Solar variability weakens the Walker cell

Tallbloke's Talkshop

Credit: PAR @ Wikipedia
This looks significant, pointing directly at solar influences on climate patterns. The researchers found evidence that atmosphere-ocean coupling can amplify the solar signal, having detected that wind anomalies could not be explained by radiative considerations alone.

An international team of researchers from United Kingdom, Denmark, and Germany has found robust evidence for signatures of the 11-year sunspot cycle in the tropical Pacific, reports

They analyzed historical time series of pressure, surface winds and precipitation with specific focus on the Walker Circulation—a vast system of atmospheric flow in the tropical Pacific region that affects patterns of tropical rainfall.

They have revealed that during periods of increased solar irradiance, the trade winds weaken and the Walker circulation shifts eastward.

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Hurricanes & climate change: 21st century projections

Climate Etc.

by Judith Curry

Final installment in my series on hurricanes and climate change.

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The Physical Flaws of the Global Warming Theory and Deep Ocean Circulation Changes as the Primary Climate Driver

by William M. Gray

Professor Emeritus Department of Atmospheric Science Colorado State University        Fort Collins, CO 80523

Prepared for the Heartland Institute’s 7th International Conference on Climate Change (ICCC-7) Chicago, IL during May 21-23, 2012

Paper also available at (




Increases in CO2 and other greenhouse gases will not be able to bring about significant climate disruption in the next 75-100 years. The main problem with the Anthropogenic Global Warming (AGW) theory is the false treatment of the global hydrologic cycle which is not adequately understood by any of the AGW advocates. The water vapor, cloud, and condensation-evaporation assumptions within the conventional AGW theory and the (GCM) simulations are incorrectly designed to block too much infrared (IR) radiation to space. They also do not reflect-scatter enough short wave (albedo) energy to space. These two misrepresentations result in a large artificial warming that is not realistic. A realistic treatment of the hydrologic cycle would show that the influence of a doubling of CO2 should lead to a global surface warming of only about 0.3°C – not the 3°C warming as indicated by the climate simulations. The global surface warming of about 0.7°C that has been experienced over the last 150 years and the multi-decadal up-and-down global temperature changes of 0.3-0.4°C that have been observed over this period are hypothesized to be driven by a combination of multi-century and multi-decadal ocean circulation changes. These ocean changes are due to naturally occurring upper ocean salinity variations. Changes in CO2 play little role in these salinity driven ocean climate forcings.

1. The Earth’s Energy Budget

Although rises in CO2 act to block the normal long wave infrared (IR) radiation to space, this blockage is very small compared to the globe’s basic energy budget system. About 3.7 Wm-2 of IR energy is intercepted for a doubling of CO2 (Figure 1). Since the mid-19th century, CO2’sinfluence on IR blockage has increased by ~ 1.4 Wm-2 or 0.6 of 1 percent of the continuous average IR flux to space of 235 Wm-2. The continuous balancing of global average in-and-out net radiation flux is, by contrast, about 342 Wm2, almost 100 times larger than the amount of radiation blockage expected from a CO2 doubling over 1.5 centuries. A doubling of CO2 requires a warming of the globe of ~1°C to enhance outward IR flux by 3.7 Wm-2 to just be enough to balance the blockage of IR flux to space if all other factors are held constant.

But this pure IR energy blocking by CO2 versus compensating temperature rise for radiation equilibrium is unrealistic for the long-period and slow CO2 rises that are occurring. Only half of the blockage of 3.7 Wm-2 at the surface should be expected to go into temperature rise. The other half (~1.85 Wm-2) of the blocked IR energy to space will be compensated by surface energy loss to support enhanced evaporation. This occurs in a similar way as the earth’s surface energy budget compensates for half its solar gain of 171 Wm-2 by surface to air upward water vapor flux due to evaporation.

Note in Figures 1 and 2 that the globe’s annual surface solar absorption of 171 Wm-2 is balanced by about half going to evaporation (85 Wm-2) with the other half (86 Wm-2) going to surface to atmosphere upward IR (59 Wm-2) flux and surface to air upward flux by sensible heat transfer (27 Wm-2). Assuming that the imposed extra CO2 doubling IR blockage of 3.7 Wm-2 is taken-up and balanced by the earth’s surface as the solar absorption is taken-up and balanced, we should expect a direct warming of only ~ 0.5°C for a doubling of the CO2. The 1°C expected warming that is commonly accepted assumes that all the absorbed IR goes to balancing outward radiation (through E = σT4) with no energy going to evaporation. This is not realistic. These two figures show how equally the surface solar energy absorption (171 Wm-2) is balanced by a near equal division between temperature rise (enhancing IR and sensible heat loss) and energy loss from surface evaporation. We should assume that the imposed downward IR energy gain for a doubling of CO2 at the surface will likely be similarly divided. Such a division will cause an enhancement of the strength of the hydrologic cycle by about 2 percent (or 1.85 Wm-2 of extra global average evaporation over the ~ 85 Wm-2 energy equivalent of current evaporation).

This analysis shows that the influence of doubling atmospheric CO2 by itself (without any assumed positive feedback) leads to only very small amounts of global warming.

Fig 1

Figure 1. Vertical cross-section of the annual global energy budget as determined from a combination of ISCCP (discussed later) and NCEP reanalysis data over the period of 1984-2004. Note on the right, how small is the OLR (or IR) blockage that has occurred up to now due to CO2increases (~ 1.4 Wm-2) and how relatively small is the blockage of 3.7 Wm-2 that is estimated to occur when a doubling of CO2 takes place by the end of this century. Compare how small are these CO2 induced IR changes in Wm-2 to the global average solar impingement of 342 Wm-2units of incoming solar energy, 235 Wm-2 of outgoing IR (or OLR), 107 Wm-2 of outgoing short-wave albedo flux, and 171 Wm-2 of surface solar absorption. Without any assumed positive energy feedback from these CO2 increases, very little global warming will occur.

Fig 2

Figure 2. Estimated energy change at the surface of global mean rainfall (2.1% increase) and global mean temperature (~ 0.3°C) when, and if, equilibrium energy balance were established for a doubling of CO2 (and a blockage of IR energy to space of 3.7 Wm-2) with no positive or negative energy feedbacks.

2. Variations of Radiation is only a part of the Climate Change Physics

Internal mechanisms of the global energy budget such as evaporation-condensation and deep global ocean current variations also play an independent role from radiation as a major climate change mechanism (Figure 3). The whole AGW theory and dialog over the years has been based on radiation changes. This is far too narrow and naïve. Other important physical processes are important. Figure 1 shows that half the balancing of the earth’s surface absorption of solar radiation was accomplished by surface evaporation. And evaporation on the shorted time scales is determined primarily by the Bulk Formula as illustrated in Figure 4. Evaporation is dependent primarily on surface wind speed, sea minus air temperature difference, and surface air relative humidity. Evaporation rates are not well related to surface solar absorption on shorted time and space scales. Variations of radiation have been given far too much thought and credit and have carried far too much influence on the conceptual views of the causes of climate change.

