Make the internet a better place to learn



Any pesticides and/or herbicides not taken in by the grass are absorbed by the soil and may find their way into our water supply and surrounding water bodies.


Any pesticides and/or herbicides not taken in by the grass are absorbed by the soil and may find their way into our water supply and surrounding water bodies. (The same is true for fertilizers). If we apply more of these products that needed, the plant will not take in any more of the chemical. Some products target certain weeds, yet we apply them across the entire yard. Thus, any chemicals applied to areas of the lawn lacking in weeds end up elsewhere.

Depending on the ingredients in these products, some move easily through the soil. Pesticide and insecticides often enter our water cycle through processes such as leaching or runoff. Leaching occurs when chemicals move or percolate through the soil. Run-off occurs when chemicals wash off the surface of the lawn or field and are carried elsewhere through precipitation or intensive watering.

Some of the commonly used chemicals found in these products are dangerous, such as 2,4-D, and have been linked to cancer. Thus, safe application of chemicals and limiting pesticide and herbicide use on lawns are both important.



Humans affect erosion rates in a number of ways across the globe.


Humans affect erosion rates in a number of ways across the globe. Studies have shown that humans now cause more erosion than natural processes do.

Deforestation can drastically increase erosion rates, as healthy forests and ecosystems are filled with plants and the roots of these plants hold soil in place. Without it, we see increased erosion due to wind (soil and sand blown from place to place) and water (increased runoff).

Agricultural practices can have a very significant impact on erosion rates. Certain practices cause more erosion than others. When livestock are permitted to graze the grass to very low levels, this increases the likelihood of erosion, as soil can be transported more easily due to wind and water.

Growing monocultures (one type of crop) rather than a diversity of crops also contributes to erosion as do other forms of intensive agriculture where nutrients are depleted form the soil and the soil cannot recover in between growing seasons.

The use of certain chemicals in agriculture can also contribute to increased soil erosion, as these chemicals disrupt the organisms that live in the soil and change the chemical composition of the soil.

Human activities such as repeatedly walking or biking the same trails or areas can also contribute to erosion slowly over time. Forest fires also contribute to soil erosion, as vegetation previously holding the soil in place is often destroyed. Mining increases erosion, as soil is exposed during this process and thus available to be moved by wind and water in addition to the amount of soil and rock moved intentionally by humans. Urbanization also contributes to erosion, as vegetation is lost and replaced with buildings.

Erosion rates can be slowed by reforesting areas, using chemicals wisely on agricultural areas, growing diverse crops and using less intensive agricultural procedures, limiting resource extraction, and so forth.

To read more about this problem, see this page by WWF.



Climate change refers to changes in our planet's climate over a very long period of time.


Brief answer:
Climate change refers to changes in our planet's climate that happen over a very long period of time. Climate change is important because the impacts of climate change will be incredibly detrimental to humans and the planet and have already begun.

Extended answer:

Climate change refers to changes in our planet's climate that happen over a very long period of time. Note that climate change is not the same as changing weather.

Presently, when we refer to climate change, we are typically referring changes that are anthropogenic in origin (caused by humans). This is because there is overwhelming evidence supporting that current effects of climate change are caused by humans.

The process:

Increases in greenhouse gases, such as carbon dioxide (CO2), result in the atmosphere retaining more heat. Gases are trapped in the atmosphere and heat leaves the planet at a much slower rate. This retention of heat in the atmosphere causes the planet to experience warmer global temperatures on average.

While the climate does change naturally, the rate and magnitude of current changes are unprecedented and anthropogenic in origin. Burning fossil fuels such as CO2 contributes to climate change. CO2 is emitted when we drive our vehicles, heat our houses with coal, natural gas, and oil. Methane, another greenhouse gas, is emitted from our landfills. Trees store carbon thus deforestation contributes to climate change.

Global warming, sea level rise, increases in ocean acidification, increases in the frequency of extreme weather events, coral reef bleaching, and loss of glacial area are all effects of climate change.


Given the above mentioned effects of climate change, this is a process worth thinking about. The effects of climate change are already being felt in some places. Small island nations are losing their land. Unable to adapt quickly enough, some species have already begun to go extinct. Poor air quality is expected to lead to increasing health problems and disease spread.

