4 ESSAY QUESTION FROM LECTURES and NCA reading
Post one example essay question that touches on a topic from each week’s lecture and the NCA reading.
four questions total, week 5,6,7 and NCA reading
week’s lecture and NCA reading are attached
due after 16 hours.
Summary Findings
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 25
NCA4 Summary Findings
These Summary Findings represent a high-level synthesis of the material in the underlying
report. The findings consolidate Key Messages and supporting evidence from 16 national-level
topic chapters, 10 regional chapters, and 2 chapters that focus on societal response strategies
(mitigation and adaptation). Unless otherwise noted, qualitative statements regarding future
conditions in these Summary Findings are broadly applicable across the range of different
levels of future climate change and associated impacts considered in this report.
1. Communities
Climate change creates new risks and exacerbates existing vulnerabilities in communities across
the United States, presenting growing challenges to human health and safety, quality of life, and
the rate of economic growth.
The impacts of climate change are already
being felt in communities across the country.
More frequent and intense extreme weather
and climate-related events, as well as changes
in average climate conditions, are expected to
continue to damage infrastructure, ecosystems,
and social systems that provide essential ben-
efits to communities. Future climate change
is expected to further disrupt many areas of
life, exacerbating existing challenges to pros-
perity posed by aging and deteriorating infra-
structure, stressed ecosystems, and economic
inequality. Impacts within and across regions
will not be distributed equally. People who are
already vulnerable, including lower-income and
other marginalized communities, have lower
capacity to prepare for and cope with extreme
weather and climate-related events and are ex-
pected to experience greater impacts. Prioritiz-
ing adaptation actions for the most vulnerable
populations would contribute to a more equi-
table future within and across communities.
Global action to significantly cut greenhouse
gas emissions can substantially reduce cli-
mate-related risks and increase opportunities
for these populations in the longer term.
2. Economy
Without substantial and sustained global mitigation and regional adaptation efforts, climate
change is expected to cause growing losses to American infrastructure and property and impede
the rate of economic growth over this century.
In the absence of significant global mitigation
action and regional adaptation efforts, rising
temperatures, sea level rise, and changes in
extreme events are expected to increasingly
disrupt and damage critical infrastructure and
property, labor productivity, and the vitality
of our communities. Regional economies and
industries that depend on natural resourc-
es and favorable climate conditions, such as
agriculture, tourism, and fisheries, are vulner-
able to the growing impacts of climate change.
Rising temperatures are projected to reduce
the efficiency of power generation while in-
creasing energy demands, resulting in higher
electricity costs. The impacts of climate change
beyond our borders are expected to increas-
ingly affect our trade and economy, including
import and export prices and U.S. businesses
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 26
with overseas operations and supply chains.
Some aspects of our economy may see slight
near-term improvements in a modestly warmer
world. However, the continued warming that
is projected to occur without substantial and
sustained reductions in global greenhouse gas
emissions is expected to cause substantial net
damage to the U.S. economy throughout this
century, especially in the absence of increased
adaptation efforts. With continued growth in
emissions at historic rates, annual losses in
some economic sectors are projected to reach
hundreds of billions of dollars by the end of the
century—more than the current gross domestic
product (GDP) of many U.S. states.
3. Interconnected Impacts
Climate change affects the natural, built, and social systems we rely on individually and through
their connections to one another. These interconnected systems are increasingly vulnerable to
cascading impacts that are often difficult to predict, threatening essential services within and
beyond the Nation’s borders.
Climate change presents added risks to inter-
connected systems that are already exposed
to a range of stressors such as aging and de-
teriorating infrastructure, land-use changes,
and population growth. Extreme weather and
climate-related impacts on one system can re-
sult in increased risks or failures in other crit-
ical systems, including water resources, food
production and distribution, energy and trans-
portation, public health, international trade,
and national security. The full extent of climate
change risks to interconnected systems, many
of which span regional and national boundaries,
is often greater than the sum of risks to individ-
ual sectors. Failure to anticipate interconnected
impacts can lead to missed opportunities for
effectively managing the risks of climate change
and can also lead to management responses
that increase risks to other sectors and regions.
Joint planning with stakeholders across sec-
tors, regions, and jurisdictions can help identify
critical risks arising from interaction among
systems ahead of time.
4. Actions to Reduce Risks
Communities, governments, and businesses are working to reduce risks from and costs asso-
ciated with climate change by taking action to lower greenhouse gas emissions and implement
adaptation strategies. While mitigation and adaptation efforts have expanded substantially in
the last four years, they do not yet approach the scale considered necessary to avoid substantial
damages to the economy, environment, and human health over the coming decades.
Future risks from climate change depend
primarily on decisions made today. The inte-
gration of climate risk into decision-making
and the implementation of adaptation activities
have significantly increased since the Third
National Climate Assessment in 2014, including
in areas of financial risk reporting, capital in-
vestment planning, development of engineering
standards, military planning, and disaster risk
management. Transformations in the ener-
gy sector—including the displacement of coal
by natural gas and increased deployment of
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 27
renewable energy—along with policy actions
at the national, regional, state, and local lev-
els are reducing greenhouse gas emissions in
the United States. While these adaptation and
mitigation measures can help reduce damages
in a number of sectors, this assessment shows
that more immediate and substantial global
greenhouse gas emissions reductions, as well as
regional adaptation efforts, would be needed to
avoid the most severe consequences in the long
term. Mitigation and adaptation actions also
present opportunities for additional benefits
that are often more immediate and localized,
such as improving local air quality and econ-
omies through investments in infrastructure.
