EXCERPT FROM THE HANSEN 1988 CONGRESSIONAL TESTIMONY 

CLAIM: Number one, the earth is warmer in 1988 than at any time in the history of instrumental measurements that goes back 100 years. RESPONSE-1: Anthropogenic Global Warming (AGW) is a theory about long term trends in global mean temperature. A one-year temperature event has no interpretation in this context. RESPONSE-2: In your paper Hansen 1988 and also in the official position of your NASA GISS organization you state that that AGW started in 1950 because from then the relationship between CO2 and temperature we see in the climate models closely matches the observational data. If AGW started in 1950, then what is the relevance of the 100-year instrumental record reference period for the temperature record in 1988?

CLAIM: Causal association requires first that the warming be larger than natural climate variability and, second that the magnitude and nature of the warming be consistent with the greenhouse mechanism. RESPONSE: Neither that the warming is larger than natural climate variability nor that the magnitude of the warming is consistent with the greenhouse mechanism proves causation. For that it must be shown that a statistically significant detrended correlation exists between the logarithm of atmospheric CO2 concentration and mean global surface temperature over a sufficiently long time span. The choice of 30 years as the time span for this evaluation is not supported by the literature where we find that longer time spans are required, preferably longer than 60 years.

CLAIM: The warming is more than 0.4 degrees Centigrade for the period 1958-1988. The probability of a chance warming of that magnitude is about 1 percent. So with 99 percent confidence we can state that the warming during this time period is a real warming trend. RESPONSE: The probability is more likely to be 100% that it is a REAL warming trend but none of this serves as evidence that the warming was caused by the greenhouse effect of atmospheric CO2 concentration attributed to fossil fuel emissions.

CLAIM: The data suggest somewhat more warming over land and sea ice regions than over open ocean, more warming at high latitudes than at low latitudes, and more warming in the winter than in the summer. In all of these cases, the signal is at best just beginning to emerge, and we need more data. RESPONSE: If the signal is just beginning to emerge and you need more data to figure it out then you don’t really know and your claim to 99% confidence has no basis.

CLAIM: Some of these details, such as the northern hemisphere high latitude temperature trends, do not look exactly like the greenhouse effect, but that is expected. There are certainly other climate factors involved in addition to the greenhouse effect. RESPONSE: Lip service to internal climate variability { LINK: https://tambonthongchai.com/2020/07/16/the-internal-variability-issue/ } is paid but the issue is completely ignored in the invocation and assessment of the greenhouse effect of CO2 and its alleged dangerous consequences such as extreme weather that places an enormous cost burden on all of humanity to overhaul their energy infrastructure.

CLAIM: Altogether the evidence that the earth is warming by an amount which is too large to be a chance fluctuation and the similarity of the warming to that expected from the greenhouse effect represents a very strong case. In my opinion, that the greenhouse effect has been detected, and it is changing our climate now. RESPONSE: “too large to be chance fluctuation” and “similarity of the warming to that expected from the greenhouse effect” do not constitute ” strong case”. Such suspicions may be sufficient to construct a hypothesis to be tested with data in a hypothesis test in which what is suspected is the alternate hypothesis and its absence is the null hypothesis. No such empirical evidence is presented possibly because none exists.

CLAIM: we have used the temperature changes computed in our global climate model to estimate the impact of the greenhouse effect on the frequency of hot summers in Washington, D.C. and Omaha, Nebraska. A hot summer is defined as the hottest one-third of the summers in the 1950 to 1980 period, which is the period the Weather Bureau uses for defining climatology. So, in that period the probability of having a hot summer was 33 percent, but by the 1990s, you can see that the greenhouse effect has increased the probability of a hot summer to somewhere between 55 percent and 70 percent in Washington according to our climate model simulations. RESPONSE#1: The weather bureau does not define the period 1950 to 1980 to define climatology. It simply specifies that the distinction between weather and climate is that weather is short term but climate can only be assessed over periods longer than 30 years. The period 1950 to 1980 has been arbitrarily selected by NASA and by Hansen because, in their own words, “Hansen: because in the 30-year period 1950-1980 there is a strong measurable warming rate with 99% probability for human cause” , “NASA: We start in 1950 because from then the relationship between CO2 and temperature we see in the climate models closely matches the observational data“. This kind of bias in the selection of the time span when the theory being tested is the warming “since pre-industrial” caused by the industrial economy is a form of circular reasoning and confirmation bias. It is not science. RESPONSE#2: AGW is a theory about long term trends in global mean temperature. It is not possible to relate that warming trend to the extreme form of geographical localization implied in the claim about heat waves in specific cities of the USA as in “frequency of hot summers in Washington, D.C. and Omaha, Nebraska“. Internal climate variability dominates in geographical localization of this kind. Internal Climate Variability is described in a related post. LINK: https://tambonthongchai.com/2020/07/16/the-internal-variability-issue/ where we find that “Internal variability in the climate system confounds assessment of human-induced climate change and imposes irreducible limits on the accuracy of climate change projections, especially at regional and decadal scales“. It is noted that these internal climate variability studies find that 30-years is too short a time span for the study of AGW climate change and state that the time span must be longer than 30 years preferably 60 years.

CLAIM: A study of the temperature in July, for several different years between 1986 and 2029 is computed with our global climate model for the intermediate trace gas scenario B. The results show that there are areas that are warmer than what the greenhouse model predicts and areas that are colder than what the greenhouse model predicts. This is because in the 1980s the greenhouse warming is smaller than the natural variability of the local temperature. This appears to be anomalous with the greenhouse effect but the data for a few decades later in the 19902 show show warmer temperatures across the board. RESPONSE: The NASA and the Hansen position on AGW to this day (September 2020) holds that “Hansen: AGW started in 1950 because in the 30-year period 1950-1980 there is a strong measurable warming rate with 99% probability for human cause”, NASA: “AGW started in 1950 because from then the relationship between CO2 and temperature we see in the climate models closely matches the observational data”. But the analysis presented by Hansen appears to be AGW went missing in the 1980s only to return in the 1990s. However this analysis by Hansen is flawed because AGW is not a theory that about temperature at any given time or place or any given decade or place. It is a theory only about long term trends in global mean temperature at time scales longer than 30 years preferably 60 years or more.

CLAIM: in the late 1980s and in the 1990s our model yields greater than average warming in the Southeast United States and the Midwest. This anomalous result can be explained if the Atlantic Ocean off the coast of the United States warms more slowly than the land. This leads to high pressure along the east coast and circulation of warm air north into the Midwest or southeast but there is evidence that the greenhouse effect increases the likelihood of heat wave drought situations in the Southeast and Midwest United States even though we cannot blame a specific drought on the greenhouse effect. Therefore, I believe that it is not a good idea to use the period 1950 to 1980 for the study of AGW climatology. We should see better evidence of the greenhouse effect in the next 10 to 15 years than they were in the period 1950 to 1980. RESPONSE: “That he believes that it is not a good idea to use the period 1950-1980 to study climatology is inconsistent with NASA position and that AGW started in 1950 because from then the relationship between CO2 and temperature we see in the climate models closely matches the observational data.

CLAIM: There is a need for improving these global climate models, and there is a need for global observations if we’re going to obtain a full understanding of these phenomena. RESPONSE: This statement is an admission that the assessment of the AGW presented above as an impact of fossil fuel emissions that has dangerous consequences and that therefore we must stop using fossil fuels to fight climate change was made without the information or the scientific data and arguments needed to make that assessment.

LINK TO THE FULL TEXT OF THE TESTIMONY: https://tambonthongchai.com/2019/05/09/hansen88/