[Pops]

I'm not always convinced by the latest "projection" because like they say, GIGO but...

1990 climate change predictions turn out to be accurate
Posted on December 10, 2012 - 07:59 by Emma Woollacott

In a blow to those people who believe that global warming predictions are just a lot of hot air, an international team has established that predictions made 20 years ago are turning out pretty accurate.

The report compares predictions from the first Intergovernmental Panel on Climate Change (IPCC) Assessment Report, published in 1990, with real-world global climate change data gathered since.

It's the first time that IPCC estimates have been compared with real world changes, and should give more credence to the organization's increasingly alarming predictions. Its next set of forecasts - based on much more refined computer models than those of 1990 - are due next year.

"It is important for scientists to go back and see how early climate change predictions are going," says Professor David Frame, Director of the New Zealand Climate Change Research Institute at Victoria University.

"What we've found is that these early predictions seem pretty good, and this is likely due to the climate responding to concentrations of greenhouse gases in the earth's atmosphere at a rate broadly in line with what scientists in 1990 expected."

The IPCC report predicted a rise of 0.7˚C to 1.5˚C by 2030, and of 0.35˚C to 0.75˚C by 2010. And, in fact, observations show that the actual global mean surface temperature has increased by between 0.35 and 0.39˚C - a figure that's in reasonable agreement with the 1990 predictions, says the team.

Read more at http://www.tgdaily.com/sustainability-f ... e-accurate.

http://www.tgdaily.com/sustainability-f ... e-accurate

[Lore]

However, the IPCC way underestimated ice melt.

[dohboi]

And the power of various of the non-charney "slow" carbon feedbacks.

So far we have mostly seen the effects of the fast "Charney" feedbacks"--change of albedo from snow and ice melt, and water vapor feedback--which are relatively easy to model. What will be driving the rate of warming from about now on will more and more be the carbon feedbacks--permafrost melt, methane hydrates, other soil changes, wild fires...

Still, nice to see evidence that 'models'--so often derided by know-nothings--have some demonstrated reliability. I don't see much reliability from any predictions made by anyone in the denialist camp.

Hansen's predictions from the '80s have also turned out to be pretty spot on, iirc.

[Graeme]

However, the IPCC way underestimated ice melt.

Hasn't soot from jets and arctic wildfires been implicated?

[rockdoc123]

I actually went and had a read of the paper in Nature Climate Change.
Frame, D., and Stone, D., 2012, Assessment of the first consensus prediction on climate change, Nature Climate Change, DOI:10.1038/NCLIMATE1763, p 1-3
First of all the title of this thread is inaccurate as the paper did not actually test what it was that was included in the 1990 prediction but rather used their own forcings and included a correction for natural variability which was not included in the 1990 IPCC analysis. In other words this is apples and oranges.
Secondly there has been a lot of discussion about the arguments individuals such as John Cook used to argue the IPCC predictions were correct (earlier this year I believe). Most recently Jo Nova discussed similar misleading statements made in regard to the 1990 prediction on Australian television.
http://joannenova.com.au/2012/12/the-ipcc-was-wrong-england-and-the-abc-mislead-australians/
The bottom line can be shown with two plots I believe. This first is a comparison of actual CO2 levels measured versus the IPCC model assumptions.

What this plot shows is the actual measured CO2 corresponds closely with the highest CO2 emission model that the IPCC used in the 1990 prediction. So lets look at that prediction versus reality:

What this shows is that actual temperatures correspond closer with the IPCC prediction if CO2 emissions were to be seriously curtailed. The high prediction of the IPCC corresponds to the actual CO2 model and it is quite apparent it isn’t anywhere near correct. Now various individuals argue…well yes but methane forcing has been different and that changes it. The response to that is that you can’t argue “they were right” and then turn around and argue “well they would have been right if they did this”. The simple fact is the predictions were wrong. Not only that but including methane forcing would still only bring you down to closer to the Bmodel of Hansen or the Best Estimate of IPCC which is still to high compared to actual temperatures.
And Hansens predictions were also incorrect as shown in this diagram:

Again the highest prediction corresponds to actual CO2.

