Geo Final

What is the El Nino Phenomenon?

A periodic shift in the state of the Earth’s climate, caused by temporary slackening/worsening of the Pacific trade winds (particularly the Easterly Trades close to the equator) and ocean currents every 2 to 7 years; happens somewhat randomly (can only be predicted a few months to half a year before the event)

How does the El Nino phenomenon alter the global scale?

causes tropical regions to experience unusually dry seasons and on the west coast around South America causes unusual warm and wet seasons; effects are felt primarily across the pacific ocean like North and Southern America but can affect regions outside the Pacific

How would different countries be affected by the El Nino phenomenon?

The Southwestern US will experience wet and stormy weather; Western US and Canada often dry and warm weather is experienced; Australia and Indonesia would be warm and dry weather that is related to droughts and fires

What happens during normal years?

Western Pacific: strong equatorial trade winds that drag warm surface water off the oceans from east to west which causes the upwelling of colder water closer towards the west coast of North America (low pressure system here). Over the cold waters on the west coast of North America or South America there is a development of a high pressure system as cold air is sinking towards the surface. The low pressure system causes an unstable atmosphere which causes air to rise and develop clouds and condensation that will eventually lead to precipitation (this system is called the Walker circulation); normal years it is controlled by the Walker circulation

What happens during the El Nino events?

The trade winds slacken and reverse which reverses the Walker Circulation. The atmospheric pressure falls on the coast of the Americas, creating a low pressure system with an unstable atmosphere, lifting air parcels and building clouds, condensation, and precipitation which reverses the current pattern. Atmospheric high pressure system on the tropical side of the equator which leads to the different weather phenomenon (predominately warm and wet in Southern America and Northern America is more warm and not as wet). On the other side of the Pacific there are unusual dry conditions compared to normal conditions. There is a high pressure system here because there is no upwelling of cold ocean water because the winds bring the warmer water; more of an upwelling closer to Indonesia and Australia which then suffer from dry weather that can induce droughts

What are La Nina events?

Enhanced version of the normal Walker circulation where the easterly trade winds are stronger than usual. It leads to a pronounced normal situation with stronger rain on the east coast of Australia and dryness along the west of South America with strong upwelling.  Stronger trade winds bring more surface water off the ocean causing stronger upwelling of colder ocean water therefore creating stronger temperature differences between the low pressure in one region and the high pressure in others, intensifying the system. Tend to follow El Nino events but not always and tend to last about 9 months to a year

What is ENSO?

The El Nino Southern Oscillation pattern (El Nino and La Nina)

What is the difference between El Nino and La Nina surface temperatures?

El Nino surface temperatures are higher closer to the Western Americas and South America and in La Nina years there are cooler surface temperatures closer to the west coast of South America

How does global warming relate to the El Nino events?

As the temperature of oceans rise, a higher baseline for El Nino events is set. If surface sea temperatures are getting increasingly warmer, that can also cause an intensifying of those processes and can lead to intensified El Nino events.

What primarily controls the increase in temperature when the content of CO2 increases in the atmosphere?

Greenhouse gases like carbon dioxide

What is climate change closely correlated to?

Observations of warming correlate closely with overall increase in CO2 levels in the atmosphere

How do we know the CO2 levels of the atmosphere going far back?

Primarily from the carbon dioxide concentration in parts per million from ice core records

What does the sharp increase after the 1950s coincide with?

The industrial revolution in many countries which amplifies the burning of fossil fuels and the release of more CO2 into the atmosphere

What else is sharply increasing in the last few hundred years into the atmosphere?

methane and nitrous oxide

What climate archives tell people about past climates?

Tree rings (wetter rings-more favorable conditions for tree growth and narrow-drier or colder, less favorable conditions for tree growth)

What are useful tools to reconstruct climates?

lake sediments and marine sediments are useful in reconstructing climates because they usually store sediments and organic particles that have been preserved for a relatively long time and if they are dug into, the layers can be reconstructed and the characteristics from those layers can be used to make conclusions about climate back in time

Where are changes in temperature most pronounced?

closer to the poles

As climate change approaches, what type of period may we head into?

An interglacial period (when the poles are totally ice free)

What is primarily causing climate change?

Human activity, primarily the burning of fossil fuels (proven by numerous studies and measurements), is closely linked to the rise in temperature and CO2 concentrations in the atmosphere

How do we know it is humans that are driving the increase of CO2 concentrations in the atmosphere?

warming in the troposphere and cooling in the stratosphere (the troposphere will hold more of the heat that’s radiated by the Earth which means that the solar energy budget will be kept in the air slower to the earth), more warming at night (since the surface of the Earth is primarily heating up, its reradiating that heat and storing it in the atmosphere where it’s radiated back to the surface of the earth), rising tropopause (the boundary between the troposphere and the stratosphere is generally rising in altitude as hotter air is expanding and has less air density/pressure), less oxygen in the air, and fossil fuel emissions increased over the last decades compared to pre industrial revolution measurements

How can we measure fossil fuels’ contribution to carbon emissions?

can measure our contributions using carbon isotopes in atmospheric gas (fossil fuels contain few to none of these); relative amounts of 13 C and 14 C carbon isotopes decreased over the last few decades primarily because we are adding increasingly more 12 C into the atmosphere by burning fossil fuels

What are the impacts of climate change?

temperatures will continue to rise which will affect lots of other processes on the surface of the Earth, the Arctic will likely become ice free eventually at some point (which means more ice melts, the more sea levels will rise), intensify hurricanes and other storm events, more likely to experience more droughts and heat waves

What is feedback mechanism?

a change in a system that has consequences that ultimately add to (positive) or counteract (negative) the initial change

What is positive feedback?

if a change is imposed that causes some subsequent processes that will either intensify or add to the initial change (if it counteracts, it would be negative feedback)

What is a tipping point?

a point at which a small perturbation can cause a large change to a system-such as it entering a new stable state

What are examples of positive feedback?

increase in CO2 that causes atmospheric warming which causes the temperatures to rise which causes the Artic sea ice to melt which means that reflective ice disappears which gives way for more darker ocean water that tends to absorb more heat than ice which would therefore cause temperatures to rise even more in that region, oceans get even warmer as more of it is exposed, SW absorbed, leading to further shrinkage of sea ice and so on; loops around that and the whole cycle intensifies because the subsequent lingering effects intensify the initial temperature rise. Process is known as Arctic Amplification

Where is the anthropogenic greenhouse effect particularly observed?

in the Arctic

Why is the Artic warming over twice as fast as anywhere else?

Due to Arctic amplification

What is arctic amplification?

the tendency of high-latitude regions to warm faster than the rest of the planet due to the ice-albedo positive feedback

What does the ice-albedo positive feedback result in?

The melting of Arctic sea ice on a much faster rate than expected (air temperature rapidly increased in the Arctic as well)

What is the permafrost carbon feedback loop?

lots of carbon is stored in soil especially permafrost soil (permanently frozen for at least two consecutive years). Lots of it is found in the Arctic regions in Canada or Siberia and Russia. Usually carbon is stored in the permafrost made up of old degraded plant material. Some of it has been locked into the permafrost soil for tens of thousands of years. With an increase of CO2, the atmosphere warms which causes the melting of permafrost. Permafrost and bogs thawing will release more methane. Particularly methane, but also carbon dioxide, will amplify the greenhouse effect and will cause temperatures to rise even more. It will loop around and the initial cause, temperature rise, will be amplified by subsequent processes (process due to the rise of temperature in the first place)

What else can be found in permafrost soils?

Animal remnants (bones)