Fig 3

Figure 3. Pointing out that climate variation is influenced by other processes besides variations in radiation. Evaporation-precipitation and deep ocean circulation changes also play a basic role.

Fig 4

Figure 4. Illustration of the breakdown of terms in the Bulk Formula (that determines evaporation rate) and their typical global average necessary to give a net average evaporation rate of a little under 0.3 gm/cm2 per day. A doubling of CO2 would bring about a blockage of 3.7 Wm-2 which is equivalent to variation of average global evaporation of about 4.2 percent if all this energy went into evaporation. In this case we could have a double of CO2 and no global warming at all.


3. Nature of Cumulus Convection

The AGW theory and the many AGW global model simulations assume that tropospheric relative humidity (RH) will remain quasi-constant as CO2 induced blockage of infrared (IR) radiation brings about temperature rises. Surface evaporation and rainfall must also increase under these conditions. The temperature and moisture from the CO2 gas increases are programmed in the GCM models to artificially increase the globe’s upper-tropospheric moisture with increased global temperature and rainfall. The resulting extra increased upper tropospheric moisture is assumed to block large amounts of additional outgoing infrared (IR) radiation to space beyond the blockage of CO2 by itself. This consequently leads to significant amounts of extra global temperature increase which is two to three times larger than what the CO2 doubling temperature increase can accomplish alone. Our observational analysis shows that these additional feedback warming assumptions are unrealistic. These incorrect views of convectively induced global warming originated with the National Academy of Science (NAS) report of 1979.

The NAS or Charney Report of 1979. The basic error of the global GCMs has been the model builder’s general belief in the National Academy of Science (NAS) 1979 study – often referred to as The Charney Report- which hypothesized that a doubling of atmospheric CO2 would bring about a general warming of the globe’s mean temperature between 1.5 – 4.5oC (or an average of ~ 3.0oC) (Figure 5). This was based on the report’s assumption that the relative humidity (RH) of the atmosphere would remain quasi-constant as the globe’s temperature increased from CO2’s influence to block IR energy loss to space. The Clausius-Clapeyron equation specifies that as the temperature of the air rises the ability of the air to hold more water vapor rises exponentially. If relative humidity (RH) of the air were to remain constant as atmospheric temperature rose then the water vapor (q) amount in the atmosphere would accordingly rise. The water vapor content of the atmosphere rises by about 50 percent if atmospheric temperatures were to increase by 5oC and relative humidity remained constant. Rising water vapor content, particularly in the upper troposphere greatly reduce the amount of outgoing longwave radiation (OLR) which can escape to space.

Fig 5

Figure 5. The very influential NAS report of 1979 which deduced that any warming of the globe from CO2 increases would occur with constant relative humidity (RH). This would, in general, lead to an additional increase in atmospheric water vapor (q) and decrease outgoing longwave radiation (OLR). But this NAS report did not specifically deal with the water vapor content in the upper troposphere during periods of deep convection.

My colleague, Barry Schwartz and I have performed (Gray and Schwartz, 2010 and 2011) observational research using the NOAA-NCEP reanalysis data from 1950. We have also processed the International Satellite Cloud Climatology Project (ISCCP) data for the period 1984-2004 for infrared (IR) and albedo energy flux to space and used this information in conjunction with the reanalysis data. Figure 6 shows the data sets we have used and Figure 7 shows the areas and locations over which we have combined our data sets with monthly and some daily rainfall information to observe how measured IR and albedo vary with different rainfall amounts. The NAS 1979 Charney Report and the numerical GCM simulations do not stand up to what we have found. Processing this data over the last few years has shown us that:

1. Upper tropospheric water vapor does not increase with increasing amounts of rainfall and temperature near the critical upper level IR emission level (Table 1).

2. Any extra blockage of infrared (IR) radiation to space due to increased CO2, rainfall or cloudiness is usually compensated by increase in albedo from the cloud tops (Figure 8). Increases in global rainfall lead to more net radiation (IR + albedo) flux to space and, all other factors held constant, to a weak global cooling. This is diametrically opposite to the AGW theory and what the GCMs climate simulations indicate.

Fig 6

Figure 6. Data sets used along with the data periods used for analysis. Both reanalysis and International ISCCP observations were analyzed.

Fig 7

Figure 7. Areas and specific locations where we have analyzed outgoing IR and albedo radiation to space vs. rainfall amounts.

Table 1. Changes in 300 mb temperature, specific humidity (q), and relative humidity (RH) in tropical areas between two rainfall difference data sets for the tropics. Rain differences average 3.9 percent for the 10 highest minus 10 lowest monthly differences (top) and 1.9 percent for the [(95-04) – (84-94)] data set differences (bottom). Negative values are in red. All 300 mb moisture parameters showed decreases with enhanced rainfall.

Table 1

The typical enhancement of rainfall and updraft motion in deep cumulus and cumulonimbus clouds within heavy raining meso-scale disturbance areas acts to increase the return flow mass subsidence in the surrounding broader clear and partly cloudy regions (Figure 8). Global rainfall increases typically cause an overall reduction of specific humidity (q) and relative humidity (RH) in the upper tropospheric levels of the broader scale surrounding convection subsidence regions. This leads to a net enhancement of radiation energy to space over the rainy areas and over broad areas of the globe. Albedo is typically decreased to space as much (or slightly more) than IR is increased to space in the broad scale clear and partly cloudy areas. But over the rain and cloudy areas albedo energy to space is increased slightly more than infrared (IR) radiation is reduced to space. The albedo enhancement over the cloud-rain areas tends to increase the net (IR + albedo) radiation energy to space more than the weak suppression of (IR + albedo) in the clear areas. Near neutral conditions occur in the partly cloudy areas (Figure 9).

Our observational studies (Gray and Schwartz, 2010 and 2011) of the variations of outward radiation (IR + albedo) energy flux to space (ISCCP data) vs. tropical and global precipitation increase (from NCEP reanalysis data) indicates that there is not a reduction of global net radiation (IR + Albedo) to space which is associated with increased global or tropical-regional rainfall. There is, in fact, a weak tendency to go the opposite way.

Fig 8

Figure 8. Two contrasting views of the effects of how the continuous intensification of deep cumulus convection would act to alter radiation flux to space. The top diagram emphasizes the increasing extra mass flow return subsidence associated with an ever increasing depth and intensity of cumulus convection. Radiation flux to space increases with enhanced deep convection and rainfall due to a lowering of the upper-level emission level and an increase in albedo. By contrast, the bottom diagram interprets the increase of deep convection (like the GCMs have done) as acting to add moisture to the upper tropospheric levels and cause a decrease of radiation to space. The bottom diagram is not realistic and is the primary reason why the GCMs exaggerate CO2’s influence on global warming.

