- One country’s solution may be another country’s problem. Climate engineered to improve rainfall in one region may well decrease rainfalls in others. There is considerable scope for disagreement on the use of climate engineering technology across nations.
- Unpredictability: Our plans may not take into account 1 in 100 phenomena such as volcanic eruptions, periods of substantial solar flare activity, or even human activity such as land clearing and burning, as has happened in Indonesia in recent years. During 1997-98, approximately 2 million hectares (4.9 million acres) of forest and 5 million hectares (12.4 million acres) of non-forested areas burned, across large parts of Southeast Asia. Smoke was detectable across a large area of the globe, affecting even the flight path of planes. Carbon emissions from the fires have been estimated at between 15 and 40 per cent of annual global fossil fuel pollution. The swathe of smoke from burning agricultural land in Indonesia threatened to become a planet affecting event.
- Agricultural productivity changes: these may actually improve in some areas and deteriorate and others. So changing climate can result in winners and losers. Not likely to be popular.
- Marine current changes: it is well known how critical the Gulf Stream flow is in maintaining all the temperatures in northern Europe especially in England. Experimenting with the climate they have huge unintended consequences. Imagine the horror in Northern Europe and the British Isles if we managed to redirect the Gulf Stream.
- Failure of orbital implementations such as a sunshade or solar mirror may be very hard to remediate. It is costly to get these facilities into orbit and to keep them serviced and safe there. A simple financial recession could well cripple the capacity of a country to fix space or orbital based facilities.
- Focusing on new solutions such as cloud engineering may well siphon energy away from carbon dioxide reduction strategies across nations. In short, we may all stop working together to achieve a common goal. It is considered that the best strategic outcome arises when all nations cooperate in achieving common goals.
- The focus on non-CO2 technologies is likely to involve promotion of new nuclear strategies. Thorium power plants may be an excellent alternative to uranium nuclear power plant strategies. There would be pollution concerns with nuclear strategies. Clean and green people generally find any nuclear option abhorrent.
Global Warming by the Numbers
Kinkajou : Tell us about some of the energy transfer numbers involved in global warming.
Greenhouse gases in earth's atmosphere, while largely transparent to Incoming solar radiation, absorb most of the infrared emitted by earth's surface. Moreover, the surface emits infrared upwards only. The air's greenhouse gases radiate both up- and downwards. So some infrared comes back down. The net effect being heat retention.
Clouds also absorb infrared well, resulting in heat retention.
Again, cloud tops are usually cooler and emit less infrared upwards than the surface, while cloud bottoms radiate some infrared back down. All in all, part of the infrared emitted by the surface gets trapped. Again the net effect being heat retention
Kinkajou : So tell us about how global warming occurs, by the numbers?
Erasmus :Satellites looking at the Earth from space tell as that approximately 240 W per square metre of infrared (heat) is emitted from the planet.
However analysis of the Earth’s surface suggest an average of roughly 390 W per square metre of infrared is emitted at the Earth’s surface.
The difference it into energy levels i.e. approximate 150 W per square metre is trapped by greenhouse gases and clouds. This energy comes into the Earth’s atmosphere, is radiated from the Earth but then is retained by the atmosphere namely gases and clouds. This is not a bad phenomenon. This effect is critical in making the earth habitable.
If the earth were a big Bald Rock, (with no atmosphere), an infrared emission rate of 240 W per square metre would normally arise from a surface of approximately -18°C. However the Earth surface has a mean temperature nearer 16°C. This means the natural greenhouse effect from atmospheric trapping of incident solar energy results in a warming of approximately 34°C.
Erasmus :This effect makes the Earth’s surface temperature approximately average out at about 16°C, whereas radiation analysis of a bare rock planetary body would suggest a temperature of about -18°C should be present on the surface. As I said this effect is critical in making the earth habitable.
Technically the effect is not a “greenhouse” effect. Greenhouses retain heat by limiting convection (including advection) losses. The Earth retains heat by atmospheric absorption and remission of infrared radiation.
The inputs/outputs to this greenhouse effect are complex. 60 to 70% is due to water vapour which is a dominant greenhouse gas in US atmosphere. It is interesting that while everyone talks about the effect of CO2, if warming occurs the amount of water vapour in the atmosphere will rise as well. Over emissions of particulates may well reduce the amount of water vapour in the atmosphere by encouraging precipitation. Other important agents in the greenhouse effect besides carbon dioxide are
- Nitrous oxide
- DMSO (sulphates)
- Clouds are important.
