“Nature” – the “International weekly journal of science” published an editorial (3 Dec 2009 “Climatologists Under Pressure” [http://www.nature.com/nature/journal/v462/n7273/full/462545a.html]) admitting there is no real evidence of anthropogenic greenhouse gas warming other than computer models.
Obviously Nature does not think information should be provided by researchers – just their conclusions.
So where are the “robust lines of evidence” for causation?
“Denialists often maintain that these changes are just a symptom of natural climate variability. But when climate modellers test this assertion by running their simulations with greenhouse gases such as carbon dioxide held fixed, the results bear little resemblance to the observed warming. The strong implication is that increased greenhouse-gas emissions have played an important part in recent warming, meaning that curbing the world's voracious appetite for carbon is essential”.
That’s it – running model simulations. That’s all there is. No real evidence. The models don’t work without CO2. Just curb your appetite. If there was actual empirical evidence of CO2 causation they would have mentioned it.
One of the most disturbing aspects of Nature’s promotion of the global warming scare (besides the name calling of anyone who questions it) is their lack of understanding of the scientific method.
The use of models is a valid part of science – it is often involved in steps 2 and 3 above.
Step 1 – warming and other symptoms have been observed.
Step 2 – CO2 was hypothesized to explain it.
Step 3 – Models have been created; the doomsday future has been forecast.
Step 4 – Oops – Nature forgot this one – they think step 4 is: promote incomplete science as a belief.
The following figure (left) is from the IPCC AR4 Summary for Policymakers figure SPM-4 [http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf]. It shows “observed” global annual average temperature anomaly (black), model simulations with only natural forcings (blue) and models including anthropogenic greenhouse gases (pink). The models cannot simulate the warming that occurred in the 1930s-1940s. The right-hand figure shows the Hadley global temperature data used by the IPCC superimposed on their “summary” graph (from the Hadley Climatic Research Unit (CRU) which provides the data used by the IPCC [http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/]).
The following figure is from the IPCC Fourth Assessment Report (AR4) Figure 9.6 (2007). It shows the change in temperature (C per decade) by latitude. The black line shows the observed temperature, the blue band shows the output of the computer models including only natural factors, whereas the pink band shows the output of computer models including anthropogenic CO2. Notice that the models with only natural factors (blue shaded area) can explain all of the warming for most of the world up to 30 degrees north latitude. This figure also shows that the recent warming is mainly in the Arctic.
James Hansen is one of the biggest promoters of the anthropogenic CO2 global warming (AGW) scare. And yet his own work shows that the AGW theory is false. In 1988 he provided temperature predictions based on climate models (results of which he presented to the US congress to promote the scare). He modeled three scenarios: ‘A’ had an increasing rate of CO2 emissions, ‘B’ had constant rate of CO2 emissions, while scenario ‘C’ had reduced CO2 emissions rate from 1988 levels into the future “such that the greenhouse gas climate forcing ceases to increase after 2000” [http://pubs.giss.nasa.gov/abstracts/1988/Hansen_etal.html].
The following figure superimposes the Hadley temperature anomaly data used by the IPCC and shown previously (superimposed on the IPCC global model plot and here changed to red) on Hansen’s 1988 model projections. The vertical blue line indicates the year in which the projections were made. (The zero level is different since Hansen used 1951-1980 as the base period for the calculation of temperature anomalies, while the IPCC currently uses 1961-1990.) The actual data are below Hansen’s modeled scenario C that had reduced CO2 levels.
In the 20 years since Hansen’s model projections, the global temperature is below the scenario ‘C’ in which “the greenhouse gas climate forcing ceases to increase after 2000”. So his scenario ‘C’ most closely matches reality. But there is a problem: CO2 has continued to increase. Obviously there is a problem with the models.
Without Step 4 of the scientific method, the science is incomplete – i.e. not conclusive. Models do not necessarily represent reality. Without empirical evidence to support them, the models are pure speculation.
[2012/10/09] Roger Pielke Sr. has compiled quotes from papers showing that climate models do not match reality.