Climate Change exam 2
How large is sea level projected to rise by 2100?
0.5-1.2 m
According to IPCC, what is the range of climate sensitivity?
1.5-4.5C
Sea level during LGM
120 m lower
Under RCP8.5, how much warming does IPCC project by 2100?
2.5-4.6 C
Under 2oC and 4 oC warming, what percentage of plant and animal species will be at risk of extinction, respectively?
20-30% of plants and animals under 2 C. 40-70% at risk w a temp rise of 4 C.
best estimate of climate sensitivity
3 Degrees C
List ecosystem boundaries delineated by climate.
3 ex. Desert ecosystems in the subtropics, tropical rain forest ecosystems near the equator and tundra ecosystems near the poles
Under RCP2.6, how much warming does IPCC project by 2100?
3.8-6.8 C
To stabilize CO2 level at 450, 550, 750 ppm, by which year we need to reach emission peak?
450 (2020); 550 (2040); 750 (2080)
How much will sea level rise with an eventual melting of Greenland / West Antarctic ice sheet?
5.7 m; 5 m
positive biological pump
A slowing of ocean circulation reduces the mixing of nutrients. Slows biological productivity. Weakens biological pump; reduces ocean's ability to absorb co2.
positive land biosphere loop
A warmer land → increased growth and respiration (CO2 byproduct) of soil microorganisms → carbon in soils is now being converted to co2 at increasing rates
positive ocean loop
A warmer ocean has less ability to absorb atmospheric co2.
What are required to achieve lower stabilization targets?
ALL Require sharp reduction in co2 emissions following the peak, LOW stabilization levels require co2 emission rates to fall below the current rate within a few decades
what is meant by climate change "uncertainty"
Agreed range of climate sensitivity. IPCC uses likelihood to talk about it
Besides coral (3.p21), what other animal species will be at particular risk of extinction under continued climate change?
Amphibians bc they live in cloud forest ecosystems. As climate warms, trade winds rising up the slope condense at higher elevations causing it to get drier and nights to get warmer. Warmer nights may favor growth of the chytrid fungus - a potentially fatal pathogen that grows on the skin of amphibians. Polar bears bc they depend on expansive sea ice cover to reach and feed on seals. Forces them to stay on tundra and fast/survive on fast reserves which puts stress on females who must nurse her dens
What is an ecosystem?
An interdependent community of plants, animals, and microscopic organisms and their complex physical environment
What are the main reservoirs of carbon and processes of carbon transfer in the carbon cycle?
Atmosphere, ocean, vegetation, soils, and detritus on land. Processes include photosynthesis, respiration, ocean-atmosphere gas exchange, and ocean mixing
Is photosynthesis important? Respiration?
Both impt, blue box and red box. P means carbon transferred atmosphere to land biosphere. R means land to atmosphere
How were atmospheric concentrations of greenhouse gases (GHGs) different during LGM?
CO2 content is 50% of what it is today (180 ppm). Methane was about ⅕ and Nitrous Oxide was about ⅔ of what it is today.
positive biological pump
CaCo3 is relatively dense and acts as a ballast once an organism dies, carrying its tissue to deep ocean. This "pump" of carbon removes co2 from surface waters, allowing more co2 to be absorbed. Loss of the ballast reduces the ocean's ability to take up atmospheric co2.
How are Representative Concentration Pathways (RCPs) defined?
Defined 4 based on their total radiative forcing by 2100
What is a hysteresis loop?
Describe a linear phenomenon w two stable states
What causes the delay in warming in response to a doubling of CO2?
Equilibrium climate sensitivity (ECS); takes into account that the full amount of warming in response to an increase in GHGs may not be realized for many decades bc of delayed ocean warming.
What is meant by a "conservation/mitigation" scenario?
Future reduction of fossil fuel use
How will water demand change?
Globally, water demand is likely to escalate significantly, primarily due to population growth; many region's fresh water resources may be becoming more scarce due to climate change
negative rock weathering
Increased temps and rainfall stimulate the chemical weathering of rocks → increased removal of atmospheric co2.
How is precipitation projected to change? Why?
Increased winter precipitation in polar and subpolar regions; decreased summer precipitation in many mid-latitude regions due to projected poleward shift of jet streams Poleward expansion of hadley cell will cause decreased precipitation in subtropics Warmer atmosphere will increase precipitation near equator
What is meant by a "business-as-usual" scenario?