- Particulate atmospheric aerosols are important.
Clouds in Global Warming
Kinkajou : So what is the effect of Clouds & Gases?
Erasmus :Clouds which consist of either water droplets or ice particles or both, are an important cause of greenhouse effects. The tops of clouds in sunshine look brilliantly white because they reflect sunlight, (approximately 50 W per square metre is calculated to be reflected). Clouds also trap infrared radiation sourced from the ground (either land or sea surface), calculated at approximately 30 W per square metre being trapped.
So the net effect of the cloud as a cooling effect of 20 W per square metre in radiation terms.
However clouds cover only approximately 30% of the Earth’s surface. (This is also described as the earth having a reflectivity or albedo/whiteness of approximately 30 %.) This creates an overall 6 W per square metre average overall cooling, caused by cloud cover.
The other complicating factor in cloud effects on earth’s surface temperature are due to evaporating water soaking up heat at the Earth’s surface, and releasing this heat when the water vapour condenses as in cloud formation in the upper atmosphere. This is described as convection. This “convectional” heat loss adds to the above radiated heat effects.
Kinkajou : Looking all these numbers is easy to see why models predicting global climate change or global warming, fall apart. The devil is in the details.
Kinkajou : Can historical data help us to make a decision?
Erasmus :Human activities have resulted in changes in greenhouse gas levels over the last 200 years.
Carbon dioxide (CO2) went up from about 280 ppmv (parts per million by volume) in the year 1800 to about 358 ppmv in 1994
Methane (CH4) increased from roughly 0.8 ppmv in 1800 to more than 1.7 ppmv in 1992.
Nitrous oxide (N2O) rose from a preindustrial level of about 0.275 ppmv to 0.310 or so ppmv in 1992
The Pink Planet : Earth : once upon a time
Erasmus :If the only variables in calculating warming or cooling effects were surface temperature and air temperature, it is predicted that a CO2 doubling would eventually warn the Earth’s surface by 1 to 1.2°C. However, the variables of water vapour content, cloud coverage, ice distribution on the planet, and biological feedback adds considerable complexity to the calculation of the net warming or cooling of the “greenhouse” effect.
The presence of water vapour is generally warming, clouds tend to have net cooling effects, and biological effects are very complex. These variables are to some extent interdependent. For example increasing global temperatures would increase global humidity which would be expected to have a warming effect. However if cloud cover increases this would be a cooling effect. With the net effect be then warming or cooling? Human activity creates particulates which could have a cooling effect if it removes cloud cover, buffering the effects of increased CO2.
Erasmus :The cloud feedback effects on global warming may be large, yet not even its sign is known. Are our human induced changes in cloud cover on the planet warming or cooling to the planet?
Erasmus :Low clouds tend to cool, high clouds tend to warm. High clouds tend to have lower albedo and reflect less sunlight back to space than low clouds. Clouds are generally good absorbers of infrared, but high clouds have colder tops than low clouds, so they emit less infrared space wards. To further complicate matters, cloud properties may change with a changing climate, and human-made aerosols may confound the effect of greenhouse gas forcing on clouds. With fixed clouds and sea ice, models would all report climate sensitivities between 2°C to 3°C for a CO2 doubling. Depending on whether and how cloud cover changes, the cloud feedback could almost halve or almost double the warming
Erasmus :The problem with working out the effect of greenhouse gases on a surface temperature is to work out how the effects balance. On a day-to-day basis energy in equals to energy out. This means if more energy is retained, the temperature of the system rises, and generally other sources will generate more infrared at these high temperatures resulting in energy balance.
To the best of present knowledge, the so-called equilibrium surface warming, also known as the `climate sensitivity', is likely to sit somewhere between 1.5°C to 4.5°C for a CO2 doubling, with a best estimate of 2.5°C .
Erasmus :For example, increased CO2 levels in the atmosphere cause warming, resulting in higher humidity which also causes warming, increasing cloud cover which causes cooling but perhaps decreasing cloud cover with increased aerosol particulates (causing warming)
The final result could be warming, but as can be seen from the complexity of the cloud effects on temperature, this need not be so. It is thought the Earth’s surface will probably warm, although there is considerable uncertainty as to how much and how swiftly.
