The illogical brain

The brain seems to learn by forming associations at random, then reinforcing those associations unless they are directly disproved. As an example, consider that you are lamenting your ex-girlfriend, whose birthday is Nov 28, was too glimpery for you. Your buddy says " Wasn't she born in November ?
All Scorpio chicks are glimpery like that."
On the reinforce-success model, your brain now assumes that your ex-girlfriend is a Scorpio and that all Scorpio chicks are glimpery. Any reference to Scorpio, or glimpery chick jokes will reinforce this opinion, which can finally even survive the fact that Nov. 28 is not Scorpio. The brain is constantly making associations like this and jumping to conclusions based on them. In the absence of immediate negative feedback those conclusions remain embedded and are reinforced. It is the basis for effective advertising - associating a product with sexually attractive images is far more effective than any factual claim you might make and has the further advantage of not being refutable. Even though we know that advertisers are doing this deliberately, it still works.
In the case of factual claims, a habit of checking against a simple model will draw your attention to discrepancies that your brain's associations would otherwise cause you to gloss over or ignore. If a particular ad campaign habitually distorts the facts, consistent checking will eventually trigger your brain's pattern-recognition capability. You will still be swayed by the associations that are set up, but this will at least somewhat be countered by your recognition that you are dealing with a liar.
Simple models are an extremely useful tool in ordering one's understanding of the physical world. They are far less helpful in the world of opinion-shaping, but can at least help you know that you are being manipulated.

Do humans matter to climate?

From the simple model and its effects we can see that more detailed knowledge of how warming is occurring would be useful. One detail that is extremely useful to know is whether we have an effect on the trend.
We have no mechanism to influence the heat coming out from the earth, or arriving from the sun. We can and do affect every energy transfer mechanism from the earth's surface to the top of the atmosphere. Our agricultural practices determine the reflectivity of the land. We put enough particulates and aerosols into the air to cause more cooling than all but the most violent volcanic events. Our biggest effect, both relative to background levels and in absolute energy flow terms, is changing atmospheric infrared transmission through fossil fuel burning.
Scientists know with greater and greater precision how our influence on land albedo, atmosphere reflectivity, and greenhouse gasses affects our environment.
The simple model of an earth that freezes and thaws cyclicly, with the average ice line showing trends, combines with easily obtainable facts and figures to show that what the scientists are saying is reasonable. Our behavior is the major variable affecting world climate at this time, and changing our behavior will change the climate in knowable ways.

Same and warmer - so?

Does this climate prediction of "more of the same, with a warming trend" that we got from the simple model, have any use outside of science? The quick answer is yes- there are important planning aspects to this information from individual to global scale.
More of the same means that we do not face global scale climate catastrophe in this century.
What changes we do see will be related first to ice-melt, as the dominant weather factor, and perhaps to temperature extremes.
The importance of Northern ports increases as their number of ice-free days increases. Thinner polar ice changes the sonar conditions in the best hiding place known for nuclear submarines - the U.S. Navy is already developing strategy to acknowledge these changes. Fishing effort will be able to go further north, for longer. On land, roads that depended on permafrost will become unreliable. Resorts that depend on snowpack will increasingly have to make their own.
As ice or snowpack on land melts, it can flow downhill. This ice-melt caused over half a foot sea level rise in the 20th century. A continuation of this trend is obviously of interest in Vanuatu, which is barely above high tide as it is. A half-foot rise in sea level will significantly affect hurricane insurance risk in Forida, indeed in the entire southeastern U.S.
Water that falls as rain does not conveniently store itself on hillsides or in pastures for several months at a time. California, for example, will need to approximately double its reservoir capacity for the same amount of water when it falls as rain rather than snow in the Sierras.
Northern extension of growing seasons is of great interest in agriculture, there is a lot of potential cropland in Russia and Canada.
Temperature extremes routinely kill people and livestock. Thousands have died in single heat waves, hundreds in blizzards. The warming trend makes heat exposure an even worse threat - of definite interest in civil emergency planning.
Yes, knowledge that the average climate is warming while staying with the familiar cycles is important. Detailed knowledge of rates or of local changes is of definite interest in many places, and in some places can mean physical or economic survival.

Why simple models

Simple models are a way of being sure of what you know. Like double entry bookkeeping, they force you to deal with reality rather than opinion.
Both Feynman and Fermi made a constant habit of building simple mental models. Feynman especially used it as a conscious technique when confronted with a new problem. His use of simple modelling allowed him to make contributions in several different research fields, and he highly recommended the technique. Perhaps his most famous simple model was the o-ring and clamp he dropped in a glass of icewater when he and other members of the Challenger review board were being interviewed. The o-ring's painfully slow recovery of its shape when cold was obvious to all, and pretty much quashed attempts to spin the blame away.
This forced focussing on the obvious is a huge benefit in careful thinking, in that it gets around a key drawback to the way our brains work. Simply put, the brain does not use logic. It relies instead on a principle called 'reinforce success' when it was standard military strategy in the USSR. This is a hugely successful way of dealing with the world, but it results in a thinking instrument that ignores or rewrites contrary information, and that has such a backward grasp of statistics that Las Vegas not only exists but is profitable.
Simple models based in scientific understanding allow this imperfect thinking instrument to get past the random associations it has built up and focus on the actual problem. When the system considered is simple enough, conflicts between the model and reality become obvious. Defects in understanding are thus easy to fix. If complexity is not addressed until the simple model is well understood, apparent complexity often is shown to be unimportant, or easy to deal with.
Using simple models gets one in the habit of forcing one's thoughts to conform with physical possibility in a reasoned way. A reasoned understructure for one's knowlege is of immense value in an era where people increasingly try to sway opinion by applying knowledge of the illogical way the brain works. Applied consistently, simple models "enable you to detect when a man is talking rot"(J. A. Smith, 1914)

Watch the simple model

When water freezes into ice or snow, it becomes very reflective, causing it to absorb less energy, causing more cooling. As ice or vapor turns into water, it becomes an almost perfect blackbody, absorbing more heat, causing more warming. This positive feedback makes the freeze/thaw cycle the dominant weather driver on earth. We observe it daily at the equator wherever mountains stick up high enough. We observe it annually as the poles are alternately stuck into shadow and 24-hour daylight.
The annual freeze-thaw cycle will dominate earth's weather as long as there is polar ice.
Positive feedback makes the freeze-thaw boundary remarkably distinct, and much easier to track over the long term than temperatures.
The long-term trend for these cycles is progressive thawing, toward both altitude and the poles. It should not result in the arctic becoming ice-free in summer before the next century but growing seasons, frost-free days, and permafrost melting are all progressing northward. Vertical thawing is eliminating snowpack and glaciers worldwide.
Our climate prediction from the simple model and its behavior is:

More of the same, with a warming trend.

First simple model - earth climate

The earth is a ball of iron alloy, coated in rock, coated mostly in water, with a gas layer on top.
Heat (energy) comes out from the center to the rock/gas and water/gas interfaces, where we live.
Energy comes in through space from the sun.
Energy is radiated from the outside of the earth, from the interfaces out to the outside of the gas layer, into space.

The earth does not put out enough energy to keep the surface from freezing without help from the sun.
This is the basic energy-flow model.