What factors contribute to rising sea levels?
- The expansion of water as it is heated (thermal expansion responsible for 50% of the rising sea levels)
- The melting of glaciers
- The melting of the floating Arctic ice sheet has little effect on sea levels. (same as ice melting in your drink) What we’re concerned about is the continental glaciers.
What are the consequences of rising sea levels?
- Erosion of shorelines and barrier islands, climate refugees
- Higher water levels and increasing salinity in estuaries and coastal wetlands change the plant community
What is used by scientists to forecast climate change?
- General circulation models simulate the physical processes that determine Earth’s energy budget:
- Absorption and reflection of heat by the atmosphere
- The heating of land and ocean
- IR radiation given off by land and ocean
- Circulation of heat from the equator to the poles
- Ocean circulation
- Backcasting: comparing prediction about the past using data with actual data. GCM forecasts lose accuracy as the land under consideration gets smaller.
- Two assumptions are generally agree upon:
- Rainfall will increase in areas with high altitudes such as Eurasia and Canada
- Rainfall will decrease in subtropical and temperate areas that are already arid.
What is mitigation?
- Actions that directly decrease an environmental threat such as CO2 emissions.
- Increased energy efficiency and conservation (in buildings, heating, public transportation)
- Increased use of renewable resources (wind, solar, biofuels have net 0 carbon emissions since corn wood etc. pull CO2 from the atmosphere. However, there’s significant concern about the implications of biofuels on the global food supply)
- Nuclear energy
- Biostorage (actions that increase the storage and absorption of CO2) like planting trees or promoting agricultural practices like efficient fertilizer use that encourage carbon storage.
- Carbon capture storage technologies
- Climate engineering (perhaps)
What are examples of adaptation techniques to climate change?
- Adaptation techniques are important as not all nations will be affected equally. Additionally, the capacity to adapt to climate change is also not distributed equally.
- Switching to drought resistant crops in southwestern US, the Mediterranean, the Middle East or Sub-Saharan Africa.
- Water pricing, drip irrigation (efficient irrigation), turning salt water to fresh water
- Pumping systems, water walls, canals, water resistant construction in areas that are prone to water level rise and subsequent flooding, storms
- Wildfire management systems
- Effective systems to protect vulnerable populations from heat rise
- Restoration of natural ecosystems such as coral reefs, coastal wetlands, seagrass forests as natural buffers of waves has been considered as opposed to water walls as an adaptation technique.
- Legislation: carbon-cap and trade, carbon taxes
What was the Earth’s average temperature during the last ice age? What are the projections for 2100?
- 10 degrees.
- The current average is 15 degrees.
- A change of 5 degrees gave us an ice age.
- Predicted temperature increase until 2100 ranges between 1-4 degrees.
- Different scenarios (business as usual, sustainable world, today’s world) show different degrees of temperature increase.
- However, all scenarios include higher warming at higher latitudes and more warming over land than ocean.
What implications does global warming have for water?
- Increased rainfall in most tropics and higher latitudes.
- Decreasing rainfall and increasing drought in middle latitudes and semi-arid low latitudes.
- Resulting in changing climate and shifting biomes.
- Leading to water stress for millions of people.
What implications does global warming have for coasts?
- Increased damage from storms and floods.
- Sea level rise.
What are the implications of global warming for ecosystems?
- Large-scale extinctions
- Coral bleaching and loss of species dependant on coral reefs.
- Increases species range shifts and phenology changes.
- Increased wildfire risk. (due to changes in precipitation/moisture, higher temperatures)
- Carbon source/sink dynamics change. (hard to predict because they’re not in isolation)
Explain coral bleaching
- Algae and corals have a mutualistic relationship through which corals give algae protection and nutrients. In exchange, algae give corals oxygen and energy compounds & help remove wastes.
- Warm temperatures change the mutualistic relationship between coral and algae to one where corals don’t benefit.
- The corals expel the algae and become white.
- This has both community and ecosystem consequences.
What percentage of CO2 emitted remains in the atmosphere? How much diffuses into the ocean, why?
- About a quarter of this diffuses into the ocean (higher to lower concentration).
- This means that as the concentration of CO2 in the atmosphere increases, more of it diffuses into the ocean.
- The CO2 in the ocean turns into carbonic acid, leading to a pH drop.
- Lower ph makes it harder to form CaCO3 shells for mollusks and corals.
Explain carbon cycle feedbacks
- Aspects of climate change can influence the rate of future climate change.
- Positive Feedback: Change in one factor drives change in the system that amplifies the initial change. (albedo)
- Negative Feedback: Change in one factor that drives changes in the system that diminishes the initial change.
Give an example of a positive feedback cycle involving tundra.
- Temperature goes up
- Tundra warms up
- Organic matter is revealed from permafrost and is consumed by decomposers.
- More CO2 enters the atmosphere
- This is a short term change, in the long run, the growth of vegetation may propose a negative feedback cycle.
- As a result of this, global tundra has decreased significantly.
What is phenology? Why is it significant with regard to climate change?
- The timing of seasonal activities such as;
- When snowshoe hares change their coat color.
- Emerging from pupa or other dormant stage
- Nesting or reproducing
- Organisms can use different cues to do these activities. Using photoperiod or temperature is common.
- Timing can be really important, especially in places that have distinct seasons.
- Phenological changes can change species interactions (such as pollinator x flower and parasite emergence x birds nesting). These types of mismatchings can lead to population crashes and community / ecosystem effects.
Why are species range shifts significant for climate change?
Different species have different displacement rates. Herbaceous plants and trees are slower at displacement, deeming them especially prone to risk.
What are the implications of global warming on human health?
- General health declines
- More physical hazards in the environment (head, floods, etc.)
- Increased occurrence of some diseases.
- Change in the distribution / abundance of some disease vectors. (zika virus, increased tick caused moose mortality)
Explain mountain pine beetle and climate change
- The beetle can occur at higher latitudes and elevations.
- Trees are often weakened by drought.
- The beetle also has two life cycles per year rather than one.
- Females bore holes in the pine bark, lay eggs and infect the tree with blue-stain fungus.
- Trees die due to phloem disruption and infection.
How will global warming impact global food production?
- Production will increase in some areas and decrease in others.
- On average, production will decrease.
Explain legislation and acid rain / ozone
- Since the 1990 Clean Air Act has been implemented, surface water sulfate concentrations have declined significantly in Europe and North America.
- 1987 Montreal Protocol to phase out CFC has lead to the recovery of the ozone layer (2065)
- Both of these events demonstrate the ability of nations and the world to overcome large scale environmental problems. This could also apply to climate change.
How would you conduct an experiment to see if phenology was changing alongside climate change?
- Bradley et. al tracked these for 20 year periods:
- The arrival of migratory bird species
- The first song of non-migratory bird species
- The first bloom of flowering species
- 18 species changed somewhat, 17 species changed significantly.