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

Leads to CO 2 Stabilization Scenarios

Basic Future Predictions n n A 2°C rise from today's temperatures produces 30% species extinction A 3°C warming will lead to widespread coral deaths Water availability in the moist tropics and in the high latitudes will increase, but will drop in the semi-arid low latitudes A 1°C warming will decrease agricultural yields in the low-latitudes; 2°C increases yields at high latitudes

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

Reinforced with 2 D Representation

Winter Signal is Strongest

Central Europe Summer Signal n Huge test statistical signal via baseline/area

Record Events depend on wave form evolution

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

Convolution of positive and negative forcings are what we observe. n GHG produces the net positive here

And all is superimposed on El Nino Cycle

Putting it altogether

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

Sea Ice – opening of the NW Passage 2007 2006

Glacial Retreat and Mass Balance 1941 - 2005

Wholesale Change in Mass Balance

Permafrost indicators

Summary of the Cyrosphere (frozen land) observations

Droughts

Water vapor increases?

Cloud Cover n Extremely difficult to really measure with any accuracy n Extant data are inconclusive and noisy

Wave height data shows something!

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!

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):

Future predictions remain uncertain

Physics of Atmospheric Energy Transport is difficult n n n Potential energy Internal energy Kinetic energy Latent heat Latitude dependent; vertical dependence

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

Global Warming Potential n n n TH = Time Horizon (20 or 100 years) Ax = increased forcing from X (Watts m^2 kg) x(t) = decay following some hypothetical instantaneous release of X Denominator is relevant quantities for CO 2 Nominal value for Methane is 21

Do Tipping Points Exist in Climate? n Does the system have critical phenomena? Or do the various and somewhat unknown feedback mechanisms serve to counter this?

The Next Level of Physics in Climate Science n n More strongly incorporates the role of various feedbacks particularly water vapor Identifying critical points (or lack thereof) is essential in future models Improved modeling of aerosols and their scattering properties Improved modeling of tropical convection to better understand ocean/atmosphere heat exchange