Fig 9

Figure 9. Typical variations of IR, albedo and (IR + albedo) associated with three different areas of rain and cloud for periods of increased precipitation.

SUMMARY. Our data indicates that, in general, the positive water vapor feedback assumptionsof the GCM global climate simulations for CO2 doubling are not valid. We should put no credence in their projections of large amounts of global warming (~ 3°C) for a doubling of CO2.


4. The Ocean as the Primary Driver for Global Climate Change

This paper hypothesizes that it is variations in the global ocean’s Meridional Overturning Circulation (MOC) that are the primary driver of climate change over the last few thousand years. These changes are manifested in alterations of the deep water formation of the Atlantic Thermohaline Circulation (THC) and the Surrounding Antarctica Subsidence (SAS) regions (Figure 10). Figure 11 shows how the MOC is a combination of the high latitude deep water formation of the Atlantic THC and the Antarctic SAS region. These deep water formation changes are driven by upper ocean salinity variations on various multi-decadal to multi-century time scales. Figure 12 shows typical Atlantic Ocean current differences when the Atlantic THC is strong (and more sinking is occurring) and when it is weak (and less sinking is occurring).

A slowing down of the global ocean’s Meridional Overturning Circulation (MOC = THC + SAS) is the likely cause of most of the global warming that has been observed since the latter part of the 19thcentury. Shorter multi-decadal changes in the MOC are hypothesized to be responsible for the more recent global warming periods between 1910-1940 and 1975-1998 and the weak multi-decadal cooling periods between 1945-1975 and 2000 to the present. This current weak cooling is projected to go on for the next couple of decades. Figure 13 shows the typical parameter circulation features which accompanies periods when the MOC (or THC) is stronger than normal and when it is weaker than normal. Note the typical changes in North Atlantic blocking action, El Nino activity, middle-latitude zonal winds, etc for strong vs. weak phases of the MOC (or THC).

When the MOC (or THC) is stronger than average there is more upwelling of cold water in the South Pacific and Indian Oceans, and an increase in global rainfall of a few percent occurs. This causes the global surface temperatures to cool. The opposite occurs when the MOC (or THC) is weaker than normal. There is less upwelling of cold water, global rainfall is reduced a few percent and the global surface temperature warms.

Fig 10

Figure 10. Idealized representation of the globe’s salinity driven ocean Meridional Overturning Circulation (MOC) which is composed of deep ocean sinking by the North Atlantic Thermohaline Circulation (THC), areas H, and in the Surrounding Antarctic Subsidence (SAS), purple areas X. Figure adapted from John Marshall.

The MOC (or THC) average strength over the last 150 years has likely been below the multi-millennium average and that is the primary reason we have seen this long global warming since the late 19th century. The globe appears to be rebounding from the conditions of the Little Ice Age to more Holocene average or above-average conditions which were typical of the earlier ‘Medieval’ and ‘Roman’ warm periods.

Fig 11

Figure 11. Illustration of how the global ocean Meridional Overturning Circulation (MOC) is defined as a combination of the high north latitude Atlantic Thermohaline Circulation (THC) upper ocean subsidence and the high latitude Southern Hemisphere Surrounding Antarctic Subsidence (SAS) upper ocean subsidence.

Fig 12

Figure 12. Idealized portrayal of the primary Atlantic Ocean upper ocean currents during strong vs. weak phases of the thermohaline circulation (THC).

Fig 13

Figure 13. Portrayal of typical circulation differences that occur with a strong or above average global MOC (or THC) – top, and a below average or weak MOC (or THC) – bottom. Note the many global circulation differences, especially for the North Atlantic blocking action, global rainfall, El Nino activity, etc.

GCMs do not yet accurately model the globe’s deep-water ocean circulation. Accurately modeling the global ocean’s deep circulation is fundamental to any realistic understanding of global temperature change. The multi-decadal global warming periods between 1910-1940 and 1975-1998 and the multi-decadal cooling between 1880-1910, 1945-1975 and 2000-present are hypothesized to be due to Atlantic upper ocean salinity variations (Figures 14 and 15). The longer multi-century warming of the last 150 years is hypothesized to be largely due to the longer period multi-century full global slow-down in the strength of global ocean deep water formation. Both the Atlantic THC and the Antarctic SAS play a role in this multi-century MOC weakening. This long-period combined weakening of the MOC is viewed as being driven by a global upper ocean salinity decrease. CO2changes play little role in these global-scale ocean changes. Figure 15 shows the long global warming curve of the last 130 years with the superimposed multi-decadal periods of up-and-down global temperature change which are superimposed on this longer upward warming cycle.

There is no way we can blame most of the last century’s global warming of 0.7°C on rises in CO2. Most of this long-period temperature rise has been caused by natural climate changes of which humans have played no significant role. This long-period warming of ~ 0.7°C is hypothesized to be a result of the long period slow down of the global ocean’s Meridional Overturning Circulation (MOC) which is driven by natural multi-century variations of upper ocean salinity. The shorter period multi-decadal up-and-down global temperature changes we have experienced during the last 100-150 years are a result of stronger and weaker multi-decadal THC periods driven primarily by Atlantic multi-decadal variations of salinity (Figures 14 and 15).

Fig 14

Figure 14. The global surface temperature change is given by the solid blue line; the dotted blue and dotted red lines illustrate how much error one would have made by extrapolating a multi-decadal cooling or warming trend beyond a typical 25-35 year period of warming or cooling. Note the recent 1975-2000 warming trend has not continued, and we are currently in a weak global cooling period that should continue, I believe, until about 2025-2030.

Fig 15

Figure 15. Idealized portrayal of the negative long-term multi-century THC (or MOC) that we have had since the mid-19th century (purple dotted line) due to the last 150 year weakening of the THC due to global multi-century upper-ocean salinity changes. This has caused the last century-and-a-half mean warming of 0.7°C. Superimposed on this salinity driven long-term ocean circulation warming are the multi-decadal warming and cooling periods shown by the up-and-down red line that is influenced by the multi-decadal variation in the salinity-induced strength of the Atlantic Ocean THC (green line). When the Atlantic THC is weak the globe typically undergoes multi-decadal weak warming periods. When the THC is strong the globe typically experiences weak cooling periods.


