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Tag Archives: IPCC
I have said this before – but it bears repeating Climate change is complex. And I feel the need to repeat it now because of a current myth being pushed very strongly by climate change deniers/contrarians/sceptics. The claim that “there has been no global warming for 16 years.”
If you doubt climate change is complex have a look at this global temperature record from NASA’s Goddard Institute for Space Studies.
Isn’t cherry picky wonderful?
There’s a lot of noise in that graph but it does sort of support the conclusion that global temperatures have increased in the last 100 years. Mind you, if you want to create a contrary impression you can easily take a short time period – say around 1950, 1960 – 1980, 1985 – 1995 – or even the last 16 years. Cherry picking is a great thing – if your aim is to support a predetermined conclusion, and avoid (or even hide) evidence to the contrary.
So we get this sort of thing being promoted by climate change deniers (thanks to Andy for this one). Didn’t someone say a little knowledge is a dangerous thing? And isn’t cherry picking a great way of restricting knowledge?
So, just to repeat myself – here’s an extract from my post Climate change is complex. It indicates some of the scientific knowledge that climate change deniers/contrarians/sceptics ignore when they cherry pick to make this silly claims.
Natural influences just can’t explain global temperature
The figure below shows the results of simulations of global temperature from 1900 to 2005. Figure a included all the natural and anthropogenic influences. The black line is the actual measured global temperature anomaly (obtained by subtracting the average temperature for 1901 to 1950). The individual simulations are shown as thin yellow curves. The red line is the multi-model ensemble mean (see Figure 9.5 – AR4 WGI Chapter 9: Understanding and Attributing Climate Change).
Figure b is a similar plot using simulations which consider only the natural influences on climate. The individual simulations are shown as thin blue curves. The thick blue line is the multi-model ensemble mean.
So, climate scientist have considered both natural and anthropogenic influences. And they are unable to reproduce the global temperature changes since 1970 unless anthropogenic influences are included.
That is why the IPCC has concluded that there is a high probability (>90%) that human influences are contributing to the current observed global temperature increase.
Notice also that the experts talk about probabilities. It’s a complex field and things are rarely cut and dried. We are more certain about some influences than others. And the IPCC doesn’t hide this fact – far from it. It doesn’t make sweeping claims in the way that some of their opponents do.
Knowing what we don’t know
We can see this in another figure from the report (Figure 2.20 – AR4 WGI Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing). It shows the estimated influences of several human caused effect and solar radiation since 1750. Notice the error bars. They are much bigger in some cases than others. Notice the assessment of scientific understanding for these influences. We have a high understanding for some of them and a low understanding for others.
So, climate scientists aren’t hiding anything. They are not ignoring natural effects. They are up-front about probabilities. They acknowledge that we need more information is some areas. They are behaving like professionals.
Considering there are areas where scientific understanding is low there is clearly room for debate, discussion and more research. But deniers and contrarians who take an extreme reductionist stance, misrepresent the IPCC reports and attack honest scientists doing the research are not in a position to contribute to this.
Here I respond to a letter sent to The Listener by a former scientific colleague, Doug Edmeades. He is now a science spokesperson for local groups which attack the current scientific consensus on climate change as well as attacking local climate scientists.
Doug and I are old mates. In the past we fought together against commercial and bureaucratic attacks on our research. Now we find ourselves on opposite sides of the “barricade.” But I am sure there is enough mutual respect to enable a reasoned discussion of the claims made by Doug about climate change science in his letter.
I have invited him to respond in turn to my comments and hopefully he will be happy that I post his response, at least in part, here.
I am responding to claims you made in your recent letter to The NZ Listener reproduced on the Climate Conversation Group Blog (see In a climate of listening). Space limitations clearly prevented you from justifying these five claims (your refer to them as “facts”). However they are, in my view, either not factual or misleading. I explain why below and welcome your response to my comments.
Publisher: Institute of Policy studies (November 2009)
Paperback: 303 pages
This book is a much-needed authoritative introduction to the UN International Panel on Climate Change (IPCC) reports. It is readily accessible by the interested lay person, as well as by students and professionals. Those interested enough to take part in public discussion around this issue will appreciate the book.
Poneke’s recent blog post, 13 years of Climategate emails show tawdry manipulation of science by a powerful cabal at the heart of the global warming campaign, precipitated a lively discussion. Well, perhaps “discussion” is too kind because it was dominated by extreme deniers.
Now, I don’t want to label people unjustly. I respect those who are sceptical of the IPCC climate change conclusions, but are willing to stick with the science in discussing them. I reserve the term “deniers” for those irrational souls who grab at anything they can (cold days, snow, 1998 temperatures, IPCC mistake on Himalyan glaciers, etc., etc.). No interest in the science – just in using “sciencey” claims to advance their preconceived conclusions.
But my point in this post is to deal with one of Poneke’s claims which is demonstratively untrue.
Book Review: Poles Apart by Gareth Morgan and John McCrystal
Published: May 15, 2009
Publisher: Random House New Zealand.
Can you trust the advice of an economist or financial adviser when it comes to the science of climate change? After all, we even suspect their advice on economic matters these days.
That might be a natural reaction to the new book “Poles Apart” by Gareth Morgan and John McCrystal. Gareth is a well-known New Zealand economist and investment portfolio manager. John McCrystal is a Wellington writer and researcher.
Surely they can’t offer anything useful on climate change? Well, strangely they can.
Creationists commonly appear to also be anti-science when it comes to the human contribution to global warming (see Intelligent design/creationism and climate change). Locally Christian News New Zealand will often copy climate change denial material from their parent US creationist website Uncommon Descent. Now, the Christian Apologetics website Thinking Matters is getting into the act with Global Warming a New Religion. (Isn’t it strange how fundamentalists use the “religious” label to discredit belief systems they don’t like?)
This article doesn’t even bother misrepresenting the scientific data to attack the scientific understanding of the anthropogenic contribution to climate change. The author seems happy enough to attribute public concern on the issue to communism, humanism, belief in an ancient earth, and disbelief in any “world wide flood hypothesis.”