Global Climate Bio Exam 1

Climate

Climate scribes long-term average weather patterns over many years, and is determined by the atmosphere and other components of the earth system.

Weather

weather describes short-term variation in the atmospheric conditions that determine temperature, precipitation, wind, humidity, etc.

Five earth spheres 

geosphere (solid earth)e, atmosphere (gaseous layer)), hydrosphere (liquid water), cryosphere (solid water ex. ice sheet), biosphere(living organisms)

Look at graphs of precipitation and temp

Climate change indicators

increase in global mean temperature ~ 1.2 degrees calcius above pre-industrial

decrease extent of arctic sea ice ~ 30% decline since 1979

rising sea levels ~ 4mm/year today

 Climate tipping points: what are they?

critical threshold in some component of the climate system beyond which additional change becomes self-perpetuating.  ex. WAIS and permafrost

West Antarctic Ice Sheet (WAIS)

Once it retreats, the collapse is irreversible. Ice rests on ocean floor. If it melts, the amount of rising sea level would be large.

positive feedback

positive feedback is a process that amplifies the initial temperature response to a forcing.

ex. albedo feedback (climate loop where melting ice or snow makes Earth’s surface darker, so it absorbs more heat, which causes even more melting)

negative feedback

A negative feedback is a process that dampens the initial temperature response to a forcing.

ex. increased outgoing infrared radiation as Earth warms (energy loss helps cool Earth)

Two land masses that contribute to Glacial melt and Sea Level Rise?

Greenland and Antarctica, Antarctica has more ice but is slower to melt, Greenland currently contributes more because its melting is surface melting.

Sea level rise throughout time…

The rate is increasing because of glacier melt and thermal expansion. This acceleration means that future impacts will be more dramatic.

Paleoclimate

The paleoclimate is the study of earth’s climate in the distant past. 

contemporary climate change vs past

Past climate looks at volcanic eruptions, natural greenhouse gases, and humans not being a big contributor (slow). Contemporary Is driven my humans, deforestation, and industrialization (fast)

 What is ECS and why is it not straightforward to estimate?

How much the earth warms from a doubling of CO2 and reaches a new balance. Scientists usually estimate ECS to be around 2.5–4°C of warming, but with uncertainty because of feedbacks such as cloud feedback

Milankovitch cycles

1) eccentricity of earths orbit

2) variation in the tilt of the earths axis

3) variation in the precession of the earths axis.

They change the distribution of sunlight and drive glacial-interglacial cycles

Green house effect

Absorption and re-admission of infrared radiation emitted by the earth by some chemicals in the atmosphere.

How does greenhouse effect change earth’s temperature

-18 C without the greenhouse effect and with it it is 12-15 C. The greenhouse effect warms Earth by trapping some of the heat that would otherwise escape to space, and adding more greenhouse gases makes Earth’s temperature rise further

UV

low wavelength/high intensity from the sun and are shortwaves

IV

High wavelength/low intensity from the earth.Earth’s surface absorbs sunlight and then re-emits energy as infrared radiation

ENERGY BUDGET

• Sunlight arrives at the top of the atmosphere and some is reflected back to space, this reflection is called albedo

• Rest of the sunlight is absorbed by surface and this is what warms the planet 

• earth re-emits energy as infrared waves 

• greenhouse gases aboard some of these waves and re-rediate back to the earths surface. This extra radiation keeps the earth warmer than it would be

• Now ~ more energy is being trapped then released which effects global warming

• energy budget of incoming solar = 340 W/m2

What are the greenhouse gasses and how do they ‘trap’ heat?

 carbon dioxide, methane, nitrous oxide, ozone. It re-emits that energy as infrared radiation (invisible heat waves). Greenhouse gases absorb these infrared waves because their molecules vibrate in ways that match the energy of that radiation. After absorbing, they re-radiate the heat in all directions.

• Some escapes to space.

• Some is sent back down toward Earth’s surface.

• That “back-radiated” heat keeps Earth’s surface warmer than it would be otherwise.

carbon cycle

natural movement of carbon between atmosphere, oceans, land, and living things

pools vs fluxes 

 pools are the areas where elements are stored (ex. Oceans) and fluxes is the transport elements from one pool to another ex. Photosynthesis and respiration.

photosynthesis

co2 + h2o = c6 h12 o6 + o2  is the flux that moves Carbon from the atmosphere onto land.

NPP (net primary production) VS GPP (Gross primary production)

GPP is the total amount of energy produced by plants. NPP is the amount of energy that is converted to produce biomass (aka. The amount of energy used to make a new plant). 

permafrost tipping point

Frozen soils contain vast carbon stocks

*warming thaws permafrost —> microbes release CO2 and CH4

*Positive Feedback: more warming —> more thawing —> more GHG release

    Ocean acidification

Ocean acidification is when CO₂ from the atmosphere dissolves in seawater, forming acid that makes it harder for marine organisms to build shells and skeletons. The CO2 makes hydrogen ions which lower the waters PH

  Anthropogenic emissions

Anthropogenic emissions are greenhouse gases and pollutants released by human activities that trap heat and drive climate change. (fuel burning, agriculture, deforestation)

How much humans add years of carbon?

9-10 gt of carbon which upsets carbon cycle balance