[dorlomin]

The bottom line can be shown with two plots I believe. This first is a comparison of actual CO2 levels measured versus the IPCC model assumptions.

CO2 is not the only greenhouse gas. Most of the others, especially methane, seriously undershot the IPCC projections.

Youd have to asses all the human sourced greenhouse gasses for total radiative forcing. Also as our friends are eternally keen to remind us, solar is lower that would have been anticipted. Sulphate loadings will be different with less in the high northern hemisphere and more (lots more) in the low lattitudes around India, Indonesia, Brazil and most especially China.

Plus we can plug in ENSO as happened.

[Lore]

However, the IPCC way underestimated ice melt.

Hasn't soot from jets and arctic wildfires been implicated?

Soot is an implication of climate change.

SOOT SPEEDING GREENLAND'S ICE MELT

Wildfires in the Arctic have become more frequent in recent years as rising temperatures allow the area to dry out. For example, the Anaktuvuk River fire burned more than 621 square miles of tundra on Alaska's North Slope in 2007. The area hadn't seen a fire of that scale in at least 5000 years, according to research led by Feng Sheng Hu of the University of Illinois.

http://news.discovery.com/earth/soot-sp ... 21207.html

[dorlomin]

How exactly do those two straight lines for UAH and HadCRUT go all the way up to 2015?

[Pops]

Thanks for buying the paper doc.

I'm confused, the article said the model predicted a rise of "0.35˚C to 0.75˚C by 2010. And, in fact, observations show that the actual global mean surface temperature has increased by between 0.35 and 0.39˚C "

So did the model predict .35º-.75º rise or didn't it?

[vision-master]

[dohboi]

How tiresome and predictable these repetitious denialist claims are.

http://www.skepticalscience.com/cosmic- ... arming.htm

http://www.skepticalscience.com/global- ... n-mars.htm

http://www.skepticalscience.com/global- ... system.htm

[rockdoc123]

How tiresome and predictable these repetitious denialist claims are.

how tiresome it is when the only source of information you have is John Cook who uses bait and switch argument techniques.
A number of people have eviscerated the discussion you point to including Jo Nova who I pointed to above.

http://joannenova.com.au/2012/05/the-ip ... ere-wrong/

An important point because you no doubt missed the bait and switch Cook was using is he talks about "radiative forcing" of CO2 and not what the IPCC in 1990 were talking about which is CO2 emissions. Cook is basically claiming the IPCC said something completely different than they actually did which is:

Under the IPCC Business as Usual emissions of greenhouse gases the average rate of increase of global mean temperature during the next century is estimated to be 0.3C per decade

they are talking about predictions based on emissions, not forcings or actual PPM content in the atmosphere (which is what Cook is referring to). And there is no way around the argument that the IPCC prediction of emissions was almost the same as what has occurred. Everything else is not pertinant to the question as to whether the IPCC got it right.

[rockdoc123]

CO2 is not the only greenhouse gas. Most of the others, especially methane, seriously undershot the IPCC projections.

Youd have to asses all the human sourced greenhouse gasses for total radiative forcing. Also as our friends are eternally keen to remind us, solar is lower that would have been anticipted. Sulphate loadings will be different with less in the high northern hemisphere and more (lots more) in the low lattitudes around India, Indonesia, Brazil and most especially China.

Plus we can plug in ENSO as happened.

Of course but that is not what the IPCC prediction (they used the term prediction not projection back then and the difference is not subtle) said. What they said was under an emission level of X this is the temperature increase expected (didn't happen). A revisionist look at what they said is all well and good as that is what you are claiming to do.

