Midterm #1 Flashcards
Climate (def.)
The statistical description of the weather of a place averaged over a period of time, usually 30 year,s AND the average of the type, frequency, and intensity of weather events.
Weather (def.)
the actual state of the atmosphere at any particular time
Temperature Anomaly
a departure from a reference value or long-term average temperature \ The difference between absolute and reference temperature
positive = warmer; negative = colder
Climate is what we _______ weather is what we _____
expect, get
Instrumental record (def.)
the period of time over which we have measurements from instruments (1880-recent)
A warming of ______ Celsius between 1880-2019
1.1 degrees
Inter-annual variability
It is not getting progressively warmer every single year, there’s some year to year differences BUT each decade is warmer than the preceding decade (for the last several decades)
Indicators of a warming world
Increased water vapor, increased sea levels, thermal expansion of the ocean, increased ocean surface temp, increased temp over land, increase air temp near the surface (troposphere), decreased sea ice, decreased snow cover, decrease in size of glaciers & ice sheets
Human activities causing climate change
CO2 and other greenhouse gas emissions, deforestation, land use that alters albedo, pollution releasing aerosols
Aerosols
suspension of fine solid particles or liquid droplets in air or another gas
IPCC Wording: The combined forcing of aerosol–radiation and aerosol–cloud interactions is negative (cooling) over the industrial era (high confidence), offsetting a substantial part of greenhouse gas forcing, which is currently the predominant human contribution
How do we attribute climate change?
computer models that simulate with and without human effects;
using the “hockey stick” on longer climate records which shows an extreme change within a short period of time caused by human involvement
framed in 2 ways:
the fractional contribution of climate change
the probability of the event occurring with or without climate change
Emissions vs. concentration
Emissions is the rate at which CO2 (or other greenhouse gasses) enter the atmosphere and concentration is the build-up of the gas in the atmosphere
Why is the atmosphere a global commons
It’s well mixed meaning the emissions from one person or country is evenly spread and will affect everyone else regardless of if they put out the emissions themselves
*Often times those who are responsible for climate change aren’t the ones most affected
Climate Change Attribution (def.)
The study of how we are best able to attribute climate change to human activities and the increase of greenhouse gases in the atmosphere
Gigaton (def.)
billion tons (metric)
Current global CO2 emissions from consumption of energy in Gigatons
36 Gt CO2/year
sea level rise (causes)
Sea-level rise is caused by melting ice sheets and glaciers (ocean mass) and by thermal expansion of warming ocean water (steric sea level)
Certainty: It is 100% certain that sea-level rise is an impact of climate change. It is certain that sea-levels will continue to rise, and the rate of increase is accelerating.
Global mean sea level increased by 0.20 [0.15 to 0.25] m between 1901 and 2018
precipitation patterns
wet areas are getting wetter and dry areas are getting drier
Type of precipitation shifting: snow to rain
Consequences: increased rain in places unprepared for it; some areas rely on snow for water throughout the year (e.g. California relies on snow throughout the year for water)
IPCC
the leading international body for the assessment of climate change established by the UN to provide the world with a clear scientific view on the current state of knowledge of climate change and its potential environmental and socio-economic impacts
Increasing temperatures (caused by humans? IPCC answer)
It is virtually certain that hot extremes (including heatwaves) have become more frequent and more intense across most land regions since the 1950s
land evapotranspiration
the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants; increases in agricultural and ecological droughts
Ocean Acidification
Caused by the ocean absorbing increased CO2 from the atmosphere which changes the PH of the water
consequences: makes it more difficult for organisms with carbonate sells to build their shells
Climate Proxies
environmental recorders that are used to estimate past climatic conditions
e.g. preserved in tree rings, locked in the
skeletons of tropical coral reefs, extracted as ice cores from glaciers and ice caps, and buried in sediments from lakes and the ocean
Ice Cores
Important Paleoclimate measure (seen as one of the best paleoclimate measures)
Can be used to study the past composition of the atmosphere using trapped air bubbles in the ice in addition to other important climate data
Paleocene-Eocene Thermal Maximum (PETM)
a short interval of maximum temperature lasting approximately 100,000 years roughly 55 million years ago; likely caused by a massive release of greenhouse gases; many scientists consider the PETM as a good analog for current climate warming
Paleoclimatology
How we know about Earth’s climate history; the study of climate prior to the the widespread availability of instrumental data
Why are we worried about climate change now?
The rates of change in the climate system (i.e. CO2 concentrations, temperatures) are generally higher now than have been observed in the past, and humans have never existed in a climate as warm as what will happen if we don’t slow the rate of change
Paleoclimate Archives
Long, continuous, datable undisturbed climate archive with climate proxy data.
