First, of course, the definitions. People have every right to be concerned about humanity’s effects on the climate. I certainly am, as you will see in great (mind-numbing?) detail when I talk about my response to skeptics. But there is a group of people who are dining out on exaggerated claims of the effects of human-caused climate change. Surprisingly, few of them are scientists. The vast majority are affiliated with environmental causes or have political beliefs that make the climate cause a little too congenial for them.
“Global warming’ will kill most of us, and turn the rest of us into cannibals.” Ted Turner
I call people alarmists when they take a solid premise—that human actions have a measurable effect on our climate and that this effect could bring with it negative consequences, especially in the developing world—and cheerfully exaggerate the effects of climate change, constructing scenarios that resemble a dark science fiction film or book. (In fact, there is a burgeoning sub-genre of science fiction based on disastrous climate change. It is called Cli-Fi. It is uniformly unreadable.) Many of them who have published books, articles or weblogs work for or are closely affiliated with environmental organizations such as Greenpeace, The Sierra Club, the WWF, etc.
“When we’ve finally gotten serious about global warming, when the impacts are really hitting us and we’re in a full worldwide scramble to minimize the damage, we should have war crimes trials for these bastards (global warming skeptics) — some sort of climate Nuremberg.” David Roberts, Grist Magazine
We’ll talk about the science of climate change throughout this blog (although this is not intended in any way as a primer on climate science—there are many such and I am certainly not qualified to write one myself), but let’s take a look at what science says about the effects of climate change.
The IPCC says that the science they have reviewed indicates that temperatures will climb between 1.5C and 4.5C over the course of this century. That’s a very wide range, given that the average temperature is about 14.5C. What would that mean for the world?
Obviously, a 1C rise in temperatures will not cause significant problems. Problems start cropping up when the rise gets to 2C and damages from climate change are forecast to climb steeply should temperatures rise beyond 2C. But between 2C and 4.5C of temperature rise it is muddy going to say ‘this will happen at 2.8C and this will then happen at 3.4C. So let’s cut to the chase and see what scientists and economists forecast for our world should temperatures rise by the maximum—4.5C. (There are some people who say that temperatures might rise even beyond—but I have seen no scientific studies that show that as anything other than the remotest of possibilities.)
The impacts of 4.5C can be quantified loosely—sea level rise will be at the top end (59 cm) of the IPCC’s estimates for the century. Biodiversity will suffer—the rate of extinctions can be expected to rise. And although there will be winners and losers in agriculture, the winners will likely be in the rich Northern hemisphere and the losers in the developing South. But all of these involve a fair amount of guesswork—(try searching for a global figure for land expected to be lost due to climate change, if you want to experience a frustrating afternoon—Tol and Darwin came up with figures of 348,375 linear miles of coastland, as well as 335,421 square kilometers of land threatened by 50 cm of sea level rise. That’s out of a total of 149 million square kilometers of land area on the planet, so it’s about
2.5% 0.25% of the total (thanks, HaroldW). But how helpful is that figure? Rich countries would protect their land, while poor countries couldn’t afford to.) The same is true for most of the metrics involved.
We can look at the impacts of climate change economically and get a single figure. Nordhaus and Boyer, using their highly respected DICE model, estimated the costs of climate change at $5 trillion in 2000 dollars. That’s a staggering figure—but it includes all the costs that will be incurred over the 21st Century. If we decided today to put $5 trillion (adjusted for the inflation that has occurred since 1990, yielding $8.92 trillion 2013 dollars) in the bank to cover all the present and future costs of global climate change it would be 6% of the world’s GDP. On the other hand, the IPCC SRES (scenarios of possible future paths) project world GDP in 2100 to be between $235 trillion and $550 trillion just in the year 2100. So if we waited until then to pay all the costs of global warming, it would amount to between .2% and .1% of the world’s output for just that one year. Of course, in all likelihood, global warming will be dealt with on a pay-as-you-go basis, decreasing the financial impact even further.
In any event, it is clear right from the start that global warming is not projected to be a planet buster or any kind of global disaster causing widespread loss of life. It is a real problem, to be sure. It needs attention and the sooner we start dealing with it the better. But even at its worst it is manageable, well within the context and scope of other problems we are successfully dealing with today.
Contrast those figures with what Alarmists say for public consumption, ranging from predictions that humanity would be reduced to a few breeding couples living in Antarctica to half of all species disappearing by 2020, from an ice-free Arctic by the year 2000 to predictions that temperatures would rise by 2 degrees Celsius by 2010. There are actually hundreds of dire predictions, some of which have already been proven false, others that just contradict what the IPCC and mainstream science actually say. Perhaps the motivation for the barrage of scary quotes is captured in a quote from Al Gore: “I believe it is appropriate to have an over-representation of factual presentations on how dangerous it is, as a predicate for opening up the audience to listen to what the solutions are, and how hopeful it is that we are going to solve this crisis.”
 Estimates of the Economic Effects of Sea Level Rise, Roy Darwin and Richard Tol, Environmental and Resource Economics, 2001, Kluwer Academic Publishers