geography 3 final
are el nino years characterized by warmer of colder global surface temperartures?
hotter
The sea level rise is less concentrated close to Greenland because
the land actually rises as the ice melts and its weight is lifted (isostatic adjustment).
Which of the following could be considered a radiative forcing that would cause climate change: (a) An increase in the radiative output of the Sun (b) An increase in CO2 concentrations caused by increased volcanic activity (c) An increase in sunlight-blocking pollution caused by human activities (d) A change in ocean currents that cause the ocean to absorb more heat from the atmosphere
(a) An increase in the radiative output of the Sun (b) An increase in CO2 concentrations caused by increased volcanic activity (c) An increase in sunlight-blocking pollution caused by human activities
Imagine CO2 concentrations increase, reducing the amount of outgoing longwave radiation (Qlw). Which of the following is a negative feedback on this climate forcing? a) Increased Earth surface temperatures. b) Decreased ice concentrations. c) Increased water vapor concentration in the atmosphere.
(correct answer!) a) CO2 increase ⟹ Qlw ↓ ⟹ Increased surface temperatures ⟹ Qlw ↑ (negative feedback;brings budget back into balance). Temperature-radiation feedback b) CO2 increase ⟹ Qlw ↓ ⟹ Increased surface temperatures ⟹ Decreased ice concentrations⟹ albedo*Qsw ↓ (positive feedback; leads to even more imbalance). Ice-albedo feedback c) CO2 increase ⟹ Qlw ↓ ⟹ Increased troposphere temperatures ⟹ Increased water vapor concentration ⟹ Qlw ↓ (positive feedback; leads to even more imbalance). Temperaturewater vapor feedback
ice-albedo feedback and what type of feedback is this?
(forcing=) increased CO2 levels-----------------------------> warming------------------------------------------------------> sea ice melts-------------------------------------------------> lower albedo------------------------------------------------> this cycle continues this is a positive feedback
The heat capacity (amount of warming per unit energy absorbed) of the ocean is 1000x that of the atmosphere! Why?
(i) Water takes more energy/mass to heat up than air (ii) The ocean is 300x more massive than the atmosphere
For the California coast (sea level rise in Santa Barbara would be similar to that in San Francisco), sea levels will rise anywhere from ___________________ by the end of the century. Likely range is ________________.
-0.5 ft to 10 ft (25 cm to 3 m) -0.5-4 feet
ocean acidification: threat to coral reefs
-2005: 380 ppm CO2 -2019: 410 ppm CO2 -2030: 450 ppm CO2."Extremely marginal" conditions for corals living in the Western Tropical Pacific (e.g. Great Barrier Reef) and elsewhere. -2050: 500 ppm CO2.Almost all corals will be living under marginal or worse conditions.
In total about _______________ of ice melted off Greenland and Antarctica over the past 15 years. That's about _______ of sea level.
-400 trillion kg -1 inch
CO2 is not the only agent of anthropogenic climate forcing-> negative
-Aerosols are tiny particles in the air. Sources include industrial combustion. ---> this is negative-> cooling
Arctic Sea Ice in Decline
-As the globe warms, ice pack in the Arctic Ocean has been thinning. We have a continuous record since1979, when satellites first started measuring sea ice extent.
How Do We Know How Atmospheric CO2 Has Changed Over Time? Mauna Loa
-Atmospheric CO2 concentrations have been monitored since 1958 at the Mauna Loa observatory on the Big Island of Hawai'i. -The record of CO2 levels from Mauna Loa is called the "Keeling curve" after C. D. Keeling, the scientist who pioneered these measurements.
Future Sea Level Rise Impacts: Santa Barbara--> some highlights
-By 2100, city could lose 98% of its bluff-backed beaches to erosion -By 2100, city could lose 60% of its sandy beaches to erosion -SB harbor in its current configuration would be unusable by 2100 -El Estero Wastewater Treatment Plant and Charles E. Meyer Desalination Plant will be inoperable by 2100 if no action taken -All over the city sewage and irrigation lines are subject to tidal inundation and storm flooding. Most beaches are overrun at high tide and during storms.
