The Causes of Global Climate Change

How has the global temperature fluctuated in the past? What were the causes of these changes?

Describe the pattern of climate change shown above

Climate Forcing: Any mechanism that alters the global energy balance and ‘forces’ the climate to change in response.

Climate Forcing: Any mechanism that alters the global energy balance and ‘forces’ the climate to change in response.

What are the Natural Causes of Climate Change?

Solar Output Describe the pattern of solar output from 1800 to 2000. What are the two main patterns that you see?

Solar Output

Describe the pattern of solar output from 1800 to 2000.

What are the two main patterns that you see?

2. Volcanic Eruptions What effect do volcanic eruptions have on global climate? Use the diagram on the right to explain the effect of volcanic eruptions on the climate

3. The Milankovitch Cycles Why would the surface temperature of the earth change if the tilt of the earth or orbit changes?

There is overwhelming evidence to suggest that our current climate is different from that of previous human experience: The level of Co2 in the atmosphere is far above the “natural” level and continues to rise 11 of the 12 warmest years on record occurred between 1995 and 2006 1950 to 2000 was the warmest 50 year period for 1300 years Temperature rises have been recorded on all continents since 1970 Satellite observations since 1993 suggest an annual rise in sea level of 3.1 mm Extreme weather events are increasing

So shouldn’t we just blame only natural causes for the warming that we are experiencing today?

The observed widespread warming of the atmosphere and ocean, together with ice mass loss, support the conclusion that it is extremely unlikely [<5% chance] that global climate change of the past 50 years can be explained without external forcing and very likely that it is not due to known natural causes alone. During this period, the sum of solar and volcanic forcings would likely [>66% chance] have produced cooling, not warming. IPCC 4 TH Assessment 2007

The observed widespread warming of the atmosphere and ocean, together with ice mass loss, support the conclusion that it is extremely unlikely [<5% chance] that global climate change of the past 50 years can be explained without external forcing and very likely that it is not due to known natural causes alone. During this period, the sum of solar and volcanic forcings would likely [>66% chance] have produced cooling, not warming.

IPCC 4 TH Assessment 2007

What are the Human Causes of Climate Change?

Suggest the causes of the sudden increase in green house gases after the 1800’s? What are the sources of greenhouse gases?

Where previously, temperature rise has caused a rise in Co2, in the modern era, it is Co2 which is preeceeding the temperature increase.

http://mabhobs.org/de/content/global-temperature-world-population-co2-concentration-graph-1880-2008

Go www.thegeographer.co.uk/videos Click on 11 th Hour and make full screen. Select the section from 12- 28min Watch and make notes.

Go www.thegeographer.co.uk/videos

Click on 11 th Hour and make full screen.

Select the section from 12- 28min

Watch and make notes.