Bob: You keep referring to NASA data...help me out???

Question

The same figures you refer to also show global warming on both Mars and Venus at almost IDENTICAL rates as here on Earth.

Could you please explain to me how that's possible?

Also, while doing so, can you give me a quick run-down of how the last ice age ended...better yet, why? I mean wasn't it before the industrialization of this planet???

Thanks. Really.

Answer 1

The Milankovitch cycles created the variations in our recent climate due to the earth's orbit and axis of rotation variations after the continents migrated close enough to the poles.  This may have created a "trap" for sea ice formation which resulted in increased cooling cycles from previous times when the oceans may have moderated the Artic temperatures more.  We are in an Ice Age.  We came out of the last period of glaciation less than 10,000 years ago.   That doesn't mean that we have another 30,000 years left for the next ice age.  It may begin at anytime but it will be gradual and take several lifetimes.  In the meantime, there are other solar cycles that will lower and raise the temperature naturally.   After the last interglacial, CO2 levels were up, most of the ice was melted so there should have been lots of land and water to absorb the solar radiation, yet we still moved into a period of glaciation.  This indicates that those who fret over runaway global warming have very little understanding of the mechanisms involved (not claiming I do either), and they don't understand geologic history which I believe is the good point you were making that seems to go over Bob's head IMO or he simply ignores the implications.

There were other important events taking place about 3 million years ago also including the formation of island arcs in indonesia and the isthmus of Panama which might have drastically altered sea currents.

Answer 2

Welcome back Bob, where ya been?

Might I recomend Hawaii sometime, it is wondeful here.

Answer 3

OK.

All the planets aren't warming (so it isn't an increase in solar radiation).  Just a few, for different reasons.  On Mars, it's because of giant dust storms unique to Mars.

http://www.nasa.gov/centers/ames/researc...

More about it here:

http://environment.newscientist.com/chan...

The last Ice Ages ended because of changes in solar radiation called "Milankovic cycles".  You can Google that.

How do we know it's not that now?  Simple, the cycles aren't magic.  They cause an easily measurable increase in solar radiation.  Scientists have looked for it, and it's not there.

"Recent oppositely directed trends in solar

climate forcings and the global mean surface

air temperature", Lockwood and Frolich (2007), Proc. R. Soc. A

doi:10.1098/rspa.2007.1880

http://www.pubs.royalsoc.ac.uk/media/pro...

News article at:

http://news.bbc.co.uk/1/hi/uk/6290228.st...

Your questions are reasonable, but think about this.  Would scientists consider these things?  The answer is yes.  Here's the result (from FoxNews):

"While evidence suggests fluctuations in solar activity can affect climate on Earth, and that it has done so in the past, the majority of climate scientists and astrophysicists agree that the sun is not to blame for the current and historically sudden uptick in global temperatures on Earth, which seems to be mostly a mess created by our own species."

http://www.foxnews.com/story/0,2933,2583...

Thanks Stinky.  I've been on vacation.  The weather has been cold where I'm at, so, being no fool (and understanding the difference between weather and climate), I went someplace the weather is warmer.

EDIT - There is some uncertainty about the details.  But, on the main point, man made global warming that's a serious problem, scientists are 99% sure.  Plenty sure enough to justify serious action.  You don't want to risk your future well being on a 100:1 shot.

Thanks for actually reading the links.  That's all I ever want.

Answer 4

Bob's explanation is only partial.  Milankovich changes in solar radiation are insufficient to account for all of the warming observed in past climate cycles.  The Milankovich cycles trigger greenhouse gas release, which then accounts for most of the additional warming over thousands of years:

http://www.aip.org/history/climate/cycle...

"An important clue came from some especially good ice core records that showed a lag in the levels of CO2 and methane. They seemed to rise or fall a few centuries after a rise or fall in temperature. This confused many people, who thought the time lag contradicted the greenhouse theory of global warming. But in fact the lag was not good news. Scientists quickly realized that it strongly confirmed that the Milankovitch-cycle shifts in sunlight initiated a powerful feedback loop. Evidently the close of a glacial era came when a slight rise of temperature stimulated massive changes in gas levels, which drove the temperature still higher, which drove further changes in the gas levels, and so forth. Ice ages were thus the reverse of our current situation, where humanity was initiating the change by adding greenhouse gases. Once that began to warm the planet, would the feedbacks begin to drive things higher on their own?"

  

"It was now clear that not only the most obvious feedback, but also the most momentous one, was the connection between global temperature and greenhouse gas levels. Relatively straightforward analysis of the data showed that a doubled level of CO2 had always gone along with a rise of a few degrees in global temperature. It was a striking verification, with entirely independent methods and data, of what computer models had been predicting for the planet’s greenhouse future."



While you're looking at past episodes such as ice ages, consider other archeological evidence:

http://www.aip.org/history/climate/co2.h...