CO2 is not the only agent of anthropogenic climate forcing-> positive
-CO2 has the largest climate forcing. Methane (CH4), nitrous oxide (N2O), halocarbons (CFCs) and ozone (O3) are also greenhouse gases. --> this is positive warming
How Do We Know How Atmospheric CO2 Has Changed Over Time?: antarctica
-CO2 reconstructed from gas bubbles trapped in ice and snow from Antarctica and Greenland -Atmospheric CO2 concentrations have been reconstructed for hundreds of thousands of years in the past using air trapped in ice, revealing the glacial/interglacial cycles. These ice cores can be over 2 miles long!
Sea Level Rise: Local vs Global
-Changes fro location to location on a local level -ex: Rising sea level in SF, lowering in crescent city -->Why is crescent city lowering? Not actually going down, but the land is rising
Climate models
-Climate models integrate everything that we know about climate forcing and feedbacks, as well as natural climate variability (passing of energy back and forth between atmosphere and ocean). -The models can be run with and without anthropogenic climate forcing, to separate out the effects of natural variability and anthropogenic climate change. -Models with anthropogenic forcing can re-create the observed temperature changes. -Models without anthropogenic forcing cannot. -Natural climate variability is important on 10-20 year timescales.
Why have human activities caused a positive climate forcing in tropospheric ozone (O3), and a negative forcing in stratospheric ozone (like how is this helping us)?
-Driving cars causes excess ozone in the troposphere (ozone pollution). Ozone is a greenhouse gas that traps heat in the troposphere. -Human activities (CFCs) have destroyed stratospheric ozone ("ozone hole"). Ozone in the stratosphere absorbs solar radiation, so less of it leads to less energy being absorbed.
Both Goleta and Santa Barbara are preparing for the impacts of sea level rise. How?
-Each city recently completed vulnerability assessments (available online), outlining the impacts of sea level rise on the coastline, beaches, and infrastructure. -Total potential adaptation costs are $370 million ($257 million from potential oil spills, $14 million property damages).
ENSO: Local climate impacts-> santa barbara rainfall
-El Nino years = more rainfall (on average) -La Nina year = normal to slightly drier *Note there is a lot of variability - many other factors at play to determine the local weather!
Past Climate Change: GlacialInterglacial Cycles-> forcing and feedbacks
-Forcing: Subtle changes in Earth's orbit cause the Northern Hemisphere (NH) to get less insolation (Qsw) than the SH. -Feedback #1: Ice-albedo feedback. When the NH cools, glaciers begin to grow (NH has more land than SH, easier to grow ice on land than on ocean). This amplifies the cooling. -Feedback #2: As the ocean gets colder it absorbs more CO2. Less CO2 in the atmosphere reduces the greenhouse effect, leading to even colder temperatures.
What are some global climate indicators?
-Global average temperature: Temperature over land, temperature over ocean, sea-surface temperature, atmospheric temperature near surface (troposphere) -Water vapor content of atmosphere -Volume and extent of glaciers and ice sheets -Volume and extent of snow cover -Sea level -Extent of sea ice
What's Driving the Earth's Energy Imbalance?
-Human emissions of CO2 (due to burning fossil fuels to extract energy) are increasing rapidly over time. -CO2 is a greenhouse gas which traps longwave radiation (heat) near the surface, so that it cannot escape out into space.
climate example
-In November, Seattle is typically cooler and rainier than Santa Barbara. -Seattle has a different climate (cooler/rainier) than Santa Barbara.
CO2 and how it is causing an imbalance in the earth's energy budget
-Increasing CO2 in the atmosphere enhances the Earth's natural greenhouse effect. This is the anthropogenic greenhouse effect. -More heat is trapped near the surface, less heat (longwave radiation) escapes into space. -This creates an energy imbalance, as the amount of energy coming in (from the Sun) stays the same, but the amount of energy leaving decreases. -This energy imbalance is called a radiative forcing.
CO2 and Climate: Ice Core Record--> temperature and CO2 correlation
-One clear lesson from the past million years is that temperature and atmospheric CO2 concentration are highly correlated. -The temperature and CO2 are reconstructed from gases trapped in ice bubbles that are extracted from "ice cores" — long tubes of ice collected in Antarctica and Greenland.
Observations show that warming of the Earth's surface is most intense in the Arctic. Why?
-One reason is the ice-albedo feedback. As the ice melts it is replaced by water, which is less reflective (has a lower albedo). Thus the surface absorbs more energy and heats up, melting even more ice. The cycle perpetuates itself.
