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They trap heat released by the Earth.


An increase in the amount of greenhouse gases causes less energy to escape from the atmosphere. Over time, this means that more and more energy is trapped within our planet and the overall, average temperature increases.


Greenhouse gases (GHGs) are the main cause of global warming according to scientists.

To learn more check out these related questions, such as how GHGs trap heat, GHGs and the greenhouse effect, and what gases are GHGs.


Biofuels are better (in general)


Fossil fuels are limited. They contain some harmful materials. They cause air pollution when used. When we extract coal and oil, we contaminate land and water. You can read about the pros and cons of fossil fuels in this Socratic question.

Biofuels are safer. The only problem is the question "food for people or fuel for people?" To produce biofuel, we need some vegetation. Biomass energy is not always automatically renewed by nature. It may be depleted if the environment necessary for its renewal is not maintained. For biomass to be renewable, both soil and water are necessary for plant growth. If either of these or, in worst case both of these, is depleted biomass production may decrease or even halt.

The main difference between renewable alternative energy sources (such as biofuels) and fossil fuels is analogous to the difference between a checking account that receives regular periodical (such as yearly) deposits and a checking account that receives an initial large deposit but no further deposits. The account getting regular deposits will not be depleted (e.g. biofuels). Even if you spend the present balance, more will be added later. The second account will eventually be depleted even though the timing will depend on the rate at which the funds are spent.

The total energy we may be able to produce by using biofuels is as large as the total energy globally consumed each year.


Follow explanation. LCDs are better.


It seems that LCD TV’s are environmentally friendly if you want good quality and low energy consumption.

Plasma: This particular TV display is probably the worst eco-friendly option to choose. While the picture is sharp and clear, “producing that perfect image requires a high resolution, and the higher the resolution, the more bandwidth—the rate at which data is transferred—the set needs,” according to GetDirectTV. Also, with any television, size matters. The bigger the set, the more energy and light it will take to illuminate the screen.

LCD: These sets seem to be somewhere in between Plasma and LED choices. While the technology of an LCD TV uses about a third of the energy consumption than Plasma, they still don’t quite beat the innovative technology of an LED TV.

One of the best tips for choosing a more environmentally-friendly television is to look at the Energy-Star rating that can be found on each TV display. And of course, as stated earlier, size does matter! Regardless of what kind of television you choose, the size will make the biggest impact. Remember, the bigger the size, the more energy consumption it requires. Not to say you have to sacrifice size or quality, but the amount of energy consumption is something to keep in mind.

Reference: http://www.isfoundation.com/campaign/environment-fight-club-plasma-vs-led-vs-lcd-which-television-most-environmentally-friendly


Most of this water is salt water and usable freshwater is much more rare. Increased demands and climate change are predicted to increase scarcity.


The Oceans cover vast areas of the globe but the salt water in these oceans is not useable for either drinking or irrigation. There are many fresh water lakes, notably the Great Lakes of America and Canada, the water in these lakes must be filtered and cleaned before the water can be used for human consumption.

Many rivers are used not only for drinking and irrigation but also for the disposal of waste products. The human waste is dumped into the rivers making the water downstream unusable until it has been treated.

There is a limit amount of usable fresh water. Much of the water has
been polluted and will become more polluted. At the same time the human population of the world is increasing, increasing the need for fresh water. The scarcity of fresh water will only increase in intensity as the demand for fresh water increases.

The image below shows water stress by country:

Prediction of future water scarcity:
Changes in temperature , precipitation patterns (both due to climate change), and increase in demand are all drivers behind projected increased scarcity.


  1. Heat cold water from the heat released from geothermal activity.
  2. Hot water rises.
  3. Moves turbine which powers generator
  4. Water cools, falls back down pipe.


In areas around the world (notably Iceland) where geothermal activity is common due to the (less than 10 km) thinner crust, people can use the thermal energy transferred to the rock from the magma, to heat water which can be used and most notably in generating power.


Energy is generated by having pipes, with cold water in them, go down into the Earth below, to where the rock is at a favourable temperature.
These surrounding rocks heat the water, and causes it to expand and rise, often turning it into steam.
This is then used to move a turbine, connected to a generator, to generator power for use, often in the local area.
The heated water is then either used to heat local homes and be used in local homes, or is either cooled/recycled and the process starts again.


  • Renewable
  • Virtually no byproduct release
  • Small carbon foot print
  • Regular advancements in technology, leading to more efficient generators which use less materials
  • Takes up little space on land, can be built partially in the ground also


  • Small chance of causing earthquakes
  • Only works if there is geothermal activity, sometimes geothermal activity can reduce or end
  • As with any subterranean endeavour, there is often some harmful substance found (e.g. radioactive) which needs to be dealt with
  • Expensive

Hopes this helps.





The water cycle includes three main steps:

  1. Evaporation: mainly from the surface of the oceans, and secondarily from the surface of other bodies of water, plus from the vegetation.

  2. Condensation: this creates clouds.

  3. Precipitation: this create the rain.

The main source of the water cycle is the evaporation from the oceans,

Once the rain falls some of it will flow on the land surface (runoff) other will be absorbed by the vegetation and finally some will percolate underground (infiltration) to fill the aquifers that will then originate springs feeding the rivers.

Runoff and rivers will return the water to the oceans from where it will evaporate back to the atmosphere. Vegetation will partially return the water directly to the atmosphere as water vapor during the evaporation. The cycle is completed.

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