Angel of Ioren
Friendly Skeptic
Here's a thread where you can discuss the topic of global warming.
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Global Warming Happy Fun-Time
- Thread starter Angel of Ioren
- Start date
P
pixelsmith
Guest
so we have about 20 of these threads now. 
All you have to do is show empirical proof as derived from the scientific method that humans have caused CO2 levels to rise to looming catastrophe levels. Please do not forget that CO2 is necessary for life to exist on this planet and you exhale it your whole life. If you strongly believe CO2 is evil then please by all means save the planet by holding your breath for about 20 minutes. Thank you!
All you have to do is show empirical proof as derived from the scientific method that humans have caused CO2 levels to rise to looming catastrophe levels. Please do not forget that CO2 is necessary for life to exist on this planet and you exhale it your whole life. If you strongly believe CO2 is evil then please by all means save the planet by holding your breath for about 20 minutes. Thank you!
Muadib
Paranormal Adept
Here ya go:
Empirical evidence that humans are causing global warming
It still surprises me when I hear skeptics claim there is no evidence that we're causing global warming. The evidence is there in the peer reviewed literature. What they're really saying is they haven't bothered to look. So to make things easier for everyone, here is the evidence that humans are causing global warming. It's not based on theory, climate models, faith or political ideology but on direct, empirical observations. The line of evidence is as follows:
Humans are raising CO2 levels
Is it arrogant to claim we humans could possibly affect something as large as the global climate? It's not a question of arrogance. It's merely a question of numbers.
The first measurements of atmospheric CO2 were conducted by Charles Keeling in 1958 at Mauna Loa, Hawaii. Currently, atmospheric CO2 levels are being measured at hundreds of monitoring stations across the globe. For periods before 1958, CO2 levels are determined from analyses of air bubbles trapped in polar ice cores.
In pre-industrial times, CO2 has been relatively stable at around 260 to 285 ppm. Over the last 250 years, atmospheric CO2 levels have increased by about 100ppm. Currently, the amount of CO2 in the atmosphere is increasing by 15 gigatonnes every year.
We can calculate how much CO2 we're emitting from international energy statistics, tabulating coal, brown coal, peat, crude oil and cement production by nation and year. What we find is fossil fuel emissions have continued to increase. In 2008, we were emitting CO2 at a rate of 29 gigatonnes per year.
Figure 1: CO2 levels (Law Dome ice core and Mauna Loa, Hawaii) and Cumulative CO2 emissions (CDIAC).
Humanity is emitting nearly twice as much CO2 as ends up remaining in the atmosphere. Oceans and plants are actually reducing our impact on climate by absorbing a large portion of our CO2 emissions. Our actions are having a significant impact on the composition of our atmosphere. It's not arrogant to say we can change global climate. On the contrary, the arrogance lies in thinking we can act as we like without consequences.
CO2 traps heat
How does CO2 trap heat? Sunlight passes through our atmosphere and warms the earth. The earth cools by emitting infrared radiation back towards space. As infrared radiation travels through the atmosphere, some is absorbed by greenhouse gases such as water vapour and CO2. This warms the atmosphere which then reradiates the infrared radiation in all directions. Some escapes to space while some radiates downwards and further warms the Earth.
With more CO2 in the air, we expect to see less infrared radiation escaping out to space. To confirm this, satellite readings of outgoing radiation in 1970 were compared to measurements made from 1996 through to 2006 (Harries 2001, Griggs 2004, Chen 2007). They found a drop in outgoing radiation at the wavelengths that CO2 absorbs energy, consistent with theoretical expectations, thus finding "direct experimental evidence for a significant increase in the Earth's greenhouse effect".
Ground measurements also find an increase of infrared radiation heading back down towards Earth, confirmation of an enhanced greenhouse effect (Philipona 2004, Puckrin 2004, Wild 2008, Wang 2009). By closely analysing the changes at different wavelengths, scientists can calculate how much each greenhouse gas contributes to the warming effect. The results are consistent with both theory and satellite measurements of the enhanced greenhouse effect, leading the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming." (Evans 2006)
Our planet is accumulating heat
We know we're raising CO2 levels. We have proof that more CO2 causes an enhanced greenhouse effect. What is the result? When you add up all the heat accumulating in the oceans, land and atmosphere plus all the energy required to melt glaciers and ice sheets, you find that the planet is accumulating heat at a rate of 190,260 GigaWatts (Murphy 2009).Considering a typical nuclear power plant has an output of 1 GigaWatt, imagine 190,000 nuclear power plants pouring their energy output directly into heating our land and oceans, melting ice and warming the air.
