2016-10-21 12:35:12
We are used to seeing immediate weather forecasts, thanks to which we know with a certain approximation the behavior of the weather a few hours or days in advance. These predictions are not exact, but they tell us what is the probability that in our locality it will be cloudy, rainy, snowy or sunny.
When we talk about the climate, however, the vision is much broader. The weather does not tell us if it is going to rain in the next few hours in our town, but it speaks of the average conditions that may exist within tens, hundreds, or even thousands of years, in large regions of the planet. In the long term, the number of factors involved are so diverse and can vary so much that one can no longer speak of “predictions” but rather of climate “projections”. Our guest, Manuel de Castro Muñoz de Lucas, is Professor of Earth Physics at the Faculty of Environmental Sciences and Biochemistry at the University of Castilla-La Mancha, explains to us today how climate projections are made and the factors that must be taken into account in calculating future climate behavior.
To obtain a climate projection it is necessary to use mathematical models based on the equations provided by the laws of Physics. Solving these mathematical equations is not easy, they have nothing to do with the ones we solved in high school or university, in order to extract information you have to use very powerful computers.
The climatic conditions of the different regions of the Earth make it necessary to divide the planet into smaller parcels, as if it were an immense honeycomb, for study. A typical parcel usually has dimensions of 50 kilometers wide and 50 km long and several hundred meters high. Although, on our scale, they do not seem small, they are compared to the size of the Earth. In fact, it takes billions of trillions of cells that size to cover the entire planet. The challenge of climate prediction is to solve the model equations in each and every one of those cells.
In order to achieve a climate projection tens of years from now, the models must be fed with the initial data on pressure, temperature, humidity, wind speed, etc. and, most importantly, take into account the future behavior of human beings, who, as is known, is contributing significantly to the evolution of the climate with the excessive release of greenhouse gases. The computing power required to meet the challenge requires the use of the most powerful computers in the world. Even so, Manuel de Castro tells us, months of calculations with the largest existing supercomputer are needed to obtain a climate projection that, ultimately, gives us a probability that the climate will evolve in one direction or another.
There are only a few computing centers in the world with supercomputers capable of addressing climate projections for the entire planet in their entirety, and alongside them are hundreds of research sites, such as the Numerical Modeling for the Environment Group of the UCLM, with less powerful supercomputers, but capable of addressing the problem in smaller regions of the globe. Taken together, they all provide extraordinary research and computing power that enables them to make climate projections that are giving us an ever clearer picture of future climate challenges.
Although the mathematical equations of the models are the same for all of them, the parameters that are introduced in them can vary slightly from one model to another. But the climate is a chaotic system and small variations can lead to large differences in behavior, hence the projections are not exact but have a probability associated with them. Thus, future climate projections face many different challenges.
However, the results obtained already allow us to give an image of the dangers that lie in wait for us in the future, if the human being continues to release greenhouse gases at the current rate. These results are what have allowed the Intergovernmental Panel of Experts on Climate Change (IPCC) to prepare reports that have helped 195 countries sign the first binding global agreement at the Paris Climate Conference (COP21), held in December 2015.
At the University of Castilla-La Mancha, Manuel de Castro directs the (MOMAC) group where a dozen researchers use an HPC supercomputer to make, in collaboration with European and Ibero-American research groups, future climate projections on a regional scale in Europe and South America.
I invite you to listen to the explanations of Manuel de Castro Muñoz de Lucas, Professor of Earth Physics at the Faculty of Environmental Sciences and Biochemistry of the University of Castilla-La Mancha in Toledo (Spain) and director of the Institute of Environmental Sciences of the UCLM.
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