Here are the questions to ask yourself. It is the mission of this website to help you answer them.
• Q. Is the climate changing and if so, is it bad news?
• A. No one questions the fact that it is changing. It has always changed and the paleoclimate record from ice and ocean sediment cores confirms this very clearly. Scientists have analysed ice cores going back around 800,000 years and have now identified regions in Antarctica they say could store information about Earth’s climate and greenhouse gases extending as far back as 1.5 million years. By studying the past climate, scientists can understand better how temperature responds to changes in greenhouse-gas concentrations in the atmosphere. This, in turn, allows them to make better predictions about how climate will change in the future. Ice-cores contain little air bubbles and, thus, represent the only direct archive of the composition of the past atmosphere. The 3.2-km-long ice core completed in 2004 at Dome Concordia (Dome C) in Antarctica revealed 800,000 years of climate history, showing that greenhouse gases and temperature have mostly moved in lockstep as shown in this graph. Note that in 2015, the high point on the chart below passed the 400ppm mark!
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The activities of humanity have caused changes within 200 years that took thousands of years in the natural cycles of ice age and interglacial. Change that is this rapid leaves no time for evolutionary adjustment to the changing environment and mass extinctions of species result – humans could be among them.
• Q. What can we learn from these ice core records?
• A. Within the current major glaciation period, the past million years saw regular interglacial warm periods, initiated by natural variations in the Earth’s orbit around the Sun (~100,000 year Milankovitch cycles). The Milankovitch theory describes the collective effects on the Earth’s climate of cyclic changes in Earth’s orbit around the Sun. For each cycle, it took an average 5,000 years for temperatures to rise by 4 – 7°C and for the global average CO2 concentrations to rise by ~80 ppm. Current CO2 levels are ~400ppm, higher than at any time in the last million years. This is a rise of ~120ppm from the pre-industrial level of ~280ppm. During the natural cycles, Antarctic temperatures and variations in global CO2 concentrations appear closely correlated and CO2 concentration rises do not precede temperature rises:
The emissions of greenhouse gases due to human activities since the beginning of the Industrial age, have overpowered this natural cycle. By emitting large quantities of CO2 and other greenhouse gases, in such a short period of time, we have created an imbalance in the natural cycle. This has amplified the greenhouse effect and temperatures are steadily rising as a consequence. Currently the rise is roughly ten timesfaster than the average rate of ice-age-recovery warming.
• Q. Is climate change caused or affected by human activity?
• A. There is an overwhelming scientific agreement that it is. The scientists tell us that over millions of years, plants and algae took CO2 out of the atmosphere and sequestered it in the form of fossil fuels (coal, oil & gas.) In the past two centuries, since the industrial revolution, humans have learnt how to extract and burn fossil fuels and, over a short period, have released back into the atmosphere large amounts of CO2 that had been sequestered over many millions of years. At the same time, they have cleared away the forests that used to trap CO2 and often replaced them with domesticated animals that themselves produce methane – another greenhouse gas. Due to human activities, the atmospheric concentration of CO2 has been rising extensively since the Industrial Revolution and has now reached dangerous levels not seen in the last 3 million years. Human sources of CO2 emissions are much smaller than natural emissions, but sufficient to have upset the natural balance that existed for many thousands of years before the influence of humans. This is because natural sinks removed around the same quantity of CO2 from the atmosphere that was produced by natural sources. This kept CO2 levels balanced and in a safe range. But human sources of emissions have upset the natural balance by adding extra CO2 to the atmosphere without removing any. Although our output of 29 gigatons of CO2 is tiny compared to the 750 gigatons moving through the carbon cycle each year, it adds up because the land and ocean cannot absorb all of the extra CO2. About 40% of this additional CO2 is absorbed. The rest remains in the atmosphere, and as a consequence, atmospheric CO2 is at its highest level in 15 to 20 million years. (A natural change of 100ppm normally takes 5,000 to 20,000 years. The recent increase of 100ppm has taken just 120 years). Human CO2 emissions upset the natural balance of the carbon cycle. While fossil-fuel derived CO2 is a relatively small component of the global carbon cycle, the extra CO2 is cumulative because the natural carbon exchange cannot absorb all of the addition. The level of atmospheric CO2 is building up, the additional CO2 is being produced by burning fossil fuels, and that build up is accelerating.
• Q. How fast is the climate changing?
• A. Many of the world’s climate scientists believe it is happening at a rate that will threaten the stability of human populations due to major adverse weather events, famine, war, mass migrations, sea level rise and ocean acidification within the lifetimes of our grandchildren. Some argue that there remain serious gaps in scientific understanding and that each year of inadequate action increases the likelihood of the Earth reaching a tipping point where we move from the current rate of change into one that is disastrous or abrupt.
• Q. Why is CO2 a greenhouse gas?