Figure 3: Total Earth Heat Content from 1950 (Murphy 2009).
What about claims that it hasn't warmed since 1998. Could we be experiencing global cooling? Not at all. How do we know? Think about what global warming really is. The planet is accumulating heat. More energy is coming in than is going out. Is this energy imbalance still occuring?
To answer this question, think about where most of global warming goes? Around 95% goes into warming the oceans. Measurements of ocean heat content find a warming trend through to the end of 2008 (Schuckmann 2009). There's strong evidence that the oceans are still accumulating heat. Global warming is still happening.
Figure 3: Time series of global mean heat storage (0–2000 m), measured in 108 Jm-2.
So why have we experienced surface cooling in recent years? It's not unusual or unprecedented for surface temperatures to show cooling over short periods. As the ocean contains much more heat than the atmosphere, relatively small exchanges of heat between the ocean and air can cause significant changes in surface temperature.
In 1998, we experienced the strongest El Niño on record. This moved massive amounts of heat from the Pacific Ocean into the atmosphere, leading to an abnormally warm year. Conversely, the last few years have seen the strongest La Niña conditions in over 20 years which had a cooling effect on global temperatures. It's not unusual or unprecedented for surface temperatures to show short term cooling during a long term warming trend.
So we have a clear line of evidence. Our CO2 emissions far outstrip the observed rise in CO2 levels. Surface and satellite observations confirm an enhanced greenhouse effect. And ocean heat observations tell us the planet is accumulating heat. Science tells us we need to reduce our CO2 emissions to stop global warming. But like any issue, we'll never come close to resolving it unless we admit there is a problem.
How do we know more CO2 is causing warming?
The greenhouse gas qualities of carbon dioxide have been known for over a century. In 1861, John Tyndal published laboratory results identifying carbon dioxide as a greenhouse gas that absorbed heat rays (longwave radiation). Since then, the absorptive qualities of carbon dioxide have been more precisely quantified by decades of laboratory measurements (Herzberg 1953, Burch 1962, Burch 1970, etc).
The greenhouse effect occurs because greenhouse gases let sunlight (shortwave radiation) pass through the atmosphere. The earth absorbs sunlight, warms then reradiates heat (infrared or longwave radiation). The outgoing longwave radiation is absorbed by greenhouse gases in the atmosphere. This heats the atmosphere which in turn re-radiates longwave radiation in all directions. Some of it makes its way back to the surface of the earth. So with more carbon dioxide in the atmosphere, we expect to see less longwave radiation escaping to space at the wavelengths that carbon dioxide absorb. We also expect to see more infrared radiation returning back to Earth at these same wavelengths.
Satellite measurements of outgoing longwave radiation
In 1970, NASA launched the IRIS satellite that measured infrared spectra between 400 cm-1 to 1600 cm-1. In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations. Both sets of data were compared to discern any changes in outgoing radiation over the 26 year period (Harries 2001). The resultant change in outgoing radiation was as follows:
Figure 1: Change in spectrum from 1970 to 1996 due to trace gases. 'Brightness temperature' indicates equivalent blackbody temperature (Harries 2001).
What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as carbon dioxide (CO2) and methane (CH4) absorb energy. The change in outgoing radiation is consistent with theoretical expectations. Thus the paper found "direct experimental evidence for a significant increase in the Earth's greenhouse effect".
This result has been confirmed by subsequent papers using more recent satellite data. The 1970 and 1997 spectra were compared with additional satellite data from the NASA AIRS satellite launched in 2003 (Griggs 2004). This analysis was extended to 2006 using data from the AURA satellite launched in 2004 (Chen 2007). Both papers found the observed differences in CO2 bands matching the expected changes from rising carbon dioxide levels. Thus we have empirical evidence that increased CO2 is causing an enhanced greenhouse effect.
Surface measurements of downward longwave radiation
A compilation of surface measurements of downward longwave radiation from 1973 to 2008 find an increasing trend of more longwave radiation returning to earth, attributed to increases in air temperature, humidity and atmospheric carbon dioxide (Wang 2009). More regional studies such as an examination of downward longwave radiation over the central Alps find that downward longwave radiation is increasing due to an enhanced greenhouse effect (Philipona 2004).