Another example suggests that, at the moment, stratospheric ozone loss may play an important role. It may also have a hand in the slight cooling of the upper troposphere over the past decades.
Aerosols : affecting Climate
Kinkajou : So tell us more about aerosols and their effect on global climate?
- Aerosols are airborne particles, effectively in the one nM to 1000 nm size range (.001 10 µm to 10 µm.) Aerosols can affect the climate a number of ways:
- Absorbing solar radiation,
- Scattering solar radiation,
- Acting as cloud condensation nuclei,
- Enhancing reflectivity and lifetime/ durability of clouds
- it is thought that human made aerosols (being predominantly carbon from burning organic materials or sulphates downwind of industrialised areas) currently cancel about 50% of the warming effect of human made greenhouse gases. However, there is considerable uncertainty as to this effect. Most high atmosphere aerosols are washed out after a week.
Aerosols can also arise from natural sources such as volcanic eruptions causing high atmospheric sulphate aerosols and dust to accumulate, again leading to cooling. Aerosols arise from wind turbulence over the ocean. If you have ever stood on a beach and looked downwind, you can see the clouds of white particulate dust rising from the ocean and extending over the land, blown by the wind.
Aerosol effects are hard to measure. Major variables are size, shape, composition and atmospheric and geographic distribution of the particles. Assessing how aerosols affect climate involves modelling of regional weather and clouds, both of which currently generate large numerical uncertainties in predicting their effects. (Different authors give different opinions).
Oceans Affecting Climate
Kinkajou : So what about the ocean?
The ocean has a huge effect on global climatic change. This effect is mediated by:
- Its huge heat capacity
- Its huge carbon sinks capacity
- Convection effects (mediated by currents)
In mathematical terms the heat capacity of the water column about 2.5 m in depth matches the heat capacity the atmosphere lying above it. Less than 2 m of water column depth is required to match the heat capacity of an average land surface. The ocean in parts of the earth is kilometres deep. This means that oceanic currents will often mediate or buffer temperature change by acting as a heat sink.
Because of their massive size oceans show a slow response time to temperature changes, so temperature may rise for many years after stabilisation of greenhouse gas levels.
Kinkajou : Tell us how the numbers on carbon and CO2 affect world CO2 levels.
Erasmus: One gigatonne is equivalent to 10E9 metric tonnes, this being the mass of one cubic kilometre of water.
3.67 gigatonnes of CO2 contains approximately one gigatonne of carbon.
7.8 gigatonnes of CO2 corresponds to a one ppmv change in the CO2 level of the atmosphere.
Erasmus :The biggest problem with predicting the effects on the global atmospheric CO2 level using models of carbon inputs into the eco-sphere, is the buffering effects inherent in biological systems. Different authors have predicted that the effects of marine life seizing available CO2 in the atmosphere could cause changes in atmospheric CO2 between 10 to 200 ppmv. This is a massive variation, able to completely destroy the validity of any computer model.
Erasmus :The Ocean is also a major natural source of atmospheric sulphate aerosols. Dimethyl sulphide (DMS) arising from biologicals in marine environments is likely to affect marine cloud cover and surface temperature. However DMS production is hard to predict because it depends on many factors such as species present in the marine environment and marine biomass.
Kinkajou : How much carbon is there active on the planet?
