Science Friday: James Hansen's 1981 Cassandra-like Prediction | Will Your House be Undersea in 2100 | MIT's Solar Panel Pancakes
James Hansen at a recent TED Talk
- Sometimes it helps to take a step back from the everyday pressures of research (falling ill helps). It was in this way we stumbled across Hansen et al (1981) (pdf).
In 1981 the first author of this post was in his first year at university and the other just entered the KNMI after finishing his masters. Global warming was not yet an issue at the KNMI where the focus was much more on climate variability, which explains why the article of Hansen et al. was unnoticed at that time by the second author. It turns out to be a very interesting read.
They got 10 pages in Science, which is a lot, but in it they cover radiation balance, 1D and 3D modelling, climate sensitivity, the main feedbacks (water vapour, lapse rate, clouds, ice- and vegetation albedo); solar and volcanic forcing; the uncertainties of aerosol forcings; and ocean heat uptake. Obviously climate science was a mature field even then: the concepts and conclusions have not changed all that much. Hansen et al clearly indicate what was well known (all of which still stands today) and what was uncertain.
Next they attribute global mean temperature trend 1880-1980 to CO2, volcanic and solar forcing. Most interestingly, Fig.6 (below) gives a projection for the global mean temperature up to 2100. At a time when the northern hemisphere was cooling and the global mean temperature still below the values of the early 1940s, they confidently predicted a rise in temperature due to increasing CO2 emissions. They assume that no action will be taken before the global warming signal will be significant in the late 1990s, so the different energy-use scenarios only start diverging after that
- We all know sea levels are rising — since 1880, global sea levels have risen by about 8 inches, and the rate of rise is increasing every year — but what sort of effect can we expect these increases to have on our day-to-day lives?
One way to measure their impact is to forecast the direct effect that rising seas will have on where we live. The folks at Climate Central have put together an interactive map application that lets you see how rising seas will effect coastal regions of the United States over the next century. The map offers an impressive level of detail, allowing you to zoom down to the level of individual neighborhoods and linking to statistics, factsheets,and even action plans.
Here's a link to the MIT paper
- What’s better than one pancake? A whole stack of pancakes! Using the same logic, a team of MIT researchers have stacked a bunch of photovoltaic solar cells together to produce up to 20 times the power output of conventional solar power installations.
Normally I’m the first to drop my jaw in awe at MIT’s latest and greatest innovations, but this one really is a bit of a no-brainer. Basically, photovoltaic cells themselves aren’t all that expensive — according to MIT, they’re only around 35% of the total cost of a solar power installation. The main issue with solar power (and its main cost) is its low energy density, and thus the sheer surface area required to generate a sizable amount of electricity. This is why you need to cover your whole roof with cells to power your light bulbs, and why solar power plants would have to occupy tens of square miles of desert to produce as much power as a nuclear power plant.
To combat this issue, MIT has built 3D stacks of photovoltaic cells. These have the same footprint of a conventional, flat solar power setup — but as you can see in the picture above, the total surface area is much, much larger. The team built a variety of 3D designs, including a cube, and in all cases they produced between two and 20 times as much power as a flat panel. The most interesting facet of this discovery, though, is that these 3D stacks produce lots of extra power whenever the sun is near the horizon, i.e. in the morning, evening, winter, or at latitudes far away from the equator. With conventional, flat cells, it’s hard to capture low-angle light, but with an accordion structure (as pictured) the relative angle would be closer to 45 degrees.