Taking this a step further, an analysis of high resolution spectral data allows scientists to quantitatively attribute the increase in downward radiation to each of several greenhouse gases (Evans 2006). The results lead the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming."
Figure 2: Spectrum of the greenhouse radiation measured at the surface. Greenhouse effect from water vapor is filtered out, showing the contributions of other greenhouse gases (Evans 2006).
Conservation of Energy
Huber and Knutti (2011) published a paper in Nature Geoscience, Anthropogenic and natural warming inferred from changes in Earth’s energy balance. They take an approach in this study which utilizes the principle of conservation of energy for the global energy budget using the measurements discussed above, and summarize their methodology:
Figure 3 is a similar graphic to that presented in Meehl et al. (2004), comparing the average global surface warming simulated by the model using natural forcings only (blue), anthropogenic forcings only (red), and the combination of the two (gray).
Figure 3: Time series of anthropogenic and natural forcings contributions to total simulated and observed global temperature change. The coloured shadings denote the 5-95% uncertainty range.
In Figure 4, Huber and Knutti break down the anthropogenic and natural forcings into their individual components to quantify the amount of warming caused by each since the 1850s (Figure 4b), 1950s (4c), and projected from 2000 to 2050 using the IPCC SRES A2 emissions scenario as business-as-usual (4d).
Figure 4: Contributions of individual forcing agents to the total decadal temperature change for three time periods. Error bars denote the 5–95% uncertainty range. The grey shading shows the estimated 5–95% range for internal variability based on the CMIP3 climate models. Observations are shown as dashed lines.
As expected, Huber and Knutti find that greenhouse gases contributed to substantial warming since 1850, and aerosols had a significant cooling effect:
There are multiple lines of empirical evidence that increasing carbon dioxide causes an enhanced greenhouse effect. Laboratory tests show carbon dioxide absorbs longwave radiation. Satellite measurements confirm less longwave radiation is escaping to space at carbon dioxide absorptive wavelengths. Surface measurements find more longwave radiation returning back to Earth at these same wavelengths. The result of this energy imbalance is the accumulation of heat over the last 40 years.
Empirical evidence that humans are causing global warming
It still surprises me when I hear skeptics claim there is no evidence that we're causing global warming. The evidence is there in the peer reviewed literature. What they're really saying is they haven't bothered to look. So to make things easier for everyone, here is the evidence that humans are causing global warming. It's not based on theory, climate models, faith or political ideology but on direct, empirical observations. The line of evidence is as follows:
Humans are raising CO2 levels
Is it arrogant to claim we humans could possibly affect something as large as the global climate? It's not a question of arrogance. It's merely a question of numbers.
The first measurements of atmospheric CO2 were conducted by Charles Keeling in 1958 at Mauna Loa, Hawaii. Currently, atmospheric CO2 levels are being measured at hundreds of monitoring stations across the globe. For periods before 1958, CO2 levels are determined from analyses of air bubbles trapped in polar ice cores.
In pre-industrial times, CO2 has been relatively stable at around 260 to 285 ppm. Over the last 250 years, atmospheric CO2 levels have increased by about 100ppm. Currently, the amount of CO2 in the atmosphere is increasing by 15 gigatonnes every year.
We can calculate how much CO2 we're emitting from international energy statistics, tabulating coal, brown coal, peat, crude oil and cement production by nation and year. What we find is fossil fuel emissions have continued to increase. In 2008, we were emitting CO2 at a rate of 29 gigatonnes per year.
Figure 1: CO2 levels (Law Dome ice core and Mauna Loa, Hawaii) and Cumulative CO2 emissions (CDIAC).
Humanity is emitting nearly twice as much CO2 as ends up remaining in the atmosphere. Oceans and plants are actually reducing our impact on climate by absorbing a large portion of our CO2 emissions. Our actions are having a significant impact on the composition of our atmosphere. It's not arrogant to say we can change global climate. On the contrary, the arrogance lies in thinking we can act as we like without consequences.
CO2 traps heat
How does CO2 trap heat? Sunlight passes through our atmosphere and warms the earth. The earth cools by emitting infrared radiation back towards space. As infrared radiation travels through the atmosphere, some is absorbed by greenhouse gases such as water vapour and CO2. This warms the atmosphere which then reradiates the infrared radiation in all directions. Some escapes to space while some radiates downwards and further warms the Earth.
