IPCC Climate Change Report Moving Towards Consensus Based
IPCC Climate Change Report Moving Towards Consensus Based on real world data
IPCC Consensus process is Conservative by Nature
IPCC Consensus Evolution n n FAR: 1990: The unequivocal detection of the enhanced greenhouse gas effect from observations is not likely for a decade or more SAR: 1995: The balance of evidence suggestions a discernible human influence on global climate
Getting Stronger n n TAR: 2001: There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities AT 4: 2007: Most of the observed increase in globally averaged temperatures since the mid-20 th century is very likely due to the increase in anthropogenic greenhouse gas concentrations.
Climate Modeling Evolution
Better Grid Resolution
Basic Approach n Coefficient of doubling CO 2
Preponderance of Evidence Want to find indicators of climate change n Requires a) a robust definition and measure of what constitutes climate and b) an instrumental precision sufficient to measure change n No one indicator (e. g. smoking gun) exists; aggregate of all data then forms the preponderance n
Hockey Sticks Galore
1 D Temperature is unreliable n You list the reasons but still …
Reinforced with 2 D Representation
Winter Signal is Strongest
More Recent Data – Russian Heat Wave/Fires
Extreme Weather Expectations
And all is superimposed on El Nino Cycle
Convolution of positive and negative forcings are what we observe. n GHG produces the net positive here
Global Aerosols – leads to dimming n Mostly Industrial; African Source is pyrogenic and biogenic in nature (drought related)
Other indicators n Sea Ice n Glacial retreats and glacial mass balance n Permafrost n Droughts n Water vapor feedback n Cloud cover n Ocean wave heights n Sea surface temperature anamolies
Glacial Retreat and Mass Balance 1941 - 2005
Wholesale Change in Mass Balance
Arctic Ice Loss Rapidly Escalating
But 2009 did not continue this catastrophic trend n And 2009 point is consistent with long term trend
But 2010 mostly did: Significant
Droughts
Sea Level Rising n Sea Level measured at San Francisco
Known SST oscillations increasing in amplitude n North Atlantic Oscillation (notice the post 1995 slope):
Complete Feedback Models too Difficult to reliably construct
Source of Uncertainties § Roles of clouds and aerosols in radiative transfer § § models? (e. g. scattering!) Role of tropical convection and the water vapor feedback loop? How well do observations constrain the input climate parameters? How to weight the inputs for best fit statistical model? Contributions of other greenhouse gases specifically methane from permafrost release
Feedbacks
Ocean Sea Surface Temperature Response n Its important to realize that virtually all of the extra (heat) flux goes into the oceans
Big reservoir of heat n n n 0. 1 degree C increase transferred (instantly) to the atmosphere produces 100 degree C increase. Ocean circulation and redistribution of excess heat is (fortunately) a slow process But that is where the “pipeline” warming is even if CO 2 was stablized today!
- Slides: 33