I am amazed that an article filled with such a vast amount of FUD is frontpaging. But let's go point-by-point, lest the science described in thousands of papers of climate research get lost in the cloud of false skepticism, shall we?
> The models roughly describe the shrinking extent of Arctic sea ice observed over the past two decades, but they fail to describe the comparable growth of Antarctic sea ice, which is now at a record high.
The science of why Antarctic sea ice extent is growing is perfectly well known: the discharge of melting cold water from the Antarctic glaciers forms ice as it hits the coastal winds of the continent. That the models don't necessarily account the extent of this is almost irrelevant, since the sea ice extent has a very minute impact on climate patterns.
Let us note that this is a not-at-all subtle piece of FUD that would appear to account that Antarctic sea ice is compensating for Arctic melting. It's not. There's over 500 Gt of yearly glacier loss in the Antarctic, and the sea ice extent which is, at most, a few meters thick, is absolutely minuscule in comparison to the amount of additional water dissolving into the sea from kilometers-thick walls of ice. Also, the topic has been reasonably well-studied, and the changes in the atmosphere are more than enough to account for the observed effects.
> Even though the human influence on climate was much smaller in the past, the models do not account for the fact that the rate of global sea-level rise 70 years ago was as large as what we observe today—about one foot per century.
It is most definitely increasing, and it is accelerating rapidly, especially if the West Antarctic Ice Sheet accelerates its collapse (http://www.skepticalscience.com/sea-level-rise.htm). The fact that we have been observing linear trends thus far doesn't mean that we'll continue to observe them; evidence points that we're in the beggining of an exponential loss of ice.
> A crucial measure of our knowledge of feedbacks is climate sensitivity—that is, the warming induced by a hypothetical doubling of carbon-dioxide concentration. Today's best estimate of the sensitivity (between 2.7 degrees Fahrenheit and 8.1 degrees Fahrenheit) is no different, and no more certain, than it was 30 years ago. And this is despite an heroic research effort costing billions of dollars.
This is, again, FUD.
First of all, the radiative forcing produced by CO2 is well-known and established by physics. It is known that the Earth's albedo is decreasing, and the certainty that out lower bounds are erroneous has increased substantially.
Moreover, we are now aware of potential feedback loops that we didn't know about. It's interesting that he's never mentioning the Big One: the potential for frozen clathrates in Siberia and the Arctic to release methane that would trigger a certain mass extinction event.
> A transparent rigor would also be a welcome development, especially given the momentous political and policy decisions at stake. That could be supported by regular, independent, "red team" reviews to stress-test and challenge the projections by focusing on their deficiencies and uncertainties; that would certainly be the best practice of the scientific method. But because the natural climate changes over decades, it will take many years to get the data needed to confidently isolate and quantify the effects of human influences.
So, in his opinion, the models clearly described in papers, the data publicly available by NASA and dozens of different government organizations is not enough? A 3000-page report summarizing the findings of hundreds of papers, with multiple, independently corroborated lines of evidence using different data sets isn't enough?
This an obvious attempt to discredit climate scientists. I would suggest anyone who has a shred of doubt as to the integrity of these people that you just walk into any Atmospheric Sciences Department of your local university and buy any teacher a cup of coffee and have a chat. Seriously, they will talk your ear off about their research.
As a personal note, most climate scientists are the kind of people smart enough and capable enough to be making decent cunks of money outside of their chosen field (a combination of knowledge in physics, chemistry, and computational modeling are desired skill in many lucrative fields). They're not doing this for the money, or the recognition, and it pains me that people are willing to believe the ramblings posted in a Murdoch-owned newspaper on the matter without willing to question the economic interests behind climate denialism. But I digress.
> But climate strategies beyond such "no regrets" efforts carry costs, risks and questions of effectiveness, so nonscientific factors inevitably enter the decision. These include our tolerance for risk and the priorities that we assign to economic development, poverty reduction, environmental quality, and intergenerational and geographical equity.
There's something that should be really important, which people raised on the typical media diet of "two sides of the story" and "fair and balanced" should understand:
We're not debating whether climate change is something serious or not.
The current debate is whether we're facing a future where "merely" the following things will happen:
* An acidified ocean where almost all fish stocks will collapse, with a PH that will make the growth of crustaceans and zooplankton difficult, to say the least.
* Megadroughts will become a common occurency, as will increased levels of flooding resulting in losses of crop efficiencies above 10%
* All of the planet's ecosystems will be permanently affected, making the harvesting of crops such as coffee and cocoa a thing of the past
* An acceleration into our current period of mass extinction, with unforeseen consequences
Or, nn the other extreme, quite literally, we have a scenario of a degradation of the Earth's biosphere to the point where humans face complete extinction within the next century.
The last scenario could be triggered by one of the many feedback cycles which include the sudden release of methane clathrates, an exponential collapse of the West Antarctic Ice Sheet leading to the rapid increase in sea level of multiple feet, or just sufficiently large megadrought events in enough places in the globe to disrupt the global food supply chain. Hell, just an increase in temperature of 4 degrees C ("just") would be enough.
My final rebuttal:
> Individuals and countries can legitimately disagree about these matters
No, they cannot, unless they're legitimate experts in climate science with an understanding that actually improves upon what we have, they have squat to say on the science of it.
This fake notion that anyone can have an opinion on knowledge that's in flux is intellectually dishonest. Experts are allowed to disagree. Us laymen have almost nothing to add to the conversation, unless we want to gamble with our own demise. Anyone who thinks otherwise is plainly ignorant of the science, and that's not a point in discussion.
The only thing this discourse does is play down the supposed "alarmism" of the situation. I don't know man, if you think that a potential, non-trivial chance of the collapse of the biosphere isn't something to be alarmed of, then I don't know what is.