We want to continue to use the brain’s trust in our audience to refine and harden the articles about the all-climate article by article.
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We’ll start with one article at a time. When this works well it becomes a regular feature.
So here is the next one. Please give us your input. If you want to email highlighted Word or PDF documents, use the information on this page to send.
Pro: Climate models have proven to be accurate.
By Alan Buis,
NASA’s Jet Propulsion Laboratory
An animation of a GISS (Goddard Institute for Space Studies) climate model simulation produced for the United Nations Intergovernmental Panel on Climate Change’s Fourth Assessment Report, showing five-year mean anomalies in surface air temperature in degrees Celsius from 1880 to 2100. The temperature anomaly is a measure of how much warmer or colder it is in a given place and time than the long-term average temperature, defined as the average temperature over the 30-year base period from 1951 to 1980. Blue areas represent cool areas and yellow and red areas represent warmer areas. The number in the upper right corner represents the global mean anomaly.
Photo credit: NASA’s Goddard Institute for Space Studies
There’s an old saying, “The proof is in the pudding,” which means that you can’t really judge the quality of something until it’s been put to the test. This is the case with climate models: mathematical computer simulations of the various factors that work together to influence the earth’s climate, such as: B. Atmosphere, ocean, ice, land surface and sun.
For decades, people have rightly asked how well climate models work in predicting future climatic conditions. Based on solid state physics and the best available understanding of the Earth system, they skillfully reproduce observed data. Even so, they largely respond to rising carbon dioxide levels, and many uncertainties remain in the details. However, the hallmark of good science is the ability to make verifiable predictions, and climate models have been making predictions since the 1970s. How reliable were you?
A new assessment of global climate models, with which the future global average surface temperatures of the earth in the last half century are projected, now answers this question: Most of the models were pretty accurate.
In a study accepted for publication in the journal Geophysical Research Letters, a research team led by Zeke Hausfather of the University of California at Berkeley performed a systematic assessment of the performance of previous climate models. The team compared 17 increasingly sophisticated model projections of global mean temperature developed between 1970 and 2007, including some originally developed by NASA, with actual changes in global temperature observed through late 2017. The observation temperature data came from several sources, including Goddard of NASA’s Institute for Space Studies for Surface Temperature Analysis (GISTEMP) Time Series, an estimate of global change in surface temperature.
The results: 10 of the model projections were in close agreement with the observations. After considering the differences between modeled and actual changes in atmospheric carbon dioxide and other factors influencing climate, the number rose to 14. The authors found no evidence that the climate models either systematically overestimated or underestimated warming over the period of their projections.
“The results of this study of previous climate models increase scientists’ confidence that both they and today’s more advanced climate models are skillfully projecting global warming,” said study co-author Gavin Schmidt, director of NASA’s Goddard Institute of Space Studies in New York. “This research could help remove public confusion about the performance of previous climate modeling efforts.”
Models used in the IPCC 4th Assessment Report can be assessed by comparing their roughly 20-year-old predictions with what actually happened. In this figure, the multi-model ensemble and the average of all models are plotted next to the surface temperature index (GISTEMP) of the Goddard Institute for Space Studies (GISS) at NASA. Climate drivers were known for the “hindcast” period (before 2000) and were predicted for the time afterwards. Temperatures are plotted relative to a baseline from 1980-1999. Photo credit: Gavin Schmidt
Con: Global ocean temperatures are only warming ~ 50% of the rate of climate model projections
Dr. Roy Spencer, climate researcher at the University of Alabama, Hunstville, examined the accuracy requirements of climate models by comparing them with the temperatures actually measured.
From Dr. Roy Spencer’s blog
The following diagram (Fig. 1) shows the monthly global (60N-60S) average fluctuations in sea surface temperature since 1979 for 68 model simulations from 13 different climate models. The 42-year-old observations since 1979 (bold black line) show that warming occurs much more slowly than the average climate model dictates.
Fig. 1. 68 CMIP6 climate model simulations of the global average sea surface temperature (relative to the 5-year average 1979-1983) and compared with observations from the ERSSTv5 data set.
Regarding the linear temperature trends since 1979, Fig. 2 shows that 2 of the above sea temperature datasets show warming trends near the bottom of the range of the climate model simulations.
Fig. 2. Linear temperature trends, 1979-2020, for the various model and observation data sets in Fig. 1 as well as the HadSST3 observation log.
Most of the deep ocean warming could be natural
A related problem is how much the deep oceans are warming. As I mentioned earlier, the (undeniable) energy imbalance that has been associated with deep sea warming over the past few decades is only about 1 part (less than 1 watt per square meter) in 300 of the natural energy flows in the climate system.
This is a very small energy imbalance in the climate system. We know that NONE of the natural energy flows that precisely.
That means global warming can be mostly natural and we wouldn’t even know it.
I am not suggesting that it is. I just want to point out the level of confidence associated with adapting climate models, which inevitably leads to warming due to increasing CO2 emissions, as these models simply assume that there is no other source of warming.
Yes, more CO2 must lead to some warming. However, the extent of warming makes the difference to global energy policy.
The public is seldom ever informed about these obvious discrepancies between basic research and the statements of politicians and pop scholars.
Why does it matter?
It is important because there is no climate crisis. There is no such thing as a climate emergency.
Yes, there is irregular heating. Yes, it is at least partially due to human greenhouse gas emissions. But rarely mentioning the benefits of a slightly warmer climate system or the benefits of having more CO2 in the atmosphere (which is necessary for life on earth).
But if we waste trillions of dollars (that’s only here in the US – in the meantime, China will always do what is in China’s best interests) then that’s trillions of dollars that are not available for real life needs.
Prosperity will suffer, and for no good reason.