"But the concept of a safe threshold is a myth and tends to distract attention from evidence that we are already seeing widespread and consequential impacts of climate change."
Chris Field
Canegie Institution's Department of Global Ecology
This is because each molecule of CO2 traps a small amount of infrared radiation. We can't measure the temperature increase from each molecule, we're not that good, but eventually we can. By then, the excess CO2 will affect other systems in observable ways, besides just our thermometers. That's where we are currently at.
Each molecule of CO2 absorbs a small amount of infrared radiation because of CO2's quantum vibrational energy absorption spectrum. The energy of infrared radiation absorbed by CO2 molecular vibrations is almost exactly at the peak of the Earth's black body spectrum (667/cm, where the units are in terms of wavenumber).
Of course it's not a safe limit. It's a tradeoff. Like the speed limit on a highway.
ReplyDeleteBut another easy misconception that this article addresses, is that it's all about the Earth's mean temperature. Two degrees may not feel like much, but it's almost half of the glacial-interglacial swing. What we're going to see (and already seeing) is that climatic conditions move places. Areas that are currently fertile and producing lots of food will get more arid (the zone from California to Florida, and Europe North of the Mediterranean), while other areas will see their growing season get longer (Canada, Siberia). The problem there is that it's the former areas where our production infrastructure and workforce is, not the latter areas. Same as with sea level: "optimal" sea level is where our coastal towns and coastal infrastructure are now. Otherwise, any level goes.
Yup.
ReplyDelete