Factors that Determine Temperature other than Carbon Dioxide
When you drive down a highway on a hot summer day, you think you see streams of heat rising off the surface in the distance. It's not a mirage. It's heat convecting upward. It's actually visible, because the density of the air is different when heated causing refraction differences to show the rising air.
What this means is that heat gets into the air any old way it wants to.
Conduction, Convection and Evaporation
Conduction, convection and evaporation are how most heat gets into the air. Some (not many) Ph.Ds. do not know this. They claim all heat in the air got there by being absorbed by greenhouse gases. This claim showed up on the web site of the Union of Concern Scientists for more than a decade (quote here), and on the first page of the web sites of the state and local governments on the immanent perils of carbon dioxide in the air. You can look down the highway on a hot summer day and see that they are wrong; but you can't look out the window and see global warming.
This puppy has more to do with changes in temperature of the atmosphere than most other factors. This effect results from volcanoes, which are highly variable at this time but were much more active between 300 and 100 million years ago.
Sulfur dioxide from volcanoes drifts into the upper atmosphere where it cause moisture to precipitate creating thin clouds which reflect away solar energy. Because of this effect, the global temperatures cooled significantly after the volcanic eruption of Mt. Pinatubo in the Philippines in 1991.
Ocean temperatures vary immensely for reasons which science does not understand. El Ninos and La Ninas are examples. They heat and cool the surface of the Pacific Ocean near the equator. As the ocean surface heats up, large amounts of humidity enter the air creating major disturbances in weather. A lot of rain occurs nearby, which generally means Central America and northern South America. Temperature increases and decreases occur in various, unpredictable ways around much of the globe. In general, global temperatures increase during El Nino events.
Right now, the Pacific Ocean is warmer than usual. Some scientists think the reason might be a volcano on the bottom of the Pacific Ocean. The result is more humidity in the air over the U.S., which has two, readily observable consequences. One, precipitation increases over the U.S., and two, increased clouds result in warmer winters and cooler summers.
Recent science is finding solar intensity to vary more than previously assumed. The earth's temperature is greatly affected by solar intensity. It is generally assumed that the warm up during the Medieval Warm Period and cool down during the Little Ice Age which followed were a result of variations in solar intensity.
Some scientists believe that ice ages are caused by variations in solar radiation due to wobble in the earth's motion called Milankovich Cycles. I disagree that Milankovich Cycles are the cause of ice ages. For one reason, those cycles have so many interacting complexities that they are not very distinct. All they could do is relocate the same amount of radiation from northern to southern hemispheres, as the same amount of total radiation would occur. Another reason, is because recent ice ages have been cycling at precisely 100 thousand year intervals for only a million years, while the Milankovich Cycles have been occurring for much longer.
Arctic Ice Melting
Arctic Ice melts on and off continuously for unknown reasons. The melting of Arctic Ice has major effects upon climate. It puts more moisture in the air in northern areas causing more snowfall, particularly in Canada.
The Arctic melted some time around 1900, upon which plans were made for a shipping route through the "Northwest Passage." It was navigated by Amundsen in 1903-1906. But ice soon closed it back up.
Recent ice ages have been occurring every 100 thousand years. As ice ages take form, ocean water evaporates and comes down as snow on the ice sheets. The result is oceans being drained. They drop about 400 feet during an ice age. As warm-up occurs, the melting ice fills the oceans back up to present level.
Both the atmosphere and the oceans warm back up between ice ages. The warm-up occurs for about 12 thousand years, and then the next ice age begins. Oceans warm continually by trapping solar energy, and only an ice age cools them back down.
The next ice age is due to occur any time. Statistically, it could have occurred already. It looks like it will begin in the next 50 to 200 years. The oceans have to get warm enough to cause more snow to fall than can melt during the summersthat is, in Canada. It almost occurred a few years ago, but luckily, the snow in Canada melted.
Scientists do not know what causes ice ages to occur. They are drifting toward the theory of Milankovich Cycles being the cause of ice ages. It's not Milankovich Cycles. It looks like the cause is the fact that oceans always heat continually until an ice age cools them back down, because solar energy gets trapping in the oceans and does not easily come back out. As the oceans warm up, the sea level rises cause warm water to flow over the Bering Strait melting Arctic ice. The warm Arctic water causes a lot of snow to fall in Canada. If the Canadian snow does not melt during the summer, it reflects away solar radiation triggering the next ice age.
Nothing to do with Carbon Dioxide
This stuff has nothing to do with carbon dioxide. It takes more science than looking out the window to determine what is going on.