It is very common these days for uninformed people to write articles denying climate change, or claiming there's some kind of conspiracy behind it, whether from lightbulb manufacturers or red infiltrators from Eastern Europe subverting the environmental movement. Sometimes there are claims of megalomaniac government institutions bent on taking away freedom, or more prosaically imposing punitive taxation.
In amongst all the noise though, is the science. Barry Pittock is one of the world's leading authorities on climate change, having led the Climate Impact Group in CSIRO, and is a lead author on all four reports of the Intergovernmental Panel on Climate Change. Not only has he done the research, but he has subjected it to open scrutiny, assessed the level of uncertainty, measured the risks, evaluated policy options and economic impact and investigated the accuracy of climate models. His book, Climate Change: The Science, Impacts and Solutions, presents the whole complex business with remarkable clarity and honesty.
He starts with a detailed presentation of the indisputable facts of climate change and why it is of critical importance to us. Whether it is the loss of polar ice, or the acidification of the oceans, or the rise in sea temperature, or the increase in sea level, or the level of carbon dioxide in the atmosphere, or even the changing patterns of the Gulf Stream, the Jet Stream and the El Niño-La Niña complex, Pittock presents the evidence. Not only does he present the evidence but he quantifies the uncertainties in the measurements.
For example, many people talk about the rise in sea level during the twentieth century of around 17 cm, but Pittock presents it more accurately as 17 ± 5 cm. In other words, somewhere between 12cm and 22cm but most likely around 17 cm. Throughout the entire book, Pittock takes pains to explain the level of uncertainty. But, as he names one of his chapters "Uncertainty Is Inevitable, But Risk Is Certain," that's why we should take notice.
He reviews our climate past and explains the changes in terms of the known geophysics, explaining what data is available, its significance and limitations, and the difference between direct measurements such as temperature and sea level, compared with proxy data such as ice cores.



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Article comments
1 - Peter
Another inaccurate article trying to take a stance on 'climate change'.
Let's get this straight - NOBODY disputes climate change. Climate change is the cyclical natural phenomenon present in nature that leads to variations in temperature, weather, ice coverage, sea levels etc.
Again and again we see these ill thought out articles saying that people are 'denying' (a childish connotation resorted to by bullying personalities) climate change.
They are NOT. They are asking for definitive EVIDENCE (not policy maker statements for politicians) that the current round of climate changes are in any way attributable to the emissions by mankind of a life-giving gas.
EVIDENCE is not the opinion of an 'expert' or a politician or Greenpeace or the WWF - it is hard data of unquestionable validity.
To date, no such data is available.
Don't try to change my mind with propaganda and name calling - deliver some irrefutable EVIDENCE.
Then, maybe, you will have the right to present your 'theories' to gullible politicians so that they can tax me to death.
The current financial system is in collapse. Surprise surprise here comes a 'carbon based economy'. Carbon credits, cabon derivatives, cap and trade. Carbon 'emitters' pay carbon 'absorbers' to enable them to produce the same amount of carbon. The only difference is that they had to pay extra. Because they pay extra, the consumer pays extra.
What an absolute farce.
Even if you buy into all this MGW nonsense, can you not see that politicians and financiers will not be using their powers to save the planet (despite what they are currently spouting). Politicians have not suddenly, for the first time in history, become noble.
2 - Bob Lloyd
Peter, you are just not looking at the evidence.
[They are asking for definitive EVIDENCE (not policy maker statements for politicians) that the current round of climate changes are in any way attributable to the emissions by mankind of a life-giving gas.]
Pittock presents more than a hundred pages of hard direct evidence (and a further fifty of supporting evidence), with countless references to the original sources. How anyone can pretend that there is no definitive evidence is beyond me and frankly either dishonest or woefully ill-informed.
[EVIDENCE is not the opinion of an 'expert' or a politician or Greenpeace or the WWF - it is hard data of unquestionable validity.
To date, no such data is available.]
That is blatantly untrue. The evidence is there, and it's open and available to everyone. Just look on the IPCC site.
It is important to understand the implication of your demand for "definitive" evidence. If you are waiting for 100% certainty before you will ever act, then presumably that also applies when you go to see a doctor? They'll tell you the most likely cause of your problem and treat you for it. If they waited for 100% certainty, they'd only tell you at the autopsy. Neither medicine nor any science works like that for obvious reasons.
However, Pittock looks precisely at the uncertainty, quantifies it, and spells out the implications. Precisely because models of climate are so complex, there are levels of uncertainty which instead of predicting a precise amount of global warming, result in a range of outcomes.
Equally important is the measurement of the impact of carbon dioxide from human activities. These can be and are precisely quantified so that their effects are known to a high level of accuracy. These figures are used in detailed climate models whose predictive power has already been demonstrated and whose accuracy is increasing year on year as they are refined and as they use more data.
You can pretend that there is no evidence but it is available in such quantity that the claim is ludicrous. You may not like the conclusions of the science but they are independent of opinion. Regardless of what any scientists think about what should be done, global warming is demonstrably caused by human activity.
That being demonstrated (and you can look at the evidence yourself), the political questions then come to the fore. Adaptation and mitigation, or some combination of both, are all we have available. Sequestration of carbon dioxide from the atmosphere is still not viable on the scale required.
Your anger at the politicians and financiers who were responsible for the last crash is entirely justified. Who would trust that bunch of sheisters to fix global warming? The politicians couldn't even agree what to talk about when they met in Copenhagen, and every single target is argued down and down by the hydrocarbons lobby. And you're right that the very same people who crashed the financial system want to make money out of carbon trading. But that's no reason to ignore the science or claim it's propaganda.
The deniers may accept the reality of global warming (after all what choice have they got?) but they persistenly deny the scientific evidence that humans are responsible. The evidence is multitude and increasing and only the wilfully blind can't see it. It is more than ever important that people get informed, try to understand the science, look at the evidence. People blustering about propaganda and farces are throwing up a smoke-screen to distract people away from the unpalatable truth.
Distrust of politicians and business shouldn't obscure the very real facts that scientific evidence shows. If anything it should make people more determined to hold them to account.