With more CO2 in the air, we expect to see less infrared radiation escaping out to space. To confirm this, satellite readings of outgoing radiation in 1970 were compared to measurements made from 1996 through to 2006 (Harries 2001, Griggs 2004, Chen 2007). They found a drop in outgoing radiation at the wavelengths that CO2 absorbs energy, consistent with theoretical expectations, thus finding "direct experimental evidence for a significant increase in the Earth's greenhouse effect".
Ground measurements also find an increase of infrared radiation heading back down towards Earth, confirmation of an enhanced greenhouse effect (Philipona 2004, Puckrin 2004, Wild 2008, Wang 2009). By closely analysing the changes at different wavelengths, scientists can calculate how much each greenhouse gas contributes to the warming effect. The results are consistent with both theory and satellite measurements of the enhanced greenhouse effect, leading the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming." (Evans 2006)
Our planet is accumulating heat
We know we're raising CO2 levels. We have proof that more CO2 causes an enhanced greenhouse effect. What is the result? When you add up all the heat accumulating in the oceans, land and atmosphere plus all the energy required to melt glaciers and ice sheets, you find that the planet is accumulating heat at a rate of 190,260 GigaWatts (Murphy 2009).Considering a typical nuclear power plant has an output of 1 GigaWatt, imagine 190,000 nuclear power plants pouring their energy output directly into heating our land and oceans, melting ice and warming the air.
Figure 3: Total Earth Heat Content from 1950 (Murphy 2009).
What about claims that it hasn't warmed since 1998. Could we be experiencing global cooling? Not at all. How do we know? Think about what global warming really is. The planet is accumulating heat. More energy is coming in than is going out. Is this energy imbalance still occuring?
To answer this question, think about where most of global warming goes? Around 95% goes into warming the oceans. Measurements of ocean heat content find a warming trend through to the end of 2008 (Schuckmann 2009). There's strong evidence that the oceans are still accumulating heat. Global warming is still happening.
Figure 3: Time series of global mean heat storage (0–2000 m), measured in 108 Jm-2.
So why have we experienced surface cooling in recent years? It's not unusual or unprecedented for surface temperatures to show cooling over short periods. As the ocean contains much more heat than the atmosphere, relatively small exchanges of heat between the ocean and air can cause significant changes in surface temperature.
In 1998, we experienced the strongest El Niño on record. This moved massive amounts of heat from the Pacific Ocean into the atmosphere, leading to an abnormally warm year. Conversely, the last few years have seen the strongest La Niña conditions in over 20 years which had a cooling effect on global temperatures. It's not unusual or unprecedented for surface temperatures to show short term cooling during a long term warming trend.
So we have a clear line of evidence. Our CO2 emissions far outstrip the observed rise in CO2 levels. Surface and satellite observations confirm an enhanced greenhouse effect. And ocean heat observations tell us the planet is accumulating heat. Science tells us we need to reduce our CO2 emissions to stop global warming. But like any issue, we'll never come close to resolving it unless we admit there is a problem.
How do we know more CO2 is causing warming?
The greenhouse gas qualities of carbon dioxide have been known for over a century. In 1861, John Tyndal published laboratory results identifying carbon dioxide as a greenhouse gas that absorbed heat rays (longwave radiation). Since then, the absorptive qualities of carbon dioxide have been more precisely quantified by decades of laboratory measurements (Herzberg 1953, Burch 1962, Burch 1970, etc).
The greenhouse effect occurs because greenhouse gases let sunlight (shortwave radiation) pass through the atmosphere. The earth absorbs sunlight, warms then reradiates heat (infrared or longwave radiation). The outgoing longwave radiation is absorbed by greenhouse gases in the atmosphere. This heats the atmosphere which in turn re-radiates longwave radiation in all directions. Some of it makes its way back to the surface of the earth. So with more carbon dioxide in the atmosphere, we expect to see less longwave radiation escaping to space at the wavelengths that carbon dioxide absorb. We also expect to see more infrared radiation returning back to Earth at these same wavelengths.
Satellite measurements of outgoing longwave radiation
In 1970, NASA launched the IRIS satellite that measured infrared spectra between 400 cm-1 to 1600 cm-1. In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations. Both sets of data were compared to discern any changes in outgoing radiation over the 26 year period (Harries 2001). The resultant change in outgoing radiation was as follows:
Figure 1: Change in spectrum from 1970 to 1996 due to trace gases. 'Brightness temperature' indicates equivalent blackbody temperature (Harries 2001).
