Warming seas are enticing octopus to British waters

Meaning:If something is infamous, it is well known — but known for something bad. That is the difference from famous: a famous singer is known for great songs, an infamous one for a scandal. At Brixham the octopus is infamous among the fishermen because it gets into their pots and eats the crab and lobster they were after.

Meaning:To withstand something is to take it without breaking, giving way, or being damaged. You withstand a force pressing on you — heat, cold, wind, weight. In the article, cod and haddock cannot withstand the warmer water: above a certain temperature their bodies no longer work properly, so they do not stay.

Meaning:Your livelihood is the work you earn your living from — the money that pays for your food and your home, not just a job you could drop tomorrow. The word points at the thing you depend on. For the Brixham fishermen, crab and lobster are the livelihood, so when those animals vanish from the pots, their income vanishes with them.

Bluefin tuna were once everywhere off the British coast. Then they were gone — and the sea itself had not changed. People had simply caught them faster than new tuna were being born. Fisheries scientists call this overfishing.

Here is how it works. A fish population is not a fixed pile of fish. Every year some are born and some die, and the number born depends on how many adults are left to breed. If boats take fewer fish each year than are born, the population holds steady and you can go on fishing forever. If boats take more, fewer adults are left, so fewer young are born the next year, so there are fewer adults the year after that. Each year of over-catching makes the next year worse.

Picture a bowl at home that gets refilled with ten sweets every Sunday. Take ten a week and the bowl never runs out. Take fifteen and it is empty within a month. Fish are harsher than the bowl, though, because the fish are the refill. Take too many adults and next Sunday's refill is smaller too.

That is the part worth remembering. Overfishing does not just shrink today's catch — it shrinks the thing that makes next year's.

Read that sentence closely, because it does not say what people often think it says. It does not say the sea off England is 2.2°C. It says it is 2.2°C warmer than something — "average conditions over the previous 40 years". The comparison is the measurement.

Sea-surface temperature is the temperature of the ocean's top layer, roughly the first few metres. Climate scientists watch that layer because it is the part the sun heats directly and the part most sea creatures live in. Satellites read it from above and floating buoys read it from in the water, day and night, all over the world. Average all the readings around England and you get a single number — the mean.

But one number on its own tells you nothing. Is 17°C warm for the sea off England? You cannot say until you know what it normally is. So scientists first work out the ordinary value by averaging many past years — 40 of them here. That long average is called the baseline. Every new reading is then reported as the gap from the baseline, and the gap is what shows whether anything is changing.

You already think this way about your own results. Getting 18 out of 25 on a test means nothing by itself. It means a great deal the moment you know you usually get 12. A baseline is what turns a number into news.