Are humans the only cause of global warming?

Answer 1

Humans have everything to do with global warming. Global warming means the recent (200 years) rapid warming of the earth (not the very slow warming and cooling between Ice Ages).

This rapid warming is totally being caused by humans burning fossil fuel, cutting down forests, mismanaging agriculture and many other things, all of which are adding the greenhouse gases carbon dioxide and methane to the atmosphere.

Answer 2

Yes.

• Destroying the world's forests is one cause (deforestation).
• The burning of fossil fuels (coal, oil and natural gas) in industry, transport and the generation of electricity, which releases carbon dioxide (CO2) is the other.

Answer 3

Yes, we have been cutting down forests and burning fossil fuels since 1750, the beginning of the Industrial Age. Combustion of fossil fuels releases long-held carbon dioxide (CO2) which adds to the greenhouse gases. Reduction of forests means that more CO2 remains in the atmosphere. The extra CO2 is turning the natural greenhouse effect into an accelerated one, which is causing global warming.

Answer 4

Global warming refers to the rise in temperature of the earth, especially since the beginning of the Industrial Age (1750), and more recently the rapid increase in temperature since the late 1970s.

It is anthropogenic, that is, man-made. We burn fossil fuel (coal, oil and natural gas) in industry, transport and to generate electricity. Combustion of fossil fuels releases long-held carbon dioxide (CO2), a greenhouse gas, into the atmosphere.

About the same time we began destroying many of the great forests of the planet. Vegetation absorbs CO2 through photosynthesis. It releases the oxygen and stores the carbon, often for hundreds of years. Carbon can make up half the body weight of a tree. Fewer trees means there is more CO2 left in the atmosphere.

The earth's carbon cycle moves carbon in and out of the atmosphere all the time, supporting the natural greenhouse effect, which has kept the planet comfortably warm for millions of years.

This sudden inrush of CO2 is disrupting the carbon cycle, which is unable to move all the extra gas out of the atmosphere. It is also affecting the greenhouse effect, which, with more gas, is getting warmer. This accelerated greenhouse effect, plus deforestation, is what is causing global warming.

The majority of climatologists and others who believe it is happening as a result of human action call this "Global Climate Change", as some areas may be warmer, some cooler, some wetter, some drier. Understand, as well, that climate is not the same as weather when the climate change issue is discussed by climatologists, it is an important distinction to be made and understood.

Those who believe that human influence on the atmospheric contents is the cause of a climatic warming trend, think that human activities since the time of the industrial revolution have caused an increase in the content of CO2, methane, and other gases in the atmosphere, and that these gasses help to trap solar heat. At the same time that this introduction of new sources of environmental gasses began to trap the heat, additional human activities across the globe have reduced the forest cover that had traditionally absorbed excesses of these same materials. These two factors together have caused an increasing level of these atmospheric constituents, which has led to a chain of chemical and physical changes, that have increased the world's average temperature.

Scientific observations of atmospheric gas composition, average sea water temperatures, atmospheric temperatures, etc. confirm the trends and support the proposition.

If this warming trend continues to increase the temperature of the Earth, they are concerned that some of the following results will occur:

1. The sea levels may rise. Technically, this may be caused by melting ice from the polar ice caps, or by an increase in sea height caused by the less dense warmer water that will be less compressed. Low lying land like many Pacific Islands and Miami could be under water as a result.

2. Serious effects of climate changes may result from diverted ocean currents. As an example of one of the situations where global climate change could make some places get colder, consider the Gulf Stream that keeps Europe warm. If this important stream of ocean current is not running, Europe could become much cooler and drier. Crops may not grow.

3. Ecological changes on the land could include a move of various species of animals and plants extending their ranges to the previously too cold polar regions. Their move could prove devastating to local flora and fauna, causing them to become extinct. An example of this kind of change is the similar recent spread of Africanized bees and Fire Ants. Sea life may also be impacted, both through the introduction of competitive species (which are presently kept separate in other areas by water temperature preferences and needs) and by the inability of local species to adapt to water that has a lower saline content.

4. Human society may be disrupted in numerous ways, changing life as we know it, if climate changes cause variations in rainfall and temperatures in places which, in turn, cause crop failures and disruption of the food chains.

Either there is a basis for fear about climate change, or, there isn't. Some people who have opinions on this have also said that they base their reactions on some of the following considerations:

• If Climate Change isn't real and we do nothing - good! Except, of course, many of the problems that science has identified and blamed as causing Climate Change are just plain wastes of resources, and inefficient and uneconomical practices that should be addressed anyway. A polluted, climatically steady world with no fish and no oil will be no fun at all.

• If Climate Change is not real and we do all the things that we should - reduce emissions, cut fuel use, re-establish forests - we could run out of money (maybe), but in general, the world would be a better and more sustainable place.

• If Climate Change is real and we do nothing - we are dead (or at least very miserable).