Some benefits, such as restoring ecosystems
and increasing community vitality, may be
harder to quantify.
5. Water
The quality and quantity of water available for use by people and ecosystems across the country
are being affected by climate change, increasing risks and costs to agriculture, energy production,
industry, recreation, and the environment.
Rising air and water temperatures and chang-
es in precipitation are intensifying droughts,
increasing heavy downpours, reducing snow-
pack, and causing declines in surface water
quality, with varying impacts across regions.
Future warming will add to the stress on water
supplies and adversely impact the availability
of water in parts of the United States. Changes
in the relative amounts and timing of snow and
rainfall are leading to mismatches between wa-
ter availability and needs in some regions, pos-
ing threats to, for example, the future reliability
of hydropower production in the Southwest
and the Northwest. Groundwater depletion is
exacerbating drought risk in many parts of the
United States, particularly in the Southwest and
Southern Great Plains. Dependable and safe
water supplies for U.S. Caribbean, Hawai‘i, and
U.S.-Affiliated Pacific Island communities are
threatened by drought, flooding, and saltwater
contamination due to sea level rise. Most U.S.
power plants rely on a steady supply of water
for cooling, and operations are expected to be
affected by changes in water availability and
temperature increases. Aging and deteriorating
water infrastructure, typically designed for past
environmental conditions, compounds the cli-
mate risk faced by society. Water management
strategies that account for changing climate
conditions can help reduce present and future
risks to water security, but implementation of
such practices remains limited.
6. Health
Impacts from climate change on extreme weather and climate-related events, air quality, and the
transmission of disease through insects and pests, food, and water increasingly threaten the
health and well-being of the American people, particularly populations that are already vulnerable.
Changes in temperature and precipitation are
increasing air quality and health risks from
wildfire and ground-level ozone pollution.
Rising air and water temperatures and more
intense extreme events are expected to in-
crease exposure to waterborne and foodborne
diseases, affecting food and water safety. With
continued warming, cold-related deaths are
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 28
projected to decrease and heat-related deaths
are projected to increase; in most regions,
increases in heat-related deaths are expected
to outpace reductions in cold-related deaths.
The frequency and severity of allergic ill-
nesses, including asthma and hay fever, are
expected to increase as a result of a changing
climate. Climate change is also projected to
alter the geographic range and distribution of
disease-carrying insects and pests, exposing
more people to ticks that carry Lyme disease
and mosquitoes that transmit viruses such
as Zika, West Nile, and dengue, with varying
impacts across regions. Communities in the
Southeast, for example, are particularly vul-
nerable to the combined health impacts from
vector-borne disease, heat, and flooding. Ex-
treme weather and climate-related events can
have lasting mental health consequences in af-
fected communities, particularly if they result
in degradation of livelihoods or community
relocation. Populations including older adults,
children, low-income communities, and some
communities of color are often dispropor-
tionately affected by, and less resilient to, the
health impacts of climate change. Adaptation
and mitigation policies and programs that help
individuals, communities, and states prepare
for the risks of a changing climate reduce the
number of injuries, illnesses, and deaths from
climate-related health outcomes.
7. Indigenous Peoples
Climate change increasingly threatens Indigenous communities’ livelihoods, economies, health,
and cultural identities by disrupting interconnected social, physical, and ecological systems.
Many Indigenous peoples are reliant on nat-
ural resources for their economic, cultural,
and physical well-being and are often unique-
ly affected by climate change. The impacts of
climate change on water, land, coastal areas,
and other natural resources, as well as infra-
structure and related services, are expected to
increasingly disrupt Indigenous peoples’ liveli-
hoods and economies, including agriculture and
agroforestry, fishing, recreation, and tourism.
Adverse impacts on subsistence activities have
already been observed. As climate changes con-
tinue, adverse impacts on culturally significant
species and resources are expected to result
in negative physical and mental health effects.
Throughout the United States, climate-related
impacts are causing some Indigenous peoples
to consider or actively pursue community re-
location as an adaptation strategy, presenting
challenges associated with maintaining cultural
and community continuity. While economic,
political, and infrastructure limitations may
affect these communities’ ability to adapt,
tightly knit social and cultural networks present
opportunities to build community capacity and
increase resilience. Many Indigenous peoples
are taking steps to adapt to climate change
impacts structured around self-determination
and traditional knowledge, and some tribes are
pursuing mitigation actions through develop-
ment of renewable energy on tribal lands.
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 29
8. Ecosystems and Ecosystem Services
Ecosystems and the benefits they provide to society are being altered by climate change, and
these impacts are projected to continue. Without substantial and sustained reductions in global
greenhouse gas emissions, transformative impacts on some ecosystems will occur; some coral
reef and sea ice ecosystems are already experiencing such transformational changes.
Many benefits provided by ecosystems and the
environment, such as clean air and water, pro-
tection from coastal flooding, wood and fiber,
crop pollination, hunting and fishing, tourism,
cultural identities, and more will continue to
be degraded by the impacts of climate change.
Increasing wildfire frequency, changes in insect
and disease outbreaks, and other stressors are
expected to decrease the ability of U.S. for-
ests to support economic activity, recreation,
and subsistence activities. Climate change has
already had observable impacts on biodiversity,
ecosystems, and the benefits they provide to
society. These impacts include the migration
of native species to new areas and the spread
of invasive species. Such changes are project-
ed to continue, and without substantial and
sustained reductions in global greenhouse
gas emissions, extinctions and transformative
impacts on some ecosystems cannot be avoid-
ed in the long term. Valued aspects of regional
heritage and quality of life tied to ecosystems,
wildlife, and outdoor recreation will change
with the climate, and as a result, future gener-
ations can expect to experience and interact
with the natural environment in ways that are
different from today. Adaptation strategies,
including prescribed burning to reduce fuel for
wildfire, creation of safe havens for important
species, and control of invasive species, are
being implemented to address emerging im-
pacts of climate change. While some targeted
response actions are underway, many impacts,
including losses of unique coral reef and sea ice
ecosystems, can only be avoided by significant-
ly reducing global emissions of carbon dioxide
and other greenhouse gases.
