• Question: What evidence is there that climate change does exist and that it's not just a natural cycle?

    Asked by mimi to Nathalie on 24 Jun 2010 in Categories: .
    • Photo: Nathalie Pettorelli

      Nathalie Pettorelli answered on 24 Jun 2010:

      Hi mimi,

      There are several different points here:
      – are we observing changes in climate: yes. We gained nearly one degree on average on earth over 100 years
      – do we also observe increases in greenhouse gas concentrations in the atmosphere: yes, the global atmospheric concentration of dioxide carbon (CO2) increased from a pre-industrial value of about 280ppm to 379ppm in 2005
      – we then know that increase in greenhouse gas concentrations lead to warming (it’s a very easy experiment to do: take two closed boxes, with one having a greater CO2 concentration than the other – put it somewhere in your garden mid-afternoon and measure the temperature inside)
      – we also know that environmental variation such as solar cycle can also affect climate

      So, considering what we know, we can conclude that the changes we report in climate are linked to human activity and can be modulated by environmental variation such as solar cycles. Hope that helps 😉

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