Climate Change:Evidence

Climate Change is not a new thing

The worlds climate has been changing over the last 18,000 years, sometimes getting hotter and sometimes colder as you can see from the graph below. The period of time since the last

glaciation, about 10,000 years ago. We are still in the Holocene (the time since the end of the last major "ice age) today.

Is the name for a cold climatic event lasting about 1500 years which interrupted the warming of the Earth after the last ice age.

Little Ice Age is a time of cooler climate in most parts of the world.

Where do we get evidence for climate change from?

Ice Cores • Best evidence for climate change comes from Greenland and Antarctic ice cores.

• Ice cores are a frozen record of past climates (like a time capsule).

• Within these layers the ice contains air bubbles which contain carbon dioxide and oxygen isotopes.

Location of the

Greenland ice

cores

Ice Cores- How accurate and reliable are these sources of data?

• The sequences of sea level change links very closely with oxygen and CO2 isotope levels suggesting that this is a very reliable source.

Evidence from recent weather observations

• One effect of climate change is that extreme weather events are likely to get more common in the future.

• So do recent weather records show any evidence that the weather is getting more extreme?

Evidence of climate change in Iceland?

• Mean temperatures is 3.5°c in Stykkisholmur, a small fishing port on the west coast of Iceland.

• The mean July and August temperatures here are below 10°c.

• However, in July 2008, Iceland experienced its hottest summer on record – between 24-27°c (higher than Portugal temperatures)

• Evidence of climate change?

Study the graph. Describe the trend in annual temperatures in Stykkisholmur between 1800 and 2000. (5)

• The trend of the graph shows the annual temperature increases.

• It does not rise at a steady rate • As the average temp starts to drop around

1850 and then rise again and then drops again in 1950.

• The temp increases on average from 2.5 to over 4.0

• It was at its highest in 2003 at 5.4