Iceagenow Blog Complains that Record Lows Are Being Ignored

[WeatherRusty]

2C is their low end bound and I could see that happening by 2100, though I think I'd favor slightly under that at this point. Their business as usual scenario had a mean of 3.6C of warming above 1990-1999 mean temps by 2100...their A1B scenario was about 2.8C.

These projections depend ultimately on the actual radiative forcing to be realized based on various assumed emission scenarios AND the uncertainty in climate sensitivity. Notice the range of uncertainty involved.

• Scenario B1
  
  • Best estimate temperature rise of 1.8 °C with a likely range of 1.1 to 2.9 °C (3.2 °F with a likely range of 2.0 to 5.2 °F)
    
  • Sea level rise likely range [18 to 38 cm] (7 to 15 inches)
    

  [*]Scenario A1T

  • Best estimate temperature rise of 2.4 °C with a likely range of 1.4 to 3.8 °C (4.3 °F with a likely range of 2.5 to 6.8 °F)
    
  • Sea level rise likely range [20 to 45 cm] (8 to 18 inches)
    

  [*]Scenario B2

  • Best estimate temperature rise of 2.4 °C with a likely range of 1.4 to 3.8 °C (4.3 °F with a likely range of 2.5 to 6.8 °F)
    
  • Sea level rise likely range [20 to 43 cm] (8 to 17 inches)
    

  [*]Scenario A1B

  • Best estimate temperature rise of 2.8 °C with a likely range of 1.7 to 4.4 °C (5.0 °F with a likely range of 3.1 to 7.9 °F)
    
  • Sea level rise likely range [21 to 48 cm] (8 to 19 inches)
    

  [*]Scenario A2

  • Best estimate temperature rise of 3.4 °C with a likely range of 2.0 to 5.4 °C (6.1 °F with a likely range of 3.6 to 9.7 °F)
    
  • Sea level rise likely range [23 to 51 cm] (9 to 20 inches)
    

  [*]Scenario A1FI

  • Best estimate temperature rise of 4.0 °C with a likely range of 2.4 to 6.4 °C (7.2 °F with a likely range of 4.3 to 11.5 °F)
    
  • Sea level rise likely range [26 to 59 cm] (10 to 23 inches)
    

[ORH_wxman]

These projections depend ultimately on the actual radiative forcing to be realized based on various assumed emission scenarios AND the uncertainty in climate sensitivity. Notice the range of uncertainty involved.

Right...their upper bound is pretty unrealistic IMHO. I can see their lower bounds being correct, but they seem to skew everything high. Recent papers have said how their higher end estimates are not very realistic.

[WeatherRusty]

How much warming would have to occur to catch up to model predictions? When you figure that we are likely headed for 2 or 3 decades of stagnating if not cooling global temps, we are only going to get further from predicted.

Sorry, but you are not logically permitted to assume 2 or 3 decades of stagnating if not cooling global temps if that in essence is what we are arguing. You are assuming you have won the argument before you have and then using that unsubstantiated supposition as partial proof of your original argument. No fair!

But to answer your question, at this point we would need to make up about 0.1C due to a suppression in temps from solar minimum and a preponderance of La Nina conditions over the past couple years.

Global temp was expected, based on a strictly linear temperature rise ( not realistic), to have risen by 0.2C over the past decade. It rose about 0.1C, but I know you will argue against that too.

[ORH_wxman]

Sorry, but you are not logically permitted to assume 2 or 3 decades of stagnating if not cooling global temps if that in essence is what we are arguing. You are assuming you have won the argument before you have and then using that unsubstantiated supposition as partial proof of your original argument. No fair!

But to answer your question, at this point we would need to make up about 0.1C due to a suppression in temps from solar minimum and a preponderance of La Nina conditions over the past couple years.

Global temp was expected, based on a strictly linear temperature rise ( not realistic), to have risen by 0.2C over the past decade. It rose about 0.1C, but I know you will argue against that too.

We actually haven't warmed at all in the past decade...but since the start of 2000, the trend has been 0.07C per decade according to GISS.

[WeatherRusty]

Right...their upper bound is pretty unrealistic IMHO. I can see their lower bounds being correct, but they seem to skew everything high. Recent papers have said how their higher end estimates are not very realistic.

I see no valid reason to preclude either a high or lower outcome based on just a few years of data. Based simply on statistical analysis the most likely outcome is in the mean, but I know nature couldn't care less about statistics.

