The Intergovernmental Panel on Climate Change report this year includes a concise and clear Summary for Policy Makers (SPM) document that summarizes the evidence and a range of predictions for the coming centuries. It turns out that the largest uncertainties are not scientific, but economic. This figure from the SPM shows a range of different temperature forecasts for the 21st century based on different world economy models. The 18 page SPM is an excellent resource for anyone interested in global climate change, and in particular the anthropogenic versus natural contributions.

Image credit: IPCC Working Group I Fourth Assessment Report; Summary for Policymakers.

To assess my earlier selfish concerns about our new house in Orlando, the report provides some reassurance for my future property value: all the scenarios shown in the figure above have sea level increases of 0.2-0.6 meters by the last decade of the century, that is, less than 2 feet.

After a couple of decades of stagnation it is possible to get an electric vehicle that is useful for short commutes or errands. ZAP has a number of dealers and is taking orders for the Xebra electric vehicle. I say “vehicle” because although it looks like a small car, it is imported from China as a motorcycle, thus enabling them to avoid the safety requirements of a car. With a top speed of 40 mph and a range of ~20 miles on a single charge, it is not going to fulfill the needs of most car drivers anyway. According to ZAP, the lead-acid batteries cost ~$1200 to replace, so it is a bit disappointing that there is not a version that costs ~$1000 more than the target price of $10,000 and has twice the range. That would take it up to a range that would give many more commuters enough of a buffer to make it viable for an urban commute.

ZAP also plans to market the Brazilian Obvio which I wrote about earlier. The electric version of the Obvio has far more impressive stats than the Xebra (120 mph and a 200 mile range). It also has a far more impressive price ($49,000). It doesn’t take much inspection to see that there is a bit of price gap and performance gap here. Where is the $25,000 car with a range of 80-100 miles? That would be enough to satisfy almost everyone’s daily driving needs except for cross-country treks. The economics are still held back by the high cost and relatively short lifespan of batteries. The Xebra, for example, costs about $1 to fully charge, so if you only get 20 miles for that dollar it’s like a 50 mpg gasoline car, and when you factor in a $1200 battery replacement every 3 years, that’s another $1 a day. However, maintenance costs are likely to be trivial for the simple electric motor, and there is of course the benefit of vastly reduced pollution.

I was looking for reports on Antarctic ice melting and the potential contribution to sea level rise and ran across a couple of blogs criticizing the growing consensus that fossil fuel burning is a major cause of global warming. The following statement on one site (www.abd.org.uk) is a common criticism:

The Ross Ice Shelf has disappeared and reformed many times due to natural cycles. Indeed, during the past million years, temperatures were often 2 or 3 degrees higher than now despite CO2 levels never rising above 300 parts per million, compared to today’s 380 ppm.

Or this from www.worldclimatereport.com:

So, don’t sell the beachfront property just yet – the jury seems as if it will be out a tad bit longer on global sea level rise since the precise cause of a rise is questionable. Testimonials by climate change alarmists that coastal regions of the world will be inundated as glacial melt water streams into the world’s oceans have just been met with evidence that a large portion of the Antarctic ice sheet has thickened over the last of the 20th century.

As a new homeowner in Orlando, Florida (not exactly beachfront, but also only about 20 feet above sea level and of course paid for by a salary that depends on the continued existence of Florida’s beachfront-driven economy), nothing would make me happier than to see a thickening Antarctic ice sheet and stable sea levels for centuries to come. And it is undeniable that there have been huge swings in the Earth’s climate in the past that had nothing to do with humans burning fossil fuels. However, those facts are irrelevant when it comes to whether what we are now doing will raise temperatures and perhaps lead to a calamitous rise in sea level. It is as if someone were to say, “murder is not a problem because people die of natural causes all the time.” Or, “Don’t worry about all those forests we’re burning down in the Amazon because there were forest fires in the past that had nothing to do with people.” Yes there were forest fires before humans, but that doesn’t mean we aren’t in the process of burning down the rain forests all by ourselves right now. Similarly, non-anthropogenic changes in the Earth’s climate in the past have no bearing on the fact that we are dumping unprecedented amounts of greenhouse gases into the atmosphere. Carbon dioxide has a known infrared opacity and it is not difficult to calculate that an increase of atmospheric CO2 will lead to an increase in global temperatures.

Another argument I have heard is that since we can’t predict the local weather more than a few days in advance, how can anyone trust global weather predictions decades in advance. The answer is that it is much easier to predict global climate trends than it is to predict whether it will rain on a particular day in a particular town or county. I can easily tell that if a dam breaks water will run downhill, but it is much more difficult to identify the exact location and size of each individual wave produced when the dam breaks. Similarly, it is relatively easy to predict the average global consequences of global forcing on the climate.