Sea Level Rise Impacts: Florida
-Sea level has risen 8 inches since 1950 on the Florida East Coast. -Cause are mainly ice melt from glaciers and ice caps, and a slowdown of the Gulf Stream
Sea Level Rise Impacts: Santa Barbara
-Sea level has risen about 6 inches along the southern and central California coast since 1950. -Causes are mainly ice melt from glaciers and thermal expansion. Projections are for ~5-18 additional inches of SLR by 2050.
Sea Level Rise: Thermal Expansion vs. Added Water (what percentage of each is contributing the sea level rise)
-Sea levels are also rising due to the extra water in the ocean from melting glaciers and ice caps. -Right now sea level rise is ~50% due to thermal expansion, and ~50% due to added water (ice sheets and glaciers). This could change drastically... or not.
These relevant quantities are called climate indicators. Let's look at the climate indicators for Santa Barbara.
-Temperature: Average temperature is 61.7oF (annual high 69.9oF, annual low 53.5oF) -Precipitation (rain or snow): Annual precipitation is 19.41 inches. It snowed once! -Seasonality (seasonal changes in relevant quantities: large extremes vs. little variability) Little variability. See graph below. -Wind: Not too windy - except March/April -Frequency of extreme days (freezing/extreme heat): Freeze rarely (couple days/year); Rarely > 100oF (couple days/year) -Frequency of cloudy/sunny days: 283 sunny days/year
Future Sea Level Rise Impacts: Santa Barbara assessment
-The city of Santa Barbara considered 3 time horizons in its assessment, with sea level rise based on latest data from the State of California Sea-level Rise Guidance (2018), based on their medium-high risk aversion guidelines: -- Year 2030: 0.8 feet sea level rise -- Year 2060: 2.5 feet sea level rise -- Year 2100: 6.6 feet sea level rise
CO2 in the Ocean: Ocean Acidification
-The ocean absorbs CO2, which helps warming-wise. But CO2 is acidic when dissolved in water -- so as the ocean absorbs CO2 it leads to ocean acidification.
Is There Currently an Imbalance in Earth's Energy Budget?
-The radiative imbalance at the top of the atmosphere is 0.6±0.4 W/m2 (less than a dim flashlight). -That sounds small, but it's 2.7 million TWh of energy per year, or more than 100 times the annual energy consumption of the U.S.!
why are the waters near Greenland cooling and not warming?
-This is because you have the currents disrupting it-> overturning of cold water -Slowdown in the overturning circulation there, cool water is not being overturned to warm water
Sea Level Rise: Observed
-Tide gauges: Global mean sea level rose about 8 inches from 1880 to 1995. -Satellites: Global mean sea level rose about 3.6 inches from 1993 to 2019. -Tide gauge measures the rise and fall of water, relative to nearby location on land
Last Glacial Period in Santa Barbara
-With so much water locked up in ice during the last glacial period, the sea level was almost 400 feet lower than today (see blue shading on map). -Mammoths were able to swim from the mainland out onto the Channel Island(s). -Over time the mammoths evolved to be much smaller — typical of animals trapped on small islands.
anthropogenic climate change drivers examples
-emissions and pollution from power plants and cars (emit CO2 and aerosols) -deforestation (removes plants that absorb CO2)
The local rate of sea level rise can vary from place to place, depending on
-if the land is rising/sinking, -other factors such as ocean currents
other than cutting down CO2 emissions how can we help the whole global warming situation
-renewable energy -Machines that take CO2 out of air-> put CO2 into the ground -Or maybe we just lower our expectations
Climate Change Impacts (examples)
-sea-level rise -melting sea ice -coral bleaching and ocean acidification -droughts and heat waves -increased hurricanes and storms
how far back does the instrumental record for global measurements extend? and how much has Earth's temperature changed over this record?
-since 1850 ~1.4° F
CO2 emissions must be reduced to avoid climate impacts (agreements that have been made)
-the emission pledges the US (not anymore), EU, Chinam and India leave no room for other countries to emit in a 2° budget (66% chance) -Emission pledges from top 4 emitting countries (Paris agreement) are probably not enough to limit warming to 2oC (4oF). Need more rapid transition away from fossil fuels. -Or, may have to lower expectations - limit warming to 3-4oC (6-8oF)? Climate consequences not looking good in that scenario
what are Nor'Eaters and why do they cause flooding?
