General Knowledge · Class 11 · Geography and India
Climate and the oceans
The air has warmed about 1 °C in a century. But most of the extra heat did not go into the air at all. Where did it go?
Small test at the end: scroll down to the end of this page for five short questions that check what you have learnt. Tap an answer, then press Check answer. Go to the questions ↓
Jump to: Read first · Try it away from the screen · Check it yourself · Check yourself · For teachers
Read first
6 facts. The questions below make you use them, not just remember them.
- Oceans cover about 71% of Earth's surface. They have taken up more than 90% of the extra heat trapped by greenhouse gases, and about a quarter of the carbon dioxide we release.
- Carbon dioxide in the air has risen from about 280 parts per million before factories and engines to more than 420 now, mostly from burning coal, oil and gas.
- Sea level has risen about 20 cm since 1900, because warmer water expands and ice on land, like glaciers and ice sheets, melts into the sea.
- When the Pacific near South America becomes unusually warm, called El Niño, India's monsoon is often weaker.
- Carbon dioxide dissolving in seawater makes it more acidic, which makes it harder for corals and shellfish to build their shells.
- India has set a target of net zero emissions by 2070.
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Try it away from the screen
Fill a glass to the brim with cold water and ice cubes floating in it. Watch as the ice melts: does it overflow? Then think: why does melting ice on land raise the sea, while floating ice barely does?
Make it on paper. Keep it with you. Nothing to upload.
Check it yourself
Climate claims online range from "nothing is changing" to "the world ends next year". Check the reports of the Intergovernmental Panel on Climate Change (IPCC) or the India Meteorological Department, which give ranges and how sure they are.
Check yourself
Five questions about what this page teaches. Choose an answer and press Check answer, or open "See the answer and why". Nothing is saved or sent: your choices stay on this screen and disappear when you leave or reload the page.
How do you want to answer? You choose, and you can change at any time.
See the answer and why
- A. Into the air Not this one. The air has warmed, but it holds only a small share of the extra heat.
- B. Out into space, through holes in the ozone layer Not this one. The ozone hole is a different problem; it does not let the extra heat escape.
- C. Into the oceans Correct. Yes. More than 90% of it.
- D. Into the ground under cities Not this one. Land holds only a small share.
See the answer and why
- A. 50 Correct. Yes. The rise is 140, and 140 ÷ 280 = 0.5, or 50%.
- B. 150 Not this one. That is the new value as a percentage of the old one.
- C. 140 Not this one. That is the rise in parts per million, not the percentage.
- D. 33 Not this one. That divides by 420. A percentage rise compares with the starting value, 280.
See the answer and why
- A. Rivers carry more sand into the sea Not this one. Sand makes almost no difference to sea level.
- B. Floating sea ice melts and makes the sea overflow its edges Not this one. Floating ice already displaces its weight in water, so it barely changes sea level.
- C. More rain falls into the sea Not this one. Rain comes from evaporated sea water, so it does not add new water.
- D. Warm water expands and land ice melts into the sea Correct. Yes. Both add to sea level.
See the answer and why
- A. It is often weaker than usual Correct. Yes. El Niño is often linked to below-normal rain in India.
- B. It starts in December Not this one. The south-west monsoon still comes in June.
- C. Nothing at all; the Pacific is too far away to matter Not this one. Ocean warming far away can change winds and rain in India.
- D. It always floods the whole country Not this one. El Niño years are more often dry, not flooded.
See the answer and why
- A. It makes the water more acidic, so building shells is harder Correct. Yes. Acidic water dissolves the shell material.
- B. It makes the water freeze Not this one. It does not change the freezing point much.
- C. Shellfish breathe it in and choke Not this one. The harm is to their shells, through acidity.
- D. It makes the water too salty Not this one. Carbon dioxide changes acidity, not saltiness.
For teachers and grown-upsWhere the facts come from, and how to use this round.
Sources and notes
- IPCC AR6 (2021): about 91% of the energy increase is stored in the ocean; global mean sea level rose about 0.20 m from 1901 to 2018.
- CO2 levels: NOAA Mauna Loa record. India's net zero by 2070: announced at COP26, 2021.