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Climate change has change since the Quaternary Period. - Coggle Diagram
Climate change has change since the Quaternary Period.
What is the Quaternary period?
The period of geological time from about 2.6 million years ago to the present. The entire Quaternary period is often called an ice age to the presence of a permanent ice sheet on Antartica.
Climate change during the Quaternary period
There has been climate change during the Quaternary Period. Temperatures have fluctuated wildly, but overall have gradually cooled. There have been cold "spikes", which are shown as glacial episodes. In between each cold spike are warmer inter glacial episodes. Today we live in an inter glacial episode. The average temperature today is higher than almost of all of the Quaternary Period.
Climate Change Since 1000AD
Have been several periods of warming and cooling since 1000AD. The Mediavel Warming Period lasted from 950 to 1250AD. In some regions, the temperatures were equal or higher than today. However, overall temperatures were lower on average than today.
Modern Warming
In comparison to average temperatures from 1901-2000, average global temperatures have increased in the last few decades
Evidence for climate change
Global temperature data
NASA use over 1000 ground weather stations and satellite information to map global temperature. Average global temperatures have increased by 0.6 Degrees since 1850. However, weather stations are not evenly distributed, especially in Africa, so reliability could be questioned.
Ice cores
Scientists often use ice cores to detect changes in temperatures. When snow falls it traps air into the ice. When scientists take a sample of ice it reveals the atmospheric gas concentrations at the time the snow fell. This is used to calculate temperature at that time. The ice can reveal the temperature of each year for the past 400,000 years. Scientists that study the ice cores say there is clear evidence that there has been a rapid increase in temperature in the past decades.
Paintings and diaries
Diaries are written observations can suggest evidence of climate change at the time such as: Increase in price per a grain in Europe. sea ice preventing ships from landing in Iceland. People emigrating due to crop failures.
Tree Rings
The cause of climate change
Natural causes of climate change
Variation in energy from sun.
Sunspots are darker patches on the Sun's surface. They are caused by magnetic activity inside the sun. Sunspots increase from a minimum number to a maximum number in a sunspot cycle of about every 11 years. Scientists suggest that the more sunspots there are, the more heat is given off by the sun. However, solar output from the Sun has barely changed in the last 50 years, so it cannot be responsible for the climate change see since the 1970s
Changes in the earths orbit.
The distribution of the Sun's energy on the Earth varies due to changes around the Sun are called Milankovitch cycles. There are three of them: axial tilt, precession and eccentricity
Precession
The earth is not a perfect sphere, as the Earth spins it wobbles on it's axis in a 26,000 year cycle.
Eccentricity
The Earth's orbit around the sun is not fixed and changes over time from being almost circular to being mildly elliptical. The cycle takes 100,000 years. Colder periods occur when the Earth's orbit is more circular and warmer periods when it is more elliptical
Axial Tilt
The earth spins in its tilted axis. The angle of the tilt changes due to gravitational pull of the Moon. When the angle of the tilt is greater, it is associated with a higher average temperature. The angle of the tilt moves back and forth every 41,000 yrs
Volcanic Activity
Volcanic eruptions throw huge quantities of ash, gases and liquids into the atmosphere. When sulphur dioxide mixes with water vapour it becomes a volcanic aerosol. Volcanic aerosols reflect sunlight away, which reduces global temperatures. Wind carries material far beyond where it was ejected from the volcano, so the reduced temperatures also experienced elsewhere.