9. Agriculture and Food
Rising temperatures, extreme heat, drought, wildfire on rangelands, and heavy downpours are
expected to increasingly disrupt agricultural productivity in the United States. Expected increas-
es in challenges to livestock health, declines in crop yields and quality, and changes in extreme
events in the United States and abroad threaten rural livelihoods, sustainable food security, and
price stability.
Climate change presents numerous challenges
to sustaining and enhancing crop productivity,
livestock health, and the economic vitality of
rural communities. While some regions (such
as the Northern Great Plains) may see con-
ditions conducive to expanded or alternative
crop productivity over the next few decades,
overall, yields from major U.S. crops are expect-
ed to decline as a consequence of increases in
temperatures and possibly changes in water
availability, soil erosion, and disease and pest
outbreaks. Increases in temperatures during
the growing season in the Midwest are pro-
jected to be the largest contributing factor to
declines in the productivity of U.S. agriculture.
Projected increases in extreme heat conditions
are expected to lead to further heat stress for
livestock, which can result in large economic
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 30
losses for producers. Climate change is also ex-
pected to lead to large-scale shifts in the avail-
ability and prices of many agricultural products
across the world, with corresponding impacts
on U.S. agricultural producers and the U.S.
economy. These changes threaten future gains
in commodity crop production and put rural
livelihoods at risk. Numerous adaptation strate-
gies are available to cope with adverse impacts
of climate variability and change on agricultural
production. These include altering what is pro-
duced, modifying the inputs used for produc-
tion, adopting new technologies, and adjusting
management strategies. However, these strat-
egies have limits under severe climate change
impacts and would require sufficient long- and
short-term investment in changing practices.
10. Infrastructure
Our Nation’s aging and deteriorating infrastructure is further stressed by increases in heavy pre-
cipitation events, coastal flooding, heat, wildfires, and other extreme events, as well as changes
to average precipitation and temperature. Without adaptation, climate change will continue to de-
grade infrastructure performance over the rest of the century, with the potential for cascading im-
pacts that threaten our economy, national security, essential services, and health and well-being.
Climate change and extreme weather events
are expected to increasingly disrupt our Na-
tion’s energy and transportation systems,
threatening more frequent and longer-lasting
power outages, fuel shortages, and service
disruptions, with cascading impacts on oth-
er critical sectors. Infrastructure currently
designed for historical climate conditions is
more vulnerable to future weather extremes
and climate change. The continued increase in
the frequency and extent of high-tide flooding
due to sea level rise threatens America’s tril-
lion-dollar coastal property market and public
infrastructure, with cascading impacts to the
larger economy. In Alaska, rising temperatures
and erosion are causing damage to buildings
and coastal infrastructure that will be costly
to repair or replace, particularly in rural areas;
these impacts are expected to grow without
adaptation. Expected increases in the severity
and frequency of heavy precipitation events
will affect inland infrastructure in every region,
including access to roads, the viability of bridg-
es, and the safety of pipelines. Flooding from
heavy rainfall, storm surge, and rising high tides
is expected to compound existing issues with
aging infrastructure in the Northeast. Increased
drought risk will threaten oil and gas drilling
and refining, as well as electricity generation
from power plants that rely on surface water
for cooling. Forward-looking infrastructure
design, planning, and operational measures and
standards can reduce exposure and vulnerabil-
ity to the impacts of climate change and reduce
energy use while providing additional near-
term benefits, including reductions in green-
house gas emissions.
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 31
11. Oceans and Coasts
Coastal communities and the ecosystems that support them are increasingly threatened by the
impacts of climate change. Without significant reductions in global greenhouse gas emissions
and regional adaptation measures, many coastal regions will be transformed by the latter part of
this century, with impacts affecting other regions and sectors. Even in a future with lower green-
house gas emissions, many communities are expected to suffer financial impacts as chronic
high-tide flooding leads to higher costs and lower property values.
Rising water temperatures, ocean acidification,
retreating arctic sea ice, sea level rise, high-tide
flooding, coastal erosion, higher storm surge,
and heavier precipitation events threaten our
oceans and coasts. These effects are projected
to continue, putting ocean and marine species
at risk, decreasing the productivity of certain
fisheries, and threatening communities that
rely on marine ecosystems for livelihoods and
recreation, with particular impacts on fishing
communities in Hawai‘i and the U.S.-Affiliated
Pacific Islands, the U.S. Caribbean, and the Gulf
of Mexico. Lasting damage to coastal property
and infrastructure driven by sea level rise and
storm surge is expected to lead to financial
losses for individuals, businesses, and commu-
nities, with the Atlantic and Gulf Coasts facing
above-average risks. Impacts on coastal energy
and transportation infrastructure driven by sea
level rise and storm surge have the potential
for cascading costs and disruptions across the
country. Even if significant emissions reduc-
tions occur, many of the effects from sea level
rise over this century—and particularly through
mid-century—are already locked in due to his-
torical emissions, and many communities are
already dealing with the consequences. Actions
to plan for and adapt to more frequent, wide-
spread, and severe coastal flooding, such as
shoreline protection and conservation of coast-
al ecosystems, would decrease direct losses and
cascading impacts on other sectors and parts
of the country. More than half of the damages
to coastal property are estimated to be avoid-
able through well-timed adaptation measures.
