The Conditions For Life on Earth

Prevents most gases from escaping into space. Atmospheric pressure high enough to prevent liquid water boiling.

Produces suitable temperatures

At an angle to its orbit around sun to produce seasonal variation.

Deflects solar winds that strip the atmosphere.

Enzymes don’t denature, biological processes can occur.

2.7 billion years ago, Archaea developed ability to photosynthesise. Oxygen reacted with iron in oceans. 2.45 billion years ago, surplus of oxygen released in atmosphere. Oxygen absorbed UV, created ozone. 540 million years ago, most Archaea and anaerobic respiration died out, aerobic organisms evolved.

Inter-connected biological processes developed = relatively small amounts of nutrients could support life for long periods.

Once plants evolved + colonised, returned water vapour to atmosphere, increased precipitation in areas = more plant growth.

Solvent Transport within organisms Temperature control High specific heat capacity aquatic habitats Uv absorption

CO2 for photosynthesis, nitrogen for protein synthesis, greenhouse effect.

Warm enough for liquid water, not hot enough to denature proteins.

Sun for photosynthesis, provides energy. Infrared absorbed, converted to heat.

• Lack of ancient historical data. • Limited reliability of proxy data. • Limited coordination between researchers. • Lack of sophisticated equipment for accurate measurements. • Inability to measure many factors. • Lack of data collected in many areas.

• More accurate, quantitative data. • Can extend further back in time. • Allows collection in remote areas. • Data collected continuously. • Data collected is more reliable than proxy data.

Dendrochronology - Tree’s growth rate changes in response to seasonal climate changes. Can be altered by other things. Pollen analysis - Determine what plants were living in an area at a particular time.