Increasing fossil fuel use
Can they protect coral from global warming?
MPAs cannot protect coral from global warming.
What are MPAs
MPAs restrict human activity for a conservation purpose, typically to protect natural or cultural resources.
How is this related to migration rates?
May lead to extinction if they cannot adapt or migrate fast enough
What does this imply for future climate change?
Means positive dominates and warming is reducing nature's ability to absorb co2.
How are sunspots related to solar intensity?
More = brighter sun, fewer = dimmer
How are floods and droughts projected to change? Why?
More droughts due to decreased summer precipitation and increased evaporation due to warming surface temps More flooding due to more evaporation, more precipitation and more rigorous water cycle
Is it truly indicative of a pause in global warming?
No by other measures (such as increasing heat content of oceans and accelerating Arctic sea ice loss) climate change and global warming are proceeding on, or ahead of, schedule
Is the surface warming spatially uniform?
No, greatest warming in the polar areas of the NH and larger warming over land (relative to oceans)
Which continent will see the most warming?
North America
negative ocean loop
Ocean acidification reduces the production of calcium carbonate (CaCo3; limestone) by organisms (corals, plankton). Since this process releases co2 into the ocean, less calcification will increase ocean's ability to absorb atmospheric co2.
Where do estimates of climate sensitivity come from?
Paleo observations over the past 160 years, climate proxy data, and natural factors
Tipping points?
Past a threshold... indicates ice melting is irreversible.
negative land biosphere loop
Plants increase their growth in response to elevated co2 ("CO2 Fertilization")
Can it be simulated by most model simulations?
Temporary surface cooling not taken into account in most model simulations
How does climate change affect ecosystems?
They have shifted in response, however human activity is making climate change rapidly, pushing ecosystem resilience which may lead to extinction
Why are future projections of climate change uncertain?
Unknown trajectory of future GHG emissions and uncertain response of the climate to these emissions
Ice sheets during LGM
Vast ice sheets covered much of Canada, northernmost US, Scandinavia, and Europe, about half of cooling is due to the increase in reflectivity.
How was the Last Glacial Maximum (LGM) different than today?
Very different, colder and a lot more ice. Sea level was lower (120 m;395ft)
How are they related to "abrupt climate change"?
We don't know when it's coming and once it reaches a tipping point, it may rapidly disintegrate
How has CO2 varied over geologic time scales?
Were high 500 MYA, then fell to 300 MYA at the height of the Permo-Carboniferous glaciations on Gondwana. Levels rose and fell reaching 175 MYA in the late Triassic.They stayed high through the next 100 MYA (dinosaur age) and have fallen reaching another minimum close to present day.
Are they effective at reducing fish and coral loss?
YES; MPAs being established around world; have proven effective at staving off coral and fish losses, and are of great economic benefit; restrict human activity for a conservation purpose, typically to protect natural or cultural resources
Has CO2 varied a lot, or a little?
a lot
How long will it alternate between El Nino and La Nina?
alternates every few years between El Nino and La Nina
climate sensitivity
amount of warming we expect to occur when there is a change in the factors that control climate. expressed in terms of how much surface warming will occur in response to a doubling of Co2 from preindustrial levels
Why is the LGM cooler than today?
atmospheric concentrations were dif, ice sheets were vast, and the orbit was different
What caused faux pause?
background volcanic activity; short-term reduction in solar output; series of La Nina events; all of which have led to temporary surface cooling
RCP 8.5
business as usual
Can MPAs project corals from ocean acidification?
can't coral protect from acidification effects of CO2; if fossil fuel burning continues to increase, corals will be unable to grow skeletons by the end of this century
How will climate change affect water pollution
combo of warmer water, more intense rainfall events, and longer periods of low river levels and stream flows will also exacerbate water pollution; combined w/ other aggravating factors (population growth and increased urbanization); these impacts put intense pressure on fresh water supplies
According to the IPCC, what is the most vulnerable ecosystem? Why?
coral reefs bc they have little scope for adaptation
Why are coral reefs and wetlands important?
coral reefs provide food for hundreds of millions of ppl, a defense barrier against tropical cyclones and tsunamis, ans rouce of tourism income (11.5B). Wetlands reduce flooding downstream from storm waters, sediment contamination (iron, acidity, nitrogen are removed as water percolates through wetland before entering our drinking and irrigation water), and are biologically diverse. Also used to bird watch, hike, canoe, and fish.