Carbon reservoirs in GtC
- Atmosphere (1990) 750 gigatonnes of carbon
- Surface ocean 1000 gigatonnes of carbon
- Terrestrial vegetation 600 gigatonnes of carbon
- Marine biota 3 gigatonnes of carbon
- Soils & detritus 1600 gigatonnes of carbon
- Dissolved organic carbon 700 gigatonnes of carbon
- Deep ocean 38000 gigatonnes of carbon
Natural carbon fluxes in GtC/year, <--> denotes a two-way flux
- Atmosphere --> terrestrial vegetation 120 GtC/year Photosynthesis
- Terrestrial vegetation --> atmosphere 60 GtC/year Respiration
- Terrestrial vegetation --> soils & detritus 60 GtC/year
- Soils & detritus --> atmosphere 60 GtC/year Respiration
- Atmosphere <--> surface ocean 90 GtC/year
- Surface ocean <--> deep ocean 100 GtC/year
Carbon dioxide sources:
- Fossil fuel burning, cement production 5.5 (5.0-6.0) GtC/year
- Changes in tropical land use 1.6 (0.6-2.6) GtC/year
- Total emissions 7.1 (6.0-8.2) GtC/year
Partitioning among reservoirs:
- Storage in the atmosphere 3.3 (3.1-3.5) GtC/year
- Oceanic uptake 2.0 (1.2-2.8) GtC/year
- Northern Hemisphere forest regrowth 0.5 (0.0-1.0) GtC/year
- Other terrestrial sinks: CO2 fertilization,
- N fertilization, climatic variations 1.3 (-0.2-2.8) GtC/year
Except for atmospheric CO2, carbon reservoirs and natural fluxes are
Hard to measure.
Both volcanic CO2 and CO2 removal via silicate weathering is in the order of 0.1 GtC/year and play a role on geologic time scales only.
Kinkajou : So tell us more about how climate changes may relate to greenhouse gas levels throughout recent history?
Erasmus :Local weather is a complex phenomenon. Although greenhouse gases have changed little in the past thousand years there have been some major climactic events. There has been a glaciation event with extinction of mammoths and a large mammalian species brought me 10,000 years ago. There has been a mini glaciation event; typified by the Thames River freezing near London several hundred years ago, approximately 15th to 19th centuries, and the Medieval Warm Period, from perhaps the 9th to the 14th century, are cases in point.
However in geological scales, changes in greenhouse gas levels do contribute significantly to coolings and warmings. Some authors have suggested that there is a striking correlation between temperature and concentrations of carbon dioxide and methane over the past 220,000 years. This information on gas levels was taken from the Vostok ice cores from Antarctica.
In the last glaciation event, occurring roughly 10,000 to 18,000 years ago, the CO2 decrease markedly lagged the onset of cooling. This suggests that the greenhouse gases were not the primary cause of change. It is possible that they acted as a feedback amplifier for the climatic shift underway instead. I.e. as the world cooled, a reduction in CO2 and water vapour, reduced heat retention and thereby provided a cooling effect.
Kinkajou: Again we returned to the concept of “tipping” point.
Erasmus :In the past to the glaciation events, carbon dioxide levels appear to have perhaps lagged temperature changes by about 1000 years. Again this suggests that greenhouse gases were not the primary cause of the change.
However new data suggest that asynchronous regional coolings and warmings are common. For example, data suggest that in Sweden and in the Sargasso Sea, summers were warmer in the early 1500s, a fact in contrast to events of the Little Ice Age in England.
Erasmus :We have previously considered that the Medieval warm period and the Little Ice Age were global phenomena. There are no data available to tell as were the so-called Medieval warm period globally averaged was any warmer than the Little Ice Age. There is some data suggest that the global warming since around 1900 represents a persistent consistent and uniform trend in temperature change.
Decline and subsequent rise of solar activity to its present level may have contributed to the Little Ice Age and to the warming thereafter.
It is possible that there may be other events triggering the last glaciation and the glaciation events recorded in the ice core data.
Warming cooling events can be triggered by variations in the Earth’s orbit. These variations cause, among others, changes in high northern latitude summer insolation, which are critical for the waxing and waning of ice sheets. Northern summer insolation was unusually low at the onset of the last glaciation around 115,000 years ago, it was high during de-glaciation. However it is believed that the direct effects of orbital changes on solar radiation inputs outputs is too small to cause glaciation or de-glaciation.
Erasmus :The Sun also has a cycle of energy changes, typified by solar flare activity. This has increases and decreases over approximately 11yrs. What longer term changes occur in solar radiation output, is unknown.
Kinkajou : It is data like this that makes the prediction of climatic change due to changes in greenhouse gases so difficult.
Erasmus :Without knowing natural climatic variations reasonably well, elucidating their causes is difficult. Even the causes of well-known events can be hard to identify. 1976-77 the behaviour of El Nino-Southern Oscillation appears to have changed. El Nino episodes got more frequent, sea surface temperatures in the tropical Pacific tended to be high, precipitation over the tropics and subtropics from Africa to Indonesia declined. While some model results suggest that greenhouse gas induced climate change may look similar, it is still open whether this was incipient climate change or a natural fluctuation
Kinkajou : So tell us where you think we are going now?