5. Failure of the Global Climate Models

AGW theory fails because the basic physics behind it is flawed. Its primary scientific justification has come from global climate model simulations which have serious embedded physical assumption errors. These model assumption errors cause their 75-100 year climate forecast simulations to give unrealistically too high global warming results by a factor as much as 10. These GCMs indicate that when CO2 doubles near the end of this century that the global average surface temperature should increase by about 3°C. All of the 19 global numerical models calculations that were discussed in the latest IPCC-AR4 (2007) report show about the same 3°C global warming for a doubling of CO2 (Figures 16 and 17). If this magnitude of warming were realistic it would bring about a major disruption in our global climate system and severely impact all life on earth. But it is not physically possible for this magnitude of 3°C global warming to occuras a consequence of the doubling of CO2 and a resulting blockage of but 3.7 Wm-2. All the global circulation models have the same major physical flaw which is known as the ‘positive water-vapor feedback loop’. The argument goes like this:

1. Models assume that as CO2 increases to doubling that this causes the atmosphere to warm 1°C in order to send more IR energy to space in order to come into a radiative equilibrium. However, as discussed in section 3, the real warming for a doubling of CO2should be only half this amount (~ 0.5°C). These GCM models then incorrectly assume that as the atmospheric temperatures increase approaches 1°C, that the relative humidity (RH) of the atmosphere remains constant. Any warming with constant RH causes the water vapor content of the atmosphere to rise. This extra assumed water vapor increase resulting from this warming then is assumed (incorrectly) to cause a large additional blockage of IR energy to space. This additional IR blockage due to the extra moisture increase is 2-3 times as large as the original IR blockage from the original CO2 doubling. This is known as the positive water-vapor feedback loop or the needed additional moisture-temperature rise that must occur to keep RH constant while achieving a new radiational equilibrium after CO2 doubles. This extra water vapor gain is needed to maintain constant RH while CO2 doubles. This makes it necessary that IR energy flux to space be further decreased by about twice (~ 7.4 Wm-2) the amount of the original IR blockage from CO2 doubling alone. To accomplish all these changes and maintain their numerical climate model in radiation equilibrium they must increase their global temperatures by an additional 2°C beyond the original 1°C warming needed to balance 3.7 Wm-2.

This strong additional water vapor gain and resulting 2°C temperature increase to obtain radiation equilibrium are not realistic. In fact, our project’s observational analysis (Gray and Schwartz, 2010 and 2011) show that in the critical upper tropospheric RH does not go up as temperature rises and rainfall increases. By contrast, we find that upper level water vapor slightly decreases (Table 1) with additional rainfall and temperature rise. This is a result of the mass balancing upper-level subsidence drying from the return flow of the deep penetrating cumulonimbus (Cb) convective updrafts (Figure 8).

This strong positive water vapor feedback loop which the GCMs rely so heavily on for the largest part of their global warming simulations is not strongly positive as they have assumed all these years, but slightly negative. There cannot be an extra global warming which is twice as large as the original amount of warming coming from the doubling of CO2by itself (if 1°C) or four times as large a warming if the modelers had used the correct 0.5°C warming – as discussed above. This is the huge conceptual error of the GCM numerical simulations and the primary reason why they have so grossly exaggerated the global warming that would result from a doubling of CO2. A number of us have for years been pointing out this massive conceptual error in the GCM simulations. But the modelers take no notice and proceed on with their erroneous GCM simulations and dire future warming predictions.

Fig 16

Figure 16. Scatter plot of the extra global feedback energy increases resulting from water vapor, albedo, cloud, and lapse-rate changes due to a doubling of CO2 from 19 GCMs of the 2007 IPCC-AR4 report. All models give strong positive energy feedbacks equivalent to about 2°C warming.

Fig 17

Figure 17. Comparison of the mean GCM feedback magnitudes (yellow circles) vs. what our observations (Gray and Schwartz, 2010 and 2011) imply as to the magnitude of the various feedback processes (red squares).

We envisage the expected 0.5°C warming from a doubling of CO2 that occurs with enhanced global rainfall to cause a small negative (not positive) feedback of about – 0.2°C, certainly not the positive feedback of 2.0°C that the GCMs indicate. The estimated global temperature change which my colleague (Barry Schwartz) and I project from a doubling of CO2 near the end of the 21st century is only about 0.3°C, which is only about one-tenth of the global warming projected by nearly all of the recent GCM climate simulations (Figure 18).

Fig 18

Figure 18. Comparison of the IPCC-AR4 GCMs prediction of global warming vs. the author’s estimate of global warming when CO2 amounts double near the end of the 21st century.

6. Summary of Basic Climate Change Physics

During the last one-to-two thousand years of the Holocene period when the solar influence of the earth’s changing orbital parameters have been small, it is hypothesized that the back-and-forth variations of the globe’s deep ocean circulation patterns operating on multi-century and multi-decadal time scales can explain most of our globe’s prominent surface temperature variations. Solar variations, sunspots, and cosmic ray changes are energy-wise too small and mostly in the noise level to play a significant role in the large energy changes that occur during these important multi-decadal and multi-century temperature changes as shown in Figures 19 and 20. Figure 21 shows idealized differences of typical strengths of Atlantic THC circulation between the 19th and 20th centuries. It is the weaker 20th century MOC which is hypothesized to have brought about the global warming of about 0.7°C during this century. Figure 22 gives evidence of large differences in ocean deep water formation between the 19th and 20th century.

Volcanic influences are present for only a few years and cannot explain the long-period observed multi-decadal and multi-century temperature changes. And CO2 changes could not have played any significant role in these long multi-century temperature changes of the past.

It is the earth’s internal fluctuations which are the most important cause of climate and temperature change. These internal fluctuations are driven primarily by deep multi-decadal and multi-century ocean circulation changes of which naturally varying upper ocean salinity content is hypothesized to be the primary driving mechanism. Salinity controls ocean density at cold temperatures and high latitudes where the potential deep water formation sites of the THC and SAS are located. North Atlantic upper ocean salinity changes are brought about by both multi-decadal and multi-century induced North Atlantic salinity variability. More detailed explanations will be given in forth-coming papers.

Fig 19

Figure 19. Last two thousand year surface temperatures between 30-90°N constructed from a synthesis of a large variety of observational data sources. Red lines denote long multi-century periods of warming, blue lines denote long multi-century periods of cooling. This figure illustrates the 300 to 700 year-long multi-century temperature changes hypothesized to be caused by the multi-century variation in the full globe ocean’s salinity changes on this time scale. The long red warming periods are times when the MOC and global rainfall are weaker than average and the long blue cooling periods are when the MOC and global rainfall are above average.

Fig 20

Figure 20. Same as in Figure 19, but emphasizing the multi-decadal variation of surface temperature which have an average period of about 60 years. These multi-decadal changes are hypothesized to be primarily a result of the variations of the Atlantic Thermohaline Circulation (THC) on this time scale. Naturally occurring multi-decadal variations of Atlantic salinity are believed to be the primary cause for these approximate 60-year fluxuations.

Fig 21

Figure 21. Hypothesized differences in the strength of the Atlantic THC between the 19th and 20thcenturies, that has been inferred from various data sources, such as that shown in Figure 22.