Substantial and sustained reductions in global
greenhouse gas emissions would also signifi-
cantly reduce projected risks to fisheries and
communities that rely on them.
12. Tourism and Recreation
Outdoor recreation, tourist economies, and quality of life are reliant on benefits provided by our
natural environment that will be degraded by the impacts of climate change in many ways.
Climate change poses risks to seasonal and
outdoor economies in communities across the
United States, including impacts on economies
centered around coral reef-based recreation,
winter recreation, and inland water-based
recreation. In turn, this affects the well-being
of the people who make their living supporting
these economies, including rural, coastal, and
Indigenous communities. Projected increases
in wildfire smoke events are expected to impair
outdoor recreational activities and visibility
in wilderness areas. Declines in snow and ice
cover caused by warmer winter temperatures
are expected to negatively impact the winter
recreation industry in the Northwest, North-
ern Great Plains, and the Northeast. Some
fish, birds, and mammals are expected to shift
where they live as a result of climate change,
Summary Findings
Fourth National Climate AssessmentU.S. Global Change Research Program 32
with implications for hunting, fishing, and other
wildlife-related activities. These and other cli-
mate-related impacts are expected to result in
decreased tourism revenue in some places and,
for some communities, loss of identity. While
some new opportunities may emerge from
these ecosystem changes, cultural identities
and economic and recreational opportunities
based around historical use of and interaction
with species or natural resources in many areas
are at risk. Proactive management strategies,
such as the use of projected stream tempera-
tures to set priorities for fish conservation, can
help reduce disruptions to tourist economies
and recreation.
Global Climate Models
Week 6 – July 27th, 2020
Announcements
Lab #4 Due Sunday, August 2nd to Canvas
Due date is always flexible, just let me know if you need more time and I’ll happily grant any extensions!
Lecture Readings
Chp. 7 in textbook – dense; check out the note on the next slide about readings for this Chapter in your textbook!
Climate Rage Naomi Klein (2009) – PDF on Canvas
What the Queer Community Brings to the Fight for Climate Justice Aletta Brady, Anthony Torres, and Phillip Brown (2019) (https://grist.org/article/what-the-queer-community-brings-to-the-fight-for-climate-justice/)
Climate Justice is Racial Justice Abeer Almahdi (2019) (http://www.mcgilltribune.com/climate-justice-is-racial-justice/)
The non-textbook readings for this week are meant to give you head start on the topics of next week. Please complete them this week, but we will engage with them fully in the discussion for Week #7
A quick word about Chp. 7
This is a dense chapter and we do not cover all materials presented in the textbook here in lecture. I will go over the main points discussed in Chp. 7 as listed in the Lecture Outline in the next slide.
This week focus heavily on the readings assigned to you, and read over the parts in the textbook that I also go over here – but don’t spend too much time on the nitty gritty details in Chp. 7. These sets of slides will be light given the increase in reading and the amount of different activities you need to complete for Lab #4.
Alright….let’s go!
Lecture Outline
Intro to Global Climate Models (the basics)
Momentums and prognostic variables
Time steps and forward modelling
Errors and temporal scale
Construction and Evaluation – we will skip these sections from the textbook (these are the details referred to on the previous slide)
Applications
Paleoclimate studies – you’re experts on those now!
Detection and attribution – HUGE when it comes to anthropogenic climate change
Global Climate Models
So what is a GCM? They’re models that track the exchange of energy momentum and matter between boxes
You need a few things in the model – specifically, prognostic variables (e.g. temp), and 3 momentums are calculated per box (zonal, meridional, and vertical)
Think of these momentums as the rate of change from those three different axes (zonal is latitude, meridional is longitude, and vertical would be the Z axis)
Flux between the boxes at each time step updates the prognostic variables (forward modelling) without observations – i.e. temperature is modeled across the boxes based on the momentums and the starting condition
Global Climate Models
Top and bottom boundary conditions are important when modeling (you need to know what’s going on at the surface and what’s going on in the atmosphere aloft)
Bias and error lead to discrepancies in model predictions and observations
Model variables must be of similar/compatible scales (both spatially and temporally)
Hyper-fine time series data often leads to model errors, but hard to exclude (e.g. clouds)
And that is literally as deep as I can go for this class in fine detail about GCMs – I would love to spend more time in exactly how the calculations are constructed and which variables matter most, and when/where, etc. However, we just don’t have time in 10 weeks to go that deep. If you’re interested in learning more about specifically how climate models are used or how they vary (e.g. how does one model differ from the next?), I encourage you to check out the upper level course on weather and climate that I teach (GEOG 314 – alternating winter terms, may increase in frequency based on enrollments).
Applications
Paleoclimate studies are often a big part of global climate modeling
Reconstructed climates are great ways to evaluate (don’t worry this is as deep as we’ll go!) the skill with which the GCMs are predicting unknown climates.
IF the GCMs recreate similar climate models as those created via paleoclimate reconstructions, then climate scientists can have confidence their GCMs have been constructed well
Additionally, when combined with GCMs, these two types of climate modeling can provide information both into the past and forward into the future
Applications – Paleoclimate Studies
Comprehension Check!
