What significant predictions has the theory of natural global warming made?
Some claim that the observed trend of warming global temperatures is attributable to natural, that is, non-anthropogenic causes. If this is true, what could we predict to observe as a consequence? Have any such predictions turned out to be accurate?
2011-09-20T13:45:09Z
For example, the theory of gravity allows us to predict what happens if we drop a ball from our window, or how hard we need to push a rocket to get it into space.
Does the commonly believed theory (outside mainstream science) that global warming is due to natural, non-anthropogenic causes, yield useful predictions like this? For instance, it might predict all planets in the solar system are getting warmer, or that there is a strong correlation between global temperature and solar output? And have any such predictions been observed to come true?
Dana19812011-09-20T09:11:35Z
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That depends on the 'natural' cause. The beauty of denialism is that they don't restrict themselves to any single alternative argument. They say it's the sun, cosmic rays, oceanic cycles, clouds, etc. etc. Each of these explanations would result in different predictions.
However, it's very hard to explain some of the 'fingerprints' we've observed. For example, the cooling upper atmosphere as the lower atmosphere and surface warm. There aren't a lot of 'natural' causes of global warming that can explain that, but of course it's totally consistent with an increase greenhouse effect.
Here is the state of our climactic understanding in a nutshell... Okay, well, a big nutshell.
We have a couple of hundred years of surface temperature data, and perhaps a hundred years of geographically wide spread surface temperature data. We have thousands of years of coarse proxies (ice cores, tree rings, etc) at single points.
From this data we attempt to deduce signals. That is, meaningful variations on the data. Unfortunately our ability to accurately measure causes of such signals in the proxies on the geological time scale is limited. We can only infer, extrapolate, and guess. On our progressively better data it gets better, but the best stuff really is only recent.
There were many limitations to our ability to make spacial measurements of the globe until we had satellites capable of the feat. Nice and even readings over the whole globe, depending on the accuracy of the equipment involved. They really provide our best data but we only have a couple of decades worth of data there. There's only so much gluing one data set type onto another that you can do before you've introduced more error than makes the process worth while.
Some of those signal patterns are on geological time scales rather than decade time scales, and thus, predictions on what those signals actually represent may take just as long to test. Unlike a gravity experiment which can be done and measured on demand, waiting for the entire climate system to reach a particular experiment point, for most practical purposes, is impossible. As are efforts is changing particular individual conditions to test specific characteristics in exclusion of others. We cannot clone the earth for an experiment.
What about computer modeling? Some might ask this as a follow up. Computer modeling is not science, just like math is not science. Math is a completely artificial construct that is often useful to describe a scientific observation. Like math, a computer model might be a useful artificial construct to describe a scientific observation. I can claim my math equation will accurately predict my gravity experiment and then proceed to verify that hypothesis. Proving these out simply requires tests with measurements and the time and effort to complete it. In the case of the global climate, our time scales for some things are geological. Don't read too much into what we think we know, there may well be a lot of signals we haven't accounted for and are not represented in our historical proxies. Hind casting is also not fool proof, you can produce equations that match a historical chart accurately but have zero predictive power. The only way we'll have really solid stuff is to have the hypothesis born out with experimental data. And that's going to take a long long time depending on the signals you are looking for.
Bottom line, climate science is not mature enough to give you any solid predictions and our understanding is really rather small.
The IPCC has published several very large reports on this. The last one in 2007 was the 'Fourth Assessment Report'
In the "Summary for Policymakers", a summary for the worlds politicians, there is a section called "Projected climate change and its impacts" Here they list projected impacts.
This is the document http://www.ipcc.ch/publications_and_data/ar4/syr/en/spms3.html
"Have any such predictions turned out to be accurate?" Day to day it's hard to tell what is weather and what is climate. Ask again in 7 years. Then you'll be able to look at the projections made for 2020 and see if they happened or not.
Gravity is no longer a theory; it is an accept fact of what is there. As for global warming, this planet has gone through it before and will again. To have ice ages we had to have had warming ages as well.
That when the globe warms enough, iceburgs will calve off. This will dump tonnes of fresh water into the ocean, which will slow the thermohaline circulation. http://rivernet.ncsu.edu/courselocker/PaleoClimate/Bond%20et%20al.,%201997%20Millenial%20Scale%20Holocene%20Change.pdf http://en.wikipedia.org/wiki/Daansgard-Oeschger_cycles The two are related. Think of the thermostat on your wall regulating the house temperature in the summer and the winter.