If you're feeling particularly pessimistic about the world staying within 2°C of warming, this post is for you. I must admit that in my research I grew more and more alarmed as it looked increasingly like it would take superhuman changes to society and certain industries in order to avoid the 2 degrees scenario. However, in my research, I also came across many ideas beyond the concept of 2°C of warming.
Firstly, a reminder that 2°C of warming is not the edge of a cliff. As I have said before, the "threshold" of 2°C of warming is one point on a spectrum, and it indicates a probability of avoiding "dangerous climate change". Perhaps we are wrong and 2°C will not be vastly different from 1°C (which we have already surpassed). But studies have suggested that keeping within 2°C of warming gives us the highest chance of avoiding some dangerous outcomes. Because of this, if we miss the 2°C target, it's not the end of the world. A great article at Vox reminded me of this, and how the 2°C temperature rise line is not "a magical line between 'success' and 'failure'". The writer, Brad Plumer, advocates avoiding the line of thinking that, at a certain threshold (whether it's 2°C, 4°C or even 6°C), there's "game over". Even if you don't believe we can stay within 2°C, it's still worthwhile trying; and if we overshoot 2°C, continuing to try to keep temperature rise as low as possible. Additionally, this thinking also applies to the realm between 1-2°C of warming that we are currently in. Just because we haven't hit 2°C of warming yet, that doesn't necessarily mean we can avoid dangerous consequences (and we already witnessing some, such as the more frequent recurrence of El Niño). That's why a lot of discussions and scientific studies continue to look beyond 2°C and analyse what might happen at 1.5°C, 3°C, 4°C or even higher.
Secondly, there are alternative ways to measure our impact on the Earth and how we can reduce the negative impacts we are creating. Victor and Kennel (2014) argue that we should be tracking a range of "vital signs" instead of just global mean temperature and carbon emissions. An example of a vital sign they think we should be tracking is ocean heat content, by arguing that oceans are taking up "93% of the extra energy being added to the climate system", thus enabling global surface temperatures to remain relatively stable amidst huge human stresses. Another sign could be high-latitude temperature. They argue that high-latitude areas like the Arctic has been warming extremely rapidly in comparison to lower latitude areas because high-latitude areas are more sensitive to shifts in climate. They also advocate for global goals for CO2 and other greenhouse gas emissions, and translated into specific policies, in order to mobilise governments into real action. Ultimately, I think their arguments for the lack of accountability a global mean temperature goal creates are strong. But the results of COP21 have shown that countries are willing to step up, and if individual nations dive further into the plans of reducing carbon emissions, stopping global warming and other harmful climate changes, 2°C of warming can be kept as a figurehead reminder of the end goal.
Thirdly, I believe it's worthwhile thinking beyond 2°C of warming to understand the way changes in climate can impact us. For example, my previous blog post stipulated that with between 2-3°C, 20-30% of plant and animal species would be at high risk of extinction. The same source (the IPCC) suggests that if global average temperature exceeds 4°C, significant extinctions of 40-70% of species assessed are projected to occur. Evidently, the difference between the two temperature scenarios (only 1-2°C difference) can result in a larger difference in the impact it has on Earth and our ability to live on Earth. Other studies such as The global impacts of climate change under pathways that reach 2, 3 and 4°C above pre-industrial levels by AVOID2 (with the support of the Committee on Climate Change) look into the differences between different temperature thresholds as comparisons of each other. They argue that a 2°C world compared to a 4°C world would see a 10-25% reduction in impacts of water resource stress and drought, 30-55% reduction in impacts of river and coastal flooding, 55-65% and 65-75% of impacts on plant and mammal habitat loss would be avoided respectively, 65-80% reduction in maize yield loss, and an 80-85% reduction in exposure to heatwaves. This further strengthens the notion that impacts are likely to grow exponentially with each degree of temperature increase. It's important to note that these reductions in impacts that follow if we achieve 2°C instead of 4°C are based on probability. As with the fact that 2°C is a threshold created to achieve a good probability of avoiding dangerous consequences of climate change, anything further than 2°C does not guarantee these consequences, but increases the probability of them occurring.
