GEOG Feb 25 (L14) IPCC - Lecture notessss PDF

Preview

Summary

*Note: No slides or readings have been uploaded for this lecture I will update these notes when those have been releasedReading Questions: What two major types of reports does the IPCC produce? Synthesis Report Working Group How are scientists selected for the IPCC and how are they funded? Scientist...

Description

*Note: No slides or readings have been uploaded for this lecture I will update these notes when those have been released

Reading Questions: -

-

-

-

What two major types of reports does the IPCC produce? - Synthesis Report - Working Group How are scientists selected for the IPCC and how are they funded? - Scientists must be nominated by their government or an NGO - Funded through the UN Why review and approve IPCC reports? - All research is done on a voluntary basis and is done with the intention of improving our understanding of our climate - No political ties to the research nor are the scientists persuaded to research for money as they do not receive a salary What main climate system components are treated in today’s most recent climate models? - Atmospheric, land surface, ocean, and sea ice component Can you describe what is simulated or modulated in each component? - Atmospheric component → simulates clouds and aerosols and plays a large role int transport of heat and water around the globe -

Land surface → simulates surface characteristics such as vegetation, snow cover, soil water, rivers, and carbon-storing

-

Ocean component → simulates current movement and mixing, and biogeochemistry, since the ocean is the dominant reservoir of heat and carbon in the climate system

-

Sea ice component → modulates solar radiation absorption and air-sea heat and water exchanges

-

-

-

What is a “forcing” (with respect to climate models) and what forcings are used as input? - External factors like the change in the amount of the sun’s energy, long-lived greenhouse gases, and aerosols are “forcings” - Past forcings are determined by using evidence of changes in the Earth’s orbit, historical greenhouse gas concentrations, past volcanic eruptions, changes in sunspot counts, and other records of the distant past to create a model. How have climate models evolved over time (with respect to resolution and components)? - The resolution has greatly increased as more computing power has become available and has decreased the time needed to make calculations - Components? Besides temperature, what other conditions are projected by global climate models? - atmospheric chemistry and aerosols, land surface interactions including soil and vegetation, land and sea ice, and increasingly even an interactive carbon cycle and/or biogeochemistry

-

-

What “scenarios” are used in the most recently published IPCC Report (ARS) and what do they represent? Which is the worst-case scenario? - Special Report on Emissions Scenarios (SRES)- greenhouse gas emissions scenarios - Six scenario groups that should be considered equally sound that span a wide range of uncertainty - Encompass four combinations of demographic change, social and economic development, and broad technological developments, corresponding to the four families each with an illustrative “marker scenario” - Worst Case: A1F1 - Best Case: B1 What is an emergent pattern (with respect to climate models)? - Emergence- occurs when an entity is observed to have properties its parts do not have on their own; properties or behaviors emerge only when the parts interact in a wider whole - Whether → an example of an emergent pattern

Feb 25 Notes - Projections of Future Climate IPCC - Intergovernmental panel on climate change - Assessment reports, methodology reports, guidelines, and special reports - Synthesis Report - based on the reports of the three Working Groups of the Intergovernmental Panel on Climate Change (IPCC) and includes special reports - Working Group 1Assessing the physical science basis for the

-

climate system and change Working Group 2- Assesses vulnerability of socio-economic and natural systems Working Group 3- Options for mitigating climate change through limiting greenhouse gas TF I- Oversee IPCC natural greenhouse

Scientists in IPCC - Scientists must be nominated by government or NGO - gender/geographic balance - It can come from university, industry, etc. - No money must work for someone who will give you time to work on this Process for reports - The first draft reviewed by experts - The second draft reviewed by experts and governments - Final approval session line byline in meeting Climate models - Many inclusions in the climate model including the water cycle, atmospheric composition, ecosystem, land use and cover change, human contribution and responses, etc. - Main Components - Atmosphere - clouds/aerosols play a role in the transfer of heat and water - Aerosol: ash, black carbon - Land surface- Vegetation, snow cover, soil water, river - Ocean- Current movement, mixing, biogeochemistry, a dominant reservoir of heat/carbon - Sea ice- modulates solar radiation absorption and air-sea heat/water transfer - Grid size improves over time (goes from a 500 km to 110 km grid size - Models were coded in Fortran - 50 million calculations for a century per grid more components were included over the years - Not meant to tell you what happens locally but more on a global scale

-

There are groups who do regional models

Schematic for Global Atmospheric Model - IMAGE ON RIGHT- the grid is 19 levels thick

Who does climate modeling? - Many centers around the globe (4 in the US) - Majority in North America and Europe - Run models separately but work together to standardize the input - CMIPS (comparison model) conducted together - Ensemble average combines many predictions How to assess the performance of models - Hindcasting - assessing past - Forecast is future - 1901-2010 sea levels rose 0.19 meters - Larger than the mean rate during the previous 2 millennia - No one gets paid to write journals - IPCC jargon for confidence with specific definitions - 90-100 percent very likely - RCP: end of century radiative forcing - Number = watts/ meter squared

-

Forcing- the difference between incoming radiation absorbed and energy radiated Projections have not changed much, only have become more certain...