EEPS Midterm 2

Three Types of Climate Change

Internal, Natural Forcings, Anthropogenic Forcings

Forcing

anything that can alter the energy budget at the top of the atmosphere

Positive Feedback

response amplified by climate system (ex: ice-albedo)

Negative Feedback

response reduced by climate system (ex: low clouds reflect sunlight)

Vegetation Feedback

loss of vegetation leads to soil erosion, dust storms, causes worse condition for plant life

Seasonal Cycle

largest form of climate change we know of, but too predictable to be dangerous

Simple Model of Monsoons

contrast of heat capacity, land/ocean warms more, creates different in pressure and rainfall

ENSO

every 2-7 years, El Nino where E Pacific is warm/wet, La Nina where E Pacific is cool/dry, EN tends to benefit US while LN leads to losses

PDO

pacific decadal oscillation

NAO

north atlantic oscillation

AMO

atlantic multi-decadal oscillation

How Climate Change Affects Internal Forcing

events become more extreme

Precipitation Extremes

will increase in both directions as climate change occurs

Dust Bowl

1930s, period of extreme drought, partially forced by La Nina

Proxies Used to Reconstruct Climate

ice cores, sediment cores, corals, speleothems, tree rings

Glacial vs Interglacial

when cold climate, ice stores 16O, so 18O rises in ocean; in warm climate, 16O rises in ocean due to glacial melting

Foraminifera

small organisms that record oxygen content from the past oceans

Glacier Formation

occurs at high latitudes, high elevations

Ice Cores

contain rich info about gases, water isotopes, dust, trace elements

Last Glacial Maximum (LGM)

last ice age on Earth, about 20,000 years ago, sea level was 120m lower

Milankovitch Theory

calculated energy received at 65 degrees N (bc more land), obliquity determines insolation amt, eccentricity/precession determine seasonal amplitude

Precession

wobble of axis, every 23,000 years

Eccentricity

departure from circular orbit shape, every 100,000 years

Obliquity

severeness of axis tilt, every 41,000 years

Abrupt Climate Change

transition that occurs faster than the forcing responsible and occurs so quickly that adaptation becomes difficult

Dansgaard-Oeschger Events

extreme termination of ice ages, abrupt climate change example, unrelated to changes in orbital pattern

Younger Dryas

when large amts of fresh water enter Atlantic and disrupt THC, another example of abrupt climate change

Why Does Abrupt Climate Change Occur

climate system has tipping points

Tipping Points

point at which climate changes permanently from one state to another

3 Main Tipping Points

thermohaline circulation, methane clathrates, arctic permafrost

Holocene

stable period, past 10,000 years

Drivers of Civilization Collapse

environmental damage, climate change, hostile neighbors, friendly trade partners, society’s response to problems

Akkadian Empire

collapsed due to extreme dry conditions

Greenland Norse

collapsed due to environmental damage, climate change, hostile relations, decline in positive relations with Norway, and bad attitude

Anasazi

collapsed due to long multi-decade droughts

Ruddiman Hypothesis

due to agriculture, CO2 and methane have kicked us out of glacial period

Hockey Stick Controversy

Mann et. al. showed serious warming at unprecedented rate, set off panic

Anthropocene

current geologic time scale, human era

3 Tools of Climate Change Study

direct weather measurement, paleoclimate data, climate models

Climate Models

computer programs that encapsulate our understanding of the climate system

General Circulation Models (GCM)

provide the only physical basis

Why We Need Models

too complex to do by hand, attribute to individual forcings, predict future

RCPs

greenhouse gas scenarios, used to predict future climate change, vary the amount of possible CO2 addition

Future Climate Predictions

higher temps, declines in sea ice, higher sea level, changes in temp extremes, increases in floods/droughts

Goods

items given monetary value

Services

things that are valued but rarely bought or sold

Biodiversity

ensures the resiliency of ecosystems

Extinction

20% of species will disappear in the next decade

Adaptation

reduce the vulnerability (help ourselves)

Mitigation

reduce intensity of radiative forcings (attack the problem)

Geoengineering

deliberate large-scale intervention (solve the problem)

Tragedy of the Commons

perverse economic incentives destroying a common good

Solution to Tragedy of Commons

assign monetary value to public goods

Cost-Benefit Analysis

cheaper to act now, more expensive in future

Externality

cost/benefit that effects a party that did not choose to incurr that cost/benefit

Cap and Trade

set a cap on amount of pollutant, ppl that emit less can sell credits

Carbon Tax

set a tax on carbon content of fossil fuels

Ozone Hole

example of successful climate policy, Montreal Protocol fixed it in two phases: rich first, then developing nations