Global Warming - Scientific evidence

[shaunbhoy]

long term linear trend using all the satellite data - about 30 years - is +0.18C / decade, in line with climate model projections.

Long Term?? 30 Years??
Give me a forking break!!

[DimPrawn]

Exactly, the satellite record is a noisy signal, and so you need to take a long enough sample to average out the noise due to such influences as El Nino (and La Nina). The long term linear trend using all the satellite data - about 30 years - is +0.18C / decade, in line with climate model projections.

And that is a man-made gradual warming as opposed to a gradual natural warming because......?

What did the satellite data show for the trend before 30 years ago?

[BlasterBates]

Exactly, the satellite record is a noisy signal, and so you need to take a long enough sample to average out the noise due to such influences as El Nino (and La Nina). The long term linear trend using all the satellite data - about 30 years - is +0.18C / decade, in line with climate model projections.

Roy Spencer compiles the Satellite data check his website out:

Satellite Trend

Average rise is 0.3 degrees over 30 years.

This is almost identical to the rise between 1910 and 1940, a period in which CO2 had no neglible effect.

The 0.6 is an exaggeration from the GISS records, which is in dispute. The 0.3 rise puts a different light on the Warming since 1979, in that it isn't significantly different than the last warming period.

One of the drivers of the dispute was the difference between Satellite measurements and land/sea measurements. It didn't add up.

Note the 2010 El Nino peak is less than the 1998 peak (now cooling off), just happened a month earlier.

[Moscow Mule]

What did the satellite data show for the trend before 30 years ago?

It was flat...

[pjclarke]

The point at which a trend becomes statistically significant is a function of the length of the trend and the amount of noise, for the global temperature, it generally takes 15-20 years of data. Prior to 1979 we are reliant on weather stations, ships and buoys. http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.lrg.gif

There was a small CO2 forcing in 1910-40, but about half the warming is attributed to an increase in solar activity.

The satellite and surface data actually agree remarkably well. It is very likely that most of the recent warming is manmade for several reasons: the spatial distibution matches that predicted for greenhouse warming - for example the stratosphere is cooling while the lower atmosphere warms - a 'fingerprint' of greenhouse warming, we can estimate the size of the radiative imbalance caused by the increased Greenhouse gases and the observed warming matches it pretty closely. Other natural drivers, e.g. solar variability have actually been negative over the period. And so on and so forth. This 'gradual' warming is actually an order of magnitude faster than anything in the historical record, CO2 is higher than it has been for at least 600K years and is rising at a rate 100x faster than anything in the record.

Click, click and click.

[DimPrawn]

The point at which a trend becomes statistically significant is a function of the length of the trend and the amount of noise, for the global temperature, it generally takes 15-20 years of data. Prior to 1979 we are reliant on weather stations, ships and buoys. http://data.giss.nasa.gov/gistemp/graphs/Fig.A2.lrg.gif

There was a small CO2 forcing in 1910-40, but about half the warming is attributed to an increase in solar activity.

The satellite and surface data actually agree remarkably well. It is very likely that most of the recent warming is manmade for several reasons: the spatial distibution matches that predicted for greenhouse warming - for example the stratosphere is cooling while the lower atmosphere warms - a 'fingerprint' of greenhouse warming, we can estimate the size of the radiative imbalance caused by the increased Greenhouse gases and the observed warming matches it pretty closely. Other natural drivers, e.g. solar variability have actually been negative over the period. And so on and so forth. This 'gradual' warming is actually an order of magnitude faster than anything in the historical record, CO2 is higher than it has been for at least 600K years and is rising at a rate 100x faster than anything in the record.

Click, click and click.

This would never have happened under the Tories.

[pjclarke]

Another resource

AH - you may find this more useful.

[BlasterBates]

The satellite and surface data actually agree remarkably well.

No they don't check out Roy Spencer's website.

It shows an increase of 0.3 not 0.6

Roy spencer & John Christy compile all the data from the satellites. In Fact even in recent years the 13 the month average has done back to 0.

This is quite different from the land temperatures.

Differences between land temps and Satellite

...and that is the precise cause of sceptics trying to get the raw data from the CRU's. Everyone trusts the satellite measurements but not the land temps and they tell a very different story.

[Bagpuss]

Dosn't seem a very independant article to quote. Far too subjective! Bit surprised by you Blasterbates clutching at those sort of straws

[BlasterBates]

Dosn't seem a very independant article to quote. Far too subjective! Bit surprised by you Blasterbates clutching at those sort of straws

Anyone who challenges the GISS temps will be seen as biased, that's how the debate is at the moment.

Watts is a respected climate sceptic

But you can verify yourself at Roy Spencers website:

http://www.drroyspencer.com/latest-global-temperatures/

This website displays the satellite temps, and if you compare to GISS you can see the difference, and you can see Watts is correct.

Roy Spencer actually compiles the Satellite temp data, so that's a valid source.

The point is that GISS and Satellite temps don't agree and you can verify yourself by looking at the data. That isn't actually in dispute. What is in dispute is that the difference is due to "adjustments" i.e. cutting out temp stations and "adjusting" the data to compensate.

The sceptics argue that GISS and Satellites should be in sync, and I think they have a valid point.

The CRU's always display GISS or overlay the Satellite data on top of GISS changing the scale so it looks like they agree, i.e. "well its a similar shape". Looks good in an IPCC report but hides the glaring difference, that needs to be explained. i.e. why did they diverge, and if you had a temperature set that did correspond to the Satellite you couldn't claim the warming was unprecedented which would kind of dent the whole AGW ethos.