Could global warming be caused by natural climate change?

Weather Presenter Kate Haskell explains why sea ice is so important if when it melts it does not lead to sea level rise

Carbon Dioxide levels in our atmosphere are above 400 pars per million. The last time they were this high was during the Pliocene era, over two and a half million years ago. At that time it took tens of thousands of years for the levels of CO2 to change, giving plenty of time for the climate and organisms to adapt naturally.

There are two ways in which scientist can look at the temperature of past climate. Directly through instruments like thermometers and indirectly through the natural environment, such as ice core samples. Ice contains information about the change in CO2 on the planet. When water freezes, small tiny bubbles of air are locked into the ice, producing a frozen time capsule of the atmosphere. These can be extracted and analysed in a lab where the amount of CO2 in the atmosphere can be seen.

Ice core sample Credit: NASA

Both direct and indirect measurements tell us that the warming we are seeing today is happening much quicker, meaning the natural evolution of our ecosystems can not keep up. Scientists are able to simulate what the climate looks like with and without man made greenhouse gases. The evidence is overwhelming that we are responsible for a world that is warming too quickly. The rate of change in CO2 in recent years has been so fast that it hasn't been seen in Earths history and that can only be explain due to a rise in man made greenhouse gases - primarily CO2. The impact of that is an increase in extreme weather and failing ecosystems.