Yet another vindication for Michael Mann’s work on the legendary “Hockey Stick” comes from an analysis of global warming by decade from the World Meteorological Organisation.
Alongside this, some of the research from sea floor sediment drilling has now been published, and it should make you sit up and pay attention.
The key issue in Global Warming Science is “Climate Sensitivity”, and that’s not a measure of how prickly you are when someone wants to talk to you about how Climate Change is one big hoax.
It is essentially defined by the results of research that look into how the Earth would respond to a doubling of Carbon Dioxide in the atmosphere.
There’s the direct warming from the increase in the Greenhouse Effect, but the Biosphere reacts to warming by changing, in a wide variety of ways, some of which could cause more warming, and so the total amount of average warming could be somewhere between 3 and 6 degrees Celsius.
“High Earth-system climate sensitivity determined from Pliocene carbon dioxide concentrations : Mark Pagani, Zhonghui Liu, Jonathan LaRiviere & Ana Christina Ravelo : Climate sensitivity – the mean global temperature response to a doubling of atmospheric CO2 concentrations through radiative forcing and associated feedbacks – is estimated at 1.5 – 4.5 degrees C […] However, this value incorporates only relatively rapid feedbacks such as changes in atmospheric water vapour concentrations, and the distributions of sea ice, clouds and aerosols. Earth-system climate sensitivity, by contrast, additionally includes the effects of long-term feedbacks such as changes in continental ice-sheet extent, terrestrial ecosystems and the production of greenhouse gases other than CO2. Here we reconstruct atmospheric carbon dioxide concentrations for the early and middle Pliocene, when temperatures were about 3 – 4 degrees C warmer than preindustrial values, to estimate Earth-system climate sensitivity from a fully equilibrated state of the planet. We demonstrate that only a relatively small rise in atmospheric CO2 levels was associated with substantial global warming about 4.5 million years ago, and that CO2 levels at peak temperatures were between about 365 and 415 parts per million. We conclude that the Earth-system climate sensitivity has been significantly higher over the past five million years than estimated from fast feedbacks alone…”
Considering that the current ppm count for Carbon Dioxide in the atmosphere is today 385.99 ppm, I think it’s about time more people showed some concern :-