Agricultural practices and production will be greatly affected:

Related Socratic questions:

Climate change and its effects on animals
How can greenhouse gases harm us?



If the fuel is pure carbon, carbon dioxide is produced. But fuels used in real life are different.


Pure natural gas (CH4 or methane) produces carbon dioxide and water vapor when it is combusted.

Coal (some include less than 50% carbon) produce carbon dioxide, water vapor and nitrogen oxide, sulfur dioxide, etc.

Some fuels and their combustion products (consumed in large boilers used for electricity production) are provided below (Nazaroff and Alvarez-Cohen, 2001).

                                   Bituminous coal    Residual fuel oil (#6)     
                                 (pulverized, 1.8%S)          (2% S)

Particles 31 kg/Mg 2.9 kg/cubic m)
sulfur dioxide 35 kg/Mg 38 kg/(cubic m)
nitrogen dioxide 10.5 kg/Mg 8 kg/(cubic m)
carbonmonoxide 0.3 kg/Mg 0.6 kg/(cubic m)
Nonmethane organics 0.04 kg/Mg 0.09 kg/(cubic m)
methane 0.015 kg/Mg 0.03 kg/(cubic m)

Reference: Nazaroff, W.W. and Alvarez-Cohen, L. (2001). Environmental Engineering Science. John Wiley and Sons, Inc. New York, NY USA.



See below.


There are some environmental problems that affect almost all biomes, such as land use change. Tropical rain forests, desert biomes, savannah grasslands are all being converted to agriculture, human settlements, and used for natural resource extraction. Many biomes are increasingly threatened by invasive species, which outcompete native species and can seriously damage the ecosystem.

Examples that are more specific (but not exclusive) to particular biomes include warming temperatures in the tundra, desertification in savannas, and loss of boreal forest due to forest fires. These are further explained below.

Throughout the tundra biome, there is a decline in snow and ice. Warming temperatures have caused a loss of permafrost. These changes are happening quickly and many species adapted to the tundra climate, both plants and animals, are not adapting fast enough. The image below shows predicted loss of permafrost in Alaska. Read more about this problem here.

The Sahel region is an example of one location where the savanna biome is at risk of desertification This is mainly due to human actions such as farming and grazing. As the amount of vegetation declines, soil erosion increases, and the plants that would typically grow in this area are no longer able to survive in the dusty soil. Thus, the savanna in the Sahel is losing ground (see here and here).

The boreal forests are experiencing a lot of changes currently due to climate change. Rapidly increasing temperatures are moving too quickly for forests to keep up, thus we see an increase in forest fires and insect outbreaks that damage boreal forests (read more here). The image below shows forest loss in pink and forest gain in purple from 2001-2014 from Global Forest Watch.



Globally, agriculture makes up a very small portion of GDP and provides work for roughly 1/5th of the world's population. The role of agriculture ranges substantially by country.


Agriculture, which includes products made directly for human consumption but also animal feed and fibers for clothing, varies in its importance and impact on the world. Globally, the agricultural sector makes up very little of the economy, contributing to just under 4% of the world's gross domestic product (GDP) in 2014 according to the World Bank (see here).

However, the amount agriculture contributes to GDP varies by country, as shown in the map below.

Agriculture contributes to 2.3% of GDP in North Korea, 26.5% of GDP in Madagascar, 45.4% of GDPin Sierra Leone, and 0.7% of GDP in the United Kingdom.

The number of persons working in the agricultural section globally is 19.8% in 2010 (see here), the most recent year for which global data is available. This number too varies; 54% of people are employed in agriculture in Cambodia, 3% in Argentina, and 28% in Romania. The map below shows the number of people employed in agriculture in each country. Note that less data is available (as indicated by the country being in white) than in the previous map.

Agriculture is very diverse and thus farmers in some countries may be very wealthy whereas other farmers within the same country may be very poor. The amount of land farmed, the area of the farmland, the equipment used to farm, the crop being farmed, and other variables make for a range of incomes. Within a particular region or country, how important agriculture is will vary.

To read more about this issue in considerable depth, see this journal article.



Species diversity is measured by determining the number of species present in a given area or community.


Species diversity is measured by determining the number of species present in a given area or community.

