Answer:
1. Greenhouse gas - Without greenhouse gases, the Earth would be a frozen planet.
2. Increase of oxygen - The increase of oxygen caused a cooling event.
3. Asteroid impacts - Asteroid impacts caused climate catastrophes
4. Tectonic plates - Tectonic plates can warm or cool the planet
5. Cloud covering- Cloud cover complicates global warming
Explanation:
Explanations;
1. In the greenhouse effect, gases in the Earth’s atmosphere (such as carbon dioxide, methane and nitrous oxide) trap infra-red radiation from the Earth that would otherwise be radiated to space. Thanks to this natural process, the Earth’s surface has an average temperature of 15°C w1. Without these gases, our planet would be an icy -18°C, and life as we know it would not be possible.
2. Some 2.5 billion years ago, there was no oxygen in the Earth’s atmosphere. Although the Sun was less bright back then, our planet was habitable partly because the atmospheric concentration of methane was 1000 times greater than it is now. All this changed, however, with the Great Oxygenation Event, which was triggered by the presence of blue-green algaew5. These microscopic organisms had evolved to carry out photosynthesis, and they produced oxygen as a waste product.
3. Around 66 million years ago, the 10 km diameter Chicxulub asteroid collided with the Earth, resulting in the demise of the dinosaursw7. The impact threw dust into the stratosphere, which is thought to have blocked out 50% of the sunlight reaching the Earth. This would have compromised photosynthesis and led to the collapse of food chains. It would also have resulted in a dramatic fall in global temperatures, plunging the Earth into an ‘impact winter’ that would persist for a decade.
4. The Himalayan mountain range – formed as a result of the collision between the Indian and Eurasian tectonic plates – is a prime example of how plate tectonics can have an impact on climate. Over the past 50 million years, the slow uplift of the Himalayas has exposed new rock to chemical weathering. In this process, carbon dioxide from the atmosphere binds to certain minerals in the rock, reducing the amount of atmospheric carbon dioxide and cooling the planet.
5. Clouds have important consequences for the Earth’s climate. Low, thick clouds cool the Earth’s surface, while high, thin clouds warm the climate. Key to the formation of clouds are aerosols – tiny particles that are suspended in the atmosphere. They act as tiny ‘seeds’ on which water vapour condensesw10. Aerosols are much more than simply what you find in a hairspray can. They can be natural (such as dust or sea salt) or anthropogenic (such as pollutants or smoke). An increase in anthropogenic aerosols could therefore result in more cloud formation, which (depending on the cloud height) could potentially offset the full extent of global warming.
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