-they are common winter storms in New England. -During a Nor'Easter the winds will blow out of the northeast in New England (hence the name). -Eckman transport (90° to right of wind) will cause water to push toward shore — flooding ensues. -This "natural" flooding gets worse and worse as sea levels rise.
natural climate change drivers examples:
-variation in solar output -variation in Earth's orbit -variability in volcanic eruptions (emit CO2)
A new reconstruction of ancient climates reveals that Earth has been far _____________ in the past. We are now in a _________ climate period, but the world is rapidly _______________.
-warmer -cold -warming
Weather, climate variability, and climate change: distinctive timescales
-weather: days- months -climate variability: months-decades -climate change: decades-millenia
Global sea levels have risen about _______ over the past century.
1 foot
How Does (Global) Climate Change? Forcing and Feedbacks: example 1-> cooling/ snowball earth
1) Decrease in greenhouse gas concentration (Qlw )-> this is forcing 2) Earth cools (Qlw )-> this is the feedback 3) Ice caps grow (albedo )-> the increase of ice caps creates a "viscous cycle" that drive down surface temperatures. If nothing breaks the cycle, a "snowball Earth" can develop.
Discuss with your neighbor and classify each of these effects of climate change as creating a positive or negative feedback. Remember positive feedbacks amplify climate forcing and lead to greater energy imbalance. Negative feedbacks bring the system back into balance. 1. As Earth's climate warms, ice sheets and glaciers start to melt. 2. As Earth's climate warms, the atmosphere can hold more water. 3. Anthropogenic aerosols emitted during fossil fuel combustion act to increase the condensation of water vapor in the atmosphere, causing more clouds. 4. Increasing CO2 concentration has a "fertilizing" effect on forests, causing more trees to grow.
1. As Earth's climate warms, ice sheets and glaciers start to melt. -Positive (reduce albedo, greater imbalance). "Ice-albedo feedback" 2. As Earth's climate warms, the atmosphere can hold more water. -Positive (stronger greenhouse effect, greater imbalance). "Water vapor feedback" 3. Anthropogenic aerosols emitted during fossil fuel combustion act to increase the condensation of water vapor in the atmosphere, causing more clouds. -Negative (increase albedo, bring back to balance). "Aerosol indirect effect" 4. Increasing CO2 concentration has a "fertilizing" effect on forests, causing more trees to grow. -Negative (reduces CO2 levels and greenhouse effect). "CO2 fertilization effect"
One March morning Mr. Frumble woke up in his New York penthouse and looked outside. It was cold and snowy! It was freezing! Which conclusion should Mr. Frumble draw? A. The weather is highly variable and changes often B. The Earth's climate is cooling and global warming is a hoax
A. The weather is highly variable and changes often
As the ocean warms, it's density decreases. What happens to the volume of the ocean? A. Volume increases B. Volume decreases
A. Volume increases
From Climate Forcing to Climate Change
1. Climate forcing starts the process of climate change by creating an energy imbalance. In the case of anthropogenic climate change, it is a net positive radiative forcing due to the combined effects of greenhouse gases, so we have an energy surplus. 2. Feedbacks take over from there. Positive feedbacks amplify the effects of the forcing. Negative feedbacks reduce the effects of the forcing.
How Does (Global) Climate Change? Forcing + Feedbacks
1. Climate forcing starts the process of climate change. Usually Qsw increase/decrease due to change in insolation, or Qlw increase/decrease due to change in greenhouse gas concentration. 2. Feedbacks take over from there. Positive feedbacks amplify the effects of the forcing. Negative feedbacks dampen the effects of the forcing
The heat capacity (amount of warming per unit energy absorbed) of the ocean is
1000x that of the atmosphere!
Officially, an El Nino is called when the SST in the Nino3.4 region is
>0.5°C above normal for >3 months in a row
La Nina occurs when the SST in the Nino3.4 region is
>0.5°C below normal for > 3 months in a row
Climate change
A significant and persistent change in the mean state of the climate or its variability.
