Many of us have had an idea but now it is confirmed by scientists.
Global warming is "very likely" to have been caused by us - man.
That is hardly surprising.
What IS surprising is that the doubters have been led by propaganda for so long.
In reality, a bit like the pro-smoking lobby who maintain (yes, still to this day) that there is no evidence linking smoking to ill health.
The fact that I, in my job, see hundreds of people who have had their lives blighted (or snuffed) by smoking, and the fact that there are many like me in the same sort of job that have been witness to the same statistics, appear to count for nothing.
And what about all the evidence over the years? Smoking has been linked to ill health for well over 30 years.
Before that, we had a hunch.
Now it is proven, but pro-smoking wrigglers will find every way out of admitting the evidence.
Back to global warming.
Sea level is rising and temperatures are increasing.
Now we are at the stage that those who will deny the changes resolutely rest upon deprecating what they feel is anecdotal evidence.
Meaning, I think it's hotter and my neighbour thinks it's hotter.
Regional temperature and sea level measurements reveal a rise in temperatures and water levels.
Throughout the world, people continue to report "record levels" in terms of temperature and sea levels.
But the doubters will say it is all anecdotal.
They will especially say this if their responsibility revolves around excessive carbon emissions or if they may need to spend a bit of cash sorting their house out and putting everything into order.
So, we enter that phase of limbo - the stand off between the "knowers" and the "doubters".
Until, of course, in 50 years time, it is too late to alter things.
Perhaps it is already too late.
Irrespective, should we not at least err on the side of caution and sit in the camp of the most drastic evidence - scientific study?