Go back over Week 3 lecture slides and find a paleoclimate proxy we learned about. If I was a climate modeler interested in comparing my GCM with reconstructed climate of the past 10K years, which kinds of proxies would I hope to have in that reconstruction? What type of radiometric dating might I be expected to use given that time frame?
Detection and Attribution
This approach to research global climates first looks for something unusual in the system (the detection)
This can be anything – anomalously high global temps, for example
The second step in the process is to determine which climate forcing agents are responsible for that detection.
Solar radiation spikes?
Increased greenhouse gas concentrations?
Aerosol release?
Etc….
It’s not hard to see why these types of studies are hot right now – it’s harder and harder to ignore or deny the existence of the detections nowadays (e.g. each year we break a top 10 global temp record). Now, we’re all extremely interested in determining why we see the changes we’re seeing.
Detection and Attribution
Check out this study, which produced these key figures in the most recent IPCC report
The primary thing to focus on are the series of three global maps stack on the right hand side.
Notice how much warming you would expect under natural (non-human caused) forcing, versus what we’re seeing from the observed trend.
It’s quite clear the forcing agents involved are anthropogenic and we can attribute the detections to human origins.
Ok! That’s all for now! Interest piqued on GCMs? Email me with more questions if you have them!
Check out the next few slides for more info and an exercise on plotting climate data from NOAA/NCEI if you’d like to explore more!
NOAA Climate Models
https://www.climate.gov/maps-data/primer/climate-models
Check this link out and the data plotting exercise on the next slide for deeper learning!
Most importantly read up on what GCMs are and refresh what you’ve read in Chp. 7 of your textbook. BUT, don’t worry about grasping all of this in fine detail – it’s complicated and you can get entire PhDs in this material! It’s most important you get the basics, which is what I’ve covered here in this set of lecture slides. If you want to dig deeper, I encourage you to explore the links I provide here and from the textbook. Or…reach out via email, I’m always ready to talk climate change!
NCEI (remember, this is the “new” NCDC)
https://www.ncdc.noaa.gov/cag/national/time-series
Plot avg temperature, precipitation, and PDSI for July in the US for the entirety of NOAAs available record (for each parameter) using trend lines. Notice patterns for each parameter on a national scale. Pick the one with the strongest climate change signal, and report on it in detail.
Here’s an example plot for Sept temp…
Links to Check Out!
The Open Science Climate Lab Book by Ed Hawkins
http://www.climate-lab-book.ac.uk/
The Nature Conservancy – all around awesome organization. I’ve been lucky enough to work with some folks from the Florida branch while working on my PhD. This is a great bookmark for your browser on all things environmental!
https://www.nature.org/en-us/
Inland Northwest Land Conservancy – a new group for me! I’m not from this area and I’ve recently discovered this organization. It’s orgs like these that facilitate the connection between the research on the front lines and the community that experiences it all.
Looking Ahead…
Next week we delve into the specific impacts of climate change we have already experienced across the Earth
We’ll begin to explore Chp. 8 in our textbook and circle back to the readings you are completing for this week
PROCESSES
Week 5 – July 20th, 2020
Announcements
Lab #3 is due Sunday, July 26th by midnight
Lecture Outline
Introduction to the atmosphere (atm)
Basics of energy
Heat and Controls on Temps
Atmospheric (atm) pressure
Forces Controlling Global Winds
Atmospheric Circulation
This lecture slide is dense. It’s best to review these slides in tandem with Chp. 6 in your textbook.
Readings With Lecture
Week 5 Readings Include:
Chp. 6 in textbook
Atmospheric Profile
Earth’s atmosphere is composed of “shells” held to the planet by gravity.
Classified by:
Composition
Temperature
Function
Atmospheric Temperature Criterion
Four distinct temperature zones
Thermosphere
Mesosphere
Stratosphere
Ozone here!
Troposphere
Weather here!
Most mass in atm here!
Energy Pathways and Insolation
Passage of shortwave and longwave energy through either the atmosphere or water is transmission
Insolation at Earth’s Surface
Notice the highest locations are about 30°N and S. These are often also places of intense aridity.
Insolation Input
Four ways incoming energy is transmitted:
Scattering
Refraction
Reflection
Absorption
Scattering (Diffuse Radiation)
Scattering – The molecules change the direction of the insolation without changing the wavelength.
Diffuse radiation is the downward component of scattered light
Rayleigh Scattering
The shorter the wavelength, the greater the scattering
On the visible light spectrum, which color is the shortest wavelength? The longest?
Refraction
Changes in density through which insolation passes causes a change in its direction and speed
Light is bent
(refraction)
Reflection
Reflection – energy hitting Earth and bouncing back into space, without being absorbed or performing work
Albedo – the reflective quality of a surface measured in percent
Controls the amount of absorption for a surface
Albedo
What do you think would happen if Earth’s albedo increased?
Absorption
Absorption – assimilation (take in) of radiation by molecules of matter and its conversion from one form of energy to another
Plants absorb energy for photosynthesis
Converted to longwave radiation
Atmospheric Disruption
Mt. Pinatubo eruption in 1991
Massive amounts of sulfur dioxide droplets were shot into the stratosphere
The globe experienced a temporary cooling of 0.5°C
Atmospheric Disruption
Mt. Tambora eruption in 1815
Stratovolcano eruption shot ash and aerosol ejecta into the stratosphere
Created the Year Without A Summer in 1816
Tropical surpluses and polar deficits drive global circulation!
