Essential idea: Essential idea: Concentrations of gases in the atmosphere affect climates experienced at the Earth’s surface. By Chris Paine https ://bioknowledgy.weebly.com/ The greenhouse effect is accepted scientific theory. There are certain gasses in the atmosphere cause the sun's heat to be trapped and allow the surface of the planet to warm. Without it the surface of the planet would be too cold for life to exist. To explain the images are quotes from NASA : "Left: 1880-1889. Right: 2000-2009. These maps compare temperatures in each region of the world to what they were from 1951 to 1980 ... Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20 °C per decade”. These changes in temperature correlate with changes in CO2 levels . CO2 is now at a record high of 400 ppm. 4.4 Climate change http://climate.nasa.gov/images/ImageLarge-61.jpg
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Essential idea: Essential idea: Concentrations of gases in the atmosphere affect climates experienced at the Earth’s surface.
By Chris Paine
https://bioknowledgy.weebly.com/
The greenhouse effect is accepted scientific theory. There are certain gasses in the atmosphere cause the sun's heat to be trapped and allow the surface of the planet to warm. Without it the surface of the planet would be too cold for life to exist. To explain the images are quotes from NASA:
"Left: 1880-1889. Right: 2000-2009. These maps compare temperatures in each region of the world to what they were from 1951 to 1980 ... Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20 °C per decade”. These changes in temperature correlate with changes in CO2 levels. CO2 is now at a record high of 400 ppm.
The Earth is kept much by gases in the atmosphere that retain heat. These gases are referred to as greenhouses gases.
Q – why is the surface of the Earth warmer at night if there is cloud cover?
Q – why is the surface of the Earth cooler when there is more cloud coverage.
The water droplets in clouds retain heat during the day and at night re-radiate the heat back to the surface
The water droplets in clouds reflect a range of different wavelengths of radiation in both directions (including radiation coming inward that would have been re-emitted as heat*).
*Although clouds make the surface of the Earth cooler in the short term. They do not stop the greenhouse effect, it is just delayed or slowed down.
4.4.A2 Correlations between global temperatures and carbon dioxide concentrations on Earth.
Analysis of the gas content of the bubbles gives both the concentration of carbon dioxide in the atmosphere and the air temperature (from oxygen isotopes) at the time ice was formed.
To deduce historic carbon dioxide concentrations and temperatures ice cores are drilled in Antarctic ice sheets
The link between human emissions and atmospheric levels of CO2
Key points• There is a strong correlation
between human emissions and atmospheric levels of CO2
• As atmospheric CO2 levels have increased the amount of CO2 absorbed by carbon sinks has increased (only about 40% of emissions have remained in the atmosphere)
4.4.U6 Global temperatures and climate patterns are influenced by concentrations of greenhouse
gases.
Global average temperatures are not directly proportional to greenhouse gas concentrations. Other factors, e.g. sun spot
activity, have an impact global average temperatures
increases in greenhouse gas concentrations will likely cause:• higher global average temperatures• more frequent and intense heat waves• some areas becoming more prone to droughts• some areas more prone to intense periods of rainfall and flooding• tropical storms to be more frequent and more powerful• Changes to ocean currents, e.g. weakening of the Gulf Stream would
Research indicates that, by 2100 coral reefs may erode faster than they can be rebuilt. This could compromise the viability of these ecosystems and the (estimated) one million species that depend on coral reef habitat.
4.4.A1 Threats to coral reefs from increasing concentrations of dissolved carbon dioxide.
The ocean absorbs about 25% of the CO2 emitted into the atmosphere. Therefore as atmospheric CO2 increases so do the levels in the ocean.
Ocean acidification – the causes and effects
http://pmel.noaa.gov/co2/files/hitimeseries2.jpg
Since 1800 the pH of seawater* has fallen by 0.1 pH units. Since the pH scale is logarithmic, this represents approx. a 30% increase in acidity.
Estimates of future CO2 levels, indicate that by 2100 seawater could be nearly 150% more acidic (a further decrease of 0.5 pH) to a level not seen for more than 20 million years.
*seawater refers to the surface of oceans which are affected more than the depths.
It is not just the creation of carbonic acid that affects pH; when bicarbonate and carbonate ions are formed H+ ions are released thus decreasing the pH of seawater
4.4.A1 Threats to coral reefs from increasing concentrations of dissolved carbon dioxide.
Ocean acidification – the causes and effects
At risk Benefit
Marine calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.*
Photosynthetic algae and sea grasses
Need to absorb carbonate ions from seawater to make the calcium carbonate in their skeletons.
Low CO2 is a limiting factor for photosynthesis
*Shelled organisms are often keystone species and therefore the entire food web may also be at risk.
The pteropod is a tiny sea creature about the size of a small pea. Pteropods are a major food source for many animals including North Pacific juvenile salmon. The photos below show what happens to a pteropod’s shell when placed in sea water with pH and carbonate levels projected for the year 2100.
4.4.A3 Evaluating claims that human activities are not causing climate change.
http://www.skepticalscience.com/
Many claims that human activities are not causing climate change have been made in the media, whether it be in newspapers, on television or on the internet.
It is important to realise that not all sources are trustworthy and it is important to know the motivation of those publishing claims on either side of the debate.
Last Week Tonight with John Oliver: Climate Change Debate