Erasmus :Currently the field of climate engineering consists of coalescing some research data into computer models. However, is becoming obvious that we do not have an adequate dataset for explanation of observed changes or prediction of future changes. Our models make too many assumptions on interrelated buffering variables to yield reliable predictions.
In short, were not really sure what’s happening and certainly not really sure what to do about it. Many authors would even argue that it is impossible to know what the earth’s temperature would be without human influences. There are many issues with regards to costs and feasibility of development and deployment of various solutions to the problem of global climate change. Social and political complexities add substantially to our ability to implement change in a constructive and predictive fashion. We have concerns that some of our climate engineering solutions may cause more disruptive effects than the effects of world warming with rising CO2 emissions.
Is becoming obvious that humankind’s outpouring of greenhouse gases most notably carbon dioxide, has launched an experiment of historical geological proportions. We don’t know whether the countermeasures we have proposed may be effective. We can only say that the longer our outpouring of greenhouse gas continues and the greater the output of these gases, the more likely it becomes that climate change will occur. Whatever change may occur, will occur more extremely and more noticeably. Hopefully not to our chagrin.
Kinkajou : You mentioned some other proposals for climate engineering.
Erasmus :Yes, the issue is that once we understand how climate works, we can make predictions and plan solutions that in concert together can direct the climate to change in ways that we would prefer. For example, tethering barriers across ocean currents can redirect energy and change climates but redirecting oceanic energy flows that drive climate.
Changing the structure of cities is likely to change our weather and climate.
Planting trees in lines across the face of the planet can cause hedgerow type effects on local climates. In very cold climates, hedgerows stop the wind from reaching animals living on the exposed landscape, reducing life threatening cooling effects, enabling longer outside agistment times for farm animals.
The same structures on a regional scale could affect and change temperature at ground level, possibly with climate effects.
There are a number of structural changes that humans can make in their landscape or environment with weather / climate effects. The trick is knowing, which changes to make and knowing how successful they may be, enabling cost benefit analyses of proposals.
Kinkajou : So what have you learned Goo?
Goo :I think it is critical for humanity to gain some understanding of how its activities are affecting the environment, the weather and climate. Just as we build a house to minimise its heat profiled in Australia, I think we should be building cities and structures within the country to control their effect on the climate.
The basic problem is first measure, then predict, (using detailed computer models of the country), then make modifications to achieve specific purposes, which can themselves be measured, their results reincorporated into computer models unused to consider new modifications.
I think there is considerable room for some very basic proposals. The use of solar voltaic power systems is an incredible innovation changing how power needs to be generated within the world. However, there is little use creating systems that produce power when most people do not wish to use it. In short, power systems must incorporate storage systems so power can be generated when circumstances allow and stored until circumstances demand it be used.
I think governments are an excellent position to champion, install and maintain these types of systems. Again, the emphasis in Australia is on individuals taking the initiative. However the reality is that individuals do not have the resources to maintain operate in debug these types of systems. Governments do have a capacity to employ knowledgeable people, coordinate their activities, generate solutions and implement these on a nationwide basis to give predictable outcomes at predictable costs.
To restate this again, a government installing solar voltaic power systems with storage capacity as a nationwide initiative, would seriously impact the requirement to burn fossil fuels in power generation stations. The government could fund this activity as a rental model to the people involved. Introduction of standards to power generation would enable this activity to become an ongoing business supporting many people. People would still pay for power, but instead of the money going to mining companies in power generation utilities, the money would fund industrial activity creating building installing and maintaining roof based solar voltaic utilities.
Much can be done. I think sometimes the best thing to do is the simplest positive thing. Choose a strategy with predictable results and implement the strategy nationwide at volume. Why subsidise the losers (power generation utilities) in climate change management, by reimbursing them for their increase costs of carbon generation, when you can spend your finances and energies backing a win-win.
The trick is in knowing what to do, and then to do it with conviction. But, the world is an imperfect place. You can get second chances to get things right. The planet and life upon it is a very robust buffer for climate changes. If you make changes, measure them, and make sure they are taking you where you want to go.