Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Ecology and the Environment > Lecture 19 + 20 > Flashcards

Lecture 19 + 20 Flashcards

1
Q

You are researching a biotic process that controls the chemistry of the environment and your colleague is studying how the structure and function of that same ecosystem is controlled by geochemical processes. What field of science are you both working in?

A

Biogeochemistry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

According to the Rockstrom paper, which of Earth’s critical “life-support” systems has been perturbed most beyond Rockstrom’s “safe” level?

A

Biodiversity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Sulfur pollution was primarily responsible for what environmental problem in North America and Europe?

A

Acid rain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Prior to the Industrial Revolution, what was the level of atmospheric carbon dioxide, and what is the current level?
- Below 265 ppm pre Industrial Revolution; 200 ppm in 2014
- Below 200 ppm pre Industrial Revolution; 4,000 ppm in 2014
- Below 265 pre Industrial Revolution; 398 ppm in 2014
- Below 200 ppm pre Industrial Revolution; 30,000 ppm in 2014

A

Below 265 pre Industrial Revolution; 398 ppm in 2014

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many degrees Celsius was the global average temperature in 2011 above the long-term average from the early 20th century?

A

0.7 degrees Celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

True or false: In recent years (1993-2013) the global rate of increase in carbon dioxide concentrations has levelled off.

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What most explains the flux of carbon dioxide into the atmosphere from 1960 to present?

A

Fossil fuel combustion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Svante Arrhenius (1859 – 1927)

A

Published on fossil fuels, CO2, and the greenhouse effect in 1896
- Predicted a doubling of CO2 would warm Earth by 1.6ºC to 6ºC
- IPCC 2013 says 2º to 4.5ºC)
- Predicted it would take 3,000 years for fossil fuel burning to double CO2
- At current trends, it will take less than another 75 years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Are We on the Brink of a Pronounced Global Warming?

A

The exponential rise in atmospheric carbon dioxide will tend to become a significant factor and by early in the next century will have driven the planetary temperature beyond the limits experienced during the last 1,000 years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Half of all fossil fuels ever used have been burned in the

A

Past 25-30 years –massive releases of carbon dioxide

Earth is now warmer than in the past (probably 120,000 years)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The keeling curve

A

Dr. Charles David Keeling (1928-2005)
- developed instruments to measure atmospheric CO2
- established one of longest running continuous CO2 measurement, Mauna Loa (Hawaii)
- prior to these measurements, most scientists assumed that oceans absorb all fossil fuel CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Atmospheric CO2 at Mauna Loa Observatory

A

For climate stability, CO2 should be 350 ppm or less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The annual oscillation in the “Keeling” curve is best explained by
A) a seasonal temperature effect on the instrument measuring CO
B) a seasonal effect on CO2 uptake and release by terrestrial ecosystems, with greater uptake during the northern hemisphere summer
C) a seasonal effect on CO2 uptake and release by oceans, with greater uptake during the northern hemisphere summer
D) greater use of fossil fuels by society during the northern hemisphere winter
E) a seasonal effect on CO2 uptake and release by terrestrial ecosystems, with greater uptake during the southern hemisphere summer

A

B) a seasonal effect on CO2 uptake and release by terrestrial ecosystems, with greater uptake during the northern hemisphere summer
Seasonality of carbon storage much greater in terrestrial ecosystems than in oceans, and much more surface area of land in northern hemisphere
From 2000-2009, net accumulation in atmosphere of ~4.1 Pg C/yr
Compare with release from fossil fuel combustion of 7.7 Pg C/yr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Human Perturbation of the Global Carbon Budget

A

Deforestation results in CO2 flux to the atmosphere, as tree biomass is burned or decomposes, and soil organic carbon is respired (NEP<0)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Based on 2000-2009

A

Net accumulation in atmosphere of 4.1 Pg C/yr
Release from fossil fuels and deforestation = 8.8 Pg C/yr
-> 4.7 Pg C/year were going somewhere else!
1. fossil fuel emissions
2. deforestation
3. atmospheric CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Carbon sinks

A

Net accumulation of carbon in terrestrial or ocean biomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

As of 2015, the major sinks of carbon that were slowing the accumulation of CO2 in the atmosphere are:
A) 80% uptake by forests, and 20% by oceans
B) roughly 50% by forests and 50% by oceans
C) 80% uptake by oceans, and 20% by forests
D) highly variable from year to year, making any generalization difficult
E) too uncertain for anyone to have a good idea!

