1A - Climate Change Flashcards
What is climate change?
Is any significant change in the Earth’s climate over a long period
What is the Quaternary period?
Is the most recent geological time period (spanning from 2.6 million years ago to today)
What was the Earth’s climate like in the period before the
Quaternary?
The Earth’s climate was warmer and quite stable
During the Quaternary, what happened to the global temperature?
Shifted between cold glacial periods (lasted around 100,000 years) and warmer interglacial period (lasted around 10,000 years)
What has been happening since the last glacial period ended (around 15,00 years ago)?
The climate has been warming
What is global warming used to describe?
Used to describe the sharp rise in global temperatures over the last century
Name 4 sources of evidence for climate change
- Ice and Sediment Cores
- Tree Rings
- Pollen Analysis
- Temperature Records
What are ice sheets made up of?
Layers of ice
When is a layer of ice formed?
Each year
How can we tell what temperature was each year using ice and sediment cores?
By analysing the gases trapped in layers of ice they can tell what the temperature was each year
e.g. ice core from Antarctica shows the temperature changes over the last 400,000 years
As trees grows, when do they form a new ring?
Each year
What conditions are the rings on trees thicker?
The tree rings are thicker in warm, wet conditions
How can we tell what the climate was like each year using tree rings?
Scientists take tree cores and count the rings to find the age of the tree → thickness of each ring shows what the climate was like
Explain how analysing pollen can provide evidence for climate change
- Pollen from plants gets preserved in sediment
- Scientist can identify and date the preserved pollen to show which species were living at the time
- Scientists know the conditions that plants live now, so preserved pollen from similar plants show that climate conditions were similar
Explain how temperature records can provide evidence for climate change
- Since the 1950s global temperatures have been measured accurately using thermometers (gives reliable but short-term record of temperature change)
- Historical records (e.g. Harvest dates, newspaper weather reports) can extend the record of climate change a bit further back
Name 3 natural possible causes of climate change?
- Orbital Changes
- Volcanic Activity
- Solar Output
Explain how orbital changes could have caused climate change
- The way the Earth moves around the Sun changes
- These changes affect amount of solar radiation (how much energy) earth receives - more energy, it gets warmer
- Orbital changes may have caused the glacial and interglacial cycles of the Quaternary period
Explain how volcanic activity could have caused climate change
- Major volcanic equations eject large quantities of material into the atmosphere
- Some of these particles reflect the Sun’s rays back to space so the earth’s surface cools
- Volcanic activity may cause short-term changes in climate E.g. Cooling that followed the eruption of Mount Pinatubo in 1991
Explain how solar output could have caused climate change
- The Sun’s output of energy isn’t constant
2. Periods when solar output is reduced may cause the Earth’s climate to become cooler in some areas
What do most scientists think about the solar output causing climate change?
Most scientists think that changes in solar output don’t have a major effect on global climate change
Why doesn’t CO2 that volcanoes release cause global warming?
They don’t release enough
What (generally) causes global warming and how?
Human activities are causing global warming by making
the greenhouse effect stronger
What is the greenhouse effect?
It is where greenhouse gases (e.g. CO2 and methane) absorb outgoing heat, so less is lost to space