Are the predictions of the IPCC about climate change valid?
If you put “forecasting” into Google, the top result is www.Forecastingprinciples.com.
Here is a link (http://ff.org/centers/csspp/library/co2w... ) to a report that applied the principles of www.Forecastingprinciples.com to the IPCC’s predictions. They found that, of the 140 principles, 127 were relevant to the climate forecasts, but they also found that Chapter 8 of the IPCC’s WG1 report (that dealt with climate prediction) was so badly written that they couldn’t find enough information to make a judgment on 38 of those principle. That left 89 principles that were relevant and upon which a judgement could be made. Of those 89 principles, 72 were violated!
They conclude: “Many of the violations were, by themselves, critical. We have been unable to identify any scientific forecasts to support global warming. Claims that the Earth will get warmer have no more credence than saying that it will get colder.”
Some other interesting quotes from this report…
“…scientists had to make “educated guesses” about the values of many parameters because knowledge about the physical processes of the earth’s climate is incomplete.”
“…the GCMs failed to predict recent global average temperatures as accurately as simple curve-fitting approaches (Carter 2007, pp. 64 – 65) and also forecast greater warming at higher altitudes when the opposite has been the case.”
“…individual GCMs produce widely different forecasts from the same initial conditions and minor changes in parameters can result in forecasts of global cooling (Essex and McKitrick, 2002). Interestingly, modelling results that project global cooling are often rejected as “outliers” or “obviously wrong” (e.g., Stainforth et al., 2005).”
So, some of the IPCC’s climate models predicted cooling, but they were ignored because they were “obviously wrong”. Er? Okay.
And there’s more…
“Taylor (2007) compared seasonal forecasts by New Zealand’s National Institute of Water and Atmospheric Research with outcomes for the period May 2002 to April 2007. He found NIWA’s forecasts of average regional temperatures for the season ahead were, at 48% correct, no more accurate than chance.”
“…New Zealand climatologist Dr Jim Renwick… observed that NIWA’s low success rate was comparable to that of other forecasting groups worldwide. He added that “Climate prediction is hard, half of the variability in the climate system is not predictable, so we don't expect to do terrifically well.” Dr Renwick is an author on Working Group I of the IPCC 4th Assessment Report, and also serves on the World Meteorological Organisation Commission for Climatology Expert Team on Seasonal Forecasting; His expert view is that current GCM climate models are unable to predict future climate any better than chance (New Zealand Climate Science Coalition 2007).”
“…the NHC’s forecast for the 2006 [hurricane] season was widely off the mark. On June 7, Vice Admiral Conrad C. Lautenbacher, Jr. of the National Oceanic and Atmospheric Administration gave the following testimony before the Committee on Appropriations Subcommittee on Commerce, Justice and Science of the United States Senate (Lautenbacher 2006, p. 3):
“NOAA's prediction for the 2006 Atlantic hurricane season is for 13-16 tropical storms, with eight to 10 becoming hurricanes, of which four to six could become major hurricanes. … We are predicting an 80 percent likelihood of an above average number of storms in the Atlantic Basin this season. This is the highest percentage we have ever issued.”
By the beginning of December, Gresko (2006) was able to write “The mild 2006 Atlantic hurricane season draws to a close Thursday without a single hurricane striking the United States”.”
“…some statements were made about the ability of the models described in Chapter 8 to fit historical data, after tweaking of their parameters. Extensive research has shown that the ability of models to fit historical data has little relationship to forecast accuracy (See “Evaluating Methods” in Armstrong 2001.)”
“While the authors of Chapter 8 claim that the forecasts of global mean temperature are well-founded, their language is imprecise and relies heavily on such words as “generally,” “reasonable well,” “widely,” and “relatively” [to what?]. The report makes many explicit references to uncertainty. For example, the phrases “. . . it is not yet possible to determine which estimates of the climate change cloud feedbacks are the most reliable” and “Despite advances since the TAR, substantial uncertainty remains in the magnitude of cryospheric feedbacks within AOGCMs” appear on p. 593. In discussing the modelling of temperature, the authors wrote, “The extent to which these systematic model errors affect a model’s response to external perturbations is unknown, but may be significant” (p. 608), and, “The diurnal temperature range… is generally too small in the models, in many regions by as much as 50%” (p. 609), and “It is not yet known why models generally underestimate the diurnal temperature range.” The following words and phrases appear at least once in the Chapter: unknown, uncertain, unclear, not clear, disagreement, uncertain, not fully understood, appears, not well observed, variability, variety, difference, unresolved, not resolved, and poorly understood.”
“…we have been unable to find a single scientific forecast to support the currently widespread belief in dangerous, human-caused “global warming”. Prior research on forecasting suggests that a naïve (no change) forecast would be superior to current predictions which are, in effect, experts’ judgments only.”
Note that the “naïve” forecast would be to repeat the last century’s warming for this century; so that would be another 0.6°C. However, even the lower end of the temperature range, in the IPCC’s least warming scenario is 1.1°C - almost double the 0.6°C experienced last century. Their highest prediction is 6.4°C – over ten times the warming of the last century.
Given all the above, I think the only legitimate answer to your question is: no, the predictions of the IPCC about climate change are not valid.