A

B) roughly 50% by forests and 50% by oceans

Main sources of carbon: combustion = 7.7; deforestation = 1.1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Large exchanges with terrestrial ecosystems/oceans. Net uptake =

A

Terrestrial ecosystems net uptake = 2.4 (NEP)
Oceans net uptake = 2.3
-> based on physics and chemistry, as well as ecosystem metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The ocean sinks are temporary, and the carbon is “stored” as CO2 in the deep ocean, which will eventually be released

A
  1. Dissolving of CO2 into cold water, with sinking of water masses that are rich in CO2
  2. Biological pump (net ecosystem production, with sinking of organic matter)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Total estimated sources do not match total estimated sinks.

A

This imbalance is an active area of research.
Sources: fossil carbon (includes carbonation sink), land-use change
Sinks: ocean sink, land sink, atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The year-to-year variation in CO2 uptake by oceans and land is:
A) well understood by scientists, and due to climatic variation.
B) probably just the result of the quality of the data, and not true variation at all.
C) is not well understood at all, but may be due to climatic variation as it affects the oceans.
D) is not well understood at all, but may be due to climatic variation as it affects terrestrial ecosystems.
E) “C” and “D”

A

E) “C” and “D”
Not well understood at all, but seems real, and probably due to climatic influences on both the oceans and terrestrial ecosystem
Ocean:
-> changes in ocean conveyor belt, due to changes in precipitation, ice melting, and river runoff from year-to-year?
-> also, changes in NPP and NEP in high latitude waters, as wind-driven mixing of surface ocean waters varies?
Terrestrial:
Change in NEP, as NPP and respiration respond to differences in temperature and precipitation? Also, large fires??

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why might terrestrial C sinks exist? And how might C sinks act in the future?

A
  1. Reforestation after agricultural abandonment?
  2. Fertilization response to increasing CO2?
  3. Fertilization response to increased nitrogen deposition onto forests?
    -> Remember: increasing C sink implies increasing NEP, and not just NPP (decomposition might also be increased by nitrogen deposition)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Carbon accumulates in an ecosystem only when

A

GPP exceeds the rate of whole ecosystem respiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Soil decomposition rate increases

A

exponentially with temperature
- and remember how much soil organic carbon in some “cold” biomes
- soil is the largest repository of organic matter on land, storing more carbon than all vegetation and atmosphere combined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Predicted change in precipitation – 2095 relative to late 20th Century

A

ranges from -20% to 20%
- significant decrease (-20% to -10%) in lower latitudes
- significant increase in poles and higher latitudes (10%-20%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

True or false: Ecologists and climate scientists well understand how carbon sinks in terrestrial ecosystems and the oceans will change in the future

A

False
There is little agreement among global models with regard to how much atmospheric carbon dioxide will be taken up and stored by terrestrial ecosystems in the future
- many overheated forests may soon release more carbon than they absorb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Global models diverge greatly in their predictions of the extent of uptake of carbon dioxide by the oceans in the future, although

A

all predict greater uptake than at present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

The great conveyor belt has been slowing
-> which would likely slow the uptake of carbon dioxide by the oceans

A

This slowing is NOT included in any of the global CO2 models

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

COP21 United Nations Paris Accord target (Dec 2015): “well below 2ºC”

A

Clear recognition that warming beyond 1.5 is dangerous
- November 2021, all nations of the world agreed at COP26 in Glasgow, Scotland, that 1.5º C needs to be the goal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

IPCC 2022, final sentence:

A

“The scientific evidence is unequivocal: climate change is a threat to human well- being and the health of the planet. Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future.”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Some good news:

A

NY State Climate Leadership & Community Protection Act (CLCPA) of 2019 mandates rapid reduction in emissions from all economic sectors across the State, including 40% within 7 years
- emissions reductions driven by moving to 100% renewable electricity, and by beneficial electrification of transportation and heating (i.e., electric cars, trucks, and busses; heat pumps)
- these sort of emission reductions are exactly what is required to meet the COP21 & 26 goals, if carried out globally
-> Can NYS set an example?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

The IPCC reports historical levels of carbon dioxide in the Earth’s atmosphere over the last 10,000 years. How are they able to do this?

A

They use bubbles of atmospheric gas trapped in ice samples

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

True or false: Atmospheric CO2 concentrations are increasing at one of the fastest rates in the the last several hundred thousand years due to human activities.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

While some carbon accumulates in the atmosphere the rest is taken up by

A

Oceans and terrestrial systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

True or false: Fossil fuels contribute to global warming through the carbon cycle in part because fossil fuels are extracted from the ground, and then burned. This adds carbon that was in the ground to the atmosphere.