Fourthly, we may have already guaranteed a global temperature increase of over 2°C relative to pre-industrial levels. Ramanathan and Feng (2008) argue that we have "most likely" committed to 2.4°C (1.4-4.3°C) of warming, even if greenhouse gas emissions are held at 2005 concentration levels (which we know they haven't). They discount any cooling effects such as aerosols, but suggest that "climate-tipping" elements such as summer Arctic sea ice will result in at least 2.4°C of warming. You may be thinking that if we impose strict mitigation strategies and become carbon neutral, we may be able to stay to our current 1°C of warming. However, this would not be the case as carbon in particular has a delayed and cumulative effect on the atmosphere. That's to say that even if we stop releasing any carbon emissions right now, the carbon emissions already in the atmosphere would continue to effect climate for many years to come (and that doesn't even include other greenhouse gases). However, I'm a bit more optimistic than Ramanathan and Feng, and believe that negative carbon emissions will be able to help us keep temperature below 2°C of warming in the long run (even if we overshoot and then return down), provided we take the action to develop these technologies as well as using entirely renewable energy and becoming carbon neutral as soon as possible.
Finally, if you're interested in imagining the future under different degrees of warming, a website Global Warming, Our Future has written a highly emotive and partly based on scientific research (I assume) explanation of what happens as the Earth warms 1°C at a time. Reading this explanation painted a very "real" image in my head of what the Earth could look like long after I have existed, and brings to life how a "mundane crime" such as burning fossil fuels could spiral into Dante's "Sixth Circle of Hell".
To sum up this blog, I've explored the ways in which carbon emissions leading to 2°C+ of global mean warming can impacts humans and other organisms and how we live. I stand by my choice to focus on carbon, as, in the words of the Committee on Climate Change: "Given the link between peak temperature and cumulative carbon dioxide emissions, the ultimate aim (beyond 2050) should be to get to zero net carbon dioxide emissions globally". I firmly believe our best bet of staying below 2°C is to reduce our carbon emissions in the short term, become carbon neutral in the long term, and even potentially develop negative carbon technologies. While this blog has been a rollercoaster of optimism, pessimism, realism and any other -isms I can think of, I have found it a highly informative experience and have deepened my understanding of potential impacts of climate change in many areas including temperature, sea level rise, food security, coral bleaching and extreme weather events. I have really enjoyed researching why the 2 degrees scenario has become so important in climate change discourse, and have developed my appreciation for the importance of scientific communication as I believe one of the biggest successes of using the 2 degrees scenario as a yardstick for climate change is that it is more easily accessible for politicians and the general public (including undergrad Geography students)! I will definitely be keeping up with the news regarding the 2 degrees scenario, COP21 developments and targets, and scientific research regarding how our climate is and could in the future change.
Sunday 10 January 2016
Monday 4 January 2016
2 Degrees and Other Impacts
So after a nice Christmas and New Year's break from blogging, here's my penultimate post about the 2 degrees scenario. Keep in mind the whole focus of this blog is on the potential effects of 2°C of warming on the ability of humans and other organisms to live on Earth. Let's jump right in.
Health:
Epstein (2000) and his evocative paper "Is Global Warming Harmful to Health?", as well as countless other papers and studies on health impacts of an increase in mean global temperature, show that this concern is growing. Epstein stipulated that warming would likely lead to an expansion of the incidence and distribution of many serious medical disorders. As mentioned in the previous post, this could be due to increased extreme events such as flooding or heatwaves, as "disasters promote by various means the emergence, resurgence and spread of infectious disease". Diseases relayed by mosquitoes in particular (malaria, dengue fever, yellow fever etc.) are likely to grow more concerning as changing climate leads to ripe conditions for mosquito breeding (namely stagnant water and warm weather). Interestingly, Epstein explains that the El Niño Southern Oscillation could be used to investigate the predicted future warming, as El Niño years result in changes to meteorological conditions not dissimilar to those predicted under climate change. As such, the 1997-1998 El Niño year, which has been highly studied, showed an increase in disease outbreaks. Epstein implies that this change can be inferred for gradual warming under climate change. Therefore, areas vulnerable to these diseases may see migration and a reconsideration of the habitability of the area.
