What Percentage (%) Of Global Warming Is From People? What % Is Natural?

Answer 1

100%. "Global warming" is a term used specifically for man's contribution. The general term is "greenhouse effect". Man is responsible for only a small part of that. Most of the greenhouse effect is due to water vapor.

But man's contribution is enough to cause a rapid and very damaging climate change. Agriculture will be disrupted. Coastal areas will flood. Rich countries can cope, but the cost is enormous, and will lower standards of living. In poor countries, particularly where coastal areas are prime agricultural land, people will die of starvation.

EDIT For the people below who point out that man is a relatively small percentage of the greenhouse effect. That's true, but there is a delicate balance of natural greenhouse effect, with sources and sinks of greenhouse gases. Man's contribution is enough to tip that balance in a very bad way. 99+% of climate scientists are agreed about that.

Answer 2

This is far from easy to answer as a specific percentage.

To answer the question slightly differently, it is known that CO2 is ONE factor in global-warming, but certainly not an isolated one.

If CO2 is the major culprit, as many now believe, (even of Methane is far more dangerous than CO2 volume for volume), then the answer is as folows:-

Natural CO2 emissions from the sea = 58% of total CO2
CO2 emissions caused by respiration = 37% of total CO2
CO2 emissions caused by energy use etc.= 4% of total CO2
Other sources of CO2 = 1% of total CO2

Whilst the 4% figure may seem small in comparison to the whole, it is probably enough to encourage a speed up in global warming; especially if that figure were to increase dramatically, as it may well do with the expansion of Asian and East Asian energy use.

Broadly speaking, the earth seems to go in natural cycles of warming and cooling, and the debate is not so much about that, as about the impact of additional CO2 being created and added to the natural cycle.

Be aware, that anything proposed by scientists and politicians, is entirely concerned with the 4% to 5%, and not the 95% of naturally occuring CO2, because there is absolutely nothing they can do about the sea, as King Canute discovered.

Answer 3

Nobody knows. There are a number of greenhouse gases to which warming is attributed, and there are probably others whose contribution has not been identified, let alone determined. The increased percentage of carbon dioxide in the atmosphere over the past forty years does parallel fairly closely the emissions posited by mankind, but CO2 is not the strongest greenhouse gas in the atmosphere -- methane is more effective, and is released by both plants and animals.

Answer 4

Do a google search for "Vostok Ice Core data". And you will see that for 500,000 years the temperatures and atmospheric CO2 levels stayed between 80ppm and 180ppm but around the time of industrialization, when humans started burning fossil fuels in earnest, the atmospheric CO2 levels broke out of that natural range and have climbed ever since then. They are currently at a level of 280 ppm, or 30% higher than the highest natural level.

All REAL scientists who are not paid by corporations who profit by polluting are speaking in unison and warning us to reduce CO2 emissions now, before we produce more than the earth can absorb.

Answer 5

There are some models on this. The earth is going through a warming phase, but we are providing the boost it needs to become a problem.

Answer 6

You can estimate this from the fact that climate change has been going on longer than humans have been on the planet. It has been warmer and colder in the past and the further back the more change you find.