The IPCC assesses the available literature with regard to studies seeking to determine climate sensitivity. A Google scholar search returns this large list of studies.

SEE

As you can see, there has been no lack of studies which attempt to assess the value for sensitivity. The 2C-4.5C represents the best determination by the IPCC for the likely range based on these studies. One thing to notice, is that climate sensitivity can not be determined with confidence strictly by observation of present climate. If it were that easy we would likely not be having this conversation. Yet you are utilizing the past several years as reason to doubt the consensus of all those studies.

[WeatherRusty]

We actually haven't warmed at all in the past decade...but since the start of 2000, the trend has been 0.07C per decade according to GISS.

Depends on how you look at it. How could 8 or 9 of the past 10 years have been the warmest in the instrument record if that 10 year period were not the warmest in the record?

[ORH_wxman]

Depends on how you look at it. How could 8 or 9 of the past 10 years have been the warmest in the instrument record if that 10 year period were not the warmest in the record?

"Not warming" doesn't mean cooling. We haven't cooled so we are still flirting with the hottest years on record.

[ORH_wxman]

I see no valid reason to preclude either a high or lower outcome based on just a few years of data. Based simply on statistical analysis the most likely outcome is in the mean, but I know nature couldn't care less about statistics.

The IPCC assesses the available literature with regard to studies seeking to determine climate sensitivity. A Google scholar search returns this large list of studies.

SEE

As you can see, there has been no lack of studies which attempt to assess the value for sensitivity. The 2C-4.5C represents the best determination by the IPCC for the likely range based on these studies. One thing to notice, is that climate sensitivity can not be determined with confidence strictly by observation of present climate. If it were that easy we would likely not be having this conversation. Yet you are utilizing the past several years as reason to doubt the consensus of all those studies.

A lot of those are pretty old studies. Doesn't mean they are uselss, but I prefer to look at newer studies like Schmitter et al that place the most likely sensitivity per doubling in the 1.7-2.6C range.

Observations are important even if they can't tell us everything about the future. We've warmed at 0.07C per decade in the 2000s so far. For the sake of argument, we'll assume we warm another 0.15C per decade between now and 2030 (that is doubling our current rate of warming) which would bring us to 0.35C of warming in the 21st century. So in order to reach the middle range of aorund 3C of warming for this century per IPCC AR4 models...we'd have to warm at an average rate of nearly 0.4C per decade after 2030...which I am having a hard time believing will happen.

But hey, maybe we'll more than double our current warming rate too between now and 2030 and then we'd need a lesser rate after that...but on the flip side, we could also warm less than 0.15C per decade over the next 18 years which would make it even tougher to achieve those numbers by 2100.

[WeatherRusty]

A lot of those are pretty old studies. Doesn't mean they are uselss, but I prefer to look at newer studies like Schmitter et al that place the most likely sensitivity per doubling in the 1.7-2.6C range.

Observations are important even if they can't tell us everything about the future. We've warmed at 0.07C per decade in the 2000s so far. For the sake of argument, we'll assume we warm another 0.15C per decade between now and 2030 (that is doubling our current rate of warming) which would bring us to 0.35C of warming in the 21st century. So in order to reach the middle range of aorund 3C of warming for this century per IPCC AR4 models...we'd have to warm at an average rate of nearly 0.4C per decade after 2030...which I am having a hard time believing will happen.

But hey, maybe we'll more than double our current warming rate too between now and 2030 and then we'd need a lesser rate after that...but on the flip side, we could also warm less than 0.15C per decade over the next 18 years which would make it even tougher to achieve those numbers by 2100.

One thing I lack an understanding of is how they determine the rate of warming. Presumably the rate is an emergent quantity produced by the models, but what is the physical explanation for why 0.2C is expected over the next couple decades with likely higher rates later on?

Climate sensitivity assumes equilibrium has been reached. IF scenario X projects a certain warming by 2100, how do they know when equilibrium with a given forcing will have been attained? If the rate is slower, the projected temperature could be reached nearer 2150 rather 2100 for instance.

[ORH_wxman]

One thing I lack an understanding of is how they determine the rate of warming. Presumably the rate is an emergent quantity produced by the models, but what is the physical explanation for why 0.2C is expected over the next couple decades with likely higher rates later on?

