1.2.1 Climate Change Flashcards
Quaternary period
The Quaternary period has lasted for the last 2.588 million years.
Neogene
The Neogene period lasted 21.4 million years.
-The Earth was warmer than it is now in the period before the Quaternary period (called the Neogene period).
Within the Quaternary period
- Over the last 300,000 years, there is a cycle between glacial periods and interglacial periods.
- Glacial periods are cold and last for roughly 100,000 years.
- Interglacial periods are about 7 degrees warmer on average and last about 8,000-12,000 years.
Within the last 200 years
- Interglacial periods usually last 8,000-12,000 years.
- 200 years is very small on this timescale.
- NASA scientists find that the Earth has warmed by 0.8 degrees Celsius since 1880. Most of this warming has happened since 1970.
- Without changes to our current behaviour, some studies expect the Earth’s temperature to be 4.1°C – 4.8°C higher than in 1880 by 2100, which is 4°C more of warming by 2100.
- The behaviour of the last 150 years is what we call climate change.
The greenhouse effect
-The scientific consensus is that human activities are responsible for the recent increase in global temperatures because they are strengthening the greenhouse effect.
—> The greenhouse effect happens when greenhouse gases (e.g. carbon dioxide, methane) absorb heat that has been reflected off the Earth and re-radiate this heat back towards Earth.
Ice cores showing climate change
- Ice cores can be extracted by drilling into ice sheets.
- Each year, a new layer of ice freezes onto the top of an ice sheet.
- Examining the gases in each layer of ice can show us what the climate and temperature were like hundreds of thousands of years ago.
- Sometimes there are fossils or sediments that can give scientists even more information.
Tree rings showing climate change
- Every year, a new ring forms in the trunks of trees.
- Rings are thicker in good conditions for growth (temperate and wet climate).
- Counting the number of tree rings can show that tree’s age.
- Tree rings give us data on the climate and temperature for up to the last 10,000 years.
Temperature records showing climate change
- Temperatures have been recorded globally since 1850, however, global records are a lot better from the last 50 years.
- This data is very reliable but only stretches back 170 years.
Pollen analysis showing climate change
- Plant pollen can be preserved in sediment.
- Comparing plant pollen from sediment and plan pollen from now can indicate what differences have occurred between the current climate and past climate.