mariacostel wrote on Aug 15^th, 2015 at 12:59pm:


Methinks that hypotheses of trends from recent climate evidence require too many assumptions to support the proposition that there is no global warming.

The simple average temperature chart exemplifying constant increase in recent years and the fact of trend of recent years being the hottest recorded years after year is difficult to ignore.

Occam's Razor: "The principle states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected."

Occam's Razor: "The principle states that among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected."

The simplest model is recent year rising temperatures average and record highs year after year.

Unforgiven wrote on Aug 15^th, 2015 at 3:10pm:



Please provide a link to this model with its associated link to CO2 causing the temperature increase. Or even the correlation of the CO2 to the temperature increase.

CO2 has increased over 30% since the 1990's. The temperatures should have soared, if indeed CO2 is the 'control knob' of global warming.

I don't quite know how to respond to that 'response'. Laughter? Derisive mocking? Pity? Or maybe a simple reference to a dictionary to understand the meaning of 'model' or even 'assumption'.

The figure below from the Huber & Knutti paper illustrates the point nicely. The dotted orange and solid black lines show the unadjusted average model projection and measured global surface temperatures, respectively. The solid orange and dashed black lines show these estimates adjusted to reflect the changes in ocean cycles, solar output, volcanic activity, and surface temperature measurement biases.

Mean of CMIP5 climate model ensemble surface temperature projections unadjusted (dotted orange) and adjusted for internal variability & external forcings (solid orange), vs. Met Office (solid black) and Cowtan & Way (dashed black) observed surface temperatures.
Mean of CMIP5 climate model ensemble surface temperature projections unadjusted (dotted orange) and adjusted for internal variability & external forcings (solid orange), vs. Met Office (solid black) and Cowtan & Way (dashed black) observed surface temperatures. Source; Nature Geoscience; Huber & Knutti (2014)
Huber & Knutti show that when climate models account for these short-term natural changes, their temperature projections are right on the money.

The bad news is that we can’t yet predict changes in ocean cycles, solar output, or volcanic activity accurately, so it’s going to be hard to improve short-term climate model projections. The good news is that these factors make little difference in long-term climate changes or predictions. Solar and volcanic activity tend to be relatively stable, and will barely make a dent in human-caused global warming. Positive and negative phases of ocean cycles cancel each other out over the long-

Three-quarters of climate change is man-made
Image: greenhouse gases such as carbon dioxide have contributed around 0.85 °C to global warming since the 1950s, Swiss researchers have found (L. RINDER/GLOWIMAGES.COM)

Natural climate variability is extremely unlikely to have contributed more than about one-quarter of the temperature rise observed in the past 60 years, reports a pair of Swiss climate modellers. Most of the observed warming — at least 74 % — is almost certainly due to human activity, they write in Nature Geoscience.

Since 1950, the average global surface air temperature has increased by more than 0.5 °C. To separate human and natural causes of warming, the researchers analysed changes in the balance of heat energy entering and leaving Earth — a new ‘attribution' method for understanding the physical causes of climate change.

Their findings, which are strikingly similar to results produced by other attribution methods, provide an alternative line of evidence that greenhouse gases, and in particular carbon dioxide, are by far the main culprit of recent global warming. The massive increase of atmospheric CO2 concentrations since pre-industrial times would, in fact, have caused substantially more surface warming were it not for the cooling effects of atmospheric aerosols such as black carbon, they report.

Previous attempts to disentangle anthropogenic and natural warming used a statistically complex technique called optimal fingerprinting to compare observed patterns of surface air temperature over time with the modelled climate response to greenhouse gases, solar radiation and aerosols from volcanoes and other sources.


A balanced view
“Optimal fingerprinting is a powerful technique, but to most people it’s a black box,” says Reto Knutti, a climate scientist at the Swiss Federal Institute of Technology (ETH) in Zurich, one of the authors of the report.

Knutti and his co-author Markus Huber, also at ETH Zurich, took a different approach. They utilized a much simpler model of Earth’s total energy budget and ran the model many thousands of times, using different combinations of a few crucial parameters that contribute to the energy budget. These included global values for incoming shortwave radiation from the Sun, solar energy leaving Earth, heat absorbed by the oceans and climate-feedback effects (such as reduced snow cover, which amplifies warming by exposing darker surfaces that absorb more heat).

By using the combinations that best matched the observed surface warming and ocean heat uptake, the authors then ran the so-constrained model with each energy parameter individually. This enabled them to estimate the contribution of CO2 and other climate-change agents to the observed temperature change. Their study was greatly assisted by a 2009 analysis of observed changes since 1950 in Earth’s energy balance, says Knutti.

They utilized a much simpler model of Earth’s total energy budget and ran the model many thousands of times, using different combinations of a few crucial parameters that contribute to the energy budget. These included global values for incoming shortwave radiation from the Sun, solar energy leaving Earth, heat absorbed by the oceans and climate-feedback effects (such as reduced snow cover, which amplifies warming by exposing darker surfaces that absorb more heat).

mariacostel wrote on Aug 15^th, 2015 at 4:10pm:


Here you go. Correlation of models with actual observed temperature. You will have to open the article to see the charts depicting the models.

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/aug/25...

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http://nauka.in.ua/en/news/articles/article_detail/7182
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