Introduction to Heat
Four modes of heat transfer on Earth:
Conduction – molecule-to-molecule
Convection – physical mixing of gas or liquid in a vertical motion
Advection – physical mixing of gas or liquid in a horizontal motion
Radiation – transfer using electromagnetic waves
Introduction to Heat
Latent heat of evaporation – the energy stored in water vapor as water evaporates
Water absorbs energy to change from liquid to gas
Sensible Heat – back-and-forth transfer through convection and conduction
Principal Temperature Controls
Temperature is not uniform across the globe
Influences upon temperature include:
Latitude
Altitude/Elevation
Cloud Cover
Land-Water Heating Differences
Latitude
Remember, latitude affects insolation, sun angles, and daylength
Altitude/Elevation
Temperatures decreases higher up
Thin atmosphere means less sensible heat
Check out this graph which tracks the normal lapse rate with elevation
High Elevation
Cloud Cover
Land-Water Heating Differences
Continents and oceans are physically different
Land-Water Differences
Evaporation
Energy is stored as latent heat, resulting in lower temperatures
Happens more in marine locations than over land
Transparency
Land is opaque, water is transparent
Energy can penetrate deeper into water than soil, creating a larger heat reservoir
Land-Water Differences
Specific Heat – the heat capacity of a substance
Water heats slower, but retains heat longer
Movement
Oceans flow and mix/redistribute heat energy over a greater volume than land
Horizontal and vertical mixing
Marine Effect vs. Continentality
The only difference between these two locations is the left is closer to water. This demonstrates the marine effect, or essentially the buffering impact of water on local climate.
Earth’s Temperature Patterns
Isotherm – a line on a temperature map that connects points of equal temperature
Thermal equator – isotherm connecting all points of highest mean temperature
Shifts with seasons
North Pole vs. South Pole
North Pole Winter
South Pole Winter
Annual Temp Range Maps
Highlights areas of high to low temp range (difference between hottest summer temp and coldest winter temp).
Why are areas of greatest difference mainly in the North?
Ok, break! This first part of the lecture was focused primarily on energy and temperature.
The next half of lecture focuses on pressure and wind. Go back and review core topics on principal controls on temperature before moving on!
Essentials of High Pressure
Descending air from above, OR
Air that is colder, and heavier that stays at the surface
Prevents convection because air can’t rise and mix
Air is diverging at the surface
Stable weather
Essentials of Low Pressure
Ascending/Rising air from below, OR
Air that is warmer and rising above the surface
Promotes convection because air can rise and mix
Air converging at the surface
Weather events
Wind Basics
Wind – Horizontal movement of air across Earth’s surface
Produced by differences in pressure between one location and another
Anemometer
Vane
Wind Maps
Isobar- line connecting points of equal air pressure
Contour intervals
Wind Direction
Winds are always named after the direction from which they are blowing.
Driving Forces of Global Wind
Several Factors influence the patterns of wind on a global scale:
Gravity
Pressure Gradient Force
Friction Force
Coriolis Force
Pressure Gradient Force
Differences in pressure across Earth’s surface encourages air flow
The stronger the difference, the stronger the wind
Closeness of isobars determines the strength of the difference or gradient between high and low.
Pressure Gradient and Isobars
Pressure + Coriolis + Friction
Global Circulation System
Dynamic Pressure Area –pressure area stimulated primarily by movement or mechanical factors
Thermal Pressure Area– pressure area stimulated primarily by temperature or thermal factors
Equatorial Low Pressure trough
Thermal low pressure area
High sun angles, consistent daylength
Warm, less dense air, rises consistently
Equatorial Low Pressure Trough
Intertropical Convergence Zone (ITCZ)
Area of extreme low pressure
Calm winds under the ITCZ because of low pressure gradient and vertically rising air
Equatorial Low Pressure Trough
Zone of convergence by rising air being replaced by air moving in from the north and south
Equatorial Low Pressure Trough
Hadley Cells – the circuit completed by winds rising along the ITCZ
Trade winds – prevailing winds caused by Hadley circulation cell
N.H. = northeast
S.H. = southeast
Sub-Tropical High Pressure Cell
Dynamic descending air from the Hadley cell creates areas of high pressure (about 20-35° N and S)
Air is heated by compression as it is forced downward creating hot/dry conditions
Sub-Tropical High Pressure Cell
Westerlies – dominant surface winds from the subtropics to high latitudes resulting from divergence at the Hadley cell
Sub-Polar Low Pressure Cell
Dynamic low pressure area from ascending air at about 60° N and S
Cold air from higher latitudes and warm air from lower latitudes converge causing rising air
Spreading air masses from the poles form the polar front
Polar High Pressure Cells
Thermal high pressure area from frigid descending air at the poles
Descending air diverges at the surface and form the weak, variable polar easterlies
Coriolis deflects wind from a straight southward path
Rossby Waves
Polar front – the line of conflict between colder air from the north and warmer air from the south
Dynamically active area creates disturbances in the upper air circulation and jet stream
Rossby Waves
Wave-and-eddy formations occur and create lobes of cold air that flow away from poles.
Jet Streams
Jet streams – irregular and concentrated upper level westerly winds (2 per hemisphere)
Jet Streams
Ocean Currents
Surface Currents AND Deep Currents form the Thermohaline Circulation
Thermohaline Circulation
Ocean Currents
Driving force for ocean currents is the wind!
Frictional drag along the surface
Creates vital link between atmospheric and oceanic circulation systems
Coriolis force, density differences (temperature and salinity), placement of the continents, tides…
Whew! I think that’s enough for now.
There’s always more to learn about earth surface and atmospheric processes, so if you’re interested in these materials, reach out! I teach upper level courses in weather and climate and biogeography!
Looking Ahead…
Next week we delve into climate modeling!