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

As atmospheric carbon dioxide levels have increased, we could predict an increase in CO2 diffusion from the atmosphere into the oceans. However, there is a reduced net rate of carbon dioxide uptake by oceans. Why?
- This is due to supersaturation of the oceans and the inability of any more carbon dioxide to be assimilated.
- This is due to decreased atmospheric temperatures that decrease the solubility of carbon dioxide.
- This is the result of increased atmospheric temperatures that increase the solubility of carbon dioxide.
- The reduced net rate of carbon dioxide uptake is due to increased surface ocean temperatures that lower the solubility of carbon dioxide.

A

The reduced net rate of carbon dioxide uptake is due to increased surface ocean temperatures that lower the solubility of carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

If Earth’s oceans are carbon dioxide sinks, that means that carbon dioxide should remain in oceans infinitely. Is that accurate?
- Yes, the oceans are a sink and no carbon dioxide is ever released. This process explains ocean acidification.
- No, the oceans are not sinks although they do assimilate carbon dioxide.
- No, the carbon dioxide assimilated into the deep ocean in the Atlantic will eventually surface elsewhere and be released back into the atmosphere.
- Yes, the oceans are a sink for carbon dioxide, but only in the Southern Indian and Pacific Oceans. In a few decades the carbon dioxide is assimilated by marine animals and released when they die.

A

No, the carbon dioxide assimilated into the deep ocean in the Atlantic will eventually surface elsewhere and be released back into the atmosphere

37
Q

Feedback: Permafrost melts due to warmer temperatures and the carbon it stores ends up in the atmosphere

A

Positive feedback

38
Q

Feedback: The government spends money to reduce nitrogen pollution in a river, nutrient pollution declines so the government devotes less money to the nitrogen issue

A

Negative feedback

39
Q

Feedback: As people burn more fossil fuels more carbon is stored in the atmosphere

A

Neither

40
Q

Feedback: An endangered species population declines so the value of specimens goes up and poachers harvest more of them

A

Positive feedback

41
Q

Feedback: As a population grows larger the population growth rate declines as it approaches carrying capacity.

A

Negative feedback

42
Q

Feedback: Nitrogen pollution from agriculture results in more nitrogen in waterways, which results in higher nitrogen concentrations in the Gulf of Mexico creating a dead zone.

A

Neither

43
Q

If you used a whole-ecosystem experiment to add carbon dioxide to forests, what effect would you expect these additional amounts of carbon dioxide to have?

A

Increase NEP

44
Q

One outcome of increased atmospheric carbon dioxide is that more carbon dioxide is taken up by the ocean which resulted in?
- Acidification of the ocean and a disruption of organisms with carbonate shells
- An increase in ocean pH that could result in a crash of fish populations
- The collapse of the life surrounding deep sea vents
- An absence of available carbon dioxide for terrestrial systems

A

Acidification of the ocean and a disruption of organisms with carbonate shells

45
Q

Which of the following are natural sources of methane? (You may choose one or more answers)
- oceans
- wetlands and lakes
- ancient geological formations
- bacteria that oxidize organic carbon to carbon dioxide

A
  • oceans
  • wetlands and lakes
  • ancient geological formations
46
Q

Anthropogenic sources of methane include which of the following?
- decomposition of organic matter in landfills
- bacterial methanogenesis
- deforestation
- animal agriculture

A
  • decomposition of organic matter in landfills
  • bacterial methanogenesis
  • animal agriculture
47
Q

Coastal marshes contribute little to no methane to the atmosphere due to high levels of ________.

A

Sulfate

48
Q

The use of high-volume hydraulic fracturing techniques to release natural gas from shale is of major concern because ____________.
- Scientists have identified that natural gas from shale may have mercury in it
- Shale natural gas is composed largely of the greenhouse gas methane
- Shale natural gas is composed of chlorofluorocarbons that pollute the environment
- Scientists know that shale natural gas is bad for the environment but not as bad as coal

A

Shale natural gas is composed largely of the greenhouse gas methane

49
Q

Warming since 1800s from methane equal to

A

67% of that from carbon dioxide

50
Q

COP21 Paris Accord target: “well below 2ºC”

A

Clear recognition that warming beyond 1.5ºC is dangerous (because of tipping points, as we discussed on Feb 7)
- methane reductions are critical

51
Q

Where does atmospheric methane come from?

