1.2 - Natural causes of climate change Flashcards
Name four natural processes that lead to changes in global temperature.
asteroid collisions,
orbital changes,
volcanic activity,
variations in solar output.
Over what timescale do sunspots operate?
Every 11 years
What are sunspots?
Sunspots are intense magnetic storms on the sun’s surface which send extra solar radiation/heat to the Earth.
They work on an 11-year cycle, i.e. the strongest is every 22 years.
What caused the ‘Little Ice Age’?
Between the 1715 and 1745 there very few sunspots. This meant less radiation/heat reached the earth from the sun, leading to global cooling.
How can an asteroid strike lead to global cooling?
If a very large asteroid hit the earth huge amounts of material/dust would go up from the ground and into the atmosphere. This material would then reflect more of the sun’s light and the earth’s temperature would fall very fast.
Why don’t sunspots account for ice ages?
Sunspots operate on cycles of 11 years, ice ages last 100 000 years so are caused by orbital changes that operate over much longer timescales.
What are Milankovitch Cycles?
Milankovitch Cycles are changes to the way that the earth orbits around the sun over fixed timescales. These changes affect the amount of energy received by the Earth and therefore the temperature.
Which Milankovitch cycle operates over 100,000 years?
The shape of its orbit can change – sometimes circular, sometimes very elliptical. This varies every 100,000 years and accounts for ice ages.
Which Milankovitch cycle operates over 40 000 years?
The amount it tilts: sometimes 23 degrees, sometimes more sometimes less so sometimes the Earth is tilted closer to the sun and sometimes further causing the seasons to be more pronounced.
Which Milankovitch cycle operates over 23 000 years?
Wobble on its axis: the earth sometimes faces completely towards the sun, sometimes completely away. This affects our seasons and creates greater differences between summer and winter.
Which gas emitted by volcanoes causes global cooling?
SO2 - sulphur dioxide.
What happened to global temperatures when Mt Pinatubo erupted in 1991?
In 1991 Mt Pinatubo, a volcano in the Philippines erupted. 17 million tonnes of sulphur dioxide was thrown into the atmosphere. The SO2 gas mixed with other gases and liquids in the atmosphere to make sulphur “aerosols”. The aerosols stopped sunlight reaching the Earth’s surface. Global temperatures reduced by 1 degree C.
How do volcanic eruptions cause climate change?
They cause cooling -
- incoming solar radiation is blocked by volcanic dust.
They could also cause warming -
- CO2 can be released in some eruptions.
How do asteroid collisions cause climate change?
Large quantities of ash and dust are kicked up into the atmosphere
This causes cooling
How does sunspot activity cause climate change?
More/less solar energy is released towards the Earth
