why (msn.com)
Detecting
Urban-Rural Temperature Differences with MODIS and AppEEARS. U.S. Geological
Survey. Jume 22, 2016. LP
DAAC - Detecting Urban-Rural Temperature Differences with MODIS and AppEEARS
(usgs.gov)
Climate
Change Indicators: Heat Waves. U.S. EPA. Accessed 7/2023. Climate
Change Indicators: Heat Waves | US EPA
A
multiscale analysis of heatwaves and urban heat islands in the western U.S.
during the summer of 2021. Kaiyu Chen, Jacob Boomsma & Heather A. Holmes.
Nature. Scientific Reports. 13, Article number: 9570 (2023). June 13, 2023. A multiscale analysis
of heatwaves and urban heat islands in the western U.S. during the summer of
2021 | Scientific Reports (nature.com)
96% of
U.S Climate Data Is Corrupted, Study Shows. Frank Bergman. Slay News. July 23,
2023. 96%
of U.S Climate Data Is Corrupted, Study Shows - Slay News
Corrupted
Climate Stations. The Official U.S. Temperature Record Remains Fatally Flawed.
2022 Edition. Anthony Watts. The Heartland Institute. 2022_Surface_Station_Report.pdf
(heartland.org)
Is the
U.S. Surface Temperature Record Reliable? Anthony Watts. Heartland Institute.
March 1, 2009. Is
the U.S. Surface Temperature Record Reliable? – The Heartland Institute
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