[rockdoc123]

Pops in answer to your question here is the exact quote from the IPCC 1990 study:

Under the IPCC Business-as-Usual (Scenario A) emissions of greenhouse gases, the average rate of increase of global and mean temperature during the next century is estimated to be about 0.3 C per decade (with and uncertainty range of 0.2 C to 0.5 C). This will result in a likely increase in global mean temperature of about 1 C above the present value (about 2 C above that in the pre-industrial period) by 2025 and 3 C abouve today’s (about 4 C abouve pre-industrial) before the end of the next century.

And

Even if we were able to stabilise emissions of each of the greenhouse gases at present day levels from now on, the temperature is predicted to rise by about 0.2 C per decade for the first few decades.

It is clear from the chart I showed that actual emissions have been at the very highest model level used by the IPCC in 1990.

As to what temperature trends resulted, Foster and Ramstorf in 2011 indicated that the trend from 1979 to 2010 was 0.14 C/decade to 0.18 C/decade.

Foster, G., and Rahmstorf, S, 2011. Global temperature evolution 1979-2010, Environ. Res. Lett, 6, 044022, doi:10.1088/1748-9326/6/4/044022

We analyze five prominent time series of global temperature (over land and ocean) for their
common time interval since 1979: three surface temperature records (from NASA/GISS,
NOAA/NCDC and HadCRU) and two lower-troposphere (LT) temperature records based on
satellite microwave sensors (from RSS and UAH). All five series show consistent global
warming trends ranging from 0.014 to 0.018 K yr-1

There was a lot of finger pointing when Phil Jones said in 2009 that temperature increase in the period 1995 – 2009 had been insignificant and although he changed that view to be “statistically significant” in a subsequent comment in 2010, his calculated decadal trend was still only 0.16 C/decade.

So those “trends” were actually below the lowest scenario (0.2 C/decade) that the IPCC assumed in their 1990 models….consistent with the graphs I showed.

[Graeme]

How the IPCC is more likely to underestimate the climate response

One characterisation of the IPCC is that it is politically motivated to exaggerate the dangers of global warming and the level of human influence on climate change. When IPCC predictions are compared to observed data, the opposite is shown to be the case.

Conservative Greenhouse Gas Emissions Scenarios

For example, the acceleration in fossil fuel CO2 emissions is tracking the worst case scenarios used by the IPCC AR4 (Copenhagen Diagnosis 2009). Consequently, atmospheric CO2 is increasing ten times faster than any rate detected in ice core data over the last 22,000 years.



Figure 1: Observed global CO2 emissions from fossil fuel burning and cement production compared with IPCC emissions scenarios. The coloured area covers all scenarios used to project climate change by the IPCC (Copenhagen Diagnosis 2009).

Conservative Attribution of Global Warming to Humans

The 2007 IPCC report stated:

"Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations"

However, the body of scientific research has consistently shown that human greenhouse gas emissions are responsible for more warming than has been observed over the past half century (because aerosols and other non-greenhouse gas temperature influences have had a net cooling effect). Wigley and Santer (2012) found that this IPCC greenhouse gas warming attribution statemt is far too conservative.

"Here, the probability that the model-estimated GHG component of warming is greater than the entire observed trend (i.e., not just greater than ‘‘most’’ of the observed warming) is about 93%. Using IPCC terminology, therefore, it is very likely that GHG-induced warming is greater than the observed warming. Our conclusion is considerably stronger than the original IPCC statement."

In fact their central estimate is that humans are responsible for 100% of the observed global warming for the 1950–2005 timeframe, with greenhouse gases responsible for 160% (Figure 2).



Figure 2: Percent contributions of various effects to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), and Wigley and Santer 2012 (WS12, dark green).

As Figure 2 shows, the body of scientific literature is still very consistent in finding that grenhouse gases have most likely caused more warming than has been observed over the past half century, and thus that the IPCC has been too conservative in this respect.


Accurate Global Surface Warming Projections

Rahmstorf, Foster, and Cazenave (2012) also found that the IPCC global surface temperature projections have been acccurate thus far. The paper applies the methodology of Foster and Rahmstorf (2011), using the statistical technique of multiple regression to filter out the influences of the El Niño Southern Oscillation (ENSO) and solar and volcanic activity from the global surface temperature data, finding that when these short-term influences are removed, the IPCC projections accurately match the observed human-caused global surface warming trend (Figure 5).