NO! climate change doesn't even exsist! All of the cities in the entire world combined pollution doesn't do half as much harm to the ozone layer as the oceans do naturally
check out the great global warming swindle movie!
In some cases yes, in some cases no. There are a few truisms in their predictions, but since I assume you have heard them all before I will just point out the errors instead;
First and foremost, you should realise that whilst Global Warming has negative effects on humanity, the net effect is almost definitely positive. Warm periods in the past (Holocene optimum, Medieval Warm period, Roman optimum, etc) have all been eras of human prosperity and growth specifically because of favourable climate. There are large benefits from not only a warm climate, but particularly one with high CO2 levels. As I'm sure you know CO2 is plant food.
With respect to the negatives they have outlined;
There is no evidence that tornadoes/hurricanes/storms are more frequent or more intense because of a warmer climate. In fact, if anything it is the opposite. People like the Al Gore and the idiot media really don't have the first clue what they are talking about. There are countless people out there who criticise the IPCC for speculating and making things up in regard to this, in fact one of the world's leading experts (Chris Landsea) resigned from the IPCC specifically because he saw it as corrupt on this issue (“I personally cannot in good faith continue to contribute to a process that I view as both being motivated by pre-conceived agendas and being scientifically unsound.”).
The other main issue is sea level changes. Here is a man who goes through the specifics of how the IPCC destroyed evidence that showed the Maldives are actually experiencing a drop in sea levels;
The fact of the matter is, 90% of the world's land ice is in Antarctica and that ice mass is actually growing. We are not at all in danger of rising sea. We are expecting about 0-20cm of rise this century, and that is entirely because we are still coming out of the last ice age. Even if the sea level was rising a certain amount, the human dislocation that it would cause is dwarfed by all the other factors that contribute to human migration (changes in resource locations, fresh water, industrialisation, etc etc).
I would say that the vast majority of the IPCC's predictions on the consequences of climate change are either false, exaggerated, or speculative.
They might be over conservative and might understate global warming.
"The drafting of reports by the world’s pre-eminent group of climate scientists is an odd process. For many months scientists contributing to the Intergovernmental Panel on Climate Change tussle over the evidence. Nothing gets published unless it achieves consensus. This means that the panel’s reports are extremely conservative – even timid. It also means that they are as trustworthy as a scientific document can be."
One of the ways they are over conservative is that they omit "feedback" effects, since the data on those is sparse. An example is that warming ocean waters will release more CO2 which causes more warming and the process spins out of control. There is some historical data that suggests that happened in past (natural) warmings.
Yes they're valid because they're based on scientific data. As Bob mentioned, they may be too conservative because they don't take many feedbacks into account. The reason they don't account for feedbacks is because they're too complicated for models to include at the moment. A few models have included feedbacks and found them to increase global warming projections by about 30%.
The other reason the projections are valid is because they use a range of possible greenhouse gas values. They say 'if we emit this lower amount of greenhouse gases, this will be the temperature increase. If we emit this higher amount, the increase will be this much', so we have a realistic range of possibilities to examine.
Yea, remember all the hurricanes we were supposed to have after Katrina?
No, no one can predict the future.
its a panel of 1000 of the top climate scientists in the world.i'd say yeah...I've done research on this subject in detail and if you don't believe it its pure ignorance or arrogance...not sure yet which one.Look around the signs are everywhere and you can tell things are changing jsut like the IPCC said they would.look at last week in the west.how many cities broke all time records for high temps? and how many were liek a degree away? if you dont see it you're blind to the truth
The thing about any prediction is that only time will tell if it's right or wrong. The evidence available so far suggests that the predictions will be reasonably accurate and if we look back at how past predictions have panned out we can see a high degree of accuracy.
Making predictions for the future is phenomenally complicated and requires the computing power of some of the world's most powerful super-computers such as the one we have at the Hadley Centre. There are a great many factors to be taken into account, some of these are static, some follow known laws of physics but some are variable, it's these variables which add a degree of uncertainty.
One way to test the reliability of a model or prediction is to run the programme again using different data, then to run it again and again and again etc. Further, a number of predictions from different sources or produced using different methods can be compared for consistency. If they all produce more or less the same results then it's reasonable to assume that the prediction will prove to be an accurate one.
The IPCC predictions are the culmination of many years of work by numerous scientists and organisations around the world and as such are a composite of many sources. If you look at this graph for example http://www.globalwarmingart.com/wiki/ima... you'll see that all the organisations predict substantial warming in the future but there is degree of variability. The IPCC predictions fall roughly somewhere in the middle and are effectively an average from the different sources.
The IPCC has made a great many predictions and not all of them will be correct. Already it's revised it's prediction of how soon the Arctic ice will melt and by how much temperatures will rise in the short term, both of which are happening more rapidly than had been previously thought. This is bad news as it shows that things are proving to be worse than originally predicted.
The underlying trend of many of the predictions can't fail but to be correct. For example, the world can't do anything but warm up for the next 100 years or so even if greenhouse gas emissions were reduced to nil overnight, only human intervention or some event of cataclysmic proportions could result in the world cooling. In this respect the related predictions will be correct, time will tell just how accurate they prove to be.
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