A

Multiple sources, both natural and human-caused
- Total flux estimate well constrained, since rate of destruction by photo-oxidation in atmosphere is well known

52
Q

Two major sources of methane

A
  1. Methane formed in rock formations over geological time frame
  2. Methane formed by decomposition of organic matter by bacteria in absence of oxygen
53
Q

Methane in the atmosphere for most of the last 10,000 years vs. change since industrial revolution lets us estimate the natural fluxes vs. human-caused fluxes

A

Natural = 220 Tg of C per year
Human-caused = 350 Tg of C per year (as of end of 20th century)

54
Q

Minimal geological methane emissions during the Younger Dryas-Preboreal abrupt warming event

A

Measured C14 in methane in ice laid down in Antarctica 11,500 years ago (1 ton of ice per sample)
Before industrial revolution, almost all methane came from biological sources, not geological seeps

55
Q

Geological seeps of methane are ____ than previously thought

A

Lower
53 Tg/yr -> 0
14C content of methane in atmosphere in late 20th
Century indicates 30% was from fossil/geological sources (168 Tg/yr)

56
Q

Biological sources of methane are ____ than previously thought

A

Higher
167 Tg/yr -> 220
Century indicates 30% was from fossil/geological sources (168 Tg/yr)

Mostly from decomposition of organic matter in oxygen-free sediments of wetlands and aquatic ecosystems

57
Q

Century indicates 30% was from fossil/geological sources (168 Tg/yr)

A

115 Tg/yr -> 168

58
Q

Animal agriculture methane sources are ____ than previously thought

A

Lower
90 Tg/yr -> 67

59
Q

Rice methane sources are ____ than previously thought

A

Lower
60 Tg/yr -> 44

60
Q

Landfills and sewage methane sources are ____ than previously thought

A

Lower
55 Tg/yr -> 41

61
Q

Fossil fuels methane sources are ____ than previously thought

A

Higher
115 Tg/yr -> 168

62
Q

This 220 Tg/yr is coming from oxygen-free sediments

How much from oceans and coastal wetlands (salt marshes, mangroves), and how much from lakes and freshwater wetlands?

Total natural methane flux from ocean and freshwater systems is 220 Tg per year

The flux from oceans make up what percent of this total?

A

Less than 5%
10 Tg per year from oceans, 210 Tg per year from freshwaters

63
Q

Decreasing energy for bacteria

250 times more sulfate (SO4^2-) in seawater than in lakes

A

In lake sediments, sulfate becomes depleted, so methane formation takes over. In ocean sediments, some sulfate almost always remains.

So methane formation is very small in oceans

64
Q

As salinity increases in coastal wetlands

A

Sulfate levels increase and prevent significant formation of methane

65
Q

So oceans are not important methane source globally

A

but may become so due to melting of methane clathrates

66
Q

Rapid rise in atmospheric methane globally since

A

2008

67
Q

Hansen et al. (2007) suggested critical threshold in climate system, to avoid melting of

A

natural methane clathrates at ~1.8ºC

68
Q

How much of the global increase in methane since 2008 is driven by melting of methane clathrates?

A

Very little

Sonar image of methane bubbles rising from the seafloor off the Washington coast from sediments 515 m underwater. Note that plume disappears by 180 m, as methane dissolves into the water, where it is then consumed by bacteria.

69
Q

Animal agriculture, rice, and landfills & sewage methane produced from

A

decomposition of organic matter in oxygen-free environments (cow guts, manure piles, flooded rice paddies), etc.

70
Q

Rapid rise in atmospheric methane globally since 2008 is not from

A

tundra or clathrates

71
Q

Is rapid increase in global methane emissions since 2008 due largely to
1) biogenic sources (cows, maybe rice)?
2) fossil fuels?

A

Fossil fuels

72
Q

Shale gas development in the US

A

Almost all shale gas produced globally has been in the US
- shale gas is below sandstone and tight sand gas

73
Q

Is natural gas a “bridge fuel”?

A

For just the release of carbon dioxide during combustion
- natural gas 15, diesel oil 20, coal 25 MJ
- natural gas (including shale gas) is mostly methane
- small leaks and emissions matter

74
Q

Methane

A

Colourless, odourless gas
- invisible to the naked eye, but strong absorber of infrared radiation

75
Q

One of our major conclusions in Howarth et al. (2011):

A

Pertinent data for shale gas were extremely limited, and poorly documented.

Great need for better data on shale gas, conducted by researchers free of industry control and influence.