So far we've considered the effects of increased CO2 in the atmosphere. But not all the CO2 that humans emit ends up in the atmosphere. Some of it is absorbed by the oceans which leads to: A. Less global warming B. More global warming
A. Less global warming anthropogenic CO2 emissions-> increased CO2 levels in atmosphere-> global warming (positive radiative forcing) anthropogenic CO2 emissions-> CO2 absorbed by ocean-> less CO2 in atmosphere-> less global warming (negative radiative forcing)
A climate forcing causes Earth to warm. Warmer temperatures cause there to be more water vapor in the air (warm air holds more water). This causes _________, leading to a ______ feedback A. more warming; positive B. more warming; negative C. more cooling; positive D. more cooling; negative
A. more warming; positive
CO2 in the Ocean: How much has the ocean absorbed?
About 40% of CO2 emmissions have been absorbed by the ocean
Arctic Warming: Methane Feedback
Another Arctic-centric feedback we discussed is the release of methane from thawing lakes and permafrost. (forcing=) increased CO2 levels----------------------------> warming-----------------------------------------------------> melting of lakes/permafrost--------------------------------> methane released to atmosphere--------------------------> this cycle continues this is a positive feedback... Warming leads to more warming. It is self-perpetuating. It perpetuates itself. Over and over. And over. Again and again -here the energy comes in Qsw, and the Qlw decreases more due to methane
ocean acidification impacts: calcium carbonate shells
As the ocean acidifies, organisms that form calcium carbonate shells (clams, corals, snails etc) will be in danger of their shells dissolving. Since many of these animals are at the base of the food chain, the effects cascade upwards.
Sea Level Rise Projections: U.S. Worst Case Scenario (beyond 2100)
Beyond 2100, it could be anywhere from "kinda bad" to "disastrous". It depends on what happens to the Greenland and Antarctic Ice Sheets. If they both melt, then sea level will rise by 70 m. Big huge problem, as seen in the above map (sea level if all ice melted).
If the entire Greenland Ice Sheet melts, where do you think sea levels will rise the most? A. U.S. east coast B. Europe C. South America D. Japan
C. South America D. Japan
how to slow down ocean acidification?
Can slow it down by lowering anthropogenic CO2 levels
natural climate change
Climate change can (and does) happen naturally
Climate models and climate predictions
Climate models are also used the make predictions about Earth's future climate. Scientists use these models in the periodic reports of the Intergovernmental Panel on Climate Change (IPCC). Last full report in 2014 (IPCC 5th assessment). Next report due 2022 (IPCC 6th assessment).
Satellites measure a 0.6±0.4 W/m2 radiation imbalance at the top of the atmosphere This energy goes to warming the Earth system. How much of this energy goes into warming the ocean? A. 10% B. 25% C. 70% D. 90%
D. 90%
The ECEP heat sink strengthens and weakens in a natural cycle known as
ENSO (El Nino Southern Oscillation)
why are el nino years hotter than other years (with more normal conditions)?
El Nino years tend to be hotter than others (globally) because the ECEP heat sink is weakened. More heat stays in the atmosphere (rather than going in to the ocean) which increases global surface temperatures.
Radiative balance
Energy in = energy out
Radiative imbalance:
Energy in ≠ energy out
The climate change is perpetuated or damped (increases or decreases) by
feedbacks in the climate system
2018 (the last full year of temperature data) experienced mainly La Nina conditions for most of the year, while 2019 saw a weak El Nino. Do you think 2019 will be warmer or colder than 2018? A. 2019 will be warmer than 2018 B. 2019 will be cooler than 2018
From carbonbrief.org: 2019 will most likely be the 2nd warmest year on record (after 2016). It will almost certainly be warmer than 2018
Almost everywhere in the ocean is heating up -- except for
Greenland
Long-term pH measurements have been made at the
Hawaii Ocean Time Series (HOTS) at Station ALOHA -The observations match up well with the model predictions
Coral bleaching
In addition to ocean acidification, organisms are negatively impacted by rising ocean temperature. In the case of corals, they eject their symbiotic algae (the stuff that gives them pretty colors) to survive the warmer waters.This leaves the corals white, and is called "coral bleaching". -A bleached coral will not survive too long, as seen here.
Where in the ocean does the CO2 go? and why
Mainly in the northern atlantic -why?-> waters get cold (absorb CO2) and sink and bring the CO2 in the deep oceans then is carried south and around the ocean (overturning circulation)
Arctic Sea Ice in Decline: Negative Impacts on Arctic Wildlife
Marine and terrestrial animals in the Arctic are expected to be negatively impacted by the loss of sea ice cover.