Please be sure that you’re confident with this week’s course materials before we move on to Week 6!
As always, don’t hesitate to reach out with questions!
Climate change impacts
Week 7 – August 3rd, 2020
Announcements
Discussion #3 this week
Course Evaluations open Aug 5th!
Even though they are housed in Canvas, I have no access to them, so they are truly confidential.
Readings with Lecture
Audio interview of Ama Francis on climate-induced migration (2019) (https://www.yaleclimateconnections.org/2019/12/hurricane-maria-ravaged-her-island-nation-now-protect-climate-migrants/)
The Dakota Access Pipeline, Environmental Injustice, and US Settler Colonialism Kyle Powys Whyte (2017) – PDF on Canvas
Lecture Outline
We can expect climate change to result in the following (and many more…):
Human health impacts
Sea-level impacts (briefly)
Ecosystem impacts
Representative Concentration Pathways and projections into the future
And we’re off! Let’s start with humans because that’s what we often connect strongest with….
Human Health
Direct effects of climate change to human health:
Thermal stress, heat waves, floods, storm events
Any others you can think of?
Indirect effects:
Changes in range and seasonality of vector-borne diseases
Malaria, dengue-fever, salmonellosis, etc…
Water and air quality changes (often negative)
Food availability and shortages
Human Health, A Story…
Have you ever lived in an area that had water shut-off periods?
While conducting fieldwork in New Mexico in July 2015, the region we were in was placed under a fire and water ban. Absolutely no fires allowed *for any reason* AND from 12-4pm during the summer, all water to the town was shut off.
The fire ban is obvious, but why the water ban? Why shut off water to a town in NM in summer!? That seems horrifying, no?
Because if water is drawn to the surface, or already on the surface, during peak temperatures of the day, there is vastly increased rates of evapotranspiration (water loss from soil to air).
Thus, turning on your taps, watering lawns, flushing toilets, could not happen during peak evaporation periods.
Oh, and I forgot to mention….this town was in the middle of nowhere (i.e. closest store like a Walmart was about 50 miles away). If you needed water from 12-4pm and you didn’t have your own jugs stored….well….you better hope you had a nice neighbor…
Water security issues already exist in this country, we just often have the infrastructure and civilization set up to provide places to buy water whenever we need it. Thus the risk appears muted because of the security net, but what happens when the net fails, or you live in an area with no net at all?
Human Health
Here’s a graph from a study done in New Zealand that found the relationship between salmonella outbreaks and temperature
Notice that with increased temps, you get an increase in number of Salmonella cases.
These kinds of disease-temp relationships exist everywhere, and often are expedited in areas of flooding.
Human Health
“Developing countries are poorly equipped to deal with weather extremes…” (here’s a snippet from the IPCC AR3, similar results were found in AR4 and AR5…)
Human Health
Again, we see the connections between people and water. In this case, the presence (or absence) of water leads to stressors down the line. Add in more and more people into the 21st century and you have a water security problem…
From the IPCC AR(4)—
“the number of people living in ‘severely stressed’ river basins will increase drastically, namely by one to two billion by 2050s.”
Sea-Level Rise
Loss of coastlines (this is a biggie)
Did you know the coast of Louisiana on US maps is actually fake? The coastline of LA no longer looks like the bottom of a ”boot,” but rather a shredded shoe as more and more islands and channels are formed with sea level rise and coastal erosion!
Political ramifications (the biggest biggie) – what happens to island nations when there literally is no land left to build, no higher ground to find? Climate refugees are the result
I *highly* recommend reading the book Storming the Wall by Todd Miller – it’s a fantastic expose into the future of borderlands in a world of ever-changing climates.
More frequent and pervasive saltwater incursions into freshwater aquifers and leads to delta habitat loss
…this list is almost endless and we find new problems with sea level rise all the time…
Interested in learning more?!
I could spend an entire class on sea level rise and the Earth’s oceans, but like the details on climate modelling, we just don’t have the time in our term to dig much deeper.
Dr. Stephen Tsikalas teaches a class called Intro to Oceanography (GEOG 305)
I highly recommend taking it if you want to learn more on this topic! His email is: stsikalas@ewu.edu if you’d like to reach out to him.
So we know what to expect from sea level rise and thermal expansion.
And from our experiences living on this planet for the past decade(s) or so, we know that climate change can impact our own health.
But how are things like forests and deserts and all the rest expected to change? Or how have they already started transitioning?
Ecosystem Changes
According to the IPCC AR(4) –
“During the course of this century the resilience of many ecosystems (their ability to adapt naturally) is likely to be exceeded by an unprecedented combination of change in climate, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification), and other global change drivers (e.g., land-use change, pollution, over-exploitation of resources.”
Ecosystem Changes
Deserts
Vegetation is well-adapted, but only to a point
We will see increases in dune migration
Succulent Karoo of South Africa
2,800 endemic species
These species are found nowhere else on Earth!
2 deg C would cause a loss of 80% of habitat!!!
Ecosystem Changes
Grasslands and Savannas
Closely tied to precipitation regime shifts
Too much rain = forest, too little rain = desertification
Drought and fires will impact these ecosystems the most
Ecosystem Changes
Mediterranean
Usually the drier/warmer coastal areas like California, Australia, and the Mediterranean
Habitat loss due to sea level rise
Fire frequency increases
Ecosystem Change
Chaparrals
A Case Study on fire in the Hollywood hills!
