changing climate Flashcards
What is the Quaternary Period?
- The most recent geological time period
- 2.6 million years ago to the present day
What was the climate like before the Quaternary Period?
- The Earth’s climate was warmer and quite stable
What was the climate like during the Quaternary Period?
- Global temperatures shifted between cold glacial periods (100,000 years) and warmer interglacial periods (10,000 years)
How has the climate changed since the Quaternary Period?
- The last glacial period ended around 15,000 years ago
- Since then the climate has been warming
What is global warming?
- Term used to describe the sharp rise in global temperatures over the last century
- Type of climate change
How do ice cores give evidence for climate change?
- Ice sheets are made up of layers of ice - one layer is formed each year
- Scientists drill into the ice sheets to get long cores of ice
- By analysing the gases trapped in the layers of ice, they can tell what the temperature was each year
- Data collected from ice cores is very detailed and reliable
How does temperature data give evidence for climate change?
- Since the 1850s, global temps have been measured using thermometers
- Gives a reliable but short-term record of temperature change
- Weather stations are not evenly distributed - data is patchy
How do diaries and paintings give evidence for climate change?
- Historical diaries can show what the climate was like in the past
e.g. giving the number of days of rain, and the dates of harvest (early harvest suggests warm weather? - Paintings of fairs and markets on frozen rivers show that winters in Europe were much colder
- Not very reliable, gives one person’s viewpoint
How do sea ice positions give evidence for climate change?
- Sea ice forms around the poles in winter (when ocean temps fall below 1.8°C)
- Melts during the summer (when it’s warmer)
- By observing maximum and minimum extent of sea ice each year, can tell how ocean temps are changing
- Data is very reliable, however, accurate records don’t go far back
What are some natural factors that possible cause climate change?
- The Milankovitch Cycle
- Sunspots
- Volcanic activity
What is eccentricity and how does it cause climate change?
- The path of the Earth’s orbit around the Sun
- Earth’s orbit changes over time from being circular to mildly elliptical
- Complete cycle occurs about every 100,000 years
- Circular means colder periods
- Elliptical means warmer periods
What is axial tilt and how does it cause climate change?
- The Earth spins on its axis causing night and day
- Over a period of 41,000 years axial tilt moves between 21.5° and 24.5°
- The greater the tilt the higher the temp
What is precession and how does it cause climate change?
- The Earth’s wobble
- Complete cycle 26,000 years
- Accounts for long days and long nights
What are sunspots?
- Sunspots are cooler areas of the Sun’s surface that are visible as dark patches
- They increase the Sun’s output of energy
- Cycles of about 11 years
How do sunspots possibly cause climate change?
- Periods where there are very few sunspots, solar output is reduced
- Cause the Earth’s climate to become cooler in some areas
- Most scientists think that it doesn’t have a major effect on global climate change