Climate sensitivity assumes equilibrium has been reached. IF scenario X projects a certain warming by 2100, how do they know when equilibrium with a given forcing will have been attained? If the rate is slower, the projected temperature could be reached nearer 2150 rather 2100 for instance.

I am unclear on where they get this as well. They certainly predict an acceleration of the warming when looking at the decade by decade trends. They seem to start with a rate around 0.25C per decade in the first 20-30 years of this century and then by the end of the century between 2080-2100 it is around 0.45C per decade. I am assuming they have some pretty strong positive feedback in there.

[FloridaJohn]

I am unclear on where they get this as well. They certainly predict an acceleration of the warming when looking at the decade by decade trends. They seem to start with a rate around 0.25C per decade in the first 20-30 years of this century and then by the end of the century between 2080-2100 it is around 0.45C per decade. I am assuming they have some pretty strong positive feedback in there.

I had always assumed the rate had something to do with accelerated population growth and the increased CO2 emmisions associated with that.

Here is world population growth estimates from the UN:

And here is the IPCC projections:

[WeatherRusty]

I had always assumed the rate had something to do with accelerated population growth and the increased CO2 emmisions associated with that.

Here is world population growth estimates from the UN:

I was referring to the rate at which the oceans equilibrate with the radiative forcing. This rate would depend a lot on the rate of deep sea mixing with surface water on a global scale. Variables such as ENSO will alternately speed up and slow down the process. Surface water salinity is another which impacts the thermohaline circulation and the the rate of mixing to depth.

The rate of average SST increase spread across many decades depends on the rate at which the ocean overturns. For instance, if the deep ocean is currently absorbing a significant proportion of the energy represented by the TOA imbalance, how long until that energy is reflected in SSTs? This factor must be important in determining the rate of surface warming and by when the system reaches thermal equilibrium with a given radiative forcing.

Let's assume an equilibrium climate sensitivity of 2.7C for a doubling of CO2. How do we know by what time in the future that full response will be realized? If by 2060 CO2 concentration has reached 560ppm or a doubling of CO2 over preindustrial level, will the 3.7w/^2 forcing be fully equilibrated by 2100? 2150?

Maybe we should be expecting 0.14C/decade rather than 0.20C.

[Conclue]

Ongoing warming is increasing the probability of extreme heat. In other words the same pattern today produces warmer readings than the same pattern of 30 years ago. To illustrate what I mean, let's use the probability of a 100° day in Washington, DC as an example.

Since the 1961-1990 base period, the statistical probability of a 100° day in Washington, DC has increased 37.8% (1981-2010 base period). That increase is continuing. If one takes the most recent 30-year period (1983-2012), the statiscal probability of a 100° day in June has increased further. It is now 52.2% above the statistical probability for the 1961-1990 base period.

The increasing probability of warmth is not confined to local areas. It is global, with the greatest increase in probability occurring in the Arctic region where Arctic temperatures are decoupling from the earlier tight relationship with the AMO.

Below is a chart that compares the June outcome for ENSO and teleconnections similar to those of June 2012 and the June 2012 outcome. Consistent with the ongoing warming, one finds a much warmer outcome in 2012 than had been the case with similar ENSO-teleconnections in the past.

In sum, the synoptic situation led to the June 2012 outcomes. However, climate change led to a warmer outcome than would otherwise have occurred. That outcome is not a matter of random chance.

I really just salute you right now. I lurk more than I post and am very familiar with your presence on the forums, but this made me want to shout. Your explanations are so well poised and articulate while bringing complicated explanations to a simple level for everyone to understand. I would have had to go around the bush five times to get it out as easily as you did, lol. Kudos!

[donsutherland1]

In a blog post, Steven Goddard complains that GISS shows the Arctic region warmer in the 1970s than the earlier warm cycle that peaked in the 1940s. He wrote, "Unless the freezing point of water has changed, the earlier period must have been warmer. Yet when we look on Hansen’s graphs, it appears that the period from 1900 to 1940 was much colder than the 1970s." He included a graph that purportedly backs his opinion.

However, if one looks more closely, the graph he uses shows GISS global land and ocean temperatures, not Arctic region temperatures. In fact, the actual GISS data for the Arctic region (64N-90N) clearly shows the earlier warm cycle. In other words, Mr. Goddard's attack aimed at discrediting GISS is baseless.