• If Climate Change is real, and we work to correct all our bad habits, we might still be in trouble ... if it's too little and too late. But we'll go down fighting, because if we succeed, we will get to live.

Some people say that they do not believe the science, that global climate change isn't real, it is made up, or a figment of some peoples' imaginations. If they are right ... Wahoo!

However, no case in the summary of potential future scenarios, which is based on us sitting around doing nothing at all, has a cheery outcome.

Answer 5

Yes, the carbon cycle and the water cycle work together to provide a gentle greenhouse effect which has kept the earth warm for millions of years. This is natural.

The carbon cycle has been disturbed by man cutting down forests and burning fossil fuels for the past 200 years. Every year this is adding billions of tons of extra carbon dioxide to the greenhouse gases in the atmosphere, and the carbon cycle can no longer move it all out into the oceans, soil and trees. So the reflected heat from the sun's rays is captured by the extra greenhouse gases, and the earth is globally warming.

Answer 6

In terms of the current warming in the last ~250 years, humans are primarily the cause. This comes through the emission of greenhouse gases, which we do when we burn fossil fuel (coal, oil and natural gas). Deforestation is also one of the causes of global warming. Forests take carbon dioxide out of the air and store the carbon in roots, trunk and branches.

The radiative properties of carbon dioxide are well known from science over a century old. More CO2 in the air causes the atmosphere to warm. It's true that it is the "gas of life", we need it to survive, and that the planet would be too cold for most forms of life without it. The problem lies in the balance that is being altered as much, much more CO2 is added to the atmosphere quickly which has been primarily responsible for recent warming. While its current concentration is only 390 ppmv (parts per million), fluctuations of 100 ppmv have in the past accompanied ice ages.

Currently, we know CO2 is increasing because of us (we have a pretty good idea of how much we've emitted), we know exactly how temperature responds to CO2, and this is the basis for our attribution.

Water vapor is also a greenhouse gas, and an extremely abundant one, making up at least 95% of greenhouse gases by volume. But its residence time is a few days, so it can't build up in the atmosphere like other greenhouse gases. It also contributes nowhere near 95% to the greenhouse effect due to the physical properties of water. It happens to occupy a portion of the "atmospheric window" that is not particularly effective in trapping radiation (or more accurately, it is somewhat redundant). It turns out that CO2 is much more effective given its volume, although it is actually the least effective of other greenhouse gases such as methane and especially halocarbons in trapping this radiation.

About 30% (source is IPCC AR4 WGI) of emitted carbon currently gets stored in the ocean, where it does not simply sit for hundreds or thousands of years, but can actually be outgassed very quickly. Currently the ocean is a net sink of carbon, though it varies regionally because its ability to store carbon is largely dependent on its temperature. Because much more carbon has been emitted in recent years and ocean temperature has been warming, the ocean is storing more of it (which is increasing acidity and causing a host of ecological problems), and there are indications that it is already slowing down in its ability to sequester carbon. Models are also indicating that in the future it will become a net source of carbon, instead amplifying our carbon contribution to the atmosphere rather than mitigating it.

Regarding the sun's role in all of this: The sun supplies essentially all of our energy, however one cannot say the sun has caused global warming without demonstrating that solar flux has been increasing in tandem with the warming, which it has not. There have been minor variations in flux in recent decades and century as there always are, but the radiative forcing of this flux is an order of magnitude smaller than that of CO2 alone since the Industrial Revolution. It has been linked to recent climate changes such as the Little Ice Age and Medieval Warm Period. For example, sun spot activity was observed to be extremely low during the cool Little Ice Age between the 13th and 16th centuries. One could say the this caused the LIA and that the current warming is because of a sunspot maximum, except sunspots have been at a minimum in the last couple years and record warmth continues.

Temperatures don't get slightly warmer every year, that's not how the climate system works. There are many oscillations within the system that operate on different time scales, and the system is inherently chaotic. But over time, there's no doubt that it's been getting warmer. The warming did level off and cool a little bit around the 1960's, but this has been attributed to aerosols from industry prior to much air quality legislation, especially in the United States, that cleaned that up by the 1960's. A lot of black carbons, especially, were being emitted and essentially blocking out the sun, causing a slight cooling. When it was cleaned up, the temperature was observed to rise once more. Regionally, there is a slowing in the warming or even a slight cooling in recent years in parts of Asia where this type of industry and coal burning continues.
Yes.

Answer 7

There is no question that humans ARE to blame for global warming. Just about every peer-reviewed climate scientist in the world agrees that we have caused global warming through deforestation, burning fossil fuel and poor agricultural practices.

Answer 8

Much recent evidence shows that the global temp average has remained static for a decade and a half, while carbon dioxide levels have increased. This evidence shows that man does not have as much of an effect on global temps as was previously thought.

Answer 9

No, most scientists agree that humans are mainly responsible for global warming. Deforestation and the burning of fossil fuels are the main causes.