What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as carbon dioxide (CO2) and methane (CH4) absorb energy. The change in outgoing radiation is consistent with theoretical expectations. Thus the paper found "direct experimental evidence for a significant increase in the Earth's greenhouse effect".
This result has been confirmed by subsequent papers using more recent satellite data. The 1970 and 1997 spectra were compared with additional satellite data from the NASA AIRS satellite launched in 2003 (Griggs 2004). This analysis was extended to 2006 using data from the AURA satellite launched in 2004 (Chen 2007). Both papers found the observed differences in CO2 bands matching the expected changes from rising carbon dioxide levels. Thus we have empirical evidence that increased CO2 is causing an enhanced greenhouse effect.
Surface measurements of downward longwave radiation
A compilation of surface measurements of downward longwave radiation from 1973 to 2008 find an increasing trend of more longwave radiation returning to earth, attributed to increases in air temperature, humidity and atmospheric carbon dioxide (Wang 2009). More regional studies such as an examination of downward longwave radiation over the central Alps find that downward longwave radiation is increasing due to an enhanced greenhouse effect (Philipona 2004).
Taking this a step further, an analysis of high resolution spectral data allows scientists to quantitatively attribute the increase in downward radiation to each of several greenhouse gases (Evans 2006). The results lead the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming."
Figure 2: Spectrum of the greenhouse radiation measured at the surface. Greenhouse effect from water vapor is filtered out, showing the contributions of other greenhouse gases (Evans 2006).
Conservation of Energy
Huber and Knutti (2011) published a paper in Nature Geoscience, Anthropogenic and natural warming inferred from changes in Earth’s energy balance. They take an approach in this study which utilizes the principle of conservation of energy for the global energy budget using the measurements discussed above, and summarize their methodology:
"We use a massive ensemble of the Bern2.5D climate model of intermediate complexity, driven by bottom-up estimates of historic radiative forcing F, and constrained by a set of observations of the surface warming T since 1850 and heat uptake Q since the 1950s....Between 1850 and 2010, the climate system accumulated a total net forcing energy of 140 x 1022 J with a 5-95% uncertainty range of 95-197 x 1022 J, corresponding to an average net radiative forcing of roughly 0.54 (0.36-0.76)Wm-2."
Essentially, Huber and Knutti take the estimated global heat content increase since 1850, calculate how much of the increase is due to various estimated radiative forcings, and partition the increase between increasing ocean heat content and outgoing longwave radiation. The authors note that more than 85% of the global heat uptake (Q) has gone into the oceans, including increasing the heat content of the deeper oceans, although their model only accounts for the upper 700 meters.Figure 3 is a similar graphic to that presented in Meehl et al. (2004), comparing the average global surface warming simulated by the model using natural forcings only (blue), anthropogenic forcings only (red), and the combination of the two (gray).
Figure 3: Time series of anthropogenic and natural forcings contributions to total simulated and observed global temperature change. The coloured shadings denote the 5-95% uncertainty range.
In Figure 4, Huber and Knutti break down the anthropogenic and natural forcings into their individual components to quantify the amount of warming caused by each since the 1850s (Figure 4b), 1950s (4c), and projected from 2000 to 2050 using the IPCC SRES A2 emissions scenario as business-as-usual (4d).
Figure 4: Contributions of individual forcing agents to the total decadal temperature change for three time periods. Error bars denote the 5–95% uncertainty range. The grey shading shows the estimated 5–95% range for internal variability based on the CMIP3 climate models. Observations are shown as dashed lines.
As expected, Huber and Knutti find that greenhouse gases contributed to substantial warming since 1850, and aerosols had a significant cooling effect:
"Greenhouse gases contributed 1.31°C (0.85-1.76°C) to the increase, that is 159% (106-212%) of the total warming. The cooling effect of the direct and indirect aerosol forcing is about -0.85°C (-1.48 to -0.30°C). The warming induced by tropospheric ozone and solar variability are of similar size (roughly 0.2°C). The contributions of stratospheric water vapour and ozone, volcanic eruptions, and organic and black carbon are small."
