Climate Change Flashcards

Final Exam and Course Grade

The final exam will focus on the 4th section of the course.
The final will not be cumulative, but understanding of fundamentals from prior sections (e.g., sulfur cycling) is expected.
Course grades will be curved.
- Example: If 80% is the highest score, an 80% would receive an "A".

Sea surface warming.
Ocean "acidification".
Salinity changes.
Increases in stratification and shallower mixed layers.
Micro- and major nutrient cycling and availability.
Sea level rise.
Decrease in sea ice.
More intense and more frequent extreme weather events.
- Century storms every 3-10 years.

Movement/migration.
- Phytoplankton blooms in new regions.
- E. huxleyi in the Bering Sea.
- Reduction in the range of N2 fixation due to maximum temperature limits.
Acclimation.
- Refers to an individual's short-term, reversible physiological adjustments to a new environment.
- Difficult to acclimate to multiple stressors (e.g., lowered pH and increased temperature).
Adaptation/evolution.
- Involves long-term, genetically based changes within a population over multiple generations.
- Improves ability to thrive in a particular environment.
- Microbes can evolve rapidly.
- Example: Oil pollutant resistant genotypes appeared in 30 days in a single-celled alga (Carrera-Martinez et al. 2010).
Extinction.

Cell division rates in hours per day for a diatom at 400 and 1000 µatm pCO2 in laboratory growth experiments.
CO2 levels in top grey panels indicate the level of CO2 in the mesocosm where the lineages evolved.
CO2 levels indicated on the bottom x-axis indicate CO2 level under which growth was measured in the laboratory.
Points show cell division rates for individual lineages.
Cells adapted to 1000 µatm divide faster.

Increase in sea surface temperature.
Adverse effects on microbial community.
- Community structure modifications.
- Biogeographic range shifts.
- Adaptive evolution.
Alterations in global biogeochemical cycles.

Many areas predicted to have lower primary production in the future.
A few areas predicted to have a bit more primary production.
Figure shows projected climate-driven changes in annual mean net primary production by the end of the twenty-first century (difference between 2090–2099 and 1860–1869 decadal means).

Global Warming: An overall warming of the planet, based on average temperature over the entire surface.
Climate Change: Changes in global or regional climate characteristics, including temperature, humidity, rainfall, wind, and severe weather events.
Scientific consensus: Global warming is occurring, and anthropogenic increases in CO_2 and other ‘greenhouse gases’ result in increased atmospheric temperatures, decreased oceanic pH, and many related changes.

Gases that trap heat in the atmosphere.
-The direct radiative effect of a mass of methane is ~72 times stronger than the same mass of carbon dioxide over a 20-year time frame but it is present in much smaller concentrations.

Rates of CO_2 addition to the atmosphere are increasing. NOAA, SCRIPPS INSTITUTION OF OCEANOGRAPHY, UC San Diego.

Measurements at the Mauna Loa Observatory stopped after the 2022 eruption of the Mauna Loa volcano.
Observatory staff has established limited solar power and restored approximately 33 percent of the measurements.

Generally from Greenland & Antarctica.
Vostok ice core: close correlation between temperature and pCO_2.
- Reconstructed atmospheric CO_2 and air temperature.

Gas concentrations in the oceans and atmosphere are linked (Dore et al. 2009).
- Net air-to-sea transfer of carbon.
- CO_2 dissolves as inorganic C in surface waters.
- Affects pH.

CO_2 additions to seawater buffered through the following equation:
CO2 + H2O + CO3^{2-} \rightleftharpoons 2HCO3^{-}
- carbon dioxide + water + carbonate ion \rightleftharpoons 2 bicarbonate ions
Consumption of carbonate ions impedes calcification.

The marine carbonate system is the largest carbon pool in the atmosphere, biosphere, and ocean.
Dissolved CO_2 in ocean occurs primarily in three forms.

There will be winners and losers (From Kroeker et al 2013, in UNEP CBD Technical series #75).
Impacts on pelagic communities:
- Calcification -23% (fewer carbonate ions available as pH drops).
- Growth +17% (more CO_2 in the water for photosynthesis!).
Impacts on microbes:
- Non-calcifying phytoplankton may benefit from future OA (e.g., diatoms).
- Calcifying phytoplankton may have a difficult time producing calcified shells and tests.
- E.g., Planktonic foraminifera and pteropods - decreased calcification rates under future OA.
- Mesocosms combining both calcifying and non-calcifying phytoplankton show enhanced primary production under elevated CO_2.
CaCO_3 shells dissolve in acidified water (Pteropods, Bednarsek et al. 2012).
Shell corrosion at projected pCO_2 levels in 2100 (~800ppm) (Kerr 2010).

Ocean acidification results from the ocean absorbing CO_2 from the atmosphere.
In the Southern Ocean, ocean acidification is expected to cause alterations to ecosystem structure and function, carbon export and biogeochemical cycling.

The SLOPE differs among these important groups.
Proportional growth change predicted between historical (1950–1970) and future (2080–2100) temperature regimes under the RCP 8.5 climate scenario (Anderson et al. 2021).
The direct effects of temperature may reshape phytoplankton communities.
Need to consider which groups export a lot of Carbon.
Is important to know which phytoplankton are where and what their physiology is.