IPCC Climate Change Report Moving Towards Consensus Based on real world data

IPCC Consensus process is Conservative by Nature

IPCC Consensus Evolution FAR: 1990: The unequivocal detection of the enhanced greenhouse gas effect from observations is not likely for a decade or more 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 SAR: 1995: The balance of evidence suggestions a discernible human influence on global climate

Getting Stronger TAR: 2001: There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities TAR: 2001: There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities AT4: 2007: Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the increase in anthropogenic greenhouse gas concentrations. AT4: 2007: Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the increase in anthropogenic greenhouse gas concentrations.

Climate Modeling Evolution

Better Grid Resolution

Basic Approach Coefficient of doubling CO 2 Coefficient of doubling CO 2

Preponderance of Evidence Want to find indicators of climate change Want to find indicators of climate change Requires a) a robust definition and measure of what constitutes climate and b) an instrumental precision sufficient to measure change Requires a) a robust definition and measure of what constitutes climate and b) an instrumental precision sufficient to measure change No one indicator (e.g. smoking gun) exists; aggregate of all data then forms the preponderance No one indicator (e.g. smoking gun) exists; aggregate of all data then forms the preponderance

Hockey Sticks Galore

1D Temperature is unreliable You list the reasons but still … You list the reasons but still …

Reinforced with 2D 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. GHG produces the net positive here

Global Aerosols – leads to dimming Mostly Industrial; African Source is pyrogenic and biogenic in nature (drought related)

Other indicators Sea Ice Glacial retreats and glacial mass balance Permafrost Droughts Water vapor feedback Cloud cover Ocean wave heights Sea surface temperature anamolies

Glacial Retreat and Mass Balance

Wholesale Change in Mass Balance

Arctic Ice Loss Rapidly Escalating

But 2009 did not continue this catastrophic trend And 2009 point is consistent with long term trend

But 2010 mostly did: Significant

Droughts

Sea Level Rising Sea Level measured at San Francisco

Known SST oscillations increasing in amplitude 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 Its important to realize that virtually all of the extra (heat) flux goes into the oceans

Big reservoir of heat 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!