Since 1950, the authors find that greenhouse gases contributed 166% (120-215%) of the observed surface warming (0.85°C of 0.51°C estimated surface warming). The percentage is greater than 100% because aerosols offset approximately 44% (0.45°C) of that warming."It is thus extremely likely (>95% probability) that the greenhouse gas induced warming since the mid-twentieth century was larger than the observed rise in global average temperatures, and extremely likely that anthropogenic forcings were by far the dominant cause of warming. The natural forcing contribution since 1950 is near zero."
ConclusionThere are multiple lines of empirical evidence that increasing carbon dioxide causes an enhanced greenhouse effect. Laboratory tests show carbon dioxide absorbs longwave radiation. Satellite measurements confirm less longwave radiation is escaping to space at carbon dioxide absorptive wavelengths. Surface measurements find more longwave radiation returning back to Earth at these same wavelengths. The result of this energy imbalance is the accumulation of heat over the last 40 years.
Muadib
Paranormal Adept
How we know global warming is still happening
Skeptics proclaim that global warming stopped in 1998. That we're now experiencing global cooling. However, these arguments overlook one simple physical reality - the land and atmosphere are only one small fraction of the Earth's climate (albeit the part we inhabit). Global warming is by definition global. The entire planet is accumulating heat due to an energy imbalance. The atmosphere is warming. Oceans are accumulating energy. Land absorbs energy and ice absorbs heat to melt. To get the full picture on global warming, you need to view the Earth's entire heat content.
This analysis is performed in An observationally based energy balance for the Earth since 1950 (Murphy 2009) which adds up heat content from the ocean, atmosphere, land and ice. To calculate the Earth's total heat content, the authors used data of ocean heat content from the upper 700 metres. They included heat content from deeper waters down to 3000 metres depth. They computed atmospheric heat content using the surface temperature record and the heat capacity of the troposphere. Land and ice heat content (eg - the energy required to melt ice) were also included.
Figure 1: Total Earth Heat Content from 1950 (Murphy 2009). Ocean data taken from Domingues et al 2008.
A look at the Earth's total heat content clearly shows global warming has continued past 1998. So why do surface temperature records show 1998 as the hottest year on record? Figure 1 shows the heat capacity of the land and atmosphere are small compared to the ocean (the tiny brown sliver of "land + atmosphere" also includes the heat absorbed to melt ice). Hence, relatively small exchanges of heat between the atmosphere and ocean can cause significant changes in surface temperature.
In 1998, an abnormally strong El Nino caused heat transfer from the Pacific Ocean to the atmosphere. Consequently, we experienced above average surface temperatures. Conversely, the last few years have seen moderate La Nina conditions which had a cooling effect on global temperatures. And the last few months have swung back to warmer El Nino conditions. This has coincided with the warmest June-August sea surface temperatures on record. This internal variation where heat is shuffled around our climate is the reason why surface temperature is such a noisy signal.
Figure 1 also underscores just how much global warming the planet is experiencing. Since 1970, the Earth's heat content has been rising at a rate of 6 x 1021 Joules per year. In more meaningful terms, the planet has been accumulating energy at a rate of 190,260 GigaWatts. Considering a typical nuclear power plant has an output of 1 GigaWatt, imagine 190,000 nuclear power plants pouring their energy output directly into our oceans.
Figure 1 only goes as far as 2003 as the ocean heat data used (Domingues 2008) only goes that far. What has global warming been doing since then? Since 2003, ocean heat data has been measured by the newly deployed Argo network. However, there have been teething problems with the Argo buoys experiencing pressure sensor issues that impose a cooling bias on the data. Consequently there have been several data analyses on ocean heat since 2003. One reconstruction of ocean heat show cooling since 2003 (Willis 2008). Other analyses of the Argo data show ocean warming (Levitus 2009, Leuliette 2009, Cazenave 2009).
How do we determine which analyses are more accurate? Ocean heat data can also be independently determined through other empirical means. Cazenave 2009 uses satellite gravity measurements to create two independent estimates of ocean heat - both find warming. Sea level has been inexorably rising since 2003. As a large portion of sea level rise is due to thermal expansion from ocean warming, this is an indirect confirmation of warming.
Lastly, the planet's energy imbalance is confirmed by satellite measurements of incoming and outgoing radiation. Earth's Global Energy Budget (Trenberth 2009) examines satellite measurements for the Mar 2000 to May 2004 period and finds the planet is accumulating energy at a rate of 0.9 ± 0.15 W m?2. This is consistent with the amount of heat accumulating in the ocean. Preliminary analysis on the latest CERES satellite data shows an increasing energy imbalance from 2004 to the end of 2008 (although this data is yet to be published, more on this later).