How will decreased water flow affect energy resources?
decreased water flow threatens energy resources; steady running water required for hydroelectric plants and cooling towers used in nuclear energy production
Earth's orbital configuration during LGM
earth's orbit was also dif. Summer sunlight at high northern latitudes was reduced and winter snow could survive summer so additional ice accumulated
What is the "faux pause"?
false notion there has been a "pause" in global warming
Severe frosts?
fewer frost days; as temps warm, probability of frosts (nights with temps below freezing) will decrease; greatest decrease in interior North America and Asia, where winters are traditionally coldest,
What are the climate impacts of Arctic sea ice? (polar bear, new northern coastlines for North American and Eurasian nations, new sea routes for international trade)
future of polar bears depends on expansive sea-ice cover to reach and feed on seals; earlier spring breakup and retreat of sea-ice now forces polar bears to remain on tundra, where they must fast and survive on fat reserves; puts stress on females (spend the winter in nursing dens and need easy access to seals in the spring to rebuild their fat reserves); an open Arctic Ocean (forecast to be the norm in "middle of the road" scenarios) would have clear international implications; North American and Eurasian nations will suddenly have new northern coastlines to defend; as Arctic ice retreats, the once fabled "Northwest Passage" opens up; new sea routes connecting the north Pacific and north Atlantic Oceans
How well did past IPCC projections do?
good job. Actual co2 increases since 1990 have tracked roughly in the center of the projected range. Sea level rise projections have fallen in each successive IPCC assessment. Projections are consistent with the observed acceleration (as more land ice melts). Substantial melting of ice sheets began earlier than expected (revised in AR5)
What are the warming patterns and reasons?
greatest warming over polar latitudes in Northern Hemisphere (NH) due to positive feedbacks of melting ice; greater warming over land than ocean due to fact water tends to warm/cool more slowly; greater NH warming (more land); weak North Atlantic warming due to change in ocean currents (weakening of Thermohaline Circulation)
Heat waves? (2B.p34)
increased and intense heat waves; heat waves are very hot temps sustained over a number of days; greatest increase is predicted to occur in the western US, North Africa, and Middle East, where feedback loops associated with decreased soil moisture may intensify summer warmth
What will be human loss in the coastal regions that are even not inundated by higher sea level?
increased exposure to flood and storm damage, more intense coastal surges, altered patterns of coastal erosion, loss of human life, damage to human infrastructure/real estate, degraded water quality, Decreased availability of fresh water, loss of coastal habitats, significant population displacement
Intense rainfall events and flooding?
increases in the frequency of intense precipitation events and flooding expected due to more vigorous water cycle associated with global warming, with more moisture in a warmer atmosphere
What is El Nino Southern Oscillation (ENSO)?
is a natural irregular oscillation of the climate system, involving inter-related changes in SSTs, currents, and winds across the tropical Pacific
What are the causes of sea level rise?
land ice melting, water expansion
How is extreme weather projected to change?
likely that the frequency and intensity of extreme weather events will change, stronger
Dry spells?
longer dry spells will separate intense rain/snow events
How does sea level rise affect land and Gross Domestic Product (GDP)?
losses rise dramatically at 5 and 10 m which would be ensured by the melting of greenland and the west antarctic ice sheet.
RCP 2.5
mitigation
What are positive feedbacks associated with the carbon cycle?
more warming
What are the characteristics of ENSO projections (climate overall? ENSO magnitude?)
most (but not all) models predict a more El Nino like pattern (x-axis); equal chance of increase/decrease in ENSO magnitude (y-axis)
How will climate change affect floods and droughts, fresh water supplies
most significant potential impacts of climate change=diminished/unreliable fresh water supplies; increased drought predicted in many regions; more frequent/intense precipitation events and flooding are predicted for others; such diverse changes results from a complex pattern of shifting rain belts, more vigorous cycling of water in a warmer atmosphere, and increasing evaporation from the surface.
