Global Climate Change Caused by Humans Global change- any chemical, biological or physical property change of the planet. Examples include cold temperatures causing ice ages. Global climate change- changes in the climate of the Earth. Global warming- one aspect of climate change, the warming of the oceans, land masses and atmosphere of the Earth.

Emissions from the Developed and Developing World

Global Temperatures since 1880 Since 1880 temperatures have increased 0.8°C.

Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years No one was around thousands of years ago to measure temperatures so we use other indirect measurements. Some of these are Changes in species compositions Chemical analyses of ice

Putting It Together We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect. When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO2 gas and, as a result, they release CO2 into the atmosphere.

Consequences to the Environment Because of Global Warming Melting of polar ice caps, Greenland and Antarctica Melting of many glaciers around the world Melting of permafrost Rising of sea levels due to the melting of glaciers and ice sheets and as water warms it expands Heat waves Cold spells Change in precipitation patterns Increase in storm intensity Shift in ocean currents

Consequences to Living Organisms Wild plants and animals can be affected. The growing season for plants has changed and animals have the potential to be harmed if they can’t move to better climates. Humans may have to relocate, some diseases like those carried by mosquitoes could increase and there could be economic consequences.

The Kyoto Protocol In 1997, representatives of the nations of the world went to Kyoto, Japan to discuss how best to control the emissions contributing to global warming. The agreement was that emissions of greenhouse gases from all industrialized countries will be reduced to 5.2% below their 1990 levels by 2012. Developing nations did not have emission limits imposed by the protocol.

Carbon Sequestration An approach involving taking CO2 out of the atmosphere. Some methods include storing carbon in agricultural soils or retiring agricultural land and allowing it to become pasture or forest. Researchers are looking at cost-effective ways of capturing CO2 from the air, from coal-burning power stations, and from other emission sources. This captured CO2 would be compressed and pumped into abandoned oil wells or the deep ocean.

Natural Phenomenon that Impacts the Worlds Climate

Climate Vs. Weather Weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season. Climate, however, is the average of weather over time and space. An easy way to remember the difference is that climate is what you expect, like a very hot summer, and weather is what you get, like a hot day with pop-up thunderstorms. Volcanoes can have HUGE affects on the weather but typically, only the really big eruptions will have noticeable effects on the climate. “Climate is what we Expect and Weather is what we Get.”

El Nino and La Nina

Understanding El Niño and La Niña

Normal conditions: upwelling off the coast of Peru, warm water “piled up” in the Western Pacific

Strong upwelling

Normal conditions: upwelling off the coast of Peru, warm water “piled up” in the Western Pacific

Normal conditions

El Niño conditions: surface current reversed, pushing warm water toward the Eastern Pacific Upwelling repressed  Unusually warm water across Equatorial Pacific

El Niño conditions: surface current reversed, pushing warm water toward the Eastern Pacific Upwelling repressed  Unusually warm water across Equatorial Pacific

La Niña: Stronger trade Winds than normal, causing a strong upwelling of cold water in the Eastern Pacific

Developing La Niña after an El Niño

Declared El Niño related disasters, 1998

What are sunspots? Sunspots are temporary phenomena on the surface of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection and forms areas of reduced surface temperature.

Sunspots and climate An influence of solar irradiance variations on Earth’s surface climate has been repeatedly suggested, based on correlations between solar variability and meteorological variables. Low solar activity can enhance cold winters in northern Europe and the United States, with little direct change in globally averaged temperature.

An eruption can cause warming and cooling. An addition of carbon dioxide contributes to greenhouse warming. An addition to sulfurous gases induces cooling, because they turn into droplets of sulfuric acid that absorb and reflect sunlight, and cut down the amount of heat that reaches the ground. But most documented cases show a net cooling effect.

Benjamin Franklin The first scientist to recognize the cooling pattern. He linked the abnormal weather over Europe in 1783-84 to the great Laki eruption in Iceland, which sent volcanic gases into the stratosphere and released over 100 million tons of sulfur dioxide over just a couple of months – As much as the world’s industries release today in a year.

Most major eruptions only cause a temperature change of a fraction of a Kelvin, which doesn’t sound like much, but over an entire year it represents a large amount of heat subtracted from the Earth’s budget. Smaller eruptions don’t have a very big effect on the climate.

Earth’s Movement/ Tilt

Milankovitch Cycles Named after a Serbain mathematician, Milutin Milankovitch EXTREMEMLY long term effects that scientists think may be the cause of the ice ages. These are movements of the Earth that affect the amount of solar radiation that it gets.

Milankovitch Cycles Earth’s wobble, tilt, and orbit Precession Obliquity Eccentricity

Milankovitch Cycles Precession Direction of the Earth’s axis changes over time The Earth wobbles like a top on its axis 26,000 year cycle

Milankovitch Cycles Obliquity The tilt angle of the Earth’s axis changes over time The greater the tilt the greater the differences in the seasons. 40,000 year cycle

Milankovitch Cycles Eccentricity Varying shape of Earth’s orbit, e.g. how elliptical it is 100,000 year long cycle Click on the “Animation” link for a hot link to the web. To get back to the Powerpoint presentation, look along the bottom toolbar and click on the powerpoint logo. Animation