So the point to remember when considering short term cooling trends in surface temperature records is that the atmosphere is only one small part of a planet which is in energy imbalance. Empirical measurements show the planet continues to accumulate heat. More energy is coming in than is radiating back out to space. Global warming continued past 1998 and is still happening.
Skeptics proclaim that global warming stopped in 1998. That we're now experiencing global cooling. However, these arguments overlook one simple physical reality - the land and atmosphere are only one small fraction of the Earth's climate (albeit the part we inhabit). Global warming is by definition global. The entire planet is accumulating heat due to an energy imbalance. The atmosphere is warming. Oceans are accumulating energy. Land absorbs energy and ice absorbs heat to melt. To get the full picture on global warming, you need to view the Earth's entire heat content.
This analysis is performed in An observationally based energy balance for the Earth since 1950 (Murphy 2009) which adds up heat content from the ocean, atmosphere, land and ice. To calculate the Earth's total heat content, the authors used data of ocean heat content from the upper 700 metres. They included heat content from deeper waters down to 3000 metres depth. They computed atmospheric heat content using the surface temperature record and the heat capacity of the troposphere. Land and ice heat content (eg - the energy required to melt ice) were also included.
Figure 1: Total Earth Heat Content from 1950 (Murphy 2009). Ocean data taken from Domingues et al 2008.
A look at the Earth's total heat content clearly shows global warming has continued past 1998. So why do surface temperature records show 1998 as the hottest year on record? Figure 1 shows the heat capacity of the land and atmosphere are small compared to the ocean (the tiny brown sliver of "land + atmosphere" also includes the heat absorbed to melt ice). Hence, relatively small exchanges of heat between the atmosphere and ocean can cause significant changes in surface temperature.
In 1998, an abnormally strong El Nino caused heat transfer from the Pacific Ocean to the atmosphere. Consequently, we experienced above average surface temperatures. Conversely, the last few years have seen moderate La Nina conditions which had a cooling effect on global temperatures. And the last few months have swung back to warmer El Nino conditions. This has coincided with the warmest June-August sea surface temperatures on record. This internal variation where heat is shuffled around our climate is the reason why surface temperature is such a noisy signal.
Figure 1 also underscores just how much global warming the planet is experiencing. Since 1970, the Earth's heat content has been rising at a rate of 6 x 1021 Joules per year. In more meaningful terms, the planet has been accumulating energy at a rate of 190,260 GigaWatts. Considering a typical nuclear power plant has an output of 1 GigaWatt, imagine 190,000 nuclear power plants pouring their energy output directly into our oceans.
Figure 1 only goes as far as 2003 as the ocean heat data used (Domingues 2008) only goes that far. What has global warming been doing since then? Since 2003, ocean heat data has been measured by the newly deployed Argo network. However, there have been teething problems with the Argo buoys experiencing pressure sensor issues that impose a cooling bias on the data. Consequently there have been several data analyses on ocean heat since 2003. One reconstruction of ocean heat show cooling since 2003 (Willis 2008). Other analyses of the Argo data show ocean warming (Levitus 2009, Leuliette 2009, Cazenave 2009).
How do we determine which analyses are more accurate? Ocean heat data can also be independently determined through other empirical means. Cazenave 2009 uses satellite gravity measurements to create two independent estimates of ocean heat - both find warming. Sea level has been inexorably rising since 2003. As a large portion of sea level rise is due to thermal expansion from ocean warming, this is an indirect confirmation of warming.
Lastly, the planet's energy imbalance is confirmed by satellite measurements of incoming and outgoing radiation. Earth's Global Energy Budget (Trenberth 2009) examines satellite measurements for the Mar 2000 to May 2004 period and finds the planet is accumulating energy at a rate of 0.9 ± 0.15 W m?2. This is consistent with the amount of heat accumulating in the ocean. Preliminary analysis on the latest CERES satellite data shows an increasing energy imbalance from 2004 to the end of 2008 (although this data is yet to be published, more on this later).
So the point to remember when considering short term cooling trends in surface temperature records is that the atmosphere is only one small part of a planet which is in energy imbalance. Empirical measurements show the planet continues to accumulate heat. More energy is coming in than is radiating back out to space. Global warming continued past 1998 and is still happening.
P
pixelsmith
Guest
you are serious about this post? skepticalscience.com? really?
ok... are you sure you want to use this web site as your source? last chance..
ok... are you sure you want to use this web site as your source? last chance..
