GEOGM1405					Contact Joe
Frequently Asked Questions
Questions and answers following week two's lecture on drivers and feedbacks in the climate system:
Q1: Why would it be dramatic for the UK if the THC collapsed? The gulfstream is part of the THC and brings warm water to the UK and Europe. If this circulation stops, it is estimated that the winter in the UK would be 5 Degrees colder. If you compare the UK to other places on earth with the same lattitude, you can see how much of a difference the gulf stream makes. (Lukas)
Q2: Could the day after tomorrow scenario happen? Abrupt climate change wont just happen practically overnight, like in the movie. When scientists talk about abrupt climate change, they mean climate change that occurs over decades, rather than the usual centuries. The vast majority of the film is science fiction however there is some real science to back up concerns about potentially irreversible changes in our climate. There are a number of potential "tipping points" in the Earth's climate system - when a threshold could be crossed, resulting in substantial change. Potential abrupt changes in the ocean (which could result in rising sea levels and influence ocean circulation) The atmosphere (which could increase the frequency and intensity of extreme events) At high latitudes (including loss of Arctic sea ice) And ecosystems (species shifts, extinctions, and rapid state changes) More information can be found in the following report from the National Research Council. (Laura)
Q3: What is the effect of ocean acidification on the biodiversity of the oceans? Coral reefs provide habitat for more than one quarter of marine species, which face extinction if the reefs disappear Major impacts on temperate and polar water ecosystems Batents Sea holds some of the largest fish stock in the world (where the lower temperature absorb more CO2) Shellfish (clams, pteropods) will have trouble creating viable shells in increasingly acidic water and could experience slower growth rates Pteropods and planktonic calcifiers will experience adverse effects - important links in Arctic food chain including herring, cod, and mackerel Study of pteropods exposed to 2100 forecasted pH levels (28% lower) - after 5 days all were alive but only 30% were active swimmers Risks to 500 million people depending on coral reefs for food and income (Stephanie)
Q4: Why are RCPs defined at 2.6, 4.5, 6.0 and 8.5 Wm-2? The RCP development process was led by the research community (the Integrated Assessment Model Consortium), at the request of the IPCC. A meeting was convened in 2007 that brought together over 130 participants, including users of scenarios and representatives of the principal research communities involved in scenario development and application. The RCPs were chosen to represent a broad range of climate outcomes, based on a literature review. The RCPs had to be: Based on scenarios published in the existing literature Developed independently by different modeling groups Representative, as a set, of the total literature, in terms of emissions and concentrations Each RCP is therefore based on one or more published studies by a specific Integrated Assessment Modelling group and, as a set, they are considered to represent the entire range of published literature. It is, however, important to note that the RCPs are neither forecasts nor policy recommendations. (Amber)
Q5: Are 4 scenarios sufficient to cover all climate uncertainty? There are 4 scenario families, A1, A2, B1, and B2. They are neither predictions or forecasts, instead they provide an alternative image of how the future might unfold. The scenarios are considered an appropriate tool for summarizing current uncertainties, however developing scenarios for a period of 100 years is a new field that is made harder by large scientific and data inadequacies. therefore it can be assumed that the scenarios cover most climate uncertainty but not all. Information found here. (Richard)
Q6: What effects does ocean acidification have on ecosystems? Ocean acidification can significantly disrupt the fragile interactions of its ecosystems. Increased acidification levels will affect marine wildlife differently depending on their bodily function (Owens, 2009; Science Daily, 2013). According to scientists from the Alfred Wegener Institute, all animals in the mollusc, coral, crustacean, vertebrate, and echinoderm families reacted negatively to increased acidification of the ocean (Science Daily, 2013). Of greatest concern is that other marine animals higher on the ladder rely on many of the most affected for food and shelter and their potential loss will lead to a chain of events resulting in significant negative impacts to marine ecosystems. (Tara)
Q7: How can we prevent the release of methane from the tundra? The answer is we need to prevent the ice melting and thus the methane being released. The way to do that is to stop the feedback system of melting the ice and reducing the albedo effect. This can be done by monitoring and limiting carbon and methane emissions. Maximizing sinks, both natural and artificial for carbon and methane. Also removing CO2 from the air via atmospheric CCS. (Emma)
Q8: CO2 ppm was approximately 280 historically and is now above 400. Why were there larger swings in average global temperature historically (i.e. + 10C) but not today? This question assumes large increases in temperature are not happening or going to happen soon in response to the correspondingly large increase in CO2 ppm. Essentially, though warming may not be following increases in CO2 exactly at this point in time due to other mitigating factors, this does not mean that they will not in the future. In the past, large fluctuations of temperature (~10C) roughly followed large fluctuations of CO2 (~100 ppm) over several hundreds or thousands of years. It is only within the last 250 years that CO2 and other GHGs have been distorted from this longitudinal natural ebb and flow. Since CO2 ppm has risen to 400 quite quickly we would expect temperature to rise accordingly, which it is, and is predicted to do so further -- around 1C since 1800, and a predicted warming of anything from 0.9-5.4C within the next century. Between 1.9 and 6.4 degrees total warming over a period of 350 years (1750-2100), and more expected beyond this, from at least a 120ppm increase does not contradict the past trends of temperature fluctuation. In fact, both of the changes are happening much faster today than they were in the past. (Mark)
