The argument that global warming is a serious problem rests on the output of climate models, vast computer simulations of the atmosphere, the oceans and the biosphere. But are climate models good enough to inform policymakers? This thread argues they are not. Not even close. 🧵
Climate models are *really* big. Millions of lines of code attempting to reproduce the physics of a highly complex system, creating an artificial world, its surface divided into cells of up to 100 km × 100 km in size, multiple layers of atmosphere above, and ocean below.
Unfortunately, some features of the climate operate at smaller than this. For example, clouds are much smaller than a typical grid cell. In these circumstances, a simplified model has to be used instead. This is called “parameterisation”.
However, parameterisation can lead to unphysical results. In a recent @netzerowatch paper, Willis Eschenbach explains that sometimes the proportion of the cell that is cloud covered can become negative! netzerowatch.com/climate-models…
Eschenbach outlines similar problems. For example, NASA’s Model E includes a bit of code to make virtual melt ponds on the polar ice caps refreeze when the physics programmed into the system fails to do so at temperatures below -10°C.
There are lots of issues along these lines in Model E. Sometimes wind speeds and temperatures go far outside reasonable bounds. The model even fails to conserve energy and mass, and there is a crude fix in place for this…
It’s not surprising then that climate models tend to be not very good at reproducing the real climate. For example, most overestimate warming in the tropical troposphere, a part of the atmosphere that is supposed to be diagnostic of global warming.
https://t.co/VR4wlVNZ7fthegwpf.org/publications/c…
Given the difficulties climate models have with clouds, it’s no surprise that they get rainfall wrong too. Most climate models suggest that almost all rainfall at low latitudes will be drizzle. Observations show that’s it’s less than half. https://t.co/FHh7xAOFtOrepository.library.noaa.gov/view/noaa/4471…
So when you are told that your area will become wetter or drier or struck by drought, remember that climate models are really bad at rainfall.
There is a lesson here for policymakers. If climate models don’t get key features of the climate correct, if they don’t conserve energy, if they are full of crude fixes to stop their output looking daft, they are of *no* relevance to the policy process.
Unfortunately, they are being used to justify an unprecedented economic and social upheaval, which is leading us towards disaster. https://t.co/2b3EdVAFHkthegwpf.org/publications/t…
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Yesterday, Lord Deben gave a speech in the Lords about adaptation. While getting going, he said “I look forward to a debate with my noble friend [Lord Frost] when I shall be quoting the science and he will be quoting the prejudices.” 🧵
https://t.co/OaDA8CoEBFhansard.parliament.uk/lords/2023-07-…
I thought it would be amusing to look at the detail of what he had to say, to see how much of it was science, and how much was “science” and prejudice. Take this, for example...
“We have rising sea levels, but I see very little in this report about how we are going to deal with that.”
Today, Grant Shapps is saying that everyone is going to need a heat pump by 2050. By coincidence, I've just written a paper on the subject. It shows that Shapps is utterly wrong. Heat pumps are a mistake for most people. 🧵
The economics of heat pumps are mainly driven by:
• the ratio of electricity and gas prices
• the heat pump ‘gain’ – the units of heat energy emitted for each unit of electricity used.
Heat pumps are therefore mostly deployed in countries with cheap electricity.
In the UK, the electricity:gas price ratio has been increasing for many years, as increasing penetration of renewable energy makes the grid progressively less efficient. The ratio is currently around 4.
Hi @ELPinchbeck You said that you were happy to debate windfarm costs on the basis of facts and data, so this is an attempt to do so. (1/12)
I suggested you pick a windfarm from 2018, so we could discuss the cost data. As you haven’t suggested one, I’ve picked one myself: Glenchamber Windfarm. Feel free to suggest another.
Here are my underlying assumptions. I have optimistic and pessimistic alternatives, and I’m using the optimistic ones.
Take a look at this graph from The Carbon Trust: (1/n)👇 It purports to show the income (CfD) of offshore windfarms and the estimated levelised costs (dark blue band)
Now see what it looks like when I add the levelised costs calculated from audited accounts (red dots) and predicted levelised costs using the model of Ioannou et al (which underestimates costs a bit, but is a reasonable starting point).