Fire suppression, climate change, and natural plant ecology
Ecosystem Changes
Forests and Woodlands
Require certain temperature and precipitation regime stabilities
Too cold you get a conifer forest, not enough water you get a grassland, etc…
Drought, fire, and insect outbreak vulnerabilities will increase (or already have)
Deforestation is also releasing massive amounts of CO2 back to the atmosphere
Ecosystem Changes
Forests and Woodlands
Forest productivity due to CO2 fertilization
Tree-line increases
Ecosystem Changes
Forests and Woodlands
Range expansions in some areas at first
increased warming will offset northern expansion with tropical area loss
Rate of adaptation is outpaced by rate of climate change
Some climate models show complete Amazonian rainforest collapse…
Ecosystem Changes
Tundra and Arctic/Antarctic
Extreme levels of habitat loss
Food web collapse in high latitudes
Polar bears may only be found in zoos in the future
charismatic megafauna
Interested in learning more?
I teach two upper level courses on biogeography, ecosystems, and disturbances like wildfires.
GEOG 306 – Natural Vegetative Ecology
GEOG 421 – Dendrochronology
Both classes are 5 credit lab courses with field components. We explore topics of paleoenvironments, climate change, and wildfires.
Email me if you have questions or would like to see a syllabus!
Ecosystem Changes
Freshwater Ecosystems
Stratification phenomenon in layers of non-flowing water
Decrease in oxygen availability
No lake turnovers
Loss of lakes in arctic and tropical regions
Ecosystem Changes
Oceans and Coastal Seas
Warming water, reduced nutrient contents, sea level rise, loss of ice cover, increased disease risk, acidification, etc.
Arctic Ocean productivity depends on sea ice cover
Food web collapse through trophic cascades
No more Deadliest Catch!
Ecosystem Changes
Oceans and Coastal Seas
Poleward shifts in marine fauna ranges
Warmer water can be found farther north
North Atlantic plankton now found 1,000 km farther north than 40 years ago
Coral Reef Bleaching
Balances in symbiotic relationships
1998 saw a loss of 16% of worlds coral
Ecosystem Changes
Great Barrier Reef and loss of Ecotourism
Ok, but how do we know just how bad it’s going to get? Is there a way we can look at a spread of possibilities? Can we look at future projections of change based on different levels of fossil fuel emissions?
Yes you can! They’re called Representative Concentration Pathways, and we have created four of them, each representing different futures under different carbon in the atmosphere….
Let’s check them out now!
Representative Concentration Pathways
RCPs are different pathways Earth’s system can take under different concentrations of carbon.
According to NOAA: “Representative Concentration Pathways (RCPs) are not new, fully integrated scenarios (i.e., they are not a complete package of socioeconomic, emissions and climate projections). They are consistent sets of projections of only the components of radiative forcing that are meant to serve as input for climate modeling, pattern scaling and atmospheric chemistry modeling”
The four different pathways are:
RCP 2.6
RCP 4.5
RCP 6.0
RCP 8.5
The numbers reflect W/m2 (watts per meter sq) and indicate radiative forcing units at Earth’s surface. You do not need to know anything beyond that for this class.
Anthropogenic Radiative Forcing
Measure of how much positive (notice y axis) impact each RCP has on atm radiative change
Positive forcing = increase in radiation of heat within atmosphere
This positive forcing leads to positive increases in atmospheric temperatures
Ignore the SRES models, we don’t cover them in this class…
RCPs and atm [CO2]
The most conservative scenario is the RCP 2.6 = strong reductions post 2020
Well…we’re here in 2020, how do you think we’re doing on this scenario???
The worst case scenario is the RCP8.5 = Business as Usual (BAU) until 2100
We’ve done nothing but pursue this pathway for the past 4 years.
Check out on the graph what each potential RCP means for fossil fuel emissions and atmospheric carbon
Atm [CO2] and Global Temp Response
Carbon emission scenarios used in GCMs to project future global temp responses
READ/REVIEW IN YOUR TEXTBOOK ABOUT WHAT THE MODELS ARE PROJECTING FOR ATM TEMP CHANGE GLOBALLY (PGS. 139-145)
Variability to Warming
In the Business As Usual (BAU) scenario (the RCP8.5)
More warming over land than water
More warming in Arctic than elsewhere – but equatorial mid/upper troposphere will experience increased temp change too
This does NOT mean the Arctic is warmer than the tropics, it means there has been more change in temp in the Arctic than in the tropics!
Arctic Sea Ice Extent via RCPs
And look what each RCP means for the ice!!
RCP2.6 shows substantial ice over
RCP8.5 shows almost ice-free Arctic
There are times in the year now when areas of the Arctic are already completely ice free…
Global Sea Level Rise Projections
Based on whatever RCP ends up happening, we can also see changes to sea level rise…
Spread in scenario projects exist due to uncertainties in GCMs related to future projects of temperature
This does NOT mean models are wrong, it’s simply caution used in science!
Ok that’s all for this week! Don’t forget to do the two extra readings and watch the documentaries for discussion this week!
Links to Check Out!
Climate Models and RCPs via NOAA
https://sos.noaa.gov/datasets/climate-model-temperature-change-rcp-26-2006-2100/
This is the RCP2.6, but you’ll notice if you scroll down you can see pages for each of the other three.
RCP database (continually updated)
http://tntcat.iiasa.ac.at:8787/RcpDb/dsd?Action=htmlpage&page=welcome#acknowledge
Looking Ahead
Last week of term!
Discussion #4 is the same as the setup for #2, where you write and answer essay questions for your peers.
Exam #2 will be due Friday, Aug 14th and will be the same format as Exam #1
Don’t hesitate to reach out with questions or concerns!