Q9: Why can't we pump lots of aerosols into the atmosphere to stop warming? This option is actually being considered by scientists but is highly controversial. In general, aerosols have a cooling effect on the Earth which can be seen after volcanic eruptions. However, these are natural occurrences and the side effects of "man-made cooling" are uncertain. Some of the feared consequences include: Droughts in Africa and Asia Depletion of the ozone layer Miscalculation in the aerosol injection into the stratosphere could lead to a new ice age Might change the sky's colour Give nations less incentive to reduce their emissions Nevertheless, a group of Cambridge scientists are researching the option at the moment as they believe that it is the cheapest way to stop global warming. Overall it is quite unlikely that it will be put into action as there is no way of testing it in advance and there are too many unknown factors. (Katharina)
Q10: Is THC collapse a positive or negative feedback? THC describes the circulation of water varying density, with warmer water from the tropics and South Atlantic being pushed to the North Atlantic. Different conclusions have been reached as to what effect THC collapse would have on the global climate. While collapse due to global warming isn't thought to be likely, indications are that this would cause cooling of several degrees across the North Atlantic. Some models also indicated that general temperatures would still rise in other areas. As a result THC collapse can be said to cause both negative and positive feedbacks based on these models. Sources: CRU, UEA Science Daily, 2004 NCDC, NOAA (Ryan)
Q11: How confident are you that we can fix the problem of climate change? Why? I am not confident to solve climate change problems. We, future scientists and researchers can only support people's and governmental judgement, indicating our options to do in future and their consequences. (Daiki)
Q12: How does the cloud albedo effect impact climate? The effect of cloud cover on the albedo is highly variable due to the clouds properties; for instance the cloud's altitude, its size, and the make-up of the particles that form the cloud. In general, low, thick clouds primarily reflect solar radiation and cool the surface of the earth. High, thin clouds primarily transmit incoming solar radiation, and at the same time trap some of the outgoing infrared radiation emitted by the earth and radiate it back downwards, thereby warming the surface of the earth. The impact of clouds on climate is poorly understood quantification of its impact represents on of the main uncertainties within climate simulations. (Mary)
Q13: How is unknown technological innovation incorporated into future scenarios? It varies by scenario. A1 - rapid technological development changes but the outcomes on carbon emissions varies by sub-scenario. A2 - the slowest technological development due to a split locally interested world. B1 - quick positive change due to an environmentally aware connected world sharing ideas. B2 - a split world so innovation is therefore uneven but overall investment in R&D declines. In detail: A1 - Rapid growth and technological change. International mobility and high investments leads to rapid development and change. Several scenario groups considered reflect uncertainty in the development of energy sources and conversion technologies in this rapidly changing world. Some scenario groups evolve along the carbon-intensive energy path consistent with the current development strategy of countries with abundant domestic coal resources. Other scenario groups intensify the dependence on (unconventional) oil and (in the longer-run) natural-gas resources. A third group envisages a stronger shift toward renewable energy sources and conceivably also toward nuclear energy. A fourth group (which includes the A1B marker scenario) assumes a balanced mix of technologies and supply sources, with technology improvements and resource assumptions such that no single source of energy is overly dominant. A2 - Slowest technological change due to heterogeneous split world. Technology has limited impact on carbon emissions. People rely on the natural resources in their local areas. B1 - Push towards post-fossil fuels world due to global environmental concerns. Enlightened cooperative and homogonous actions people leads to clean technological innovation. A relatively smooth transition to alternative energy systems as conventional oil and gas resources decline. There is extensive use of conventional and unconventional gas as the cleanest fossil resource during the transition, but the major push is toward post-fossil technologies, driven in large part by environmental concerns. B2 - Technological frontiers are pushed less than they are in A1 and B1, and innovations are also regionally more heterogeneous. Globally, investment in energy R&D continues its current declining trend, and mechanisms for international diffusion of technology and know-how remain weaker than in scenarios A1 and B1 (but higher than in A2). Some regions with rapid economic development and limited natural resources place particular emphasis on technology development and bilateral cooperation. Technical change is therefore uneven. The energy intensity of GDP declines at about 1% per year, in line with the average historical experience since 1800. (Tim)
Q14: Is the suspicion regarding global warming mostly down to uncertainty and faults of scientists (email leaks etc.) or a reluctancy to change our ways? This is a very subjective issue, and probably a mixture of a few things, depending on who the sceptic is. There is probably a general reluctance to change our ways (certainly from big corporations which would lose profit), some uncertainty on the actual future impacts of climate change, and possibly some selective reporting in some popular media outlets (probably not helped by the likes of Rupert Murdoch having financial interests in fossil fuel companies and also owning The Sun here and Fox News in America...). (Tom)