There are multiple ways this can be done depending on the ecosystem in question, the resources (money, technology available, time, the amount of people available to collect data, etc) of the scientist, and the context in which species diversity is being measured.

Surveys done by scientists, camera traps, environmental DNA, and light traps are all examples of methods used to measure species diversity.

Biologists can traverse a landscape repeatedly, at different times of the day, at different times of the year, in different weather conditions, and so forth and record species presence over time to assemble a rough idea of species diversity. This is often done when one is interested only in a specific type of organism, such as mammals.

Camera traps may be used to determine the number of carnivores present at a site. Camera are placed throughout the study site and take a photo whenever triggered by movement. These images are then sorted and categorized to determine the number of carnivore species present at a site. Data is typically collected over an extended period of time and the camera traps may be moved to new locations to obtain more data.

Scientists setting up a camera trap:

A newer technique is to use environmental DNA, or DNA that can be collected indirectly from the animal through skin the animal has shed, DNA left in the soil, feces, or the water even. DNA collected is then compared to a database of known species to determine what species is present in the landscape. Environmental DNA can be collected to determine the number of fish species in a river. Read about a recent example here.

Another example of a method that may be appropriate depending on the study question is to use light traps to sample insect diversity. This is done by holding up a light to attract insects and then containing the insects in a net or some other sort of trap. Again, this type of sampling may be done repeatedly at different times of the year to determine an accurate estimate.

Scientist using a light trap:



According to the World Database on Protected Areas' 2016 report, less than 15% of the world's land and inland waters are protected.


According to the World Database on Protected Areas' 2016 report, less than 15% of the world's land and inland waters are protected in some shape or form (see report here). This includes national parks, wildlife reserves, biological refuges, and other protected areas that may be managed and owned by governments, indigenous groups, or private companies.

The amount of protected area varies greatly by country. For example, 12.3% of land is protected in Pakistan. Protected area is shown in green in the image below.

Only 6.5% of land in Paraguay is protected.



The global wind belts are the three wind belts or patterns of movement that cover the planet.


The global wind belts are the three wind belts or wind patterns that cover the planet: the tropical easterlies (or the trade winds) are found near the equator, the polar easterlies are found at the north and south poles, and the prevailing westerlies are found between the two.

The above wind belts exist in both hemispheres (see image below).

Global winds blow from high to low pressure at the base of the atmospheric circulation cells. The polar easterlies are at the base of the polar atmospheric cell, the prevailing westerlies are at the base of the Ferrel Cell, and the tropical easterlies are at the base of the Hadley Cell.

To learn more, watch this video:



As carbon dioxide levels in the atmosphere increase global warming increases, assuming no other changes.


Apart from water vapor, carbon dioxide is the most abundant greenhouse gas in the atmosphere. Greenhouse gases allow energy from the sun to pass through and reach the Earth.

This radiation is primarily of wavelengths in the visible light spectrum (about half a micron). When the energy reaches the Earth it heats it up. The heated Earth is actually releasing energy as heat, but it is in a different wavelength (averaged at 11 microns). We refer to energy around that wavelength as infrared. Greenhouse gases block energy at that wavelength.

This is what the balance looks like, it's called the solar budget. It is important to note that the total amount of incoming radiation is equal to the total amount of outgoing radiation. Greenhouse gases (indicated by the 15%) are necessary to maintain the balance.

enter image source here

If you look at the 15% and imagine a great increase in the amount of those gases, eventually that 15% will become 16%. That means that 1% of the incoming radiation is not balance by outgoing radiation. This will result in a heating of the Earth so that the amount of heat released by the Earth will increase so that the amount absorbed by the greenhouse gases becomes 15% again. Now we are back in balance until the numbers change again.

For example, lets say the heat released by the Earth was 100 units, and to balance 15% (15 units) are absorbed by greenhouse gases. If 16 units are absorb then the heat of the Earth goes up. It isn't until the Earth is releasing around 106 units that the 16 units that greenhouse gases are absorbing becomes 15% and we have a balance again. Obviously for the Earth to be releasing 6 more units of heat the overall temperature of the Earth is going to have to go up.

No one disagrees with this at all. The point of debate regarding this is there are a lot of other numbers in that balance and each represents something else that impacts on the budget. Since there are so many other factors some argue that the greenhouse gas factor is somewhat less important.