Why is global warming not uniform around the globe?

Question

Actually I have two questions one is about the title and one is about consistency with the surface record.

OK, I don't expect absolute uniformity, obviously, but if CO2 is the main driver of global warming, then I would expect something pretty close to uniformity as greenhouse gases are distributed pretty much evenly.

See, the northern hemisphere (according to UAH) has warmed since 1978 at 0.21oC/decade, whereas the southern hemisphere has warmed much slower, at just 0.07oC/decade. The north pole has warmed at a whopping 0.46oC/decade, and yet the south pole has cooled at -0.07oC/decade.

What could account for these huge differences between different parts of the globe? Does it not imply something else is at work? Something maybe a bit more chaotic? If its mainly CO2, then any differences from the overall warming are from other factors, so there has been 0.07oC/Decade additional warming in the NH, and 0.07oC/Decade relative cooling in the SH. The north pole has additionally

Answer 1

First I must object to the premise of your qeustion.  It implies that global warming is an independent process, completely removed from global cooling.  In modern discussion, "Global warming" also means "human contributions to global warming."  I do not accept the premise that the globe is continually getting warmer (look at the data over the last 6 years and you'll we've not been as hot, taking aglobal average, as were 7 years ago), nor that humans are the only contributing factor.  Or, look again at the historical cycle of ice ages and melts.  To talk about global warming independently of a larger view of global climate change leads to inanswerable questions, or to answers that only appeal to a small subset of the poulation.  

Now for your specifics --

When thinking about non-uniformity, consider surface factors.  Have you ever stood barefoot in an empty Texan  Walmart parking lot at 4PM in the middle of July?  That's hot!  If you walk across the street there is a green lawn that gets watered every day at 4PM.  The air temperature hasn't changed, nor the greeenhouse gasses, but the grass is much cooler than the asphalt.  So one thing that drives dysuniformity is the complexity of the global surface.  Should we base our global warming trends on the asphalt temperature or the lawn temp?  Should it be proportionate?  Who has the clout to determine waht those proportions should be?  Greenhouse gasses can be at the interface with surface factors, but mainly they reside in the atmosphere.  Surface temperatures are really what we're measuring when we're trying to get a feel on global warming anyway (OK, some people have started reading atmospheric temperatures, but that's not what the focus in on right now.

What other surface factor explains your concerns?  I'll give you a hint - it covers 2/3 of the planet.  Where is most of the water located?  In the southern hemisphere.  Water refelcts more light and heat than land does so we'd it expect it not to warm as quickly.  Where are our largest forests?  Although they are being regretfully laid waste, it is still the South American continent, Australia, and SE Asia where undisturbed trees are to be found (with honorable mention to our friends in the great white north, mainly unspoiled conifers of Siberia and Alaska and a few other places).  But forests provide means of decreasing the CO2:O2 ratio.

Now there are innumerabel other factors that come into play, but remember where we're measuring heat and what is aroudn it.  The earth's surface plays a huge role.  Other things to factor in: population, polution, wildliife, agriculture, plankton, solar falres, solar cycles, cosmic rays, water, clouds and ice.

Good question, though.  Keep it up.

Answer 2

The NH is warming faster than the SH because it's got more land area.  This is actually an expected result which has been predicted for decades, as discussed here:

http://www.realclimate.org/index.php/arc...

Answer 3

the world dose not necessarily need to warm uniformly. warming could effect currents and even lead to cooling in some places.

Answer 4

Well, first of all, the difference you cite is not huge.  When you convert to absolute temperatures, .21 K increase for an average earth surface temperature of 288 K is around 0.07%, and a .07 K increase is around 0.02%.  So the difference really isn't that great.  The southern hemisphere is cooler than the north for reasons completely unrelated to global warming, and therefore is likely to heat slower.