Q15: What are carbon cycle feedbacks? Generally, carbon cycle feedbacks are feedback loops (either positive or negative) in the climate system that amplify or dampen changes in climate forcings by either releasing carbon or sequestering it, respectively. A wide variety of carbon cycle feedbacks have been identified, but uncertainty about their relative magnitudes is still the cause of investigation and debate. Positive carbon cycle feedbacks include: Methane release as permafrost in arctic areas recedes. Peat bogs and methane trapped in ocean sediments are of particular concern. Water table changes could either spread existing peat material or cause it to dry, either of which would likely cause a net release of carbon. Precipitation changes may also have big impacts on rainforests, which would release carbon as they dried. It is unclear to what extent new rainforest areas would offset this loss. Frequent droughts may increase the risk of forest fires, which releases carbon sequestered in organic material. Desertification also implies the death of organic material. Again, climate models project the greening of some deserts, and it is unclear what the net effect would be. Warmer oceans absorb less carbon dioxide Negative feedbacks: Higher temperatures and more extreme weather events increase weathering, which works to reduce CO2 over the long run Plant life is more productive with higher concentrations of CO2, leading to increased organic sequestration (Bryan)
Q16: What is the lapse rate feedback? 'Lapse rate' refers to the temperature gradient up the atmosphere. Temperature decreases with height. It is predicted that due to an increase in greenhouse gases, there will be more warming in which the temperature will increase more in the atmosphere than at the earth surface, i.e. the lapse rate will decrease. This results in more cooling into space, which in turn slows down the warming process. This is known as the 'lapse rate feedback' and is a negative feedback mechanism. (Felix)
Q17: In the animation showing CO2 ppm at different stations over time, there was one station at ~60 N that had 'way more' variation in atm conc than others. Why? I replayed the animation, and to watch it carefully, I find that there is a huge variation from the latitude 45 to 60 N. I think there are at least two reasons. There are large areas of forests in mid-latitude and they fall leaves in winter, so there will be much more CO2 emission in winter as a result of the reduction of photosynthesis and the decay of the dead leaves. In the latitude 45-60 N, there are large coverage of lands and it will get quite cold in winter. as a result, there will be an increase in energy use to supply domestic heat, whereas in summer there will not. (Fan Li)
Q18: Why is the Antarctic ice expanding whilst the Arctic sea ice is melting? Antarctic Ice: The depletion of the ozone layer above Antarctica has caused an overall cooling trend on the continent. Ozone itself is a greenhouse gas and its reduction has seen more heat reflecting back into space. The cooling can cause the low pressure system in the Amundsen sea to increase in intensity or frequency. This then sucks the cold air from the frozen inside of the continent and moves it to the Ross Sea to the west which is where 80% of Antarctica's ice expansion has occurred. Arctic Sea Ice: Due to greenhouse gas forcing. This causes increased temperatures and a combination of milder winters and warmer summers means the ice is not able to recover each year. The 'ice-albedo feedback' means that the rate of melting increases because the ice/snow is a natural reflector of radiation and keeps the region cooler. When the ice melts, more radiation is absorbed because the land underneath is darker and the region warms up. (Anna)
Q19: What do you think China should do to protect our environment? This question could be interpreted that China is currently doing nothing to protect both its environment and by default the global environment when in fact there is strong evidence to suggest that they are taking environmental issues far more seriously than generally perceived in the media. From a negative point of view as of 2012, 79% of China's energy demands were driven by coal (coal produces 90% sulphur emissions) and China was the largest emitter of CO2 at 9.64 GT CO2e which at that time was equal to 70% of the world's total increased output for year. However in 2010 China was the largest wind energy provider in the world with an estimated potential of 2,380 GW of exploitable land capacity and a further 200 GW ocean capacity with over 115,900 GW hours of wind electricity being provided to the national grid. Researchers have indicated that by 2030 all of Chinas energy needs could be supplied by wind power. They also have seen an increase in hydro power (15% or 33.2 GWe) through the Three gorges dam project, and are active in promoting Thorium based nuclear power. Thorium is produced from an Uranium isotope 232 and has a low radio-active energy threshold (so relatively safe for human contact) yet 1 ton of thorium can produce as much energy as 3,500 tons of coal. (Paul)
Q20: Scientists believe that the globe is warming. However, if it is true, how can you explain the increasing occurence of regional extreme cold events? In terms of this issue, firstly, we need to understand which category they belong to. The global warming is a long term definition. According to IPCC AR5 (2013), it is regarding to the increased trend of Earth average temperature in century-scale. However, extreme weather events refer to events are rarely occur at a place and time, which mean that extreme events are short-term definition. Thus, it seems that they are two incomparable concepts. Secondly, there also considerable extreme hot events exist, and their occurances also show a significant increase. The global warming is an factually emerged fact if average weather from both space series and time series (IPCC, 2007). This indicates that the total Earth energy is dramatically rising, although some regions show its local energy is fallen. Consequently, the increasing occurance of regional extreme cold events does not against the global warming. (Wei Wei)
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