The Truth About Climate Models and How They Predict Warming

Since climate change became our biggest concern, everyone would want to learn the truth about climate models. Scientists have been bragging about developing several climate models to predict how global warming will affect us in the future. Furthermore, they will also try to find out whether we will be able to fulfill the Paris climate goal. Nevertheless, this does not mean that many climate models proved to be totally wrong and they estimate indicated many flaws.

Despite all the controversy around the Paris climate goal, there is no actual evidence proving its physical impossibility. A recent study published in Nature Geoscience led to a new analysis. The new research developed an updated estimate indicating an approximate quantity of carbon we could burn and still fulfill the Paris climate goal. The Paris Agreement is meant to limit the effects of global warming, decreasing the worldwide average temperature by 1.5 degrees Celsius compared to what we experience now.

The new study is encouraging for everyone since it indicates that we have a much bigger carbon budget compared to what we might have expected. Nevertheless, certain media used some of the results to indicate that previous climate models over-predicted warming events which occurred in recent decades. The origin of the problem relies on a claim in the study indicating that climate models tend to overestimate the observed warming by 0.3 degrees Celsius.

The truth about climate models

This represents a third of the total amount of observed warming from the last 130 years. The media used this figure to indicate that climate models are wrong. Hence, the consequence would be that the IPCC overestimated global warming. Furthermore, the results also indicate that it is less urgent to cut down on greenhouse gas emissions than we have previously believed.

However, this is only a misconception. The new study, nevertheless, indicates that observed warming is the same with the IPCC’s climate models. It is true that observed warming appears among the wide range of projections, they continue to be among the warming results. Therefore, if we still dream of reaching the 1.5 degrees Centigrade Paris goal, we still need to reduce the amount of greenhouse gas emissions in the atmosphere.

After the new study also calculates another carbon budget, it has revealed that the carbon budget is even greater than it was previously thought. Relying on their new analysis, the new carbon budget may offer us 40 years to reduce the dangerous emissions to zero. In this way, we will still have the chance to achieve humanity’s most ambitious goal of reducing global temperatures.

If this statement proves to be true, then the chances of fulfilling this purpose have switched from “impossible” to “possible”. Nevertheless, this may only happen if you struggle hard to find technical solutions to reduce the levels of carbon dioxide from the atmosphere.

Glaciers breaking down in the Arctic

Climate change contributes to the meltdown of glaciers, triggering a sea level rise.

The study evaluates only one climate dataset

Another aspect of the study is that it assesses only a single dataset containing observed temperatures. Its name is HadCRUT4. There are plenty of datasets which researchers did not include like NASA/GISS and NOAA which date back to 1880. Furthermore, there are also other datasets from the 1850s, such as Berkeley Earth and Cowtan and Way.

However, researchers have indicated a big difference between them. Other datasets use elaborated extrapolation techniques to cover data-void regions, the new dataset does not. Hence, this is important when analyzing temperature changes in datasets.

Where it all has started

Apparently, after 2020, the average human-made global warming a group of climate models predicts reaches 0.3 degrees Centigrade warmer than before. Hence, it will be warmer compared to the estimates of man-made warming from 2015. Nevertheless, specialists who developed these CMIP models missed out on something.

First, they indicate that the difference that appears in the new study is because of the fact that climate models overestimated the observed warming. This is a misinterpretation. Secondly, the difference they highlight depends on the observational dataset and the type of model they used. Mainly, this deference relies on the fact that scientists cannot compare the model output with the datasets indicating recorded temperatures. Hence, if we were to consider all this, then the difference of 0.3 degrees would vanish.

Why the climate model is not helpful

The authors of the new analysis decided to compare the observations from 2015 with the model estimates for 2020, this being part of a more complex analysis. The goal is to estimate the carbon budget that remains and then test the feasibility of their Paris goal. When trying to do so, they have estimated how much carbon might remain for us to consume and still be under the target of 1.5 degrees.

However, a thing is certain here. These models did not intend to show whether the models are “too warm”. In order to achieve that, specialists only needed to develop a comparison between the average model result in 2015 with the observations for the same year. The results indicate a difference of 0.17 degrees Centigrade, being within the range of model projections.

However, to compare the observations from 2015 with the model estimates for 2020 is a mistake. It is obvious that the model projections for the year 2020 and the temperatures that we will register in the future rely on the levels of CO2 from 2020. Hence, the levels of carbon dioxide concentrations would be higher than indicated in 2015. Therefore, we cannot directly compare these two since they are not comparable.

In order to make a comparison between 2020 projections and 2015 observations, specialists need to remove natural variability from this analysis. Natural variability represents the component of climate variability which does not rely on human factors. For instance, scientists should exclude the temperature anomalies registered during El Nino.

Summing up

The truth about climate models and how they work will help other scientists reveal how to develop better climate models. However, researchers wish to create very accurate climate models to predict whether we will fulfill the Paris goal or not. The mistake is that they do not use the right dataset to develop the models.

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William E. Eubanks
 

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

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