• A. The temperature of the Earth depends on a balance between incoming energy from the Sun and the energy that bounces back into space. CO2 absorbs heat that would otherwise be lost to space. Some of this energy is re-emitted back to Earth, causing additional heating of the planet. Most of the light energy from the sun is emitted in wavelengths shorter than 4,000 nanometers (.000004 meters). The heat energy released from the earth, however, is released in wavelengths longer than 4,000 nanometers. Carbon dioxide doesn’t absorb the incoming energy from the sun, but it does absorb some of the heat energy released from the earth.
• Q. Should I be looking at my consumption of animal products?
• A. A large source of carbon emissions is from livestock farming. Livestock’s Long Shadow: Environmental Issues and Options is a U.N. report, released by the Food and Agriculture Organisation of the United Nations on 29 November 2006. Based on this report, senior U.N. Food and Agriculture Organisation official Dr. Henning Steinfeld stated that the meat industry is “one of the most significant contributors to today’s most serious environmental problems” and that “urgent action is required to remedy the situation.” Following a Life Cycle Analysis approach, the report evaluates “that livestock are responsible for 18 percent of greenhouse gas emissions, a bigger share than that of transport.” In a 2009 issue of the Worldwatch Institute magazine, environmental assessment specialists Robert Goodland and Jeff Anhang argued in “Livestock and Climate Change” that the FAO vastly underestimated the environmental impact of the livestock sector and that it accounts for at least 51% of global GHG emissions. Some criticisms included the FAO’s use of the 100-year Global Warming Potential (GWP) of methane (CH4) rather than the 20 GWP favored by Goodland and Anhang. However, Goodland and Anhang continue to use the 100-year GWP for anthropogenic greenhouse gases in their analysis, with the sole exception of methane emissions from livestock. More controversially, Goodland and Anhang argue that animal respiration should be included, despite widely adopted conventions that they be treated as part of the short-term carbon cycle and excluded. Suffice it to say animal agriculture is a large contributor to greenhouse gas emissions and something that needs to be taken more seriously at all levels of decision making. Currently very few people want to talk about it as it raises so many questions about our lifestyles and the economy that we depend on. Whenever the issue of animal agriculture and its associated emissions are discussed the common response is that it is a very difficult area in which to reduce emissions. Very few address the elephant in the room – that emissions can be very simply reduced by reducing animal numbers. Consider this fact. On average 1 hectare can produce about 28,000 kgs of plant-based food but the same area can produce only 280 kgs of meat. If we really want to play our part in contributing to food security at the same time as reducing greenhouse gases then the answer is clear and simple. The added bonus in the case of NZ is that reducing cow numbers will help restore some health to our waterways.
• Q. What is climate forcing?
• A. Climate forcing is one of the critical factors to understand if we are going to get our heads around what is causing the current rate of climate change. There are positive and negative forcings, which are natural and man-made. “In climate science, radiative forcing or climate forcing, is defined as the difference of insolation (sunlight) absorbed by the Earth and energy radiated back to space. Typically, radiative forcing is quantified at the tropopause in units of watts per square meter of the Earth’s surface.” Radiative forcing “The natural forcing due to insolation variations, averaged over the planet, is a small fraction of 1 watt/M2. This very weak forcing is effective only because, operating over long periods, it succeeds in bringing into play two powerful slow feedbacks: global surface reflectivity changes and greenhouse gas changes…. Humans, by rapidly burning fossil fuels, have caused global warming that overwhelms the natural tendency towards the next ice age…. But human-made climate forcing is now so large that decadel-mean climate will continue to warm for at least the next few decades….because of slow feedbacks, global temperature will continue to rise for decades and millennia unless we reduce human-made climate forcings.” (page 49 – ‘Storms of my Grandchildren’ by James Hansen)
Using current global climate simulations, NASA GISS shows in the image below, the changes in effectiveness of the main radiative forcings since 1880.
As you can see, greenhouse gases are shown to have the greatest sustained positive forcing on the climate system. Stratospheric aerosols from volcanic eruptions can also have a strong, negative cooling influence, but it is very short term. Also note the small influence of solar irradiance changes since 1880. The indirect cooling impact of the release of man-made aerosols is also having a significant impact.
• Q. What can we learn from ocean sediment cores?
• A. From ocean sediment cores we have learnt that about 55 million years ago, an enormous amount of CO2 entered the atmosphere in perhaps only 1,000 years, causing global temperature to rise. Much of the CO2 was absorbed by the ocean, quickly changing its composition. Younger sediments, which do not contain any carbonate shells, lie on top of older sediments, which contain many tiny shells. This sharp boundary indicates that many shelled organisms suddenly disappeared from the ocean at that time. One theory for the source of all this CO2 is that gradual warming of the ocean melted ices containing methane that were part of shallow ocean sediments. The released methane, in turn, reacted with oxygen in the atmosphere to form CO2. The amount of CO2 that was injected into the atmosphere 55 million years ago is comparable to the amount that humans will put into the atmosphere over the next century if we do not reduce CO2 emissions. So that event of the distant past could have important lessons for today.
