Why do people consider La Ninas weather, and El Ninos part of global warming?

Question

If we make the assumption that this La Nina that has reduced temperatures world wide is not affected by co2 emissions, then why can we not also make the reasonable assumption that El Ninos are also not effected by co2 emissions? Wouldn't the large amount of El Ninos we experienced during that past 30 years pushed the average temperatures up?

http://icecap.us/images/uploads/ENSOTEMPS.jpg

Answer 1

Real-time data from moored ocean buoys for improved detection, understanding and prediction of El Niño and La Niña.  

El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific having important consequences for weather around the globe.

El Niño can be seen in Sea Surface Temperature in the Equatorial Pacific Ocean

December 1998 was a strong La Niña (cold) event. The cold tongue (blue) is cooler than usual by about 3° Centigrade. The cold La Niña events sometimes (but not always) follow El Niño events.

so El nino is a part of globle warming after pollution temprechure is going hot and ice is melt it is more effcted by ELnino

Answer 2

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Answer 3

They don't.  The five year average pretty much smooths those out.  

This was an even better question from you, that explains my answer more.

"Maybe you did not understand my question. Doesn't the El Nino event of 1998 push the average five year temperatures up. In other words if the La Nina of 1998, and other strong La Ninas, never occurred, what would be the average five year temperature trends. Would they not be lower?"

Not a lot.  1998 was maybe 0.2 warmer than average.  In a 5 year average that's a change of 0.04 degree.  And it's pretty much compensated for by the fact  that both 1999 and 2000 were well below average.

The ultimate test is just to chop out 1993-2002 from the graph, removing 1998 from all the 5 year averages.  The 30 year trend up would still be there.  The 10 year hole in the middle would have an obvious way to fill it in.

So, cutting out 1998 is actually a very good way to look at it, and see that any one year just isn't that important.

Good question.

Answer 4

They're not.  In fact the same people talking about "global cooling" due to La Nina talk about no warming since 1998 because of the strong El Nino that year.

ENSO does not change the long-term temperature of the planet because El Nino and La Nina and other such oscillations don't directly generate heat, nor do they have the capacity to retain it.  See Trevor's excellent explanation here:

http://answers.yahoo.com/question/index;...

By the way there is a much better graph of El Nino vs. La Nina here:

http://www.cdc.noaa.gov/ENSO/enso.mei_in...

*edit* Yes the El Nino of 1998 pushed the 5-year temperature up slightly, just like the La Nina of 2007-2008 will push it down slightly.  In the long-term these effects essentially cancel eachother out.  Just look at 1999-2002 which was mostly La Ninas and yet the 5-year average continued upward.

http://data.giss.nasa.gov/gistemp/graphs...

This is why we look at long-term averages, because over the long-term, these sorts of cycles cancel eachother out and you're just seeing the impact from the long-term forcings like greenhouse gases and solar irradiance and such.

There's also the question as to whether global warming impacts these oscillations.  I don't think we have an answer to that question yet.

Answer 5

But carbon dioxide has a means of retaining heat?  Dana are you saying that la nina and el nino don't generate heat but co2 does?  

I think that we get cold on a daily basis as does carbon dioxide.  Where people get off blaming carbon dioxide for any warming trend is beyond reason.

Give a scientist a living wage and he will give you knowledge.  Give him wealth and he will give you anything you want.

Answer 6

It's not merely an assumption that this La Nina has reduced the global average temperature.  All you have to do is look at the following plot, and it's clear that the cold water (known to come from deep in the Pacific by the coast of South  America) is lowering the global average surface temperature.

http://ingrid.ldeo.columbia.edu/maproom/...

But neither La Nina, nor El Ninos are technically part of the global warming "climate change" that concerns us.  The La Nina will have a global cooling effect and the El Nino will have a global warming effect, but neither is considered part of climate change. They are both short-term (generally not more than a year) weather factors.  1998 was above the climate warming trend line because of the strong 1998 El Ninos and 2008 will possibly be below the climate warming trend line because of the current La Nina.  But neither year or event as any significant impact on the 30 year (period of interest generally associated with climate) warming trend line.  They are both weather noise.

Answer 7

El Ninio and La Ninas are caused by shifting ocean currents off the west coast of the Americas.  Oceans and especially the currents are the heat pumps of the earth.  Oceans, along with weather systems, move energy (heat) from the equator to the poles.  These are all very intertwined with GW.  The ocean influences climate, but the climate also influences the the oceans.  it is very difficult to unravel and this is an area of major focus for climatologist.  The timing of the cycles of El Ninos and La Ninias may be partially a result of GW and may enhance or offset warming.  The ocean, which covers most of the planet and does a lot to keep an even moderate climate is probably one of the biggest factors in climate change.  This is also probably the area we least understand (my opinion - but I'm not an oceanographer) and is the hardest to account for in the estimates.  It can be a sink or source for co2 and heat.The shifting of the currents changes as the temperatures of the waters in various parts of the world change and this may greatly alter heat distribution.  Could help reduce warming or enhance it.  We don't have a high degree of confidence in our ability to predict in this area.

Answer 8

Both El Niño and La Niña are weather events, not climate events. In the long term, the Southern Oscillation Index, or SOI, will (in fact, MUST) have an average of zero. So in the long term, El Niño and La Niña will cancel each other out. The number of El Niño events over the last 30 years are in no way exceptional, and the same is true of La Niña events.

If you subtract out the effects of El Niño and La Niña from the climate record, along with other transitory events like large volcanic eruptions and the solar cycle, the net result is a  linear upward trend in the average temperature, caused by increased CO2 in the atmosphere.

http://arxiv.org/ftp/physics/papers/0411...