Climate and Change Flashcards
Climate Change: Definition
Any change in global temperatures and precipitation over time.
Glacial periods - definition
Time of cooler climate
Interglacial periods - definition
Times of warmer climate.
Ice age - definition
Time that’s colder than a glacial period
Natural causes of climate change - list of theories
- Eruption theory
- Sunspot theory
- Orbital theory (milankovitch cycles)
- Asteroid theory
Natural causes of climate change - eruption theory background
> Big volcanic eruptions can change the Earth’s climate.
Volcanic eruptions produce ash and sulphur dioxide gas. If it rises up high enough it will spread around the stratosphere. The sunlight is reflected back into space, which lowers the average temperature.
Natural causes of climate change - eruption theory examples
- IN 1991, Mount Pinatubo in the Philippines erupted, releasing 17 million tonnes of sulphur dioxide. It reduced global sunlight by 10% by 0.5 degrees for 1 year.
- Mount Tambora, Indonesia - lasted for 2-5 years. One year was without summer.
- 1883 explosion of Krakatoa reduced global temp by 1.2 degrees for at least one year.
Natural causes of climate change - sunspot theory
> The sun’s output is not constant. Cycles have detected reduction in heat.
The temperatures are greatest when there are plenty of sun spots.
It works on an 11 year cycle.
Over 2000 years ago Chinese started to record sun spots.
Natural causes of climate change - orbital theory (Milankovitch cycle)
> It is the changes in the way the Earth orbits the sun.
Cold glacial and ice age were 5-6 degrees colder than today. Some interglacial periods were 2-3 degrees warmer than today.
Every thousands of years.
The Earth’s orbit can change.
The Earth’s orbit can be a circle or an ellipse.
The Earth’s axis can tilt between 22.5-24.5 degrees.
Natural causes of climate change - asteroid theory
> The orbits of some asteroids have the same orbit as the Earth.
Dust and ash smoke from the asteroid which blocks the sunlight making the Earth cold.
It’s very rare for an asteroid to hit the Earth.
If one hits the Earth there is smoke and fire.
Some natural causes of climate change - book
> The Earth’s orbit changes a small amount once every 100,000 years. These are known as Milankovitch cycles.
The amount of energy radiated from the Sun changes over an 11-year cycle.
Volcanic eruptions pump ash dust into the atmosphere causing a cooling effect.
Large asteroid collisions can cause cooling as material blocks out the Sun. Asteroids hitting the Earth can cause huge fires which release massive amounts of CO2 which subsequently has a warming effect,
Ocean current changes can cause cooling and warming. In the UK, we have a warm and wet climate because of warm Atlantic currents. Sometimes the current shifts and we get a cooler climate for a short period of time.
The enhanced greenhouse effect
> Heat (UV rays) from the Sun reaches the Earth’s atmosphere; some is reflected back into space.
The land and oceans absorb the heat.
The land and oceans then radiate infrared heat back into the atmosphere.
Greenhouse gases in the atmosphere trap some of the heat (necessary for life on Earth).
Human activity increases greenhouse gases in the atmosphere leading to more warming.
Humans and climate change
> Global warming is closely associated with rising atmospheric CO2. This is a powerful greenhouse gas and is released by many human activities:
- industry
- transport
- energy production
- farming.
Evidence of human effect on climate change
- Global temperatures are rising - for example in 2015 the average global temperature was 1 degree above the average global temperature in 1850-1900.
- Atmospheric CO2 levels are rising in parallel with global temperatures. This is mostly due to human activity.
- The oceans warmed by 0.11 degrees per decade between 1971 and 2010.
- Sea levels rose globally by about 14 cm during the 20th century.
- Arctic sea ice covers 13% less of the sea each decade.
- Extreme weather events have become more frequent: heat extremes are 5 times more common now than a century ago, for example.
Possible consequences of global warming -8.
- Biodiversity loss on land and in the oceans.
- Coastal flooding from sea-level rises.
- More destruction from more frequent, stronger hurricanes.
- Spread of pests and disease.
- Changes in farming could affect food supplies.
- Loss of glaciers would mean water supply problems in some areas.
- More flood from more frequent, heavier precipitation.
- More droughts, lasting longer.
Why projections for future global temp rises and suture sea-level rises may not be accurate.
> The atmosphere and oceans are highly complex systems.
Computer models can’t always accurately predict how these systems will respond.
For example, the oceans have absorbed more heat than was expected.
Secondly, some natural events are hard to predict.
For example, volcanoes can cause atmospheric cooling and the Sun can enter a cooler phase, affecting global temperatures.
How do we know past climates?
- Ice Cores
2. Tree Rings
studying past climates - ice cores
> I ce sheets contain layers of ice, oldest at the bottom.
Each layer is one year of snowfall.
Trapped in the ice layers are air bubbles.
These preserve air from the time the snow fell.
In air bubbles there’s carbon dioxide particles.
Climatoligists can reconstruct past temperatures by drilling a core through the ice and measuring the amount of CO2 in the layers.
Studying past climates - tree rings
> In temperate climates such as Western Europe, trees grow every summer.
Periods of growth can be seen from the number of rings in a tree- each ring is a year’s growth.
Wetter and warmer = bigger growth.
Trees rarely survive more than a few hundred years, but tree fossils in peat bogs go back thousands of years.
The greenhouse gases
Carbon dioxide
Methane
Nitrous oxide
Halocarbons
Carbon dioxide
> 89% of greenhouse gases produced.
Burning fossil fuels (coal, oil, gas), deforestation which releases CO2.
30% increase since 1850.
Methane
> 7% of greenhouse gases.
Natural gas extraction, landfill, decomposition of organic matter including manure, emission from rice paddy fields.
21 times more powerful than CO2.
250% increase since 1850.
NItrous oxide
> 3% of greenhouse gases produced.
Jet aircraft engines, cars, lorries, fertiliser and sewage farms.
250 times more powerful than C02.
16% increases since 1850.
Halocarbons
> 1% of greenhouse gases.
Used in industry, solvents and cooling equipment.
3000 times more powerful than CO2.
Not natural.