Wx Savvy | Climate

Are Global Warming Predictions Right?

"Such models cannot yet simulate all aspects of climate"-IPCC Summary for Policymakers 2001

We won't know for another 50 to 100 years if the predictions are accurate. However, it's your confidence in the predictions that should be shaky. I would be especially skeptical when you read the following quotes from Dr. James Hansen who helped bring attention to global warming back in 1988...

Dr. James Hansen said in 1988 that he was,
"99 percent sure . . the [human caused] greenhouse effect has been detected and it is changing our climate now." (1)

Dr. James Hansen in 1998 wrote,
"the forcings that drive long-term climate change are not known with accuracy sufficient to define future climate change." (1)

His position changes from a near assurance that humans are changing the climate to an admittance that we don't know what changes our climate and therefore we can't with any certainty predict what will happen in the future.

It's interesting to note that in one statement he is sure of something, and in another statement can't be sure enough to predict that something in the future. This is not to say that Dr. James Hansen is wrong about global warming, on the contrary, these statements seem to summarize the current situation concerning global warming and global warming predictions. More to the point, there is a scientific consensus (5) that global warming is happening, but as Dr. Hansen states, we can't be sure exactly how it will change our planet.

Let me make this very clear, Dr. James Hansen is no doubt a very intelligent and well respected scientist (a lot smarter than me). I simply bring up these quotes to point out how the experts even believe there is much uncertainty surrounding the global warming predictions.

In a more recent statement Dr. James Hansen in 2002 said, "Most climate simulations, as summarized by the IPCC (intergovernmental Panel on Climate Change), do not include all of the negative forcings; indeed, if they did, and other forcings were unchanged, little global warming would be obtained."(3)

But wait! There's more evidence that the global warming predictions lack any confidence.

Below is a table showing how global warming predictions have changed over the years. Notice how drastically the predictions change. For example, from 1990 to 1996 the low end prediction went from 9°C (16°F) to .8°C (1.4°F).

Predictor

First Prediction
(Warming/year predicted)

Second Prediction
(Warming/year predicted)

Third Prediction
(Warming/ year predicted)

IPCC (Intergovernmental Panel on Climate Change)
9°C to 12°C (1990) (1)

.8°C to 3.5°C (1996) (1)

1.4°C to 5.8°C (2001) (4)

Let me make a more direct point about these changes in predictions. It's as if your weatherman flip-flopped on the forecast saying the weekend temps will be in the 90s, then tomorrow saying the weekend temps will be cooler in the 30s and then the next day saying the weekend temps will be in the 50s. Would you try to plan your weekend on this forecast? Well, how can we institute economy altering changes based on these global warming forecasts?

At the same time, one can argue that while the extent of the warming is debatable it is likely that humans are part of the cause of global warming and we should do something about that. But this debate is for another day, let's stick to the topic of the accuracy of the global warming predictions.

Not only do the predictions flip-flop, but the prediction itself indicates a vote of no confidence. The IPCC as of 2001 predicts a warming of 1.4°C to 5.8°C (4). In Fahrenheit, that comes to a range of 2°F -10°F! That's a huge margin of error and furthers our lack of confidence in the predictions of global warming.

Although it seems at this point there is a significant lack of understanding on exactly how our climate may change in the future, with so much focus on the topic of climate change it will only spur more research and better predictions.

Further, the lack of confidence in the projections is no reason for complacency when it comes to trying to curb our emissions of greenhouse gases. However, uncertainty in climate forecasts may reduce the degree of urgency for action. If that is good or bad for our future, we won't really know for another 50 to 100 years. In the meantime it's a hotly debated topic that likely will produce better models, better understanding and better science. So, regardless of what side you take, one has to appreciate the advancements that are and will come due to the attention on the subject.

*In order to compare predictions over the same 100 year period, I extrapolated the IPCC's 1990 prediction for warming by 2050 by doubling the prediction (it's really a 110 year period).

(1) http://www.ncpa.org/ba/ba299.html

(2) http://www.sepp.org/reality/michreviews.html

(3) http://www.globalwarming.org/article.php?uid=192

(4) http://www.ipcc.ch/pub/spm22-01.pdf

(5) http://www.sciencemag.org/cgi/content/full/306/5702/1686