Post by marchesarosa on Jan 7, 2012 3:46:48 GMT 1
Here's one for eamonn and nickrr!
There is one simple question that must be answered before we can even estimate AGW:
What is the temperature that it would be outside right now, if CO2 were still at its pre-industrial level?
Care to take a stab at an answer? Anyone?
Here's what Dr Robert Brown, a physicist at Duke University and a commenter on WUWT thinks.
I don’t think we can begin to answer this question based on what we know right now. We can’t explain why the MWP happened (without CO2 modulation). We can’t explain why the LIA happened (without CO2 modulation). We can’t explain all of the other significant climate changes all the way back to the Holocene Optimum (much warmer than today) or the Younger Dryas (much colder than today) even in just the Holocene. We can’t explain why there are ice ages 90,000 years out of every 100,000, why it was much warmer 15 million years ago, why geological time hot and cold periods come along and last for millions to hundreds of millions of years. We don’t know when the Holocene will end, or why it will end when it ends, or how long it will take to go from warm to cold conditions. We are pretty sure the Sun has a lot to do with all of this but we don’t know how, or whether or not it involves more than just the Sun. We cannot predict solar state decades in advance, let alone centuries, and don’t do that well predicting it on a timescale of merely years in advance. We cannot predict when or how strong the decadal oscillations will occur. We don’t know when continental drift will alter e.g. oceanic or atmospheric circulation patterns “enough” for new modes to emerge (modes which could lead to abrupt and violent changes in climate all over the world).
Finally, we don’t know how to build a faithful global climate model, in part because we need answers to many of these questions before we can do so! Until we can, we’re just building nonlinear function fitters that do OK at interpolation, and are lousy at extrapolation.
That's just the easy bit! His full post here wattsupwiththat.com/2011/12/30/feedback-about-feedbacks-and-suchlike-fooleries/#comment-850741 includes lots of equations and physics that some of you may be able to understand!
There is one simple question that must be answered before we can even estimate AGW:
What is the temperature that it would be outside right now, if CO2 were still at its pre-industrial level?
Care to take a stab at an answer? Anyone?
Here's what Dr Robert Brown, a physicist at Duke University and a commenter on WUWT thinks.
I don’t think we can begin to answer this question based on what we know right now. We can’t explain why the MWP happened (without CO2 modulation). We can’t explain why the LIA happened (without CO2 modulation). We can’t explain all of the other significant climate changes all the way back to the Holocene Optimum (much warmer than today) or the Younger Dryas (much colder than today) even in just the Holocene. We can’t explain why there are ice ages 90,000 years out of every 100,000, why it was much warmer 15 million years ago, why geological time hot and cold periods come along and last for millions to hundreds of millions of years. We don’t know when the Holocene will end, or why it will end when it ends, or how long it will take to go from warm to cold conditions. We are pretty sure the Sun has a lot to do with all of this but we don’t know how, or whether or not it involves more than just the Sun. We cannot predict solar state decades in advance, let alone centuries, and don’t do that well predicting it on a timescale of merely years in advance. We cannot predict when or how strong the decadal oscillations will occur. We don’t know when continental drift will alter e.g. oceanic or atmospheric circulation patterns “enough” for new modes to emerge (modes which could lead to abrupt and violent changes in climate all over the world).
Finally, we don’t know how to build a faithful global climate model, in part because we need answers to many of these questions before we can do so! Until we can, we’re just building nonlinear function fitters that do OK at interpolation, and are lousy at extrapolation.
That's just the easy bit! His full post here wattsupwiththat.com/2011/12/30/feedback-about-feedbacks-and-suchlike-fooleries/#comment-850741 includes lots of equations and physics that some of you may be able to understand!
