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