Feedbacks, feedbacks, feedbacks in climate theory



A new hole in the IPCC climate models

The whole Warmist scare is based on feedbacks that supposedly will AMPLIFY the trivial warming we saw in the 20th century. The feedbacks proposed are little better than guesswork and are in any case just a cherrypick of possible feedbacks. The research below looks at an unmentioned feedback: A vegetation-climate feedback. And guess what? Including that feedback REDUCES the predicted temperature rise

Discussing: Jeong, S.-J., Ho, C.-H., Kim, K.-Y., Kim, J., Jeong, J.-H. and Park, T.-W. 2010. Potential impact of vegetation feedback on European heat waves in a 2 x CO2 climate. Climatic Change 99: 625-635.




Background

The authors state that modeling studies in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) suggest that future heat waves over Europe will be more severe, longer lasting and more frequent than those of the recent past, due largely to an intensification of quasi-stationary anticyclone anomalies accompanying future warming, citing in support of this statement the publications of Meehl and Tebaldi (2004) and Della-Marta et al. (2007).

What was done

Jeong et al., as they describe it, "investigate the impact of vegetation-climate feedback on the changes in temperature and the frequency and duration of heat waves in Europe under the condition of doubled atmospheric CO2 concentration in a series of global climate model experiments," where land surface processes are calculated by the Community Land Model (version 3) described by Oleson et al. (2004), which includes a modified version of the Lund-Potsdam-Jena scheme for computing vegetation establishment and phenology for specified climate variables.

What was learned

The six scientists say their calculations indicate that "the projected warming of 4°C over most of Europe with static vegetation has been reduced by 1°C as the dynamic vegetation feedback effects are included," adding that "examination of the simulated surface energy fluxes suggests that additional greening in the presence of vegetation feedback effects enhances evapotranspiration and precipitation, thereby limiting the warming, particularly in the daily maximum temperature." In addition, they state that "the greening also tends to reduce the frequency and duration of heat waves."

What it means

Although Jeong et al.'s findings by no means constitute the final word on the subject of the ultimate climatic consequences of a doubling of the air's CO2 content, they indicate just how easily the incorporation of a new suite of knowledge, in even the best climate models of the day, can dramatically alter what the IPCC and other climate-alarmist organizations and individuals purport to be reality. The world of nature is so extremely complex that it is the height of arrogance -- or depth of ignorance -- to believe that the world's climate modelers are anywhere near being able to mathematically represent all that needs to be mathematically represented in a model of sufficient complexity to faithfully reproduce what actually happens in the real world of nature, and over the many orders of magnitude that they are reluctant to acknowledge are absolutely essential to obtain the answers we all seek, which are, of course, the correct answers, which are obviously still a long ways off.

SOURCE






‘Runaway climate change’ ‘unrealistic’, say scientists

Another disappointing feedback. The more we learn about them, the more pesky these feedbacks become

A new study is set to rock the boat again by calling into question one of the more frightening global warming scenarios: 'runaway climate change'. Under this scenario, rising temperatures speed up processes that catastrophically increase the rate of global warming – a positive feedback loop.

One of these processes is an increase in the rate of carbon dioxide (CO2) production by plants and microorganisms in the soil caused by an increase in temperature. As CO2 is a greenhouse gas, it has been suggested this will further increase temperatures, leading to a further increase in CO2 production until the Earth is too hot for human life.

Using Fluxnet, a global network of more than 250 'flux towers' to sample CO2 concentrations, a team of researchers from the Max Planck Institute has found that, actually, temperature has a much smaller effect on CO2 release than previous studies claimed.

The researchers, led by Miguel Mahecha, found that the rate at which plants and microorganisms produce CO2 in ecosystems from tropical rainforests to savannah does not even double when the temperature increases by 10°C from one week to the next.

His colleague Markus Reichstein says: "Particularly alarmist scenarios for the feedback between global warming and ecosystem respiration (CO2 production) thus prove to be unrealistic."

Climate change sceptics might say the new study is yet another nail in the coffin of the IPCC report, which says: "Anthropogenic warming could lead to some effects that are abrupt or irreversible, depending upon the rate and magnitude of the climate change."

But mainstream scientists will just be pleased that Fluxnet has given them real-world measurements upon which to base their computer models.

SOURCE

Posted by John J. Ray (M.A.; Ph.D.).

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