The PETM or Paleocene-Eocene Thermal Maximum was a warm period that began between 56.3 and 55.9 Ma (million years ago). The IPCC AR6 report (actually a draft, not a final edited report), released to the public on August 9, 2021, suggests that this warm period is similar to what is happening today and they expect to happen in the future (IPCC, 2021, pp. 2-82 & 5-14). During the PETM, it was very warm and average global surface temperatures probably peaked between 25.5°C and 26°C briefly, compared to a global surface temperature average of about 14.5°C today, as shown in Figure 1.
The Old Farmer’s Almanac has been making yearly long-term weather forecasts for 230 years. We pay attention to them because they are normally 80% accurate. They did not do as well last winter but were 72% in predicting the direction of temperature change, and 78% accurate in the change in precipitation. This is pretty remarkable because while the U.S. weather forecasts are 90% accurate five days in advance, they are only 80% accurate seven days out. The Old Farmer’s Almanac forecasts are far less specific, they only predict the direction of change, but their forecasts are for twelve months in the future, quite impressive. Figure 1 is their forecast for the lower 48 United States, for this winter.
This post was updated 9/24/2021 to reflect reader comments.
The phrase “greenhouse effect,” often abbreviated as “GHE,” is very ambiguous. It applies to Earth’s surface temperature, and has never been observed or measured, only modeled. To make matters worse, it has numerous possible components, and the relative contributions of the possible components are unknown. Basic physics suggests that Earth’s surface is warmer than it would be with a transparent atmosphere, that is no greenhouse gases (GHGs), clouds, or oceans. If we assume Earth is a blackbody, then subtract the solar energy reflected, from the hypothetically non-existent clouds, atmosphere, land, ice, and oceans; we can calculate a surface temperature of 254K or -19°C. The actual average temperature today is about 288.7K or roughly 15.5°C. This modeled difference of 35°C is often called the overall greenhouse effect.
Figures 4 and five have been updated to correct a programming error (7/5/2021).
By Andy May
This post is inspired by an old post on the CERES cloud data by Willis Eschenbach that I’ve read and re-read a lot, “Estimating Cloud Feedback Using CERES Data.” The reason for my interest is I had trouble understanding it, but it looked fascinating because Willis was comparing CERES measured cloud data to IPCC modeled cloud feedback. I love obscure, back-alley comparisons of models and data. They tend to show model weakness. I learned this as a petrophysical modeler.
Yes, indeed, all objects radiate energy if their temperature is above absolute zero. No question about it. But, if you place an object that is radiating at 101 degrees C next to an object radiating at 100 degrees C, they will both soon be radiating at 101 degrees C, not 201 degrees C. A cooler object cannot warm a warmer object, it does not happen, sorry. The second law of thermodynamics does apply. Continue reading →
The first version of this post had an error in Figure 1. It has been fixed along with the associated text (7/5/2021).
By Andy May
The IPCC claims, in their AR5 report, that ECS, the long-term temperature change due to doubling the atmospheric CO2 concentration or the “Equilibrium Climate Sensitivity,” likely lies between 1.5° and 4.5°C, and they provide no best estimate (IPCC, 2013, p. 85). But their average model computed ECS is 3.2°C/2xCO2. Here, “°C/2xCO2” is the temperature change due to a doubling of CO2. They also claim that it is extremely unlikely to be less than 1°C. ECS takes a long time, hundreds of years, to reach, so it is unlikely to be observed or measured in nature. A more appropriate measure of climate sensitivity is TCR, or the transient climate response, or sensitivity. TCR can be seen less than 100 years after the CO2 increase, the IPCC claims this value likely lies between 1° and 2.5°C/2xCO2, their model computed average is 1.8°C/2xCO2 (IPCC, 2013, p. 818).
The CO2 climate forcing, or the net change in radiation retained by Earth’s atmosphere associated with these scenarios is 3.7 W/m2 (IPCC, 2007b, p. 140). Using these values, we can calculate a surface air temperature sensitivity to radiative forcing (RF) of 1.8/3.7 = 0.49°C per W/m2. These values are inclusive of all model-calculated feedbacks.
Some have speculated that the distribution of relative humidity would remain roughly constant as climate changes (Allen and Ingram 2002). Specific humidity can be thought of as “absolute” humidity or the total amount of water vapor in the atmosphere. We will call this amount “TPW” or total precipitable water with units of kg/m2. As temperatures rise, the Clausius-Clapeyron relationship states that the equilibrium vapor pressure above the oceans should increase and thus, if relative humidity stays the same, the total water vapor or specific humidity will increase. The precise relationship between specific humidity and temperature in the real world is unknown but is estimated to be between 0.6 to 18% (10-90%ile range) per degree Celsius from global climate model results (Allen and Ingram 2002).
Carl Mears and colleagues (Mears, et al. 2018) have recently published a satellite microwave brightness record of TPW from 1988 to 2017 showing TPW, over the world’s ice-free oceans, increasing in lockstep with global mean temperature. This surprised me since Benestad (Benestad 2016), (Partridge, Arking and Pook 2009), (Miskolczi 2014) and (Miskolczi 2010) have previously reported that TPW, as computed from weather balloon data, has gone down recently, although their time periods were earlier and longer than the record shown in Mears, et al. Continue reading →
In my last post, on Scafetta’s new millennial temperature reconstruction, I included the following sentence that caused a lot of controversy and discussion in the comments:
“The model shown uses a computed anthropogenic input based on the CMIP5 models, but while they use an assumed climate sensitivity to CO2 (ECS) of ~3°C, Scafetta uses 1.5°C/2xCO2 to accommodate his estimate of natural forcings.”
Dr. Ronan Connolly and his co-authors respond to obvious false claims, in a supposed “fact check” about their latest paper on how solar variability may be affecting the climate. We applaud Dr. Ronan Connolly, Dr. Willie Soon, and Dr. Michael Connolly for rapidly and publicly calling out this fraudulent fact check. Misinformation and opinion articles disguised as fact checks are all too common and when they receive support in the left-wing social media, the situation just gets worse.
The phrase “Ice Age” is poorly defined and often abused, so let’s first define the climate state during most ice ages. It is called “Icehouse Earth.” The earth is in an icehouse state when either or both poles are covered in a thick, permanent icecap (Scotese 2015). Today, both poles are covered in ice year-round, so you may be surprised to learn this is very rare in Earth’s history. In fact, out of the last 550 million years, the earth has had permanent ice caps on one or both poles only nine percent of the time.
An “Ice Age” is best defined as a geologically (or millions of years long) long period of low temperatures. This usually results in the presence of continental and polar ice sheets and alpine glaciers. We are currently living in the Quaternary Ice Age, this is only the fifth significant and severe ice age in Earth’s known history, and, so far it has lasted about 2.6 million years (technically 30+ million years ago when permanent ice appeared on Antarctica). It is the most severe ice age in the Phanerozoic, the geological name for the past 550 million years. Ice Ages are rare, but humans evolved during one, so it seems normal to us.
Figure 1. Christopher Scotese’s geological interpretation of Phanerozoic global temperatures in degrees C. The vertical line on the right side, labeled “PAW” is a projection of possible anthropogenic warming according to a pessimistic IPCC climate model. In 2016 the actual global average surface temperature of the Earth was about 14.5 degrees C. as marked on the plot, in 2019 the temperature is slightly lower at 14.35 degrees according to NASA GISS. The names of the major ice ages were added by the author. After (Scotese 2015)