Figure 5: Observed annual global temperature, unadjusted (pink) and adjusted for short-term variations due to solar variability, volcanoes and ENSO (red) as in Foster and Rahmstorf (2011). 12-month running averages are shown as well as linear trend lines, and compared to the scenarios of the IPCC (blue range and lines from the 2001 report, green from the 2007 report). Projections are aligned in the graph so that they start (in 1990 and 2000, respectively) on the linear trend line of the (adjusted) observational data.

skepticalscience

[dorlomin]

Of course but that is not what the IPCC prediction (they used the term prediction not projection back then and the difference is not subtle) said. What they said was under an emission level of X this is the temperature increase expected (didn't happen). A revisionist look at what they said is all well and good as that is what you are claiming to do.

Nearly a third of human sourced greenhouse gas forcing is not CO2.

Energy that was expected to be coming from CH4 and the halocarbons is not. What else would you expect other than the models to be running low?

[dohboi]

Good graph.

Note the wide error bars on the aerosols.

They could be cooling the planet by nearly 3 degrees C. If/when we stop emitting them--which we must, since they are acidifying oceans, among other nasty things--they will fall out of the atmosphere in a few weeks to months and we will head quickly to as much as an additional 3 degrees of warming. We can hope that the error bars are wrong the other direction, and that the result of taking away the masking effect will only about double the amount of warming we've had since the Industrial Revolution--not a particularly comforting scenario either.

[rockdoc123]

Energy that was expected to be coming from CH4 and the halocarbons is not. What else would you expect other than the models to be running low?

once again read the title of the thread .....the 1990 predictions were based on a certain level of emissions (I gave the quote from the report). That is what was said in the IPCC report.
As a consequence given the emissions actually experienced for the IPCC prediction to be correct as they stated it temperature trends would have had to be higher. IT is that simple. The IPCC did not say...."everything else being equal", or "we expect other forcings to offset CO2 emissions temperatures trends won't be as high". You can not argue they were right...they just didn't take into account other forcings, a prediction is a prediction.

Hindsight is always 20/20

At this point it is probably worthwhile clearly defining the difference between prediction (as used by IPCC in 1990) and projection (as used by Cook and in AR4)

A prediction is a probabilistic statement that something will happen in the future based on what is known today. A prediction generally assumes that future changes in related conditions will not have a significant influence. In this sense, a prediction is most influenced by the "initial conditions" – the current situation from which we predict a change. For example, a weather prediction indicating whether tomorrow will be clear or stormy is based on the state of the atmosphere today (and in the recent past) and not on unpredictable changes in "boundary conditions" such as how ocean temperatures or even society may change between today and tomorrow. For decision makers, a prediction is a statement about an event that is likely to occur no matter what they do.

In contrast to a prediction, a projection specifically allows for significant changes in the set of "boundary conditions" that might influence the prediction, creating "if this, then that" types of statements. Thus, a projection is a probabilistic statement that it is possible that something will happen in the future if certain conditions develop. The set of boundary conditions that is used in conjunction with making a projection is often called a scenario, and each scenario is based on assumptions about how the future will develop. For example, the IPCC recently projected a range of possible temperature changes that would likely occur for a range of plausible emissions scenarios and a range of model-derived estimates of climate sensitivity (the temperature change that would result from a CO2 doubling). This is clearly a projection of what could happen if certain assumed conditions prevailed in the future – it is neither a prediction nor a forecast of what will happen independent of future conditions. For a decision maker, a projection is an indication of a possibility, and normally of one that could be influenced by the actions of the decision maker.

[Graeme]

Of course this argument over semantics invalidates everything that the IPCC has done.

[dohboi]

I typed too quickly. That's up to about 3 W/m^2 (not degrees) in additional forcing that aerosols may currently be masking.