Habitable zone - Controversy

You may or may not be aware of a discussion with an atheist named Ryan Anderson regarding the fact that he believes that Dr Hugh Ross is wrong when he wrote:

"If the Earth were one half of one percent closer to the sun, water on Earth would boil off. If the Earth were one half of one percent farther from the sun, all the water would freeze." (More Than A Theory)

However the statement does not exist in More Than A Theory. He attributes the quote to have been made on then John Ankerberg show, but I wonder if he saw it because the following book references the same thing:
Atheist Universe: The Thinking Person's Answer to Christian Fundamentalism By David Mills on page 250. You can read the exchange om my post: Faithful Thinkers: Audio: Major Creation/Evolution Models

Unfortunately, Anderson took things way to far alleging that Ross is dishonest and worst or doesn't know what he is talking about at best (about the Habitable zone and Creation/Evolution models). Anderson commented the following:

Also, it should be noted that as far as I know, Hugh Ross has never backed away from his absurd claim that "If the earth were 0.5% closer to the sun it would broil and if it was 0.5% farther from the sun it would freeze." [paraphrase]. The only reason I can think of for someone with a "PhD" to make such a clearly demonstratably false claim is to mislead. But that's par for the course with creationist, regardless of their "camp".

And today he said:

Actually, if you make an assertion that's wildly outside the range of what is currently thought to be the case, you have an obligation to substantiate that assertion.

He's [Dr Hugh Ross] actually a good example of why, as a layman, one should look for consensus among scientist rather than looking at one scientist. There are bad ones in every profession. But you of course will only look at the scientist that support the positions you want to believe.

Yes, indeed it is important to look at the balance of consensus among experts to determine if something is true or not. However we know that consensus does not always equal truth. There was once a consensus that the Earth was flat. And another that the whole universe revolved around the Earth. But the value of consensus is not issue now. Let's see if with simple back of the envelope calculation if we can figure out if  Dr Ross is wrong in the numbers he is proposing. First the Habitable zone is the range of distance from sun in which the earth retains liquid water. Any closer the water boils and evaporates. Farther and the water freezes.  The distance of the Earth to the Sun is called an Astronomical Unit (AU) which is about 93 x 10⁶ (93 million) miles. For the sake of this calculation I am approximating the earth's orbit as a circle although it is elliptical. I am also taking the range of the Habitable Zone from the following Wikipedia page:

Habitable zone - Wikipedia, the free encyclopedia

INNER edge	OUTER edge	References	Notes
0.725 AU	1.24 AU	Dole 1964 [18]	Used optically thin atmospheres and fixed albedos.
0.95 AU	1.01 AU	Hart et al. 1978, 1979 [19]	stars K0 or later cannot have HZs
0.95 AU	3.0 AU	Fogg 1992 [20]	Used Carbon cycles.
0.95 AU	1.37 AU	Kasting et al. 1993 [21]
–	1%–2% farther out	Budyko 1969 [22]	... and Earth would have global glaciation.
–	1%–2% farther out	Sellers 1969 [23]	... and Earth would have global glaciation.
–	1%–2% farther out	North 1975 [24]	... and Earth would have global glaciation.
4%–7% closer	–	Rasool & DeBurgh 1970 [25]	... and oceans would never have condensed.
–	–	Schneider and Thompson 1980 [26]	disagreed with Hart.
–	–	Kasting 1991 [27]
–	–	Kasting 1988 [28]	Water clouds can shrink HZ as they counter GHG effect with higher albedos.
–	–	Ramanathan and Collins 1991 [29]	GHG effect IR trapping is greater than water cloud albedo cooling, and Venus would have to have started "Dry."
–	–	Lovelock 1991 [30]
–	–	Whitemire et al. 1991 [31]

Let's take the Hart et al. 1978, 1979 reference of 0.95 AU  to 1.01 AU  for the range of the Habitable Zone. Imagine 3 concentric circles. Then inner one has a Radius of 0.95 AU, the middle has a radius of  1 AU and the outer has a radius of  1.01AU.


So what is the distance from the earth's orbit to the inner boundary of the habitable zone?

1 - 0.95 =  0.05  meaning 0.05 AU

What about from the earth to the outer boundary of the habitable zone?

1.01 - 1 = 0.01 - meaning 0.01 AU

If you want to know percentages of AU you take the differences and divide them by AU. This gives  - 0.05 and  + 0.01 .

This is well within the consensus of 0.725 AU to 3 AU. We know that any number anyone grabs from the air is an estimate and an approximation - averages. Not wrong, but nothing to assassinate a man's character over. It is obvious that Dr Ross is using Habitable Zone ranges like 0.99 AU and 1.01 AU.Again: well within the consensus range. Ryan Anderson claims to be a layman yet feels like he knows enough to criticize a professional astronomer. Anyone who knows something about Physics and published numbers know that such nitpicking is silly.