Fig 22

Figure 22. Summary statement from a paper by Broecker et al. (1999) which indicated a large difference in deep water formation between the 19th and 20th centuries.19

7. Negative Consequences of Politics Trumping Climate Science

Until the basic scientific flaws in the AGW theory are recognized and broadly accepted (as they eventually will have to be) it will not be possible for the scientific community and society to put this pernicious and harmful hoax to rest. The wide acceptance of this theory has had a profound negative influence on the US and the world. AGW’s basic scientific flaws must be made known as soon as possible so that the public can be made aware as to the fallacy of this hypothesis. This will help reduce the current economic, political, and psychological harm which is occurring around the globe due to AGW’s unrealistic warming propaganda and prevent greater harm in future years.

The AGW climate scare of the last 30 years did not come to the forefront from individual scientists beginning to coalesce around the idea that rising levels of CO2 might pose a serious future climate threat to society. This threat was, by contrast, imposed upon the world from ‘above’ by the coming together of globally influential politicians, environmentalists, internationalists, etc. who knew little about climate but saw great political opportunities by using the rising CO2 levels as a scare tactic in order to exercise control over them. People respond best out of fear. But lasting response to fear must have a firm basis in truth. The AGW scare does not.

Had I not spent my whole career (of nearly 60 years) in the meteorology-climate area and knew about AGW only from what I read or heard from the mainstream media, I may have been susceptible to accepting much of the AGW propaganda. This is why so many talented scientists from other fields have been unconsciously sucked into the wide orbit of AGW believers. Very few individuals have the long and broad ranging technical background in meteorology-climate to be able to well understand and attack the basic flaws of the AGW hypothesis. This is why so many of the world’s scientific societies and governments have been brainwashed into accepting AGW’s erroneous beliefs.

The warnings of President Eisenhower of the capture of overwhelming government support by an elite industrial-military complex are now being realized. But in this more recent version it is our country’s global warming – environmental – world government elites who have captured our country’s overwhelming government support for AGW funding and society intervention. The just published book by Senator James Inhofe titled “The Greatest Hoax” gives much information on the recent political history of the take-over of society by those advocating world government.

I have absolutely no doubt that the AGW hypothesis will become fully discredited within the next decade or so. A doubling of CO2 near the end of the 21st century should, by itself, only bring about a global warming of about 0.3°C or only about one-tenth of the ~3°C global warming projected by nearly all of the GCM models.

America’s economic growth and its confidence in the future will be greatly enhanced when the false dangers of the AGW hypothesis threat have been fully exposed and put behind us. America independence requires that we avoid the controlling tentacles of world government based on an unrealistic fear of human-induced climate degradation. Our Federal Government’s current AGW beliefs and its massive funding to promote this agenda should be terminated.

8. References (Partial Listing)

Crichton, M., 2003: Aliens Cause Global Warming. California Institute of Technology Lecture. Available on the internet.

Crichton, M., 2004: State of Fear. Harper Collins, 579 pp.

Douglass, D.H., Christy, J.R., Pearson, B.D. and Singer, S.F, 2007: A comparison of tropical temperature trends with model predictions. Int. J. Climatol., DOI: 10.1002/joc.1651. DOI: 10.1260/095830509787689277.

Gray, W.M., 2001: Natural versus anthropogenic climate change. Proceedings of the 1stInternational Conference on Global Warming and The Next Ice Age, Halifax, N.S., Canada (4 pages).

Gray, W. M., 2008: Human-Induced Global Warming: The Great Exaggeration. First Heartland Institute Conference on Climate Change, 73 pp., New York, March 2-4, 2008.

Gray, W. M., 2009: Climate change: Driven by the ocean, not human activity. 2nd Annual Heartland Institute Conference on Climate Change, 22 pp., New York, March 8-10, 2009.

Gray, W. M., 2010: Climate change: Driven by the ocean, not human activity. 4th Annual Heartland Institute Conference on Climate Change, 24 pp., Chicago, May 18-20, 2010.

Gray, W.M., J.D. Sheaffer, and C.W. Landsea, 1997: Climate trends associated with multi-decadal variability of Atlantic hurricane activity, in Hurricanes. Climate and Socioeconomic Impacts, edited by H. F. Diaz and R. S. Pulwarty, pp. 15-53, Springer-Verlag, New York.

Gray, W. M. and P. J. Klotzbach, 2011: Have Increases in CO2 Contributed to the Recent Large Upswing in Atlantic Basin Major Hurricanes since 1995? Evidence-Based Climate Science. (pp. 223-249). Elsevier Inc. (ISBN: 9780123859563).

Gray, W. M. and B. Schwartz, 2010: The association of outgoing radiation with variations of precipitation – implications for global warming. Presented at the 29th Conference on Hurricanes and Tropical Meteorology (AMS), Tucson, AZ, May 10-14, 2010.

Gray, W. M. and B. Schwartz, 2011: The association of albedo and OLR radiation with variations of precipitation – implications for AGW. Presented at the 91st meeting of the AMS Conference, Seattle, WA, January 23-27, 2011.

Ljungqvist, F.C., 2010: A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia. Geografiska Annaler: Series A, 92, 339-351. Michaels, P.J. and colleagues, 2005: Shattered Consensus, Rowman & Littlefield Publishers, Inc., 304 pp.

Michaels, P.J. and R. Balling, Jr., 2000: The Satanic Gases, Cato Institute, 224 pp.

Mooney, C., 2007: Storm World: Hurricanes, Politics, and the Battle Over Global Warming. Harcourt, 400 pp.

Pilkey, O.H. and L. Pilkey-Jarvis, 2007: Useless Arithmetic: Why Environmental Scientists Can’t Predict the Future. Columbia University Press, 248 pp.

Schiffer, R.A., and Rossow, W.B., 1985: ISCCP (International Satellite Cloud Climatology Project) Global Radiance Data Set: A New Resource for Climate Research. Bull. Amer. Meteor. Soc., 66, 1498-1505.

Singer, F., 1997: Hot Talk Cold Science. The Independent Institute, Oakland, CA. 207 pp.

Singer, F. and D.T. Avery, 2007: Unstoppable Global Warming – Every 1500 Years, Rowman and Littlefield, 264 pp.

Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.), 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 996 pp.

Weart, S.R., 2003: The Discovery of Global Warming, Harvard University Press, 228 pp.

Hurricanes and Climate Change: Attribution

Key Quote:  “…the IPCC AR5 best estimate is that all of the warming since 1951 has been caused by humans.

So, what caused the early 20th century global warming? This issue has received remarkably little attention from climate scientists. Lack of an explanation for the early 20th century global warming diminishes the credibility of the attribution statement for warming since 1951.”

Climate Etc.

by Judith Curry

Part II:  what causes variations and changes in hurricane activity?

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Climate Fish Tales

Reblogged from Watts Up With That:

What’s Natural? Guest essay by Jim Steele



American folk lore is filled with stories of how Native Americans observed changes in wildlife and foretold future weather changes. I was fascinated by an 1800s story of Native Americans inhabiting regions around Marysville, California who had moved down into the river valleys during drought years. They then moved to higher ground before devastating floods occurred. Did they understand California’s natural climate cycles? Could changes in salmon migrations alert them?