"A final nail in the skeptics' coffin came in 2005, when a team compared computer calculations with long-term measurements of temperatures in the world's ocean basins (it was not in the air but the massive oceans, after all, that most of any heat added soon wound up). In each separate ocean basin, they showed a close match between observations of rising temperatures at particular depths, and calculations of where the greenhouse effect should appear. This was telling evidence that the computer models were on the right track. Nothing but greenhouse gases could produce the observed ocean warming — and other changes that were now showing up in many parts of the world, as predicted.

The computations pinned down an imbalance. The Earth was now taking in from sunlight nearly a watt per square meter more than it was radiating back into space, averaged over the planet’s entire surface. That was enough energy to cause truly serious effects if it continued. James Hansen, leader of one of the studies, called it "smoking gun" proof of greenhouse effect warming.(56)"



"Yet amid all the uncertainties about how carbon cycles operated, how much could we trust the computer models? Scientists are more likely to believe something if they can confirm it with an entirely independent line of evidence, preferably from somewhere nobody had looked before. Just such new evidence came up in the 1990s, thanks to an unexpected alliance of paleontology and plant physiology. Studies of plant species that had changed little since the rise of the dinosaurs (magnolia for one) showed that if you exposed them to a higher level of CO2, the structure of their leaves changed. Ancient fossil leaves showed just such changes. Several kinds of chemical studies confirmed that the level of the gas had swung widely over geological ages, and the temperature too."

"Eventually geochemists and their allies managed to get numbers for the “climate sensitivity” in ancient eras, that is, the response of temperature to a rise in the CO2 level. Over hundreds of millions of years, a doubled level of the gas had always gone along with a temperature rise of three degrees, give or take a couple of degrees. That agreed almost exactly with the numbers coming from many computer studies."



The author Spencer R. Weart is a physicist and historian, Director of the Center for History of Physics of the American Institute of Physics (AIP) in College Park, Maryland.  

Having researched the subject in detail and monitored emerging developments (and being qualified to do so), his own conclusions regarding global warming are posted here:

http://www.aip.org/history/climate/SWnot...

Here's more detail on his take on our prospects:

Impacts of Global Warming

http://www.aip.org/history/climate/impac...

His site is very comprehensive, accounting for nearly all of the theories presented by skeptics.  The interesting thing is that they're placed in their historical context, relying as they did on what was not known at the time.  It's fascinating to see past partial understanding or misunderstanding presented out of context today, as if no science has occured in the meantime.

Mars is thought to be undergoing a minor heating, but that's thought to be due to dust storms (albedo change).  Funny that earth warming has been claimed not to be happening in spite of thousands of stations measuring global trends over 100+ years, yet the skeptics quickly accept scant Mars data without question, so they can claim it disproves earth's anthropogenic heating.

Have you seen evidence that Venus is warming?  The report would probably be acompanied by a threory why.  Venus is an interesting data point on carbon dioxide's strength as a greenhouse gas:

"It is interesting to note that in the absence of a greenhouse effect, the earth’s mean temperature would have been 255°K, instead of the observed value of 288°K. Greenhouse warming is thus about 33°K.  This is much more pronounced around the planet Venus, whose atmosphere contains over 90% carbon dioxide (CO2), a prominent greenhouse gas. Without a greenhouse effect the mean surface temperature of Venus would have been 227°K, but greenhouse warming raises it to 750°K. This represents warming by 523°K!"

http://www.ias.ac.in/resonance/Mar1996/p...

Stephen Hawking: Earth Could Become Like Venus

http://www.livescience.com/environment/a...

Answer 5

NASA is kind of fishy.  Ive seen proponents posting info from NASA stating the suns strength is actually increasing, some stating it is decreasing.  Some said the next solar cycle will be the weakest, some are saying it will be the strongest.  The best part is, the proponents often dont know what the effects of the sun are, between minimum and maximum.  Yes it is true that the sun is no more luminous during a maximum, but its xray and UVray output doubles from minimum to maximum, and we dont understand what kind of impact that has.  Some have theorized that elevated UV ray outputs increase the amount of ozone in the upper atmosphere, which serves as a greenhouse gas.

The last ice age ended because of the milankovitch cycles, the same way the last ice age started.  The main mechanism is the 96,000 year cycle of the change in eccentricity in our orbit.  At maximum, there is 23% less sunlight while the earth is at its farthest points.  When the farthest points from the sun happen to align with the northern hemisphere summers,  we get summers where last winters snow pack doesnt melt.  The summers are cold, and the winters are even colder.  Soon, you have 1000 feet of snow that doesnt melt during the summer because it never gets warm enough, there is your ice age.  Right now, the eccentricity causes is to get 7% less sunlight during two seasons of the year, I dont know which ones though.

How do dust storms raise the temp on mars?  Just curious.  I would assume the serve as a sun blocker/difuser.

Asker:  Cloud cover might serve as insolation in the winter, but during the summer, what do they do?  They cool the area by reflecting sunlight, and sometimes causing precipitation, which draws heat out of the air.   And the constant cloud cover over the ice sheets cant be helping that much, its still -10'f or lower.  Go to weather.com, using the interactive map, look at cloud cover over the entire globe.  There is a persistent cloud cover over the the icey continents, including russia and canada right now.