Question

Q.4) Write short notes :
1) Bleaching of coral reefs
2) Flash floods
3) Tools to study Paleoclimatolgy
4) Greenhouse gases​

Answer 1

Bleeching of coral reefs:When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white. This is called coral bleaching.

Flash floods:A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions.

Tools to study paleoclimatlogy:Paleoclimatology is the study of past climates. Since it is not possible to go back in time to see what climates were like, scientists use imprints created during past climate, known as proxies, to interpret paleoclimate.

Greenhouse gases:A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range.

Answer 2

Answer:

• Bleaching of coral reefs:

                                        When corals are stressed by changes in conditions such as temperature, light, or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white. Warmer water temperatures can result in coral bleaching. The leading cause of coral bleaching is climate change. A warming planet means a warming ocean, and a change in water temperature can cause coral to drive out algae. Coral may bleach for other reasons, like extremely low tides, pollution, or too much sunlight.

• Flash floods:

                     Flash flooding occurs when it rains rapidly on saturated soil or dry soil that has poor absorption ability.lash flooding can also be caused by extensive rainfall released by hurricanes and other tropical storms, as well as the sudden thawing effect of ice dams. Human activities can also cause flash floods to occur.

The deadliest flash flood in history occurred on August 11, 1979 in the town of Morbi in the Indian state of Gujarat. The Machchhu II dam is located on the Machhu river and burst after holding back several days of heavy rainfall.

• Tools to study Paleoclimatolgy:

                                                 Paleoclimatology is the study of past climates. Since it is not possible to go back in time to see what climates were like, scientists use imprints created during past climate, known as proxies, to interpret paleoclimate. Organisms, such as diatoms, forams, and coral serve as useful climate proxies.

Historical or documentary evidence for past climatic conditions includes written temperature and precipitation records that can be found in ship logs, farm records, journals, and newspapers. These records, while useful, are limited to recent centuries.

• Greenhouse gases​:

                                Greenhouse gases are produced through activities which release carbon dioxide, methane, nitrous oxide and ozone CFC's (chlorofluorocarbons). These activities include: Burning coal and petrol, known as 'fossil fuels' Cutting down of rain forests and other forests. Greenhouse gases are gases in Earth's atmosphere that trap heat.

Six greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride. Of these six gases, three are of primary concern because they are closely associated to human activities.