The Changing Climate

Climate

Long-term, average of weather and the frequency of extreme weather events.

Weather

State of atmosphere at any given moment.

Modes of Climate Change

Climate change occurs through long-term trends (Cenozoic cooling), repeating cycles (Milankovitch cycles), and unpredictable anomalies (volcanic eruptions).

Climate Forcing Factors

Factors that are independent from and outside of the climate system but still effect it.

Climate Feedback

A process that acts to amplify or reduce direct warming or cooling effects, inside the climate system.

Cenozoic Cooling Trend

Began 55 mya, after an asteroid struck Yucatán Peninsula of Mexico - caused 75% life extinction (dinosaurs)

Due to building & uplift of Tibetan Plateau & Himalayas

No ice at either pole, CO2 concentration above 1000ppm (408 today)

Quarternary Period

Began 2.6 mya when ice sheets began growing in Northern Europe & North America

Glacial Period

Interval of cold climate that lasts about 90,000 years

Interglacial Period

Interval of warm climate that lasts about 10,000 years

Holocene Epoch

Began 11,700 years ago and continues today; is Earth's most recent interglacial period

Carbon Cycle

Continuous movement of carbon atoms between Earth's spheres

Long Term Carbon Cycle

- 99.9% of Earth's carbon is stored in the lithosphere
- Carbon transfers from atmosphere to the lithosphere through weathering and erosion and through burial and preservation of photosynthetic organisms.
-Carbon leaves the lithosphere and returns to the atmosphere through volcanic eruptions and through burning of fossil fuels
(these processes take thousands to millions of years)

Short Term Carbon Cycle

The relatively quick transfer of carbon between spheres

Most carbon is stored in oceans, climate change adds carbon to oceans

+carbon = +acidification of ocean

Carbon & Climate

Climate systems are strongly influenced by greenhouse gases like H2O, CO2, and CH4

GHG & Solar Radiation

GHG do not react with SW radiation, only LW radiation

LW radiation is absorbed and re-radiated which warms the atmosphere and surface

SW and LW Radiation

SW Radiation is emitted by the sun

LW Radiation refracted by ocean back towards space

GHG & Climate Change

+GHG in atmosphere
= +trapped heat in atmosphere
= +temperature and re-radiated heat sent to surface
= +Climate Change

Long Term CO2 & Temperature Fluctuations

Pre industrial era CO2 ppm was capped at 300ppm for 800,000 years, now it is 408ppm

+CO2ppm = +temperature anomaly (vice versa)

IPCC's 5th Assessment Findings

By 2100, CO2 will be between 550 and 900ppm

Global temp will likely increase by 1.8-4.2 ºC

Arctic Emissions

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

Albedo

% of incoming sunlight that is reflected from a surface, the ability of an object to reflect light (ice has high albedo, water has low albedo)