Humans, dependence on fossil fuels is heating up the planet with an unprecedented rate. Governments and policymakers must take urgent action. That action is guided by what science says by the impact of climate change on the earth.
This is how it’s. Calculated [ Music ]: this is ver Hamby Agnes. At the end of the 19th century, he devised formulas which linked the flow of heat, water and air 50 years later. His ideas were the basis of the first computer model, the atmosphere, a modern day, weather forecasting is born today’s.
Climate models are the highly evolved descendants of that original, except the computers, as some twenty-five trillion times faster here’s, how it works. Scientists divide the Earth’s, atmosphere into a grid of hundreds of thousands of cells and stacks like a skyscraper.
The model used by the Met Office, Britain’s. National Weather Service, for example, uses stacks, which are 85 cells high. The models then calculate how energy air and water vapor flow through each cell over a given time period.
Well, weather forecasting takes a snapshot of the atmosphere at a given time and predicts what will happen over the next few days. Climate models consider the atmospheres behavior over years and years, simulating either the world as it is, or the world as it might be.
They sketch out the sort of processes and the sort of results that you might see and that allows you to inform policy to some extent. One of the classic things that climate models have always done is just look at the world.
If the carbon dioxide level were twice as high as it is today, that was one of the first ways that climate models began to illustrate the fact that greenhouse warming really was likely to be a problem in the 21st century for all their complexity.
These models have limitations, although you’re, cutting the atmosphere into millions of cells, the atmosphere it’s, a very big thing and a millionth of a big thing is still a pretty big thing, so the cells tend to be there.
Maybe hundreds of kilometers on a side. This means the models, often struggle to capture details like cloud cover and clouds play a key role in climate. As greenhouse gases made the atmosphere warmer, it changed the amount of water vapor it can hold and how air rises and falls that in turn, changes the amount and character of cloud cover, depending on where clouds form they can either trap.
Sunlight which warms the planet will reflect it back into space, cooling it and some processes which govern cloud formation work on a very small scale, so you can’t actually model those precise processes in the computer models.
They have to build various different rules of thumb mean for what would you expect the clouds to be doing how you do that means that your model will behave differently compared to someone else’s model where they do that in a different way.
Dozens of these models exist run by teams all over the world. The modelers all want to capture the earth as close as possible to how it is, but there are assumptions about how that actually works differ from model to model and the ways that they implement.
Those assumptions change, some models tend to people say, run hot, so they tend to provide more warming for a given amount of carbon dioxide, and some models tend to run a little cold every few years.
The models are brought together, fed standardized questions and then their results are compared. This helps scientists understand the strengths and weaknesses of different climate models and improves them.
Of course, it’s impossible to assess the model’s future projections, but what researchers can do is compare the success of models from previous decades. A recent report compared the models from the 1970s to the 2000s, and it found that by and large they were reasonably good that the warming that would actually seen sat within the error bars for most of them.
So it gave us a like general sense that these things weren’t completely out of the park. The climate models are getting increasingly complicated, capturing more aspects of the earth, but there is one element that is impossible to model and it is the biggest contributor to climate change.
[, Music, ]. The thing about human activity is that you can’t get it inside the model. The model deals with sort of like physical laws of chemistry and physics and biology so that there’s no way the model can say well.
In 2050, America will have stopped emitting carbon dioxide. Instead, scientists take simplified results from these climate models and run them through economic models. In 2013, scientists use these models to examine the effect of different climate policies on the future temperature of the planet.
The first looked at what would happen if there was continued large-scale use of coal, the second, if there was continued use of fossil fuels, but some use of renewable energy. The third, if there was a much higher uptake of renewable energy and the fourth, if there was a lot of use of carbon capture technology more land to grow biofuels, the striking thing about those comparisons and by other combatants will come out later.
Is the only really tough climate policies? Get you the sort of trajectories which keep the temperature, in the words of the Paris agreement well under two degrees above the pre-industrial? What these models tell us is that the current level of emissions reduction is not remotely enough to have any assurance that you will stay under two degrees left, even less all right, close to 1.
5 degrees, climate models, don’t predict the future and they’re, not perfect. There is a long way to go before they fully represent all of Earth’s, intricate processes, but for now they are the only way the scientists have understanding how damaging an increase in carbon dioxide will be for the planet.
Ultimately, the solution to climate change won’t lie inside models, but rather what humans choose to do with the information they provide? I’m. Oliver Morton I’m. The briefings editor at The Economist.
We’ve, written a series of climate briefs to cover the basics and a bit more than the basics, on all sorts of aspects of the climate crisis that’s facing the earth. You can read them all at the link opposite.
Thank you for watching.