Observing salmon has certainly improved modern climate science. In the 1990s climate scientists struggled to understand why surface temperatures in the northwest sector of the Pacific Ocean had suddenly become cooler while temperatures in the eastern tropical Pacific suddenly warmed. Climate models predicted no such thing. However, fishery biologists noted salmon abundance in Alaska underwent boom and bust cycles lasting 20 to 40 years. When Alaskan salmon populations boomed, their populations from California to Washington busted. Conversely, decades later when Alaskan populations busted, those more southerly populations boomed.

Scientists soon realized the observed alternating patterns in fish abundance not only coincided with those puzzling changes in ocean surface temperatures, but also with regional drought-flood cycles, glacier growth and retreat, and tree-line advances and retreats. Tree rings and lake sediments also recorded cycles of 5 major Sierra Nevada droughts alternating with wetter decades during the past 300 years. This all convinced scientists of the existence of a natural “ocean oscillation” driving climate change. This climate see-saw was finally named the Pacific Decadal Oscillation (PDO) in 1997. (Science uses the term “oscillation” to describe repeating cycles with general, but imprecise time periods.)

The newly characterized PDO had yet to be included in climate models. But progress in climate research recently argues the PDO largely explains western North America’s last 100 years of climate change. So how do we separate naturally caused weather extremes from human contributions? Unfortunately, few Americans are aware of these “cycles”. But if we don’t educate our children about natural climate change, the next generation will surely fall victim to every Chicken Little climate story told by scientifically illiterate politicians or by journalists who profit from sensationalism; if it bleeds, it leads!

Similar fish tales have been reported globally. In the Atlantic, a similar oscillation was officially recognized in 2000. But according to fishery records, that oscillation has been noted since the 15th century. Norwegian fisheries documented 30 to 60-year boom and bust cycles for herring, sardines and anchovies. In the 1930s Greenland experienced a warming rivaling today’s temperatures. Simultaneously Danish Arctic ice records showed extensive sea ice melt. This all coincided with intrusions of warm Atlantic waters that brought Atlantic cod and herring northwards. Fish retreated decades later coinciding with cooling temperatures and recovering sea ice. Today’s Arctic warming and reduced sea ice has likewise coincided with greater intrusions of warm Atlantic water. Will there be a return cycle of retreating Atlantic waters that causes sea ice to rebound again?

Finally, contrary to recent claims of “unprecedented” rapid warming, Greenland’s air temperatures warmed more rapidly during the 1920s to 30s causing melting around Greenland’s ice cap. After warm waters retreated, Greenland gained ice from the 1960s to the 90s. A new period of rapid melting began in the 90s but peaked in 2012. Since then, Greenland’s melting gradually subsided and Greenland gained ice in 2017 and 2018, perhaps signaling a new cooling phase.

And there is a truly optimistic fish tale. Monterrey Bay Aquarium Research Institute’s senior scientist Dr. Francisco Chavez is a Peruvian oceanographer who studies the PDO and upwelling effects on marine life. The upwelling region off the coast of Peru is known as the most productive fishery in the world because robust upwelling brings nutrients from dark ocean depths up to the sunlit layers increasing photosynthesis. During the cold Little Ice Age – 1300 to 1850 AD – marine life off Peru’s coast was at a low point. Starting in the late 1800s as temperatures warmed, plankton rapidly increased, which promoted rapid increases in fish abundance. This dramatic improvement in marine life is well documented in preserved sediments.

To promote plant growth, commercial greenhouses add an additional 1000 ppm to the current 400 ppm of atmospheric CO2 concentrations. So, did marine life also increase due to rising levels of CO2? Or perhaps, because land temperatures warm faster than ocean temperatures, did stronger winds increase ocean upwelling? Whatever the drivers of the observed increases in ocean life, it appears likely that rising CO2 contributed definitive benefits.

If we are to truly understand climate change and discern human contributions, these fish tales all suggest we must first account for natural oscillations that have surely been operating for millennia. So, to rephrase Mark Twain, ‘reports of the earth’s imminent death within 18 years, via rising CO2, are likely greatly exaggerated’.

Jim Steele authored Landscapes and Cycles: An Environmentalist’s Journey to Climate Skepticism


Published in the Pacifica Tribune January, 29, 2019 (republished here at the request of the author).

Ocean SSTs Cooler in December

Science Matters

droguestatus Note: A drogue is a sea anchor resisting drifting speed.

The best context for understanding decadal temperature changes comes from the world’s sea surface temperatures (SST), for several reasons:

  • The ocean covers 71% of the globe and drives average temperatures;
  • SSTs have a constant water content, (unlike air temperatures), so give a better reading of heat content variations;
  • A major El Nino was the dominant climate feature in recent years.

HadSST is generally regarded as the best of the global SST data sets, and so the temperature story here comes from that source, the latest version being HadSST3.  More on what distinguishes HadSST3 from other SST products at the end.

The Current Context

The chart below shows SST monthly anomalies as reported in HadSST3 starting in 2015 through December 2018.


A global cooling pattern is seen clearly in the Tropics since its peak in 2016, joined by NH and SH…

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ARGO—Fit for Purpose?

Reblogged from Watts Up With That:

By Rud Istvan

This is the second of two guest posts on whether ‘big’ climate science missions are fit for purpose, inspired by ctm as seaside lunch speculations.

The first post dealt with whether satellite altimetry, specifically NASA’s newest Jason3 ‘bird’, was fit for sea level rise (SLR) ‘acceleration’ purpose. It found using NASA’s own Jason3 specs that Jason3 (and so also its predecessors) likely was NOT fit–and never could have been–despite its SLR data being reported by NASA to 0.1mm/yr. We already knew that annual SLR is low single digit millimeters. The reasons satellite altimetry cannot provide that level of precision are very basic, and were known to NASA beforehand—Earth’s requisite reference ellipsoid is lumpy, oceans have varying waves, atmosphere has varying humidity—so NASA never really had a chance of achieving what they aspired to: satalt missions to measure sea level rise to fractions of a millimeter per year equivalent to tide gauges. NASA claims they can, but their specifications say they cannot. The post proved lack of fitness via overlap discrepancies between Jason2 and Jason3, plus failure of NASA SLR estimates to close.

This second related guest post asks the same question of ARGO.

Unlike Jason3, ARGO had no good pre-existing tide gauge equivalent mission comparable. Its novel oceanographic purposes (below) tried to measure several things ‘rigorously’ for the very first time. “Rigorously’ did NOT mean precisely. One, ocean heat content (OHC), was previously very inadequately estimated. OHC is much more than just sea surface temperatures (SSTs). SSTs (roughly but not really surface) were formerly measured by trade route dependent buckets/thermometers, or by trade route and ship laden dependent engine intake cooling water temperatures. Deeper ocean was not measured at all until inherently depth inaccurate XBT sensors were developed for the Navy.

