Weather and climate, Year 9

It is cut off from the warm, moist sea air that powers it

提示Ask what was feeding the storm while it was out over the ocean.

为什么Evaporation from warm ocean water is the storm's fuel. Over land the supply stops and friction with the ground slows the winds, so the storm fades within days — though its rain can still cause serious flooding far inland.

hurricanes; typhoons; cyclones

提示They are three regional words for exactly the same kind of spinning storm.

为什么The storm is identical; only the label changes with the ocean. Meteorologists use 'tropical cyclone' as the general term for all of them.

The eye

提示Satellite pictures show it as a round dark hole in the swirl of cloud.

为什么Air sinks in the centre, so winds are light and the sky may even clear. Around it stands the eyewall, a ring of towering cloud with the storm's strongest winds and heaviest rain.

Water — the storm surge and flooding caused by heavy rain

提示Think about the sea being pushed ashore, and what the clouds release.

为什么Low pressure and powerful winds heap the sea into a surge that can rise several metres above normal tides, while the storm's rain floods rivers far inland. Around the Bay of Bengal, surges sweeping over low islands have caused the greatest loss of life.

A glacier

提示No river could lift blocks that size uphill; something frozen and far more powerful did.

为什么Boulders dropped far from the rock they came from are called erratics. They are among the clearest signs that ice once covered Britain: only a moving ice sheet could pick up such blocks and set them down on foreign ground.

It was locked up in ice sheets on land

提示Snow that fell on the continents stopped draining back to the ocean.

为什么With so much water frozen on the continents, the bed of the North Sea was dry and Britain was joined to mainland Europe by a plain now called Doggerland. As the ice melted the sea rose, and Britain became an island about 8,000 years ago.

The Little Ice Age

提示Its name makes it sound like a smaller version of the great freeze that ended thousands of years earlier.

为什么Londoners held 'frost fairs' on the frozen Thames, the last in 1814. The cooling was natural and modest, yet it was enough to shorten growing seasons — a reminder that climate has always shifted.

An interglacial

提示The prefix means 'between', as in 'international'.

为什么Over the last 2.6 million years, long cold glacials have alternated with shorter warm spells. The present one began about 11,700 years ago, and farming and cities have grown up within it.

carbon dioxide

提示Plants take it in for photosynthesis, and you breathe it out.

为什么Its level in the air has risen from about 280 parts per million before the Industrial Revolution to about 427 in 2025 (NOAA) — higher than at any time in the ice-core record.

It is far faster — more than 1 °C in about 150 years

提示The natural thaw was spread across many millennia.

为什么As the Ice Age ended, the world warmed by a few degrees over several thousand years. The recent rise — about 1.4 °C since the late 1800s (WMO, 2025) — has come many times faster, and it tracks the rise in greenhouse gases from human activity.

Sea ice

提示It floats, and it forms when the ocean surface freezes.

为什么Satellites give an independent check on thermometers: the frozen ocean left at the end of the Arctic summer has shrunk by about 12% per decade since 1979 (NSIDC). Different instruments, same story.

greenhouse

提示It is named after a glass building that keeps plants warm.

为什么Some of this effect is natural and keeps Earth warm enough to live on. Burning fossil fuels and clearing forests add extra heat-trapping gas and strengthen it — that added part is what is warming the planet.

Climate change mitigation

提示Switching from coal to wind power is one example.

为什么It deals with the cause: less greenhouse gas going into the air, or more taken out by forests. Its partner, adaptation, deals with the effects that arrive anyway.

Some warming and sea-level rise are already under way

提示Carbon dioxide released decades ago is still in the air.

为什么The gases already emitted stay in the atmosphere for a long time and the oceans are slow to respond, so some change is locked in. That is why most plans pull both levers: cut the cause and prepare for the effects.

Thames Barrier

提示The first word is the river it spans.

为什么In use since 1982, its ten steel gates can be raised to shut out a surge coming up the estuary from the North Sea. It had been closed more than 220 times by late 2025 (Environment Agency), and rising sea level means it will be needed more often.

2050

提示It is the middle of this century.

为什么Net zero means any emissions still produced are balanced by an equal amount removed from the air. The target became law in 2019; closing the last coal-fired power station in 2024 was one step towards it.