sceptic guide
illconsidered | May 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
More and more the models share all the same assumptions, so of course they all agree! And every year fewer scientists dare to speak out against the findings of the IPCC, this is a clear indication of the pressure there is to conform.
Answer:
The improving agreement of model results and the increasingly similar physical representations of the climate system from model to model may well look like just sharing code, or tweaking til things…
illconsidered | May 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Despite what the computer models tell us, there is actually no evidence of significant global warming.
Answer:
Global Warming is not an output of computer models, it is conclusion based on observations of a great many global indicators. By far the most straightforward evidence is the actual surface temperature record. While there are places, in England for example, that have records going back several centuries, the two major global…
illconsidered | May 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Sure, sea ice is shrinking in the Arctic, but it is growing in the Antarctic. Sounds like natural fluctuations that balance out in the end.
Answer:
Overall, it is true that sea ice extent in the Antarctic is increasing. Around the peninsula, where there is a lot of warming, the ice is retreating. This is the area of the recent and dramatic Larsen B and Ross ice shelf break ups. But the rest of the continent has not shown any clear warming…
illconsidered | April 27, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
The United States actually absorbs more CO2 into the land than it emits into the air. The world should be grateful.
Answer:
As often is the case, at the heart of this talking point is a grain of truth, though it is no longer equivalent to what it has been forcibly grown into. According to the US Department of Energy the land use changes taking place in the United States between 1952 and 1992 have resulted in a net absorption of CO2, but…
illconsidered | April 27, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Even the scientists don't know that the climate is changing more than normal and if its our fault or not. If you read what they write it is full of "probably", "likely", "evidence of" and all kinds of qualifiers. If they don't know for sure, why should we worry yet?
Answer:
Unfortunately, "likely", "evidence suggests" and "probability" is the language of science. There is no proof, there are no absolute certainties. Scientists are always…
illconsidered | April 27, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Climate science can't even fully explain why the climate did what it did in the past. How can they then claim they know what is going on today?
Answer:
There are two requirements for understanding what happened at a particular climate change in geological history. One is an internally consistent theory based on physical principles and the other is sufficient data to determine the physical properties involved. It is very hard, in some…
illconsidered | April 26, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
In 1988 Hansen predicted dire warming over the next decade and he was off by 300%. Why in the world should we listen to the same doom and gloom from him today?
Answer:
While it may well be simply ignorant repetition of misinformation in some instances, at its source, this story is a plain and simple lie.
In 1988, James Hansen testified before the US Senate on the danger of Anthropogenic Global Warming. As part of that testimony he…
illconsidered | April 26, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
The sun is the source of all the warmth on earth. Any increase in temperature is most likely due to changes in solar radiation.
Answer:
It's very true that the earth is warmed, for all practical purposes, entirely by solar radiation. So if the temperature is going up or down a reasonable place to find the cause would be the sun. Well, it turns out that it is more complicated than one might think to detect and measure changes in the amount…
illconsidered | April 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Clouds are a very large negative feedback that will stop any drastic warming. The climate models don't even take cloud effects into account.
Answer:
All of the Atmospheric Global Climate Models used for the kind of climate projections reported on by the IPCC take the effects of clouds into account. You can read a discussion about cloud processes and feedbacks in the IPCC TAR.
It is true however that clouds are one of the largest sources…
illconsidered | April 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
In the geological record it is clear that CO2 does not trigger climate changes. Why should it be any different now?
Answer:
Given the fact that the human species and our industrialization is rather unique in the history of planet Earth, do we really need to see some kind of historical precedent for CO2 triggered climate change before accepting what we observe today? Surely unprecedented consequences are not far fetched in the face of…
illconsidered | April 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
All those institutional position statements are fine, but by their very nature they hide the debate and the variety of individual positions. The real debate is in the scientific journals.
Answer:
This is a fair point. Group position statements are designed to smooth over debate and unite the different points of view that individuals may have. The best indicator of what individual scientists think is in the current scientific literature,…
illconsidered | April 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Global temperatures have been trending down since 1998. Global Warming is over.
Answer:
At the time, 1998 was a record high year in both the CRU and the NASA GISS analysis. In fact, it was not just a record year, it blew away the previous record by .2oC. (That previous record went all the way back to 1997, by the way!) According to NASA, it was elevated far above the trend line because 1998 was the year of the strongest El Nino of the…
illconsidered | April 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Sure, some glaciers are melting. But if you look at the actual studies, most of the ones that have data are actually growing!
Answer:
This is simply not true, rumours on "the internets" aside (that link is very worth reading, BTW). According to the National Snow and Ice Data Centre and their State of the Cryosphere division, on their Glacial Balance page they report an overall accelerating rate of glacial mass loss. The World Glacier…
illconsidered | March 26, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Why should we trust a bunch of contrived computer models that haven't ever had a prediction confirmed ? Talk to me in 100 years.
Answer:
Of course, given the absence of a few duplicate planets and some really large time machines, how can we hope to test a 100 year temperature projection today? Well, we can't, but does this mean that the models can not be validated without waiting 100 years? I don't thinks so.
The climate is a very complex…
illconsidered | March 26, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Scientists can't even predict the weather next week, so why should we believe what some climate model tells us about 100 years from now?
Answer:
Climate and weather are really very different things and the level of predictability is comparably different. Climate is defined as weather averaged over a period of time, generally around 30 years. This averaging over time removes the random and unpredictable behaviour of weather. Think of it as…
illconsidered | March 26, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Climate is an inherently chaotic system, and as such it can not be predicted.
Answer:
Firstly, let's make sure we define climate. Climate is generally viewed as an average of weather patterns over some meaningful time period. The number of years may vary and there are probably plenty of other finer points to quibble about in there, but the purpose of getting this definition out in front is to be sure we are safe in discounting the very…
illconsidered | March 26, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
According to the IPCC, 150 billion tonnes of carbon go into the atmosphere from natural processes every year. This is almost 30 times the amount of carbon humans emit. What difference will any reductions we try to do make?
Answer:
This is quite true that the natural fluxes in the carbon cycle are much larger than anthropogenic emissions. But in the natural process, for roughly the last 10K years until the industrial revolution, every…
illconsidered | March 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
It's clear from the ice cores and other geological history that CO2 fluctuates naturally. It is a bogus assumption that the rise happening today has to be from humans.
Answer:
Surely it is not so hard to believe that since we emit billions of tons of CO2 into the air and, lo and behold, there is more CO2 in the air, therefore the CO2 rise is our fault. But if this simple common sense is not enough there is more to the case than that and…
illconsidered | March 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Natural variability is the null hypothesis and an anthropogenic CO2 warming effect needs compelling evidence before there is any reason to take it seriously.
Answer:
The null hypothesis is a statistical test and might be a reasonable approach if we were looking only for statistical correlation between increasing CO2 and increasing temperature. But we're not, there are known mechanisms involved whose effects can be predicted and measured.…
illconsidered | March 25, 2006This is just one of dozens of responses to common climate change denial arguments, which can all be found at How to Talk to a Climate Sceptic.
Objection:
Global Warming has been going on for the last 20,000 years.
Answer:
It is quite true that 20Kyr ago the temperature was some 8 to 10oC colder than it is today, but it is highly arbitrary and dubious to simply draw a line from that point to today and say "Look! 20K years of Global Warming!". If you have look at this nice graph of temperature starting at a point when we were finishing the climb out of deep glaciation, you can clearly see…