Biodiversity:
To move slightly away from humans for a brief moment, global warming of 2°C is likely to have severe impacts on biodiversity (see Joe's excellent blog on flora and fauna). The IPCC estimates that 20-30% of animal and plant species will be at "increasingly high risk of extinction" as a result of exceeding 2°C of warming. As mentioned a few posts ago, coral reefs are highly vulnerable, and the IPCC estimates that even 0.5°C of warming could harm coral ecosystems. As warming increases to 2°C and beyond, more and more ecosystems become affected. Notably, at 2.5°C warming, there is predicted to be "major losses of Amazon rainforest", which leads to further depletion of carbon-absorbing sources (AKA trees), and increased difficulty of removing carbon from the atmosphere.
A large component of biodiversity is the amount of habitat available for the multitude of species on Earth. And the Committee on Climate Change suggests that over 20% of plant species and approximately 10% of animal species would experience over 50% habitat loss with 2°C of warming.
Hazards:
In particular, the risk of wildfires will increase as a result of a warming of 2°C. Warming World: Impacts By Degrees claim that, with each 1°C of warming, there will be 200-400% increases in the area burned by wildfire in parts of the western United States.
Loss of ice:
In particular, many studies claim that the Arctic may be completely ice-free due to global warming in the future. Day et al. (2012) suggests that 70-95% of sea ice loss in the Arctic is likely to be due to man-made greenhouse gas emissions. While this may be a controversial claim, scientists are no doubt in agreement about the loss of ice from the Arctic over the last 50 years, potentially of up to 30% annually. An important feature of the Arctic is also the permafrost that covers a large majority of the land. Because permafrost stores carbon from dead plants, and it is estimated that Arctic permafrost holds 1.7 trillion tons of carbon (more than all human activity has generated since the start of the Industrial Revolution), as warmer temperatures thaw the permafrost, huge releases of carbon dioxide and methane could occur. There has been great speculation as to the probability and potential damage of large releases of methane from Arctic stores and if interested, I would urge you to read Rob's great post about methane hydrates.
Food:
As mentioned in previous posts, food security is a looming concern in the face of future (and present) climate change. As the population continues to grow, feeding all the people in the world under changing climatic conditions becomes more and more difficult. Challinor et al. (2014) suggest that, without adaptation measures, 2°C of warming would result in losses in aggregate production for wheat, rice and maize in both temperate and tropical regions. Although there is still a lot of uncertainty surrounding the amount of production loss, some studies agree that warming temperatures would adversely affect agricultural production, particularly in the tropical regions. Some estimates include: 5-15% of yields of crops currently grown (Warming World: Impacts By Degrees) and 10% loss of maize and 15% loss of wheat (Committee on Climate Change). Interestingly, the IPCC argue the opposite, that 2°C (and up to 4°C) of warming would lead to positive crop yields. Ultimately, crop yields around the world will likely experience both gains and losses and it is still uncertain whether the Earth as a whole will experience net gain or net loss.
There are many more areas that 2°C of warming could impact but this was a brief introduction to some of the most concerning areas. All of these areas can affect human (and other organism) life and create obstacles for living safely on Earth. I hope you will agree with me when I say that it is obvious for our interest that we stay within 2°C of warming (or overshoot slightly and return below 2°C) by 2100 and for the foreseeable future.