Does all of our CO2 emission stay in the atmosphere?
no only half 55%
Does IPCC overstate the effects of climate change?
no. example is the decreasing trend of arctic sea ice which observations found decline is larger than model projection
Are ENSO projections certain?
no.. precise regional climate change projections are hampered by uncertainties in how some global winds and ocean currents will change, most notably ENSO
Are there more sunspots (a brighter sun) than those (that) in the Little Ice Age
now we have more
If not, where does it go?
oceans and living biomass
If not, then what needs to be done?
only way to prevent this catastrophe is to reduce or eliminate CO2 emissions, or to sequester it before it escapes into the atmosphere
As climate has changed in the geologic past, ecosystems (plants, animals, microscopic organisms, etc.) have shifted in response. How is past climate change different than projected future changes?
past climate change was slower than projected changes
What do fossil-fuel emissions scenarios consider?
population growth, economic growth, technological advances and per-capita energy demand
Which type of feedback dominates?
positive
Why are they valuable?
provide us with provisions (food, fiber, medicinal and cosmetic products), environmental regulation (water and air purification, carbon sequestration, protection from natural disasters, disease, and pests), and cultural benefits (appreciation of and interaction w natural world; recreational activities
Hurricanes?
recent trend toward more intense hurricanes in certain ocean basins (tropical Atlantic); these trends closely mirror warming SSTs; warmer SSTs (all other things being equal) is likely to fuel more intense hurricanes with stronger sustained winds; models indicate a likely shift toward the strongest (Cat 4-5) hurricanes over this century
Negative feedbacks?
reduced warming
How will climate change affect the competition for natural resources?
reliance on fossil fuels threatens security of developed nations by placing them at mercy of volatile regimes; increased competition among nations for diminishing natural resources; history=this leads to unrest and unstable regimes; possibilities for conflict are endless; change in precipitation patterns will create competition for available fresh water (e.g., Middle East)
How does global warming affect air pollution? Why?
smog produced when emissions from incomplete fossil-fuel combustion react to produce pollutants; one pollutant is tropospheric ozone (lung irritant that damages crops, buildings & forests); warming accelerates ozone production & promotes air stagnation=leads to increased tropospheric ozone levels; one model says that for every 1°C increase in global temp, there will be 20K additional pollution related deaths
What are some of the uncertainties associated with IPCC projections of future sea level rise (e.g., crevices/moulins)?
state-of-the art models do not account for some newly observed effects such as crevices (moulins) that could lead to rapid disintegration of sea ice sheets. These are cracks/fissures in ice sheet and as a result, melted water can penetrate deep into the ice sheet, lubricate the base, allowing large pieces of ice to slide quickly into the ocean
What does this imply for ecosystems, biodiversity and individual species?
temp changes and limited water availability can stress individual organisms that find themselves outside their climate "comfort zone"; nearly 60% of widespread and common plant species and 35% of widespread and common animal species will see their habitat range shrink by over 50% by 2080; organisms adapt and ecosystems migrate at rates that may be too slow to prevent ecosystem collapse and the extinction of species; rate of climate change exceeds the natural migration capacities of most plants and animals for the higher-emission scenarios; climate zone migration is faster across flat areas (less mountains)
What is "coral bleaching"?
the loss of algae that live in symbiotic relationship with the coral and give it color - is linked to exceptionally hot ocean temps.
what are the two main sources of uncertainty?
the wide range of climate sensitivity and a short climate record to observe
Under climate change, what are the threats to coastal and low-lying regions (e.g., Bangladesh, Southern Florida, the Netherlands)?
they are at risk of temporary flooding and permanent inundation caused by sea level rise....Rising sea level, increasing tropical cyclone destruction, increasing coastal erosion, and larger wave heights all pose serious threats to coastal and low-lying regions. Southern florida would be submerged if sea levels rose between 4-8 m. Belgium and Netherlands would also be submerged.
Note the warming magnitude in oC relative to 2000 and relative to preindustrial.
warming of 0.2-1.8 C from 2000-2100 or 1.2-2.8 relative to preindustrial times for the most conservative scenario
Biodiversity?
we will lose biodiversity without wetlands and coral reefs
With 6 meters of sea level rise, will most of New York City be submerged?
yes
What are the negative impacts of larger precipitation variability?
•Combination of warmer water, more intense rainfall events, and longer periods of low river levels and stream flows will also exacerbate water pollution. •Combined with other aggravating factors, including population growth and increased urbanization, these impacts put intense pressure on fresh water supplies. •Decreased water flow can also threaten energy resources à steady running water is required for hydroelectric plants and for cooling towers using in nuclear energy production.
