What is the most glaringly obvious indication that climate change is very, very probable?

There are many aspects to climate change caused (mainly) by CO2 from humanity's utilisation of fossil fuels (coal, oil and gas):

The fact that CO2 is not completely transparent to light and modifies wavelengths causing (in the absence of phenomena which counterbalance) heat build up.

An enormous build up of CO2 in the atmosphere in the last forty years.

All this can be measured and assessed by complex computations.

What is the obvious indication? To me it is the fact that governments advised by national scientific and engineering bodies worldwide take this very seriously and have set up the IPCC (Intergovernmental Panel on Climate Change) under the auspices of the United Nations.

It is of course possible as an individual or a group to do your own thinking. But the phrase comes to mind - 'why hire a dog and bark yourself?' A thousand lifetimes spent studying the subject from googling articles is unlikely to give you the insight and combined experience of the IPCC effort.

If you want evidence of climate change, look at the range animals occupy. There is some pine beetle which is working its way higher into the Rocky mountains. Other bugs and weeds are slowly working their way north as the climate gets milder. Even the planting zones are being re-done.

Kids won't understand a lot of the cut and past crap that gets posted here. They will understand the movement of animals.

The earth heats from the oceans up, loses heat to space. Just like watching the frost on the windows of a cabin in winter,you can look to the meltline of the areas most exposed to the cold. Satellite imaging showing Arctic summer sea ice extent and high-altitude glacier loss worldwide really stands out over a couple of decades. Ocean heat content change is glaringly obvious to scientists, but needs understanding of graphs/datasets and statistics to appreciate.

The oceans have steadily been building up heat over the last 40 years or so.

Satellite measurements show that less energy is escaping to space at the wavelengths that greenhouse gases absorb energy, compared with previous decades. This has been confirmed by measurements from sevel different satellites, and so is refered to as "direct experimental evidence for the significant increase in the Earth's greenhouse effect".

There are different types of carbon isotopes in the air. The carbon released by fossil fuels is Carbon-12. The increase in Carbon-12 in the atmosphere is well documented and is increasing. Carbon is a known greenhouse gas and the effects of greenhouse gases on climate are well documented and scientifically proven. Because of burning of fossil fuels, atmospheric CO2 is at its highest level in 2 million years and rising.

What is hazy is the degree to which positive feedback will impact rising temperatures, but the latest scientific data seems to suggest that impacts have been underestimated, and that what was once framed as an issue for future generations to deal with, is now becoming an issue that is impacting us right now.

There are almost too many to list. I put together a list of resources a while back for people such as yourself who are interested in learning more about this from reputable, science based sources. The link is below.

http://writingfornature.wordpress.com/links-to-int...

Sadly deniers answers usually boil down to empty one lines (see Mike L or Cyclops)

or if they try longer answers then you have rubbish likes maxx's a long list of points he simply cuts & pastes, points that are as empty as most deniers.

Maxx's list has been taken apart so many times and I don't intend bothering this time, each of his points have been shown as wrong, he simply ignores this, I guess it's not that hard to point out the links he tries to use as evidence are mostly denier blogs and one from fox news, that speaks for itself really.

One I should pick up is the claim of "Lord Monckton destroys Warmist in debate (Video)"

It is a claim coming from a blog by well known denier journalist Andrew Bolt, I use the term journalist loosely,

The press club don't do winners and losers and Bolt is the only one trying to claim they do, he has a figure of 10 for Mockingtone and 1 for his opponent, which is interesting given the 80 to 100 actual people who attend press club debates and in fact can be clearly seen in the opening pans of this debate, the numbers Bolt seem to be referring to are from his own blog, not the attendees of the actual debate, I invite anyone to actually watch this debate Mockingtone destroy's nothing, he pushes the same tired old points like CO2 is a plant food, which are frankly irrelevant, It is the effect CO2 has on warming,sea level and ice not plants that are the points.

As for actual science and your question there are several things that point to warming happening temperature rise is the most obvious, denier will tell you warming stopped 15, 16, 17, 17 & 6 months or 17 years and 8 months ago, depending on which denier is replying, which overlooks several glaring problems

the warmest 2 individual years are 2005 & 2010 (just 9 & 4 years ago)

http://climate.nasa.gov/key_indicators#globalTemp

Plus the other problem that the entire devade of the 1990's was the warmest decade in the modern record until it was replaced by a warmer decade, the 2000's a deace that started inside the claim of 15 years ago.

http://climate.nasa.gov/key_indicators#globalTemp

It was 0.2c warmer than the 1990's which is inline with the decadal estimate of temperature rise from the IPCC, this makes a complete joke of no warming for 15 years (or whatever this weeks denier claim of years is)

You also have sea level rise, again denier claim this is just a continuation of the end of the last ice age, but again that is not what the science shows.

At the end of the last iceage sea level did rise very strongly, but then slowed over time first at 7000 years ago and then again at 4000 years and then pretty much stopping ~2000 years ago.

Seen here in larger detail - http://upload.wikimedia.org/wikipedia/commons/1/1d...

and here in closer (more recent) detail - http://upload.wikimedia.org/wikipedia/commons/1/1e...

If you look at the last stronger section 7000-4000 years ago, the current rate of sea level rise is 3.16mm per year (denier call this slow and nothing to worry about) but it is actually about 5 times faster than the rate of 7000-4000 years ago, does that really sound like a continuation, or something new.

But it is not just these you also have the Arctic sea ice loss, original estimates where that it might be gone in Summer by 2100, but due to the speed it is actually disappearing this is now thought to be by 2030.

On the claim of no warming for 15 (or whatever) years.

sea level has shown to be a quite good short term indicator of warming there are noticeable dips linked to the cooler years of 2008 & 2011 yet where is the overall dip for this 15 years of no warming, it seems the sea is not responding to that at all as sea level over the last 15 years has continued to rise and from the early 1990's the rate of that rise actually increased from 1.7mm per yer to 3.1mm per year

http://www.cmar.csiro.au/sealevel/index.html

Wouldn't be wonderful if denier's could respond to these points with real science links instead of blogs, or with valid science points rather than rhetoric and insults but sadly I think that is beyond them.

In simple terms that small children can understand..

You can start at a very early age by showing them how two cars parked next to each other in the sun, one white and one black to show how the colors reflect, absorb and transform sunlight into heat.

As they get a little older, you can explain that CO2 is a greenhouse gas because it allows certain colors of light, to pass through while absorbing and re-radiating the light out in other colors, even though we humans can not generally see ultraviolet and infrared. And you can then explain that humans have increased CO2 in the atmosphere by 40% by digging up fossil fuels and injecting the waste products of combustion into the atmosphere.

Then ask questions like "Do you think it is likely that if nothing else changes, this will cause the earth to retain more of the sun's energy?" Does a red car get warmer then a green car? etc...

Encourage them to question your answers, it is fun allowing them to find mistakes in your answers and they will learn a lot in the process.

Use historical evidence of climate change such as glacial and interglacial periods.

Increased summer melting of the north polar ice.

Because the climate is always changing.