Predicting changes: Studying past climates

  • Image: Laurin Rinder / Fotolia

  • Image: doglikehorse.com / Fotolia

  • Image: Luz Maria Espinoza / RGB Stock

  • Image: Science Museum

  • Image: NASA

  • Image: Science Museum

  • Image: Michele L / SXC

  • Image: Science Museum

  • Image: Nate Brelsford / SXC

    If greenhouse gas emissions keep rising at the current rate, levels of carbon dioxide in the atmosphere could be double those of preindustrial times by the middle of the 21st century. The corresponding change in global temperature is known as the 'climate sensitivity'. As well as using climate models and calculations based on basic physics, scientists make estimates of climate sensitivity by looking at past changes in climate caused by natural factors. There are many uncertainties involved and scientists have to rely on proxies for information about past climates. But the range of likely climate sensitivity derived from past climate changes is in broad agreement with the ranges predicted by climate models or made by using basic physics.