Cyber - admit your 'side' of this discussion has changed tactics -at least be honest about that.
Remember all the fuss - "Climategate" - temperature reading stations placed in the wrong spots, placed in spots where it would only show higher temperatures, "hiding the decline" - remember all that outrage? The ENTIRE point of that was that this giant secret group had somehow faked the data that showed rising temperature trends - Remember?
Funny how the Berkeley study takes place and the tune changed to "yeah, we know it's getting warmer, but we have nothing to do with it..."
Don't you think the people that study this stuff have already considered your 'natural cycles' talking point?
Haven't we already had this discussion before? Oh, that's right, you didn't like the points made which completely destroyed your talking point, because the author of that article wrote a book that depicted the 'deniers' as being an ostrich with their head in the sand...
Natural cycles have very obviously been considered in looking at temperature trends.
I'll post the 'basic' level response again so people who actually have an open mind can read it:
"A common skeptic argument is that climate has changed naturally in the past, long before SUVs and coal-fired power plants, so therefore humans cannot be causing global warming now. Interestingly, the peer-reviewed research into past climate change comes to the opposite conclusion. To understand this, first you have to ask why climate has changed in the past. It doesn't happen by magic. Climate changes when it’s forced to change. When our planet suffers an energy imbalance and gains or loses heat, global temperature changes.
There are a number of different forces which can influence the Earth’s climate. When the sun gets brighter, the planet receives more energy and warms. When volcanoes erupt, they emit particles into the atmosphere which reflect sunlight, and the planet cools. When there are more greenhouse gases in the atmosphere, the planet warms. These effects are referred to as external forcings because by changing the planet's energy balance, they force climate to change.
It is obviously true that past climate change was caused by natural forcings. However, to argue that this means we can’t cause climate change is like arguing that humans can’t start bushfires because in the past they’ve happened naturally. Greenhouse gas increases have caused climate change many times in Earth’s history, and we are now adding greenhouse gases to the atmosphere at a increasingly rapid rate.
Looking at the past gives us insight into how our climate responds to external forcings. Using ice cores, for instance, we can work out the degree of past temperature change, the level of solar activity, and the amount of greenhouse gases and volcanic dust in the atmosphere. From this, we can determine how temperature has changed due to past energy imbalances. What we have found, looking at many different periods and timescales in Earth's history, is that when the Earth gains heat, positive feedbacks amplify the warming. This is why we've experienced such dramatic changes in temperature in the past. Our climate is highly sensitive to changes in heat. We can even quantify this: when you include positive feedbacks, a doubling of CO2 causes a warming of around 3°C.
What does that mean for today? Rising greenhouse gas levels are an external forcing, which has caused climate changes many times in Earth's history. They're causing an energy imbalance and the planet is building up heat. From Earth's history, we know that positive feedbacks will amplify the greenhouse warming. So past climate change doesn't tell us that humans can't influence climate; on the contrary, it tells us that climate is highly sensitive to the greenhouse warming we're now causing." - John Cook