Whether ARGO is fit for purpose involves a complex unraveling of design intent plus many related facts. The short ARGO answer is probably yes, although OHC error bars are provably understated in ARGO based scientific literature.

For those WUWT readers wishing a deeper examination of this guest post’s summary conclusions, a treasure trove of ARGO history, implementation, and results is available at Most of this post is either directly derived therefrom, or from references found therein, or leads to Willis Eschenbach’s previous WUWT ARGO posts (many searchable using ARGO), with the four most relevant directly linked below.

This guest post is divided into three parts:

1. What was the ARGO design intent? Unlike simple Jason3 SLR, ARGO has a complex set of overlapping oceanographic missions.

2. What were/are the ARGO design specs relative to its missions?

3. What do facts say about ARGO multiple mission fitness?

Part 1 ARGO Intent

ARGO was intended to explore a much more complicated set of oceanography questions than Jason’s simple SLR acceleration. The ideas were developed by oceanographers at Scripps circa 1998-1999 based on a decade of previous regional ocean research, and were formulated into two intent/design documents agreed by the implementing international ARGO consortium circa 2000. There were several ARGO intended objectives. The three most explicitly relevant to this summary post were:

1. Global ocean heat climatology (OHC with intended accuracy explicitly defined as follows)

2. Ocean ‘fresh water storage’ (upper ocean rainfall salinity dilution)

3. Map of non-surface currents

All providing intended “global coverage of the upper ocean on broad spatial scales and time frames of several months or longer.”

Unlike Jason3, no simple yes/no ‘fit for purpose’ for ARGO’s multiple missions is possible. It depends on which mission over what time frame.

Part 2 ARGO Design

The international design has evolved. Initially, the design was ~3000 floats providing a random roughly 3 degree lat/lon ocean spacing, explicitly deemed sufficient spatial resolution for all ARGO intended oceanographic purposes.

There is an extensive discussion of the array’s accuracy/cost tradeoffs in the original intent/design documentation. The ARGO design “is an ongoing exercise in balancing the array’s requirements against the practical limitations imposed by technology and resources”. Varying perspectives still provided (1998-99) “consistent estimates of what is needed.” Based on previous profiling float experiments, “in proximate terms an array with spacing of a few hundred kilometers is sufficient to determine surface layer heat storage (OHC) with an accuracy of about 10W/m2 over areas (‘pixels’) about 1000km on a side.” Note the abouts.

The actual working float number is now about 3800. Each float was to last 4-5 years battery life; the actual is ~4.1 years. Each float was to survive at least 150 profiling cycles; this has been achieved (150 cycles*10 days per cycle/365 days per year equals 4.1 years). Each profile cycle was to be 10 days, drifting randomly at ~1000 meters ‘parking depth’ at neutral buoyancy for 9, then descending to 2000 meters to begin measuring temperature and salinity, followed by a ~6 hour rise to the surface with up to 200 additional measurement sets of pressure (giving depth), temperature, and salinity. This was originally followed by 6-12 hours on the surface transmitting data (now <2 hours using the Iridium satellite system) before sinking back to parking depth.

The basic ARGO float design remains:


And the basic ARGO profiling pattern remains:


‘Fit for purpose’ concerning OHC (via the 2000 meter temperature profile) presents two relevant questions. (1) Is 2000 meters deep enough? (2) Are the sensors accurate enough to estimate the 10W/m2 per 1000km/side ‘pixel’?

With respect to depth, there are two differently sourced yet similar ‘yes’ answers for all mission intents.

For salinity, the ARGO profile suffices. Previous oceanographic studies showed (per the ARGO source docs) that salinity is remarkably unvarying below about 750 meters depth in all oceans. This fortunately provides a natural salinity ‘calibration’ for those empirically problematic sensors.

It also means seawater density is roughly constant over about 2/3 of the profile, so pressure is a sufficient proxy for depth (and pressure can also be calibrated by measured salinity above 750 meters translated to density).

For temperature, as the following figure (in °F not °C) typical thermocline profiles show, ARGO ΔT depth profile does not depend very much on latitude since 2000 meters equaling ~6500 feet reaches the approximately constant deep ocean temperature equilibrium at all latitudes, providing another natural ARGO ‘calibration’. The 2000 meters ARGO profile was a wise intent/design choice.


Part 3 Is ARGO fit for purpose?

Some further basics are needed as background to the ARGO objectives.

When an ARGO float surfaces to transmit its data, its position is ascertained via GPS to within about 100 meters. Given the vastness of the oceans, that is an overly precise position measurement for ‘broad spatial scales’ of deep current drift and 1000000km2 OHC/salinity ‘pixels’.

Thanks to salinity stability below 750 meters, ARGO ‘salinity corrected’ instruments are accurate (after float specific corrections) to ±0.01psu, giving reasonable estimates of ‘fresh water storage’. A comparison of 350 retrieved ‘dead battery’ ARGO floats showed that 9% were still out of ‘corrected’ salinity calibration at end of life, unavoidably increasing salinity error a little.

The remaining big ‘sufficient accuracy’ question is OHC, and issues like Trenberth’s infamous “Missing Heat” covered in the eponious essay in ebook Blowing Smoke. OHC is a very tricky sensor question, since the vast heat capacity of ocean water means a very large change in ocean heat storage translates into a very small change in absolute seawater temperature.

How good are the ARGO temperature sensors? On the surface, it might seem to depend, since as an international consortium, ARGO does not have one float design. There are presently five: Provor, Apex, Solo, S2A, and Navis.

However, those 5 only ever embodied two temperature sensors, FS1 and SBE. Turns out—even better for accuracy—FS1 was retired late in 2006 when JPL’s Willis published the first ARGO OHC analysis after full (3000 float) deployment, finding (over too short a time frame, IMO) OHC was decreasing (!). Oops! Further climate science analysis purportedly showed FS1 temperature profiles in a few hundred of the early ARGO floats were probably erroneous. Those floats were taken out of service, leaving just SBE sensors. All five ARGO float designs use current model SBE38 from 2015.

SeaBirdScientific builds that sensor, and its specs can be found at The SeaBird E38 sensor spec is the following (sorry, but it doesn’t copy well from their website where all docs are in a funky form of pdf probably intended to prevent partial duplication like for this post).

Measurement Range

-5 to +35 °C

Initial Accuracy 1

± 0.001 °C (1 mK)

Typical Stability

0.001 °C (1 mK) in six months, certified


Response Time 2

500 msec

Self-heating Error

< 200 μK

1 NIST-traceable calibration applying over the entire range.
2 Time to reach 63% of nal value following a step change in temperature

That is a surprisingly good seawater temperature sensor. Accurate to a NIST calibrated 0.001°C, with a certified temperature precision drift per 6 months (1/8 of a float lifetime) of ±0.001°C. USCD says in its ARGO FAQs that the ARGO temperature data it provides is accurate to ±0.002°C. This suffices to estimate the about 10W/m2 OHC intent per 1000000 km2 ARGO ‘pixel’.

