What percentage of global warming is natural and what portion is known to be caused by human activity?

Answer 1

I don't think that ratio has been determined by scientists yet.
Good question!
Because of the global warming phenomenon that's also occuring with other planets in our solar system including Pluto, there's a possibility that our sun is on the verge of going supernova and then collapsing into a...... black hole sun, won't you come. And wash away the rain........

oops, sorry - brainfart.
It was a silent, but deadly one.

Answer 2

QUICK ANSWER
Around 90%.

EXPLANATION
It's impossible to give a precise answer because the human contribution to global warming is masking the natural contribution.

When evalauting this question we look at the known facts - how much the world has warmed up by, how much we have increased greenhouse levels by, the technical stuff relating to the greenhouse gases (radiative forcings, GWP's etc). These things have specific values.

We also need to take into account the various natural cycles that the Sun and Earth go through. Like the movements of the planets, these are well documented and we can pick a point in time (past, present or future) and know whereabouts in these cycles the Earth lies. These too have specific values.

There are natural forces that cause fluctuations in the Earth's temperature, these are variable and can't be assigned a specific value but we can assign a range to them - i.e. a minumum and maximum value.

What you end up with is an equation something along the lines of 1 + 2 + 3 + 4 + a number between 5 and 10. In this example the lowest possible outcome is 15 and the highest is 20. We can apply the same principle when calculating the contribution humans have made to global warming and the answer it yields is in excess of 80%, probably closer to 90%, possibly even as high as 94%.

Answer 3

The mechanism by which man is supposedly causing global warming is the Greenhouse Effect. The problem is that nobody has nailed down the amount of temperature due to this effect. (Temperature, BTW, is an oversimplification aimed towards public understanding. Temperature does not equal energy, and is not a very helpful quantity when calculating this planet's heat "management".)

We do know that the amount of energy retained through the greenhouse effect is very small compared to the amount of energy received from the sun - but it is the critical difference that keeps the planet in a more habitable range. We also know that man's contribution to the Greenhouse Effect is small - less than 5%. A small percent of a small percent leaves you with a MUCH smaller percent. Some say this is less than 1%.

Answer 4

I don't believe global warming has been proved. In places where there should be frost or snow in winter it's still happening. Seasons maybe early and seasons maybe late but it's still happening. Climate change on the other hand is a real possibility. Just as the sun goes through cycles, so does our weather.The sun has sun spot cycles that happen every 11 years affecting radio communications so has our climate have cycles. Global warming is a cycle as well. The length of these cycles is unknown because we haven't been at it long enough to make a confirmed decision.

Answer 5

Since there is no scientific proof that man can have an effect on the climate that has not been determined.
However if the history of the planet is taken into account.
So far 0% can bee attributed to man.