What other factor (besides ocean warming), can contribute to global sea level rise?
Melting glaciers, gulf stream-> getting flatter and current is weaker -this is added water
Climate variability
Natural changes in climate that fall within normal range of extremes for a particular region.
Will sea level rise due to the melting of all this sea ice (the Arctic Sea Ice)? A. Yes B. No
No. The sea ice is already floating in the water. It's like melting ice cubes in your drink - compare to: the volume of the drink does not change.
positive feedback
Positive in this case means "self-perpetuating", not "good". If fact, positive feedbacks in climate are usually "bad" since they accelerate climate change.
Arctic Sea Ice Projections
Projections of sea ice extent by year 2100 vary (of course). The most extreme scenarios are entirely ice-free.
Past (Natural) Climate Change
Remember that the Earth's climate has varied a lot in the past! We currently have a relatively cool climate, compared to when the dinosaurs were alive
Current Sea Level Rise: East Coast
Sea level has risen 10-14 inches since 1950 on the U.S. East Coast. Local factors vary: land subsidence in the midAtlantic, slowing Gulf Stream in the Southeast.
The mechanism of ENSO: under "normal" conditions
Under "normal" conditions of the equatorial convective (Walker) circulation, the easterly trade winds drive the equatorial current westward, causing upwelling in the eastern equatorial pacific. This upwelling of cool waters increases heat uptake in the ECEP -convective circulation occurs * so basically the water is heating up in the ECEP, causing upwelling in the Eastern pacific (wind is going away from the pacific coast-> cold water "fill in") *
does glaciation occur slower or faster than the transition to the interglacial state?
glaciation occurs slowly, but the transition to the interglacial state is rapid
in climate change radiative balance, and therefore more/less energy, leads to
global climate change
Timescales of Climate Change
The Earth's climate has changed a lot over the course of geologic time. Note the short time humans have been on Earth. -examples= "snowball earth" and "Palocene-Eocene Thermal maximum (PETM)"
Past Climate Change: GlacialInterglacial Cycles
The Earth's climate over the past ~1 million years has been marked by "ice ages" (very cold periods) and "interglacials" (times between the ice ages) -Like all climate changes, these climate oscillations are due to a combination of climate forcing and climate feedbacks
what are IPCC reports and climate projections
The IPCC 5th Assessment shows different temperature and sea level scenarios for different CO2 emissions scenarios.
Climate (simple version)
The average weather
what is the "keeling curve"
The record of CO2 levels from Mauna Loa
Climate (more rigorously)
The statistical description in terms of the mean and variability of relevant quantities over a [long] period of time. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization.
Distribution of Warming in the Earth System
The vast majority (>90%) of the excess energy in the Earth system has gone into heating the oceans.
The mechanism of ENSO: under "El Nino" conditions
Under "El Nino" conditions, the easterly trade winds slacken or reverse, allowing atmospheric convection to shift toward the east-central Pacific, reducing upwelling in the eastern equatorial Pacific. This reduces oceanic heat uptake in the ECEP. *basically, since the winds change the area where converction occurs changes, and also changes upwelling-> casues oceanic heat uptake to lower, meaning there is more heat in the air)
The mechanism of ENSO: under "La Nina" conditions
Under "La Nina" conditions, normal conditions are intensified. The western equatorial Pacific becomes anomalously warm and wet. The eastern Pacific becomes anomalously cold and dry.
what is happening to the strength of the gulf stream
Weakening (because it is flattening)
For California, we are most impacted by melting of the
West Antarctic Ice Sheet. (Notice that the sea level rise in North America is ~140% of the global average if the WAIS melts)
Which of the following is an indicator of climate change? a) It will be cold and rainy in Santa Barbara this Thanksgiving. b) The 2018 Pacific hurricane season was the most active on record. c) Santa Barbara experienced a 5-year drought from 2011-2016. d) Arctic sea ice extent has been declining over the past 40 years.
a) It will be cold and rainy in Santa Barbara this Thanksgiving. ->Nope. That's weather, not climate. b) The 2018 Pacific hurricane season was the most active on record. ->No, a single anomalous year does not necessarily indicate climate change. c) Santa Barbara experienced a 5-year drought from 2011-2016. ->Not necessarily, natural climate variability can definitely cause 5-year droughts. d) Arctic sea ice extent has been declining over the past 40 years. ->Yes, a 40-year trend is probably outside the range of natural climate variability
As humans emit greenhouse gases (e.g. CO2) into the atmosphere, part of the outgoing terrestrial radiation is...
absorbed and re-emitted back to the Earth's surface. This reduces the amount of terrestrial radiation escaping out into space.
The ocean helps to "buffer" (protect) the climate system from the effects of anthropogenic CO2 emissions by
absorbing both heat and CO2
anthropogenic climate change
alterations to climate resulting from human impact-> humans can also cause climate change
Modern climate change is mainly due to
anthropogenic CO2 emissions and increasing CO2 levels in the atmosphere.
The "fingerprint" of ENSO is
changes in the sea-surface temperatures (SST) of the ECEP
The general upward trend in global temperatures results from
climate change (global warming) due to anthropogenic forcing (e.g. increasing CO2), while the bumps and wiggles on shorter timescales are due to climate variability.
El Nino Southern Oscillation (ENSO) is one of the dominant modes of
climate variability (2-3 year cycle)
La Nina is characterized by
colder than average Sea Surface Temperatures. This means the ocean will be taking up more heat from the atmosphere.
With climate variability, Earth's overall energy budget
does not change, the distribution of energy within the Earth system (e.g. ocean vs. atmosphere, or within either of those 2) changes.
el nino and rainfall
el nino conditions in the tropical pacific are known to shift rainfall patterns in many parts of the world -e.g. soulthern half of US and northern part of Mexico, southern pacific)
climate variability means, no forcing, leading to the same amount of energy being present... instead of global climate change, what happens?
energy gets split up and passed around in different ways (between the ocean and atmosphere)
what is the eastern and central equatorial Pacific (ECEP)and what is it driven by
huge atmospheric heat sink (absorbing heat from the atmosphere). The heat sink is driven by easterly trade winds and upwelling of cool waters at the surface in the ECEP
How Does (Global) Climate Change? Change in Earth's Energy Budget
if the terms of... -incoming solar radiation (insolation) (Qsw= Qlw+albedo*Qw) -outgoing terrestrial radiation (Qlw) -albedo (Qsw) ...change, this can drive a change in Earth's climate
Anthropogenic Greenhouse Gases: "Others"
includes halocarbons (e.g. CFCs) that have been used for refrigerants and aerosol spray propellants
Anthropogenic Greenhouse Gases: Nitrous oxide (N2O)
is released from agriculture, fossil fuel combustion, and biomass burning (slash + burn)
Anthropogenic Greenhouse Gases: Methane (CH4)
is released from natural gas leaks, agriculture, livestock, and landfills
More acidic waters have a __________ pH.
lower
does a large el nino necessarily mean higher than average rain? and does a weak el nino mean lower than average rains?
nope! can see this through the multiple LA times headlines
Global sea levels are rising due to
ocean warming and melting glaciers and ice caps -oceans warm -> density decreases -> volume increases -> sea levels rise because of"thermal expansion" -ice caps melt -> water runs into ocean-> volume increases -> sea levels rise
la nina rainfall conditions are...
opposite from el nino
Coral bleaching is caused by acidification or rising temperatures
rising temperatures
As the volume of the ocean gets larger, it has nowhere to go but up, meaning...
sea levels will rise
A climate forcing (or radiative forcing)
starts the climate change. casues an IMBALANCE in the Earth's radiation budget (so Qsl (in), Qlw (out), or Qsw (out))
El Nino is characterized by
warmer than average Sea Surface Temperatures. The ocean will be taking up less heat from the atmosphere.
during El Nino the trade winds are ___________, causing __________
weaker; less upwelling in the ECEP (this means that there is less cold water at the surface) and the warm water absorbs less heat from the atmosphere
Average pH in the ocean has decreased by
~0.15 pH unit (from 8.2 to 8.05) --Because the pH scale is logarithmic, this is a 40% increase in the acidity of ocean waters -This model projects that ocean pH is now decreasing rapidly -started rapidly decreasing in ~1960
What are the relevant qualities for defining climate?
• Temperature • Precipitation (rain or snow) • Seasonality (seasonal changes in relevant quantities: large extremes vs. little variability) • Wind • Frequency of extreme days (freezing/extreme heat) • Frequency of cloudy/sunny days