BUT, there is still a major ‘fit for purpose’ problem despite all the ARGO strong positives. Climate papers based on ARGO habitually understate the actual resulting OHC uncertainty—about 10W/m2. (Judith Curry has called this one form of her ‘uncertainty monster’). Willis Eschenbach has posted extensively here at WUWT (over a dozen guest posts already) on ARGO and its findings. His four most relevant for the ‘fit for purpose’ scientific paper uncertainty question are from 2012-2015, links that WE kindly provided via email needing no explanation:

Decimals of Precision

An Ocean of Overconfidence

More Ocean-Sized Errors In Levitus Et Al.

Can We Tell If The Oceans Are Warming

And so we can conclude concerning the ARGO ‘fit for purpose’ question, yes it probably is—but only if ARGO based science papers also correctly provide the associated ARGO intent uncertainty (error bars) for ‘rigorous albeit broad spatial resolution’.

December Cooling by Sea, More than by Land

Science Matters


With apologies to Paul Revere, this post is on the lookout for cooler weather with an eye on both the Land and the Sea.  UAH has updated their tlt (temperatures in lower troposphere) dataset for December.   Previously I have done posts on their reading of ocean air temps as a prelude to updated records from HADSST3. This month I will add a separate graph of land air temps because the comparisons and contrasts are interesting as we contemplate possible cooling in coming months and years.

Presently sea surface temperatures (SST) are the best available indicator of heat content gained or lost from earth’s climate system.  Enthalpy is the thermodynamic term for total heat content in a system, and humidity differences in air parcels affect enthalpy.  Measuring water temperature directly avoids distorted impressions from air measurements.  In addition, ocean covers 71% of the planet surface and thus dominates surface temperature estimates.  Eventually…

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Little Ice Age Still Cooling Pacific

sunshine hours

Lag: a period of time between one event or phenomenon and another

Little Ice Age Still Cooling Pacific

As much of the ocean responds to the rising temperatures of today’s world, the deep, dark waters at the bottom of the Pacific Ocean appear to be doing the exact opposite.

A Harvard study has found that parts of the deep Pacific may be getting cooler as the result of a climate phenomenon that occurred hundreds of years ago.

Around the 17th century, Earth experienced a prolonged cooling period dubbed the Little Ice Age that brought chillier-than-average temperatures to much of the Northern Hemisphere.

Though it’s been centuries since this all played out, researchers say the deep Pacific appears to lag behind the waters closer to the surface, and is still responding to the Little Ice Age.

In the deep Pacific Ocean, however, temperatures are dropping. This effect could be seen at a…

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University of Exeter research sheds new light on what drove last, long-term global climate shift

Reblogged from Watts Up With That:

Public Release: 19-Dec-2018

The quest to discover what drove the last, long-term global climate shift on Earth, which took place around a million years ago, has taken a new, revealing twist.

A team of researchers led by Dr Sev Kender from the University of Exeter, have found a fascinating new insight into the causes of the Mid-Pleistocene Transition (MPT) – the phenomenon whereby the planet experienced longer, intensified cycles of extreme cold conditions.

While the causes of the MPT are not fully known, one of the most prominent theories suggests it may have been driven by reductions in glacial CO2 emissions.

Now, Dr Kender and his team have discovered that the closure of the Bering Strait during this period due to glaciation could have led the North Pacific to become stratified – or divided into distinct layers – causing CO2 to be removed from the atmosphere. This would, they suggest, have caused global cooling.

The team believe the latest discovery could provide a pivotal new understanding of how the MPT occurred, but also give a fresh insight into the driving factors behind global climate changes.

The research is published in Nature Communications on December 19th 2018.

Dr Kender, a co-author on the study from the Camborne School of Mines, based at the University of Exeter’s Penryn Campus in Cornwall said: “The subarctic North Pacific is composed of some of the oldest water on Earth, which has been separated from the atmosphere for such a long time that a high concentration of dissolved CO2 has built up at depth. When this water upwells to the surface, some of the CO2 is released. This is thought to be an important process in geological time, causing some of the global warming that followed past glaciations.

“We took deep sediment cores from the bottom of the Bering Sea that gave us an archive of the history of the region. By studying the chemistry of sediment and fossil shells from marine protists called foraminifera, we reconstructed plankton productivity, and surface and bottom water masses. We were also able to better date the sediments so that we could compare changes in the Bering Sea to other global changes at that time.

“We discovered that the Bering Sea region became more stratified during the MPT with an expanded intermediate-depth watermass, such that one of the important contributors to global warming – the upwelling of the subarctic North Pacific – was effectively curtailed.”

The Earth’s climate has always been subjected to significant changes, and over the past 600,000 years and more it has commonly oscillated between warm periods, similar today, and colder, ‘glacial’ periods when large swathes of continents are blanketed under several kilometres of ice.

These regular, natural changes in the Earth’s climate are governed by changes in how the Earth orbits around the sun, and variations in the tilt of its axis caused by gravitational interactions with other planets.

These changes, known as orbital cycles, can affect how solar energy is dispersed across the planet. Some orbital cycles can, therefore, lead to colder summers in the Northern Hemisphere which can trigger the start of glaciations, while later cycles can bring warmer summers, causing the ice to melt.,

These cycles can be influenced by a host of factors that can amplify their effect. One of which is CO2 levels in the atmosphere.

As the MPT occurred during a period when there were no apparent changes in the nature of the orbit cycles, scientists have long been attempting to discover what drove the changes to take place.

For this research, Dr Kender and his team drilled for deep-sea sediment in the Bering Sea, in conjunction with the International Ocean Discovery Program, and measured the chemistry of the fossil shells and sediments.

The team were able to create a detailed reconstruction of oceanic water masses through time – and found that the closure of the Baring Strait caused the subarctic North Pacific became stratified during this period of glaciation.

This stratification, that argue, would have removed CO2 from the atmosphere and caused global cooling.

Dr Kender added: “Today much of the cold water produced by sea ice action flows northward into the Arctic Ocean through the Bering Strait. As glaciers grew and sea levels fell around 1 million years ago, the Bering Strait would have closed, retaining colder water within the Bering Sea. This expanded watermass appears to have stifled the upwelling of deep CO2-rich water and allowed the ocean to sequester more CO2 out of the atmosphere. The associated cooling effect would have changed the sensitivity of Earth to orbital cycles, causing colder and longer glaciations that characterise climate ever since.

“Our findings highlight the importance of understanding present and future changes to the high latitude oceans, as these regions are so important for long term sequestration or release of atmospheric CO2.”