The detail of modern science is incomprehensible to almost everyone, which means that we have to take what scientists say on trust.
He does this in the context of climate change science. I wonder if he actually tried to read the key paper that describes why we know that the global temperature is increasing. The paper is Uncertainty estimates in regional and global observed temperature changes: a new dataset from 1850. Go on, read it. I dare you.
The critical thing you need to be able to understand to understand that paper is... how to calculate an average. That's a GCSE level maths subject; here's a quick page to revise that in case you've forgotten how to average.
Because, you see, the entire process described in that paper involves the following steps:
1. Get temperature data (i.e. thermometer readings) at different places around the world for many, many years
2. Work out the average temperature at each location by averaging the values between 1961 and 1990 on a monthly basis. So you end up knowing things like the average January temperature at Heathrow.
3. Now go back and work out how much the temperature for any given month and year deviates from the average: all that means is subtract the average temperature from the observed temperature for the same month. Now you know how 'different' the temperature is. This is called the anomaly. If it's getting hotter the anomalies will get bigger.
4. Divide the globe up into squares 5 degrees on each side. Find all the thermometers inside each square, find their anomalies for each month and year. Average them to get an average anomaly for that square.
5. Take all the squares in the northern hemisphere, average their anomalies for each month and year. Draw a graph showing the temperature changing. Repeat the for southern hemisphere.
6. Now take the northern and southern hemisphere temperatures for each month and year and average them to get a global temperature anomaly chart.
Child's play? Yes.
I'll admit that the rest of the paper has some harder concepts (standard deviation, anyone?). But I'll wager that the real reason that people don't understand science is not because it's too hard to understand, but because they aren't motivated.
Yes, there are parts of science that require a lot of knowledge, but covering your eyes and not trying to understand is likely where many people go wrong.
Or to put it Monbiot's way:
My heart rebels against this project: I would rather be pelting scientists with eggs than trying to understand their datasets.