• Q. If the climate is changing, is there anything I can do about altering the speed of change slowing or stopping it?
• A. You can do a teeny, weeny, little bit by altering your own carbon footprint www.karangapledge.org.nz However, if everyone took steps in this direction it would have a huge impact. You owe it to the future to do your little bit. Other big differences can be made by governments and economic pressure. There are many reasons why governments do not want to take the steps necessary. This can only be changed if they are forced to take action by a ground-swell of demand from their electorates. A massive grass-roots movement can do this. Help by signing the Karanga pledge. Economic pressure is being created by large organisations, such as investment and endowment funds, banks and cities divesting from fossil fuel investments. If enough momentum can be created so that people start to worry about fossil fuel investments becoming stranded assets then liberated funds can be redirected into renewables and new technologies.
• Q. How do New Zealanders emissions compare to other countries?
• A. Per person, NZ’s emissions are the 5th highest in the developed world (17 tonnes/person compared with 5.6 tonnes/person in Sweden – 2012). There has been a net 42% rise in NZ’s greenhouse gas emissions since 1990. This was the year of the Kyoto Protocol, an international agreement that attempted to limit greenhouse gas emissions from developed countries, and which NZ ratified. (net figures include land use, land-use change and forestry inputs.)
Q. Why do carbon dioxide emissions weigh more than the original fuel?
A. The amount of carbon dioxide (CO2) that is produced from burning a fuel weighs more than the amount of the fuel itself, because during complete combustion, each carbon atom in the fuel combines with two oxygen atoms in the air to make CO2. The addition of two oxygen atoms to each carbon atom forms CO2, which has an atomic weight of 44 – roughly 3.6667 times the atomic weight of the carbon, which is 12.
For example, sub-bituminous coal is on average 51% carbon, so the carbon in a tonne (1,000 kg) weighs 510 kg. The carbon dioxide emissions from burning a tonne of sub-bituminous coal are approximately 1,872 kg, or about 3.67 times the weight of the carbon in a tonne of coal, and 1.87 times the weight of a tonne of coal.
Q. What part do the world’s oceans play?
A. Since 1955, over 90% of the excess heat trapped by greenhouse gases has been stored in the sea ice, ice caps, and glaciers, and warming the land masses. Only the smallest fraction of this thermal energy goes into warming the atmosphere. Humans thus, living at the interface of the land, ocean and atmosphere, only feel a sliver of the true warming cost of fossil fuel emissions.
This 90% of extra heat taken up by the ocean is mostly in the upper 700 metres (m) layer (about 60% of total excess heat), while 30% is stored in layers deeper than 700 m. The ocean absorbs most of this “anthropogenic heat” because:
The complex interactions between continued emissions of greenhouse gases, consequent energy imbalance, and changes in the storage and transport properties of heat in the ocean will largely determine the speed and magnitude of long-term anthropogenic climate change impacts. These interactions have significant policy and economic implications, and must not be ignored in the climate policy discussions forum. As the climate negotiators are now shifting their focus towards reaching an agreement on appropriate stabilisation targets and designing mitigation and adaptations strategies required to meet those targets, understanding and incorporating the highly important role of ocean as the most powerful climate change mitigator becomes of utmost importance. http://www.oceanscientists.org/index.php/topics/ocean-warming
*Climate deniers have used the period 1998 – 2013, during which atmospheric temperatures did not rise as much as expected, as evidence that global warming was not happening. This has been termed the “hiatus” period. In fact now that we have a couple more years under our belt and 2014 and 2015 have been the hottest years on record it is now clear that the hiatus period is not outside the statistical trend-line. This is an example of using information selectively that suits an argument but doesn’t have wide enough parameters to give clarity. It now appears that the deep ocean absorbed more of the heat than expected during the hiatus period. This highlights the fact that the proportion of heat that is causing rising atmospheric temperatures is a small fraction of the total extra heat that can be attributed to greenhouse gases.
According to Craig Stevens, Oceanographer with NIWA (Radio NZ, Nine to Noon, 27/01/2016) research has shown that the upper layers of the world’s oceans have warmed by between 0.90C and 1.30C/decade over the last 40 years. The oceans have absorbed 20 times more heat than the atmosphere over the same period, resulting in their heat energy having doubled since 1997. He says if you took the amount of heat absorbed by the oceans and put it into the atmosphere the atmosphere would have heated by tens of degrees.
In other words without the heat sink effect of the world’s oceans we would all be cooked by now.
Q. The climate is always changing irrespective of human presence on earth or not. Why do we think that our actions make any difference?
A. Read this article and you should soon abandon such inspirations to complacency.
The posts are a collection of opinion articles written by CKM member Tom Powell for the Marlborough Express. Tom is a retired geologist who came to New Zealand in 2004 to work in the geothermal industry on the North Island, is a New Zealand citizen and now lives in Blenheim.