1) Differences in pressure between the air and the ocean cause carbon dioxide to be exchanged and 2) algae and phytoplankton absorb carbon dioxide.
The ocean can absorb carbon dioxide (

It will likely take a combination of these technologies to replace fossil fuels, and different areas will likely use different combinations. It's also worth considering that, as more people use these technologies, more money will be invested in them, and more research can be done on improving these technologies even further.
Some countries are choosing to invest their time and money into renewable energy sources:

Reducing our energy use overall though would help us rely on renewable energy. We can do this by creating better public transportation, eating foods that are local and in season, creating usable bike lanes in cities, using less energy at home and using energy efficient appliances, and so forth.
To read more about what is possible when it comes to renewable energy, check out this article.
Fossil fuels are harmful for the environment for a few reasons.
Fossil fuels are harmful for the environment for a few reasons.
The main reason why fossil fuels cause so much damage is due to the amount of carbon dioxide or CO2 emitted when fossil fuels are burned. This burning and release of CO2 is a huge contributor to the greenhouse effect and climate change. More CO2 in our atmosphere causes less sunlight to escape back into space, causing the planet to warm.
When fossil fuels are burned, CO2 isn't the only gas released. Other harmful gases such as nitrogen and sulfur oxides. Burning fossil fuels causes air pollution and smog.
Acid rain is also caused by the burning of fossil fuels. While technology has improved considerably in the US, we used to see high instances of acid rain around industrial areas where lots of fossil fuels were being burned. This is still the case in areas where air quality is not as regulated.
Another reason why fossil fuels are bad for the environment has to do with the ways they are extracted or removed from the earth. Drilling and mining for coal, natural gas, and oil all involve disrupting the natural landscape to access these materials. Drilling can disrupt the water table and if spills or accidents occur, we can have incidents like the Deepwater Horizon Spill.
An example of a coal mine:

Extent of Deepwater Horizon Spill:

To read more about this issue, check out this article on the hidden cost of fossil fuels.
It all has to do with the wavelength.
Electromagnetic radiation travels in waves, and the distance from one wave crest to the next is known as the wave length.

Generally speaking when these wave encounter something they will either through it or be blocked by it. A general rule of thumb is the smaller the wavelength the more likely it will pass through the material.

In the illustration above you can see the smaller wavelengths are things like x rays and gamma rays. If you have had to have an x-ray you know that x-rays travel freely through a lot of material (such as your skin). The calcium of your bones will block some x-rays (which is why they appear on the xray film), but the reason that you wear lead everywhere that you do not need x-rayed is that it takes lead to fully stop x-rays. Gamma rays are even harder to block, and need a much thicker lead shield.
What does this have to do with greenhouse gases?
Well you see on the picture above the area that is a rainbow? That is where most of the radiation from the sun falls, and we call it visible light. Energy at this wavelength passes freely through the atmosphere, and can strike the Earth. When it strikes the Earth the energy is absorbed and the Earth is heated. Heat is actually another form of electromagnetic radiation called infrared radiation. What is crucial to note is that this type of radiation has a longer wavelength.
Greenhouse gases (carbon dioxide, methane, water vapor, etc.) are transparent to visible light, but opaque to infrared radiation. That means the sunlight travels through them but the heat is blocked by them. That is how greenhouse gases trap heat.
Side note, we call heat infrared radiation because it is adjacent to the red end of the visible light spectrum. We call the radiation adjacent to the other side of the visible light spectrum Ultraviolet radiation, because it is adjacent the the violet end of the visible light.
Additional side note, the sun actually emits radiation over a wider spectrum than just the visible light spectrum.

The Ultraviolet part of the solar energy is blocked by ozone in the upper atmosphere (which is why we need the ozone layer). The infrared radiation of the inbound solar radiation is also blocked from entering by greenhouse gases.
An example of an ecosystem is a pond. All of the living things in the pond (frogs, fish, bacteria, water plants etc.) are considered biotic factors . The abiotic factors of the pond ecosytem would include all of the non-living factors (water, light, dissolved oxygen, nitrates etc.) which are found in the pond.
A biome is a collection of different ecosystem that share similar climate conditions. Northeastern Minnesota is coniferous forest biome. In this region of the state of Minnesota you will find pond ecosystems, forest, rivers & streams etc.
This video discusses levels of organization in ecology, including discussion of ecosystems and biomes.
Hope this helps!
They prevent heat from escaping.
Electromagnetic radiation travels in waves, and the distance from one wave crest to the next is known as the wave length.

Generally speaking when these wave encounter something they will either through it or be blocked by it. A general rule of thumb is the smaller the wavelength the more likely it will pass through the material.

In the illustration above you can see the smaller wavelengths are things like x rays and gamma rays. If you have had to have an x-ray you know that x-rays travel freely through a lot of material (such as your skin). The calcium of your bones will block some x-rays (which is why they appear on the xray film), but the reason that you wear lead everywhere that you do not need x-rayed is that it takes lead to fully stop x-rays. Gamma rays are even harder to block, and need a much thicker lead shield.
What does this have to do with greenhouse gases?
Well you see on the picture above the area that is a rainbow? That is where most of the radiation from the sun falls, and we call it visible light. Energy at this wavelength passes freely through the atmosphere, and can strike the Earth. When it strikes the Earth the energy is absorbed and the Earth is heated. Heat is actually another form of electromagnetic radiation called infrared radiation. What is crucial to note is that this type of radiation has a longer wavelength.
Greenhouse gases (carbon dioxide, methane, water vapor, etc.) are transparent to visible light, but opaque to infrared radiation. That means the sunlight travels through them but the heat is blocked by them.
All this is actually natural and is part of the energy budget of the Earth.

If you look at the diagram above you see that a certain amount of heat is supposed to be blocked by greenhouse gases. The problem is when greenhouse gases increase and block more heat than they are supposed to. This causes the temperature of the Earth to increase so that the amount of heat the Earth releases can increase and the budget can get back in balance.