10.4 Human effects on ecosystems

Global Warming

the mean global increase in surface/atmospheric temperatures, known as global warming

Human effects on ecosystems

Climate change - increased co2 levels

Depletion of resources - by overfishing

Loss of biodiversity - loss of habitats for farming

Role of greenhouse gases

reduce heat loss from the surface of the Earth

Greenhouse effect

Short wavelength infrared penetrates atmosphere to get to the surface of Earth. Earth radiates longer wavelength infrared. Water vapour and greenhouse gases absorb this infrared and re-radiate it, warming the Earth’s surface.

How can scientists measure how temperature has increased over the years?

thermometer readings, tree rings, ice cores, corals, and peat bog data

Using ice cores

Scientists drill deep down into the ice and then analyse the air trapped in different layers. The oxygen isotopes in melted ice reflect the air temperature when the ice was laid down.

Dendrochronology

the dating of past events using tree ring growth

Peat bog dating

using cores taken from peat bogs that show growth patterns over hundreds or even thousands of years

Main sources of methane

* decay of organic material by some species of bacteria, particularly in wet conditions
* digestion of herbivores like cows, sheep
* growing crops in waterlogged soil

Ocean acidification

The ocean absorbs CO2 which causes ocean acidification

Evaluation of rising CO2 levels data

correlational, so cannot decide if increase in greenhouse gases are causing increasing temperatures or are the result.