Health:
Epstein (2000) and his evocative paper "Is Global Warming Harmful to Health?", as well as countless other papers and studies on health impacts of an increase in mean global temperature, show that this concern is growing. Epstein stipulated that warming would likely lead to an expansion of the incidence and distribution of many serious medical disorders. As mentioned in the previous post, this could be due to increased extreme events such as flooding or heatwaves, as "disasters promote by various means the emergence, resurgence and spread of infectious disease". Diseases relayed by mosquitoes in particular (malaria, dengue fever, yellow fever etc.) are likely to grow more concerning as changing climate leads to ripe conditions for mosquito breeding (namely stagnant water and warm weather). Interestingly, Epstein explains that the El Niño Southern Oscillation could be used to investigate the predicted future warming, as El Niño years result in changes to meteorological conditions not dissimilar to those predicted under climate change. As such, the 1997-1998 El Niño year, which has been highly studied, showed an increase in disease outbreaks. Epstein implies that this change can be inferred for gradual warming under climate change. Therefore, areas vulnerable to these diseases may see migration and a reconsideration of the habitability of the area.
Biodiversity:
To move slightly away from humans for a brief moment, global warming of 2°C is likely to have severe impacts on biodiversity (see Joe's excellent blog on flora and fauna). The IPCC estimates that 20-30% of animal and plant species will be at "increasingly high risk of extinction" as a result of exceeding 2°C of warming. As mentioned a few posts ago, coral reefs are highly vulnerable, and the IPCC estimates that even 0.5°C of warming could harm coral ecosystems. As warming increases to 2°C and beyond, more and more ecosystems become affected. Notably, at 2.5°C warming, there is predicted to be "major losses of Amazon rainforest", which leads to further depletion of carbon-absorbing sources (AKA trees), and increased difficulty of removing carbon from the atmosphere.
A large component of biodiversity is the amount of habitat available for the multitude of species on Earth. And the Committee on Climate Change suggests that over 20% of plant species and approximately 10% of animal species would experience over 50% habitat loss with 2°C of warming.
Hazards:
In particular, the risk of wildfires will increase as a result of a warming of 2°C. Warming World: Impacts By Degrees claim that, with each 1°C of warming, there will be 200-400% increases in the area burned by wildfire in parts of the western United States.
Loss of ice:
In particular, many studies claim that the Arctic may be completely ice-free due to global warming in the future. Day et al. (2012) suggests that 70-95% of sea ice loss in the Arctic is likely to be due to man-made greenhouse gas emissions. While this may be a controversial claim, scientists are no doubt in agreement about the loss of ice from the Arctic over the last 50 years, potentially of up to 30% annually. An important feature of the Arctic is also the permafrost that covers a large majority of the land. Because permafrost stores carbon from dead plants, and it is estimated that Arctic permafrost holds 1.7 trillion tons of carbon (more than all human activity has generated since the start of the Industrial Revolution), as warmer temperatures thaw the permafrost, huge releases of carbon dioxide and methane could occur. There has been great speculation as to the probability and potential damage of large releases of methane from Arctic stores and if interested, I would urge you to read Rob's great post about methane hydrates.
Food:
As mentioned in previous posts, food security is a looming concern in the face of future (and present) climate change. As the population continues to grow, feeding all the people in the world under changing climatic conditions becomes more and more difficult. Challinor et al. (2014) suggest that, without adaptation measures, 2°C of warming would result in losses in aggregate production for wheat, rice and maize in both temperate and tropical regions. Although there is still a lot of uncertainty surrounding the amount of production loss, some studies agree that warming temperatures would adversely affect agricultural production, particularly in the tropical regions. Some estimates include: 5-15% of yields of crops currently grown (Warming World: Impacts By Degrees) and 10% loss of maize and 15% loss of wheat (Committee on Climate Change). Interestingly, the IPCC argue the opposite, that 2°C (and up to 4°C) of warming would lead to positive crop yields. Ultimately, crop yields around the world will likely experience both gains and losses and it is still uncertain whether the Earth as a whole will experience net gain or net loss.
There are many more areas that 2°C of warming could impact but this was a brief introduction to some of the most concerning areas. All of these areas can affect human (and other organism) life and create obstacles for living safely on Earth. I hope you will agree with me when I say that it is obvious for our interest that we stay within 2°C of warming (or overshoot slightly and return below 2°C) by 2100 and for the foreseeable future.
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