Evidencing Climate Change Flashcards
Complete the sentence
As time went by the Global Annual Average temperature _____________________
As time went by the Global Annual Average temperature increases
Define Quaternary Period
The Quaternary Period is a period of time which stretches from 2.6 million years ago to the present day. It is in the Cenozoic era.
What does the quaternary period mark.
This period marks a time when there was a global drop in temperature and the most recent ice age began. The Quaternary Period is split into two epochs, the Pleistocene epoch and the Holocene epoch.
Define Climate Change
Climate Change is a long-term change in the Earth’s climate, especially a change due to an increase in the average atmospheric temperature.
How has climate changed (from the quaternary period - most recent period before the present)
The entire Quaternary Period is often called an ice age due to the presence of a permanent ice sheet on Antarctica.
During the Pleistocene epoch there were cold glacial episodes lasting approximately 100,000 years, which was then followed by an ice-free period of a warmer interglacial episode.
These warmer intervals were much shorter, lasting 10,000 years. We are currently in one of these interglacial episodes.
Give examples of the evidence for climate change
Ice Cores
Ocean Sediments
Weather Recordings
Rocks and Fossils
Ice Cover and Glacial Retreat
Proxy Data
How do Ice Cores evidence climate change
Antarctic ice cores are crucial in understanding long-term climate change. As Antarctica has no long-term residents, the layers of snow remain untouched.
The layers of snow contain information about the climate at the time the snow fell, and as this builds up over time, it creates layers of information.
Ice cores can be drilled to expose these layers of snow, which can be tested and analysed.
locked inside ice are molecules and trapped air, which are preserved year on year with more snowfall.
Subtle changes in temperature can be measured from ice cores extracted in Antarctica.
The deeper the snow that is drilled, the older the snow. Records go back about 800,000 years.
Oxygen isotopes in the ice cores are commonly used to estimate what the temperature would have been. Also, when the ice cores are melted, the levels of methane and carbon dioxide they release can be compared to today’s level of those gases.
These records are not as reliable as they only indicate climate change rather than providing direct evidence of accurate temperatures.
How do Ocean Sediments evidence climate change
As with ice, the deeper the sediment, the older the sediment is.
The billions of tonnes of sediment at the bottom of the ocean act as a timeline for providing evidence of climate change.
Organisms and remains of plankton in the sediment reveal information such as past surface water temperatures and levels of oxygen and nutrients.
These records are not as reliable as they only indicate climate change rather than providing direct evidence of accurate temperatures.
How do Weather Recordings evidence climate change
Since 1914, the Met Office has recorded reliable climate change data using weather stations, satellites, weather balloons, radar and ocean buoys.
The Earth’s average surface air temperature has increased approximately by 1 degree Celsius over the last 100 years.
Sea levels have risen by 19cm since 1900 and are expected to continue to rise due to sea ice melting.
Ocean temperatures are the warmest they have been since 1850, and the world’s glaciers are decreasing in size.
How do Rocks and Fossils evidence climate change
Rocks and fossils can be studied for information covering longer time periods.
For instance, limestone found in Yorkshire would have been formed on the bottom of a warm seabed millions of years ago.
These records are not as reliable as they only indicate climate change rather than providing direct evidence of accurate temperatures.
How do Ice Cover and Glacial Retreat evidence climate change
Areas such as Greenland and the Arctic have seen thinning of ice sheets.
NASA’s data shows that since 2002, the volume of ice lost in Antarctica is 134 billion tonnes per year, and 287 billion tonnes per year in Greenland.
These records are not as reliable as they only indicate climate change rather than providing direct evidence of accurate temperatures.
How do Proxy Data evidence climate change
Proxy data is data which is recorded by natural occurrences on the planet.
This includes tree rings, fossil pollen, ice cores and ocean sediments which are used to estimate what the climate was like.
E.g.
Each year a tree grows, it forms a new ring. The width of the ring indicates the climatic conditions for the year. The thicker the ring, the warmer and wetter the climate for that year. Tree rings are useful for giving an indication of climatic conditions over time.
Analysing pollen preserved in peat bogs or the bottom of lakes indicates the species living in the past. This indicates temperatures based on what we know about the conditions different plants thrive in.
However, these records are not as reliable because they only indicate climate change rather than providing direct evidence of accurate temperatures.