Muadib
Paranormal Adept
It was quick and easy, I'm not exactly putting a lot of effort into this because I have no vested interested in proving this to you, the evidence has convinced me but I'm no climate scientist like I said. Instead of making snide posts like an asshole, why don't you present your objections?
P
pixelsmith
Guest
Moderators please remove Muadib from our forums for calling me an asshole.
Muadib
Paranormal Adept
ROFL, what a baby you are, I wasn't calling you an asshole, I was saying your posts have an assholish tone to them. You're obvious concerned about your image on the internet, which I find freaking hilarious, because it means absolutely nothing at all, whatsoever. Present your objections or please shut up.
Angel of Ioren
Friendly Skeptic
Let's refrain from name calling, okay? Pixel, Muadib does not deserved to be banned for that comment though.
Pixel, science says global warming is happening - no amount of wishing it weren't true or how much you think there's some sort of conspiracy will change that. I'll take the word of a climate scientist over that of a member of a Libertarian think tank.
Pixel, science says global warming is happening - no amount of wishing it weren't true or how much you think there's some sort of conspiracy will change that. I'll take the word of a climate scientist over that of a member of a Libertarian think tank.
Muadib
Paranormal Adept
I apologize to the forum and to Pixel, but your tone and posts imply that you think everyone who disagrees with you is some kind of mental defective, and it's annoying. Now are you going to refute the data? You asked for empirical evidence obtained via the scientific method, now you have it. I'm curious to hear your objections.
ward
Paranormal Adept
Well what do you know, Angelo does have some "Faith" after all.
Angel of Ioren
Friendly Skeptic
What do you mean?
Angel of Ioren
Friendly Skeptic
Science isn't faith based though. It's based on evidence.
If anyone has any doubt, please read what Phil Plait has to say on the topic. He'll explain it to you way better than I can.
Is science faith-based? | Bad Astronomy | Discover Magazine
If anyone has any doubt, please read what Phil Plait has to say on the topic. He'll explain it to you way better than I can.
Is science faith-based? | Bad Astronomy | Discover Magazine
Muadib
Paranormal Adept
I agree, but I think that's what he was implying, like I said I could be wrong.
P
pixelsmith
Guest
dude.. i posted that i agreed with much of what you said. Now you want to disagree with me agreeing with you?
now.. again do you really want to use skepticalscience.com as your authority? You being a newbie at this I want to give you a chance before I comment or waste time on your post. Do some googling on the bozo that runs that site and get back to me in a few days.
P
pixelsmith
Guest
no. your science is based on faith and consensus. nothing from your "side" has anything to do with scientific methods.
I gotta get some money making work done.. you boys do some actual research for a few years and then try to present something to discuss.
Here is something to consider. Can your "science" get past #2?
Scientific Method: The scientific method involves four steps geared towards finding truth:
- Observation and description of a phenomenon or group of phenomena.
- Formulation of an hypothesis to explain the phenomena - usually in the form of a causal mechanism or a mathematical relation.
- Use of the hypothesis to quantitatively predict the results of new observations (or the existence of other related phenomena).
- Performance of experimental tests of the predictions by several independent experimenters and properly performed experiments.
Muadib
Paranormal Adept
Look man, you don't know me, so I can understand that you might think I give a rat's you know what about what you think of me or how I'm viewed, on this or any other, site on the internet. It means nothing to me, I'm here to learn from the more experienced people on the site and offer my two cents when I feel like it. I don't know everything and I don't claim to. So implying you're going to embarrass me or something along those lines means nothing to me, embarrass away. I don't care who runs the site, he didn't write the reports that back up the facts in that article. I could post other articles from other sites that say exactly the same thing, so skepticalscience is hardly my "authority" on the matter, it was quick, easy and simple, something I value in stupid internet debates on which I place absolutely 0 importance of "winning" I'm honestly curious if you have something to say about the data in that article, which says that humans are a contributing factor to global warming, if you agree then why are we even having this "debate"?
I don't need a few days, I'm ready to hear what you have to say now, and if in the end I think you've presented a stronger case than the climate scientists who authored those papers, I'll happily change my opinion on the matter and won't feel even the least bit embarrassed about it. I'm not some hippy who has based his life on a crusade against global warming so if I turn out to be wrong, that's great because I learned some new useful information. That's how I roll.