76
Q

More than a decade after our first 2011 analysis, now over 1,800 peer-reviewed scientific papers on methane from natural gas as a driver of climate change

A

Best estimates come from “top-down” estimates, which integrate emissions from data from satellites, towers, airplane flyovers, etc.
- shale gas is not a bridge fuel

77
Q

High visibility paper published in March 2016 in Science: Increase in atmospheric methane since 2006 is most likely biogenic in large part, probably from cows

A

Based largely on stable carbon isotopic composition (13C vs. 12C) in atmospheric methane

78
Q

13C content of methane sources and fluxes

A

direction of change to biogenic sources (cows, wetlands) from fossil fuels

79
Q

Turner et al. (2016): “The large increase in U.S. methane emissions could account for 30–60% of the global growth of atmospheric methane seen in the past decade.”

A

Fewer cows and cattle in US in recent decades, so unlikely to be cause of increased methane

80
Q

As methane migrates through sandstone over geological time, some of the methane is oxidized, leading to fractionation

A

The methane in conventional natural gas is enriched in 13C relative to the source methane in shale gas

81
Q

Increase in emissions of 18 Tg/yr from fossil fuels (with half of this from US shale gas) and 10 Tg/yr from biological sources such as cows

(after correcting for biomass burning from Worden et al. 2017) and for 13C signal of shale gas)

A

Increase in emissions of 22 Tg/yr from biological sources such as cows and 4 Tg/yr from fossil fuels.

82
Q

Global methane sources (Tg per year)

A

Total: 570 -> 595
Total anthropogenic: 350 -> 375

83
Q

IPCC 2022, final sentence:

“The scientific evidence is unequivocal: climate change is a threat to human well- being and the health of the planet. Any further delay in concerted global action will miss a brief and rapidly closing window to secure a liveable future.”

A

It’s critical to reduce methane emissions rapidly and quickly. The good news is that fossil fuels are the major source. Moving to a fossil-fuel-free future hugely helps reduce both methane and CO2

84
Q

Some good news: NY State Climate Leadership & Community Protection Act (CLCPA) of 2019 mandates rapid reduction in emissions from all economic sectors across the State, including 40% within 7 years.

A

Emission reductions driven by moving to 100% renewable electricity, and by beneficial electrification of transportation and heating (ie, electric cars, trucks, & buses; heat pumps)

85
Q

Which of the following statements regarding methane as a greenhouse gas are correct? (You may choose one or more answers.)
- Methane absorbs infrared radiation at a different wavelength than carbon dioxide
- The wavelength at which methane absorbs radiation makes it a potent greenhouse gas
- The concentration of methane in the atmosphere is greater than carbon dioxide, which is why global temperatures have risen so drastically over the last 100 years
- Methane acts as a catalyst to produce ground-level ozone

A
  • Methane absorbs infrared radiation at a different wavelength than carbon dioxide
  • The wavelength at which methane absorbs radiation makes it a potent greenhouse gas
  • Methane acts as a catalyst to produce ground-level ozone
86
Q

How has human activity since the 19th century affected atmospheric concentrations of methane? (You may select one or more answers.)
- Since 1800, the atmospheric concentration of methane has more than doubled
- Since 1800, the atmospheric concentration of methane has increased by less than 200%
- Has increased at a rate even faster than carbon dioxide
- The increase has been associated with biomass burning and the creation of landfills

A
  • Since 1800, the atmospheric concentration of methane has more than doubled
  • Has increased at a rate even faster than carbon dioxide
  • The increase has been associated with biomass burning and the creation of landfills
87
Q

Why does the flux of methane to the atmosphere from coastal marshes drop (relative to freshwater) to near zero? (You may choose 1 or more answers.)
- Because salinity and sulfate increase which prevent methane formation
- Because methanogenesis dominates
- Because decrease in salinity is due to the increased concentration of sulfates in sea water
- Because sulfate reduction is the dominant decomposition process in coastal marshes

A
  • Because salinity and sulfate increase which prevent methane formation
  • Because sulfate reduction is the dominant decomposition process in coastal marshes
88
Q

The Global methane flux is a result of both natural processes and anthropogenic activities. Which of the following is true regarding the global atmospheric methane flux over the past decade.
- Animal agriculture has been on the rise and so it has been the largest contributor to the increased flux
- Biomass burning contributes more to the methane flux per year than animal agriculture
- Anthropogenic activities contribute less to the yearly methane flux than natural sources
- Geological seeps contribute large amounts of methane
- Methane fluxes associated with oil and natural gas production exceed the production from natural sources
- All of the above
- None of the above

A

None of the above

89
Q

Methane produced in the late 20th and early 21st centuries is distinguishable from ancient sources of methane by using _________.

A

An Isotope that is associated with radiation that has a half life of more than 5,000 years

Ecology and the Environment (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions