 What I thought I'd explained first of all is the natural processes and how they act on a range of different timescales from thousands of years to hundreds of thousands of years through to seasons. So probably a great example of how these interactions actually occur is if we look at the Vostok ice core. Now the Vostok ice core is where scientists have gone to the Antarctic and they have drilled a core down to almost two kilometres and they've extracted the ice from that core. Within that ice is little bubbles of air which you can imagine are actually then sort of horizontally aligned so we can have a sense of when that sample of the atmosphere actually occurred. They extract the air from those bubbles and they can measure the greenhouse gases in those bubbles of air. So what we do see is we see these large fluctuations occur over those 800,000 years. But when we get to the present day we see a very clear human induced signal so we see a very rapid accumulation of greenhouse gases in the atmosphere. Far greater than has occurred in the last 800,000 years and the rate of accumulation is far more rapid than any time in that observational record. So we see then that even within the historical record we see that there is natural variability that's occurring and this trend that we're starting to see from the greenhouse gas concentrations. We see things like years that are dry and years that are wet and those are associated with both El Niños and La Nina. So this is the temperatures in the Pacific Ocean and as those temperatures and those patterns of sea surface temperature change that actually changes the patterns of rainfall across the entire planet. So we have these seasonal variations that are natural and then we have this pervasive trend that's actually occurring in the temperatures because of the accumulation of greenhouse gases and as those temperatures in the atmosphere change because of the greenhouse gases they interact with the natural variability that's occurring and they're altering that natural variability.