Why are we interested in paleoclimates
To examine past climate changes and climate variability beyond the instrumental period, To better understand the causes of natural climate variability, To understand the potential for “climate surprises”
(Climate surprise = abrupt change to the Earth’s climate system), To understand feedback in the Earth’s climate system on timescales longer than a few centuries, To better understand how humans are currently influencing the Earth’s climate system
3 factors determine Earth’s climate
- The amount of incoming solar radiation
- The albedo of the planet
- How much greenhouse gas is in the atmosphere (changing the most)
Long-term (hundreds of millions of years long) geological record (what does it show)
shows that the Earth’s climate varies widely; The climate has been both warmer and colder than today’s climate
Icehouse vs. Greenhouse Periods
During ice-house periods, permanent ice sheets extend down to the midlatitudes and during greenhouse periods the earth is ice-free; we are currently in an icehouse period
Geological Record of the last 50 million years (what is the trend/what does it show)
Over the last 50 million years, the Earth has largely been cooling. (this is also associated with a decrease in atmospheric CO2 concentrations.)
Glacial-Interglacial Periods
For over 2.7 million years the Earth has been switching from glacial (ice age) to interglacial conditions. Ice ages are about 5-6°C colder than
interglacials. And the transitions can be quite sudden.
Changes in atmospheric CO2 concentrations play an important role in these glacial-interglacial cycles. (We are currently living in an interglacial.)
The last 10,000 years of earth’s history is a relatively warm, stable interglacial period.
heat waves (definition, changes due to climate change, consequences)
a period of several days to weeks of abnormally hot weather
climate change = more frequent and severe heat waves.
consequences: Extreme heat events are responsible for more deaths annually than hurricanes, lightning, tornadoes, floods, and earthquakes combined, increase air pollution in urban areas
IPCC wording “It is virtually certain that hot extremes (including heatwaves) have become more frequent and more intense across most land regions since the 1950s”
extreme precipitation events (changes due to climate change)
IPCC Wording “The frequency and intensity of heavy precipitation events have increased since the 1950s over most land area for which observational data are sufficient for trend analysis (high confidence), and human-induced climate change is likely the main
driver.”
floods (how climate change affects them and the consequences)
Extreme Precipitation can lead to more flooding events
Consequences: Damage to crops; soil erosion, inability to cultivate land, waterlogging of soils, Adverse effects on quality of surface and groundwater; contamination of water supply, Deaths, injuries, infectious diseases from floods and landslides, Disruption of settlements, commerce, transport and societies due to flooding; pressures on urban and rural infrastructures
droughts (changes due to climate change)
Dry areas are getting drier
IPCC Wording “Human-induced climate change has contributed to increases in agricultural and ecological droughts in some regions due to increased land evapotranspiration.”
tropical storms
Have become more intense and longer
IPCC Wording “It is likelythat the global proportion of major (Category 3–5) tropical cyclone occurrence has increased over the last four decades, and it is very likely that the latitude where tropical cyclones in the western North Pacific reach their peak intensity has shifted northward; these changes cannot be explained by internal variability alone (medium confidence).”
wildfires (causes/shifts due to climate change)
The frequency of large wildfires is influenced by a combination of natural and human factors including:
•temperature, soil moisture, relative humidity, wind speed, and vegetation (fuel density)
•Forest management, human-caused ignition
extreme weather & climate event cause
human-caused climate change is increasing the frequency and intensity of extreme weather and climate events.
IPCC “Evidence of observed changes in extremes such as heatwaves, heavy precipitation, droughts, and tropical cyclones, and, in particular, their attribution to human influence, has strengthened since AR5”
cryosphere
the part of the earth’s surface characterized by the presence of frozen water
mountain glaciers and continental ice sheets, seasonal snow and ice cover on land, and sea ice.
Ice Sheets
Land Ice; a mass of glacial land ice extending more than 50,000 square kilometers
Sea Ice (def.)
Sea ice is frozen ocean water. It forms, grows, and melts in the ocean. For most of the year, sea ice is typically covered with snow.
Ice and Snow are melting (causes)
Humans for nearly all of it, it is less confident only in the case of Antarctic sea ice.
IPCC Wording:
“Human influence is very likely the main driver of the global retreat of glaciers since the 1990s and the decrease in Arctic sea ice area between 1979–1988 and 2010–2019 (decreases of about 40% in September and about 10% in March).”
“Human influence very likely contributed to the
decrease in Northern Hemisphere spring snow cover since 1950. It is very likely that human influence has contributed to the observed surface melting of the Greenland Ice Sheet over the past two decades…”
“There has been no significant trend in Antarctic sea ice area from 1979 to 2020 due to regionally opposing trends and large internal variability. And… there is only limited evidence, with medium agreement, of human influence on the Antarctic Ice Sheet mass loss.”
Feedback Mechanisms (positive vs. negative)
Positive Feedback = A change in the environment that leads to additional or an amplified change in the system.
Negative Feedback = A change in the environment leads to a compensating process that reduces or dampens the initial change
Albedo
the fraction of solar energy (shortwave radiation) reflected from the Earth back into space. It is a measure of the reflectivity of the earth’s surface.
Permafrost
perennially frozen ground that remains at or below zero degrees Celsius for two or more years and forms in regions where the mean annual temperature is colder than zero degrees Celsius.
Consequences of permafrost melting
Previously frozen organic matter begins to decay, causing the release of CO2 and methane into the atmosphere
What is causing sea level rise?
Thermal Expansion & melting ice
IPCC Wording: “Thermal expansion explained 50% of sea level rise during 1971–2018, while ice loss from glaciers contributed 22%”
Consequences of Sea Level Rise
increase the frequency and extent of extreme flooding associated with coastal storms, such as hurricanes
Increase the severity of storm surges in coastal areas
flooding in coastal communities
ecosystem
an interdependent, functioning system of plants, animals and microorganisms
climate is integral to ecosystems because organisms have adapted to their regional climate over time
Impacts of climate change on species and populations
Many animals are adapting as best they can to climate change through moving, changing diets, or shifting nesting, breeding, and migratory schedules but Local and global extinctions may occur when climate change outpaces the capacity of species to adapt
Ecosystem Services
the many and varied benefits to humans are provided by the natural environment and from functioning ecosystems; The resources and services that people depend on for their livelihoods, sustenance, protection, and well-being.
Impacts of climate change on ecosystems services
Ecosystems services are jeopardized by several factors including:
land use changes and the impacts of climate change on ecosystems. Fundamental changes from climate change include decreases in agricultural and fisheries production, the supply of clean water, protection from extreme events, and culturally valuable resources
Impacts of Climate Change on agriculture
Widely varies depending on where, and what type of crops
Abrupt Climate Change
a transition of the climate system into a different mode on a time scale that is faster than the responsible forcing
It takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it.
The greenhouse effect
greenhouse gases absorb much of the energy radiated by the Earth and re-radiate it back in all directions – including back towards the Earth.
Long-Lived Greenhouse Gases
Carbon Dioxide (CO2)
Methane (CH4)
Nitrous Oxide (N2O)
Halocarbons: including chlorofluorocarbons (CFCs) and their replacements (HFCs, PFCs, SF6), referred to as fluorinated gases
Short-Lived Greenhouse Gasses
Tropospheric Ozone (O3) Water Vapor (H2O)
Carbon Dioxide
Main driver of climate change.
Emitted primarily through the burning of fossil fuels (oil, natural gas, and coal), solid waste, and trees and wood products.
Changes in land use also play a role. Deforestation and soil degradation add carbon dioxide to the atmosphere, while forest regrowth takes it out of the atmosphere.
Methane
Emitted during the production and transport of oil and natural gas as well as coal.
Methane emissions also result from livestock (digestion) and agricultural practices and from the anaerobic decay of organic waste in municipal solid waste landfills
Nitrous Oxide N2O
Emitted during agricultural and industrial activities
Emitted during combustion of fossil fuels and solid waste.
Halocarbons
CFCs:
Exclusively human-made compounds for use as coolants, foaming agents, fire extinguishers, solvents, pesticides and aerosol propellants.
Deplete stratospheric ozone.
Concentrations are currently decreasing because of regulations
HFCs: made to replace CFCs
PFCs: industrial uses
Sulfur Hexafluoride: Industrial Uses
Tropospheric Ozone
Created by chemical reactions from automobile, power plant and other industrial and commercial source emissions in the presence of sunlight
when in the troposphere it contributes to global warming as a greenhouse gas
Blackbody Radiation
All matter in the universe that has a temperature above absolute zero radiates energy across a range of wavelengths in the electromagnetic spectrum.
Wien’s Law
The hotter something is, the shorter its peak wavelength of radiated energy is
The Earth’s Energy Budget
The Earth-atmosphere system is constantly trying to maintain a balance between the energy that reaches Earth from the sun and the energy that flows from Earth back out to space
If the Earth system is changed through some climate forcing an imbalance in the Earth’s energy budget occurs, the Earth’s temperature will eventually increase or decrease in order to restore an energy balance.
Radiative Forcing
W/m2 is energy fluxes caused by changes in the earth’s energy budget
Positive radiation forcing leads to surface warming, negative radiative forcing leads to surface cooling
IPCC Wording: “Human-caused radiative forcing of 2.72 [1.96 to 3.48] W m–2 in 2019 relative to 1750 has warmed the climate system. This warming is mainly due to increased GHG concentrations, partly reduced by cooling due to increased aerosol concentrations.”
Reference Temperature
The average temperature over a period of multi-decidal (20-30-40 years) period
Non-greenhouse gasses in the atmosphere
The majority of the atmospheric make-up; doesn’t absorb infrared photons from the sun:
N2, O2, Ar2
Wording for Questions on the exam (Forcings vs. Evidence/indicators vs. impacts/symptoms)
Forcings: changes to greenhouse gasses, albedo, solar radiation - forces the earth to shift temperatures due to a change in the energy budget
Evidence/indicators: sea ice melting, ocean warming - evidence that the radiative forcing is occurring
Impacts/symptomps: extreme weather events, floods, wildfires, etc. the symptoms of climate change and their impacts on us
Why are scientists confident that the earth is warming due to humans
scientists are confident that the earth is warming due to comparing modern-day warming to the paleoclimate